IHE  METALLURGY 


FEEL 


\TRY  MARION  HOWE 


REESE    LIBRARY 


UNIVERSITY   OF  CALIFORNIA. 

Receiicd  eL  ,  & 


ESi 


^ 

*k\T  Ss\  * 


The  Metallurgy  of  Steel 


BY 


HENRY  MARION   HOWE,  A.  M.  (HARVARD),  S.  B. 


VOLUME     I. 


THE  SCIENTIFIC  PUBLISHING  COMPANY 
27  PARK  PLACE,  NEW  YORK 

189O 


,  \ 


COPYRIGHT,  1890, 
BY  TBE  SCIENTIFIC  PUBLISHING  COMPANY. 


To  SIR  LOWTHIAN  BELL.,  Bart.,  F.  R.  S.,  D.  C.  /,,  M.  S.t 


cFel'lWu  o|  tfie  oHotjcif  flc-abc-wif  o|  Science  of 


a 


PREFACE    TO    THE    FIRST   VOLUME. 


The  present  work  is  the  final  outcome  of  a  desire  on 
the  part  of  its  publishers  to  give  metallurgists  an  account 
of  our  American  steel  works. 

A  quarter  of  a  century  has  elapsed  since  the  appearance 
of  Percy's  classical  work  on  iron  and  steel.  Though  we 
have  had  meanwhile,  beside  many  other  works,  the  really 
admirable  handbooks  of  Bauerman  and  of  Ledebur,  and 
though  Bell  has  discussed  in  a  masterly  way  many  of 
the  problems  connected  with  the  metallurgy  of  iron,  and 
especially  with  the  bla -it-furnace  process,  it  has  seemed 
to  me  that  this  was  a  fitting  time  to  post  our  ledger  and 
strike  a  trial-balance :  to  offer  in  accessible  form,  and 
more  fully  than  these  distinguished  writers  have,  the 
data  which  make  up  our  present  knowledge  of  the  metal- 
lurgy of  steel,  and,  rbove  all,  to  discuss  these  data  and 
to  seek  their  true  teachings. 

In  order  that  the  work  might  the  sooner  become  avail- 
able to  the  readers  of  the  ENGINKKKING  AND  MINING 
JOURNAL  it  was  first  published  in  the  p  iges  of  that  paper. 
This  plan  has  several  serious  defects,  the  chief  of  which 
is  that  the  earlier  parts  of  the  volume  have  to  stand  as 
they  were  written,  some  of  them  nearly  three  years  ago  : 
for,  once  electrotyped,  I  cannot  readily  modify  them  in 
accordance  with  later  discoveries,  and  with  changes  of 
opinion  to  which  these  discoveries  as  well  as  further 
research,  discussion,  and  reflection  have  naturally  led  me. 
It  is  also  because  of  this  mode  of  publishing  that  the 
tables  and  figures  are  not  numbered  quite  consecutively. 

I  cannot  sufficiently  thank  my  American  fellow-metal- 
lurgists for  their  great  kindness  and  generosity  in  supplying 
me  with  information  and  with  drawings,  for  their  patience 
in  answering  my  many  questions,  and  for  their  liberality  in 
allowing  me  to  study  their  practice  minutely  and  to  take 
notes  of  it.  I  am  under  a  special  debt  of  gratitude  to 
Mr.  Robert  Forsyth,  engineer  of  the  Illinois  Steel  Com 
pany,  and  Mr.  William  Metcalf,  of  the  firm  of  Miller, 
Metcalf  &  Parkin,  who,  besides  giving  me  endless  informa- 
tion, have  each  examined  a  chapter  of  this  volume,  Mr. 
Forsyth  the  chapter  on  apparatus  for  the  Bessemer  process, 
Mr.  Metcalf  that  on  the  crucible  process  :  and  to  Messrs. 
Hunt  and  Clapp.  of  the  Pittsburgh  Testing  Laboratory, 
who  have  most  generously  made  many  chemical  analyses 
for  this  volume  gratuitously.  I  also  thank  most  heartily 
Mr.  W.  R.  Walker,  of  the  Union  Steel  Company,  now  the 
Illinois  Steel  Company;  Messrs  John  Fritz,  Maunsel  White 
and  George  Jenkins,  of  the  Bethlehem  Iron  Compai^ ; 
Messrs.  F.  A.  Emmerton  and  Thomas  Crow,  of  the  Joliet 
Steel  Company,  now  the  Illinois  Steel  Company;  Mr. 


Philip  W.  Moen,  of  the  Washburn  &  Moen  Manufactur- 
ing Company  ;  Messrs.  W.  R.  Jones  and  James  Gayley, 
of  the  Edgar  Thomson  Steel  Works ;  Mr.  S.  T.  Wellman, 
of  the  Otis  Iron  and  Steel  Company ;  Dr.  Thomas  M. 
Drown,  of  the  Massachusetts  Institute  of  Technology ; 
Mr.  F.  W.  Wood,  of  the  Pennsylvania  Steel  Company  ;' 
Messrs.  Joseph  Morgan,  Jr.,  T.  T.  Morrell,  and  John 
Coffin,  of  the  Cambria  Iron  Company  ;  Mr.  E.  S.  Moffat, 
of  the  Lackawanna  Iron  and  Coal  Company  ;  Mr.  J.  M. 
Sherrerd,  of  the  Troy  Steel  and  Iron  Company  ;  Messrs. 
E.  C.  Potter,  John  C.  Parkes  and  J.  C.  Walker,  of  the 
North  Chicago  Rolling  Mill  Company,  now  the  Illinois 
Steel  Company ;  Mr.  Phineas  Barnes,  of  the  American 
Iron  Company  ;  Mr.  G.  H.  Billings,  of  the  late  Norway 
Steel  and  Iron  Company  ;  Mr.  W.  F.  Downs,  of  the  Dixon 
Crucible  Company,  and  Mr.  E.  Gibbon  Spilsbury,  of  the 
Trenton  Iron  Company. 

With  regard  to  the  cost  of  metallurgical  processes  I 
have  in  general  given  the  quantities  of  material  and  the 
amount  of  labor  needed  for  given  work,  rather  than  the 
actual  cost  in  dollars  and  cents :  for  the  former,  though 
far  from  constant,  change  much  less  than  the  latter, 
being  almost  free  from  one  important  cause  of  variation, 
changes  in  the  current  prices  of  these  materials  them- 
selves and  of  labor.  Given  the  quantities  of  material 
and  of  labor  needed,  one  who  knows  the  market  rates  at 
a  given  spot  can  calculate  the  cost :  while  if  the  actual 
cost  for  given  conditions  alone  is  given,  the  cost  under 
other  conditions  and  where  the  prices  of  materials  and 
labor  are  different  cannot  be  determined  readily.  Again, 
while  the  managers  of  works  are  often  willing  that 
the  quantities  of  materials  which  they  use  should  be 
known,  they  for  obvious  reasons  prefer  that  the  costs 
should  not. 

Seeking  to  lighten  the  .labor  of  others  who  may  wish  to 
examine  the  matter  in  greater  detail,  or  who  may  wish  to 
verify  my  statements,  I  have  given  many  references  which 
it  would  profit  most  readers  but  little  to  examine.  Indeed, 
many  of  my  references  are  given  merely  to  indicate  that 
my  statements  have  solid  foundation.  In  a  few  cases  I 
have  been  unable  to  consult  works  to  which  others  have 
referred,  and  which  I  had  good  reason  to  believe  contained 
important  matter  bearing  on  the  subject  in  hand.  With 
like  aim,  I  have  not  hesitated  to  refer  to  them,  nor, 
where  the  same  paper  has  appeared  even  in  the  same  form 
in  different  works,  to  refer  to  several  of  them  simultane- 
ously, so  that  those  who  could  not  consult  one  might  find 
the  matter  in  another.  With  a  few  exceptions  in  the 


vl 


PKEFACE. 


earlier  pages,  where  several  authorities  are  quoted  to- 
gether, the  first  is  the  one  whose  statements  I  have 
used. 

Such  a  work  as  this  cannot,  of  course,  be  carried  out 
without  much  compilatic  n  :  but  by  far  the  greater  part  of 
the  labor  has  been  expended  in  the  original  work  of  dis- 
cussing the  data  thus  compiled,  and  in  acquiring  wholly 
new  data,  whether  by  experimental  research,  or  in  pro- 
longed exnmination  of  the  processes  described.  For  in- 
stance, there  are  about  two  hundred  tables  in  this  volume  : 
of  these  all  but  about  twenty  (and  most  of  these  twenty 
;:ir  very  small)  are  either  wholly  original,  or  consist 
mainly  or  wholly,  not  of  matter  published  by  others,  but 
of  numbers  calculated  therefrom. 

Uniform  accuracy  in  publishing  so  much  varied  and 
practically  original  numerical  matter  is  not  to  be  expect- 
ed The  author  will  be  veiy  grateful  to  any  one  who  will 
point  out  to  him  numerical  or  other  errors. 

Many  of  the  more  important  tables  have  been  calculated 
lwic;j,  wholly  independently,  and  often  by  different 
methods,  m  many  other  cases  effective  checks  1  ave  been 
used  Not  a  few  numerical  errors,  hitherto  handed  down 
from  text-book  to  text-book,  have  been  detected  and  cor- 
rected. Whenever  possible,  numerical  and  other  data 
have  been  verified  from  the  original  memoirs,  at  one  or 
another  of  the  several  important  libraries  which  have  been 
accessible.  Where  statements  have  seemed  improbable 
or  vague  verification  or  explanation  has  been  sought  and 
often  obtained  from  their  authors. 

The  numberless  determinations  of  tensile  strength  and 
elastic  limit  quoted  have,  for  uniformity,  been  reduced 
from  tons  and  kilogrammes  to  pounds  per  square  inch, 
the  measure  habitually  used  in  this  country.  Tempera- 
tures are  in  general  given  both  in  Fahrenheit  and  Centi- 
grade. 

In  describing  old  experiments  and  abandoned  processes, 
I  have  not  aimed  to  give  matter  of  historic  interest,  but 
rather  that  which  might  be  useful,  whether  in  deterring 


others  from  repeating  umicri-ssury  or  hopeless  experi- 
ments, or  in  guiding  tr-em  should  processes,  once  unsuc- 
cessful, become  commercially  possible  through  changed 
conditions. 

The  task  of  deciding  what  information  about  present 
practice  to  give,  and  what  to  withhold,  has  been  a  delicate 
one.  First  we  must  recognize  that  the  practice,  the  ex- 
perience, the  knowledge  of  a  metallurgist  or  of  a  com- 
pany is  distinctly  pr<  perty  and  that  communicating  to 
others  against  the  wishes  of  its  owner  may  be  quite  as 
much  robbery  morally  as  if  it  were  legally  punishable. 
Indeed,  in  that  it  sneaks  behind  the  cloak  of  law,  it  is 
contemptible  as  well.  But  beyond  this  there  is  a  certain 
amount  of  information  which,  once  published  by  others, 
or  once  a  matter  of  general  knowledge,  may  be  regarded 
as  more  or  less  public  property.  In  deciding  what  part 
of  this  to  publish  one  has  to  weigh  against  the  duty  of 
making  one's  work  as  useful  as  possible,  one's  regards 
for  the  wishes  of  those  whose  liberality  in  giving  other 
information  has  laid  on  him  a  burden  of  gratitude. 

t  have  sought  to  steer  between  these  shoals  on  either 
hand,  by  giving  all  information  as  to  practice  which  seems 
useful  and  which  I  have  permission  to  give,  while  trying 
to  conceal  the  identity  of  the  establishment  at  which  it 
exists.  The  important  thing  for  the  reader,  be  he  prac- 
titioner or  student,  is  to  know  that  certain  practice  exists 
or  is  possible  ;  for  the  manufacturer  that  it  be  not  known 
as  his  particular  practice.  Probably  even  the  close- 
mouthed  Krnpp  would  object  relatively  little  to  having 
his  practice  known,  provided  it  were  not  known  as  his, 
but  as  that  of  the  shadowy  X,  Y,  or  Z. 

An  exception  is  made  in  case  of  the  plans  of  certain 
works  which,  repeatedly  published,  are  already  clearly 
public  property  ;  and  in  a  few  cases,  such  as  the  great 
output  of  certain  Bessemer  works,  in  which  the  results, 
due  to  his  administrative  skill,  are  a  matter  of  pride  to 
the  manager,  and  in  Avhich  he  certainly  prefers  to  receive 
publicly  his  just  credit. 


BOSTON,  January,  1890. 


H.  M.  H. 


> 

UNIVERSITY 


TABLE    OF    CONTENTS 


Section. 

1.  Definitions 


CHAPTER  I. 

CLASSIFICATION   AND   CONSTITUTION    OF   STEEL. 


CHAPTER  II. 

CARBON   AND  I3OX,    HARDE.NIXG,   TAMPERING,  AND   ANNEALING. 

3.  Combination 

4.  Saturation  p  >int  for  carbon 

5.  a<  all'ected  by  manganese 

7.  sulphur 

8.  Condition  of  carbon  in  iro  i     ----___ 


9. 
10. 
II. 
12. 

13. 
14. 
15. 
16. 
17. 
18. 
1'J. 
20. 
21. 
22. 

23. 

24. 

25. 


EVIDEN'.'E   THAT   TIIEUK    ARK   TWO   ('  INDI  1'ioX.  ;<>'••  ro-!I;l.\ATIUN 
OF  CARBON"    WITH     ilioN. 

Ciiemical  evidence  - 

Micr.iscopic  evidence 

Accord  of  c'.iemical,  microscopic,  au'l  physical  phenomena 

Evi  lence  of  the  existence  of  other  comoination  of  carbon  and 

iron  - 

Compounds  of  carbon  wilh  elements  other  than  iron        -  - 

Thermal  relations  of  the  compounds  of  (  a:  b  >n  and  iron         - 
Distribution  of  carbo.i  bet.  veen  its  dillere.it  slates  - 

Effect  of  the  total  percentage  of  carbon 

Proportion  ot  graphite  to  combined  carbon  - 

As  effected  by  silicon        - 

"        "         "  manganese      -  - 

"        "          "  sulphur 

"         "          "  phosphorus  - 

Effect  of  other  elements  on  the  proportion  of  cement  (o  harden- 

ing carbon 
Effect  of  temperature  on  the  condition  of  carbon  - 

'•      •'  •'     "    proportion  of  graphite  to  combined 

carbon 
Effect  of  temperature  on  the  proportion  of  cement  to  liardening 

carbon  -  -  - 


EFFECT  OF  CARBON  ON  THE  PHYSICAL  PROPERTIES  OF  IRON. 

26.  Iii  general  - 

27.  Effect  on  tensile  strength 

'•       "  ductility 
28A.  Relation  of  elongation  to  tensile  strength 

29.  Effect  on  the  modulus  of  elasticity 

30.  "      "     "  compressive  strength 

31.  '•      "     "   hardness 

32.  "       '•     •'   fusibility 

HARDENING,  TEMPERING,  AND  ANNEALING. 

33.  Definitions       - 

34.  Effect  of  hardening 

A,  On  tensile  strength    - 

B,  On  elongation        - 

C,  On  elastic  limit 

D,  On  hardness 

35.  Conditions  of  hardening       - 

A,  Temperature 

B,  floating  for  hardening 

C,  Rapidity  of  cooling 

36.  Precautions      - 

38.  Tempering 

39.  Heating  for  tempering 

40.  Cooling        - 


'  Section.  Page. 

41.  Other  methods  of  hardening  and  tempering  -      23 
Page,  j                 A.  Warm  water  33 

1                   B,  Interrupted  c<  oling  -      24 

C,  Hardening  \vithou:  tempcrin--  24 

42.  Gun-tubes  and  jackets  -      34 
i   43.  Hardening  special  steels  -  2i 

45.  Annealing  -      34 

46.  Quantitative  effects  of  annealing  3,-, 

47.  Annealing  unforced  fastings  -      26 

48.  Net  effect  of  hardening  plus  annealitg  37 

RATIONALE   OF  HARDENING   AM)  ANXEALI.'.G. 

40.  In  general        -  37 

50.  Quenching  preserves  the  status  quo  28 

51.  '•         acts  through  uneven  contraction  -      2!* 
"         I.  It  causes  internal  stress  -  2J 

II.  It  kneads  JO 

52.  prevents  crystallization  t!0 

53.  Rationale  of  the  effects  of  tempering  and  annealing         -  30 

54.  Analysis  of  the  effects  of  hardening,  etc.  32 
54A.  Apparent  anomaly  -  34 

55.  Other  explanations  of  hardening,  etc.  -  34 

56.  Akerman's  theory       -  -      34 

57.  Rapidity  of  cooling  in  different  n:edia  -  35 

CHAPTER  III. 


5 

G 
G 

7 
7 
7 
8 
8 
8 
8 
9 
10 
10 

1(1 
10 

10 

11 

13 
13 
10 

17 
17 
17 
17 
17 

17 
18 
19 
20 
20 
20 
21 
21 
21 
21 


22 
33 


IRON    AND    SILICON. 

60.  Summary  3o 

61.  Absorption  of  silicon  36 

62.  Removal  of  silicon      -  -      36 

63.  Condition  of  silicon  37 

64.  Effect  of  silicon  on  teuf  lie  strength  and  ductility  -  -      K7 

65.  The  evidence  in  detail      -  37 

66.  Silicon  steel      -  40 

67.  Effect  of  silicon  on  .  oundness      -  41 

69.  "                "     fusibility,  fluidity,  oxidation    •  41 

70.  "               "    the  welding  power    -  41 

71.  "               "    cast-iron    -  -      41 

CHAPTER  IV. 

II!  ON  AND  MANGANESE. 

75.  Summary         -  42 

76.  Combining  power  *                       42 

77.  Volatility  42 

78.  Effect  of  manganese  on  fusibility  42 

79.  "    ."            "            "  blowholes  -  -      42 

80.  "     "            "            "•  oxidation  42 

81.  Manganese  vs.  sulphur  43 

82.  Influence  of  manganese  on  t'.:e  effects  of  phosphorus,  copper 

and  silicon  44 

83.  Quantitative  effects  of  manganese  on  hotshortii'  -      45 

84.  Influence  of  manganese  on  tensile  strength  and  ductility       -  48 
86.  Manganese  steel  48 

CHAPTER  V. 

IRON  AND  SULPHUR. 

90.  Summary  48 

91.  Combination    -  -      49 

92.  Condit'on  of  sulphur  in  iron  49 

93.  Removal  of  sulphur    -  -                  4S) 
94    Sulphur  causes  redshortnees                    .  52 

95.  Effect  of  sulphur  on  welding  -      58 

96.  "     "        ''        "   tensile  strength  and  duciility  53 

97.  - '        "    cast-iron           -  -      5| 


Vlll 


TABLE    OP    CO-NTENTd. 


CHAPTER  VI. 

IRON  AND  PHOSPHORUS. 

Section.  Page- 

100.  Summary  54 

101.  Condition  of  phosphorus  in  iron  5,"> 
103.  Combination  of  phosphorus  with  iron  5(5 

103.  Action  of  slags  50 

104.  Effect  of  basicity  of  sbj  5G 

105.  Basicity  of  silicates  vs.  that  of  phoshates  57 

106.  Ferruginous  vs.  calcareous  slags  -      59 

107.  Elfect  of  strength  of  oxidizing  and  reducing  conditions  G ) 

108.  "        the  carbon,  etc.,  of  the  iron  01 

109.  "          temperature  63 

110.  "         initial  proportion  of  phosphorus  in  the  iron  G2 

111.  "         carbonic  oxide  62 

112.  "         fluor-spar  0:1 

113.  Rationale  of  the  action  of  slags  Gi 
113A.  Dephosphorization  in  cupola  furnaces     -  -      65 

114.  Effect  of  fused  alkaline  carbonates        -  66 

115.  "            "            "        nitrates        -  -      66 

116.  "        manganese  60 

117.  Inter-reaction  of  sulphide  and  phosphide  of  iron  -      66 

118.  Volatilization  G7 

EFFECT  OF  PHOSPHORUS  ON  THE  PHYSICAL  PROPERTIES  OF  IRQ:;. 

122.  On  tensile  strength  and  elastic  limit  -      67 

123.  On  ductility  68 

124.  As  affected  by  carbon  -      69 

125.  "        "         "   silicon       -  70 

126.  Effect  on  structure  -      70 

127.  Influence  of  cold  on  the  effect.?  of  phosphorus  70 

128.  Illusions  concerning  the  neutralization  of  phosphorus  70 

A,  Heaton  process     -  71 

B,  Miller                                                                            -  -      71 

C,  Mallet  71 

D,  Du  Motay  -      71 

E,  Sherman  process  71 

F,  Brown  .      71 

G,  Clapp-Gritfiths       -                                   ...  71 

129.  Phosphorus  and  forgeableness                                              -  -      72 

130.  Permissible  proportion  of  phosphorus                                       -  73 

131.  Phosphorus  units                                                       -           -  -      74 

CHAPTER  VII. 

CHROMIUM,  TUNGSTEN,   COPPER. 

136.  Iron  and  chromium,  summary  -      75 

137.  Their  metallurgical  chemistry  75 

138.  Influence  of  chromium  on  the  physical  properties  of  iron  -      76 

139.  The  status  of  chrome  steel  79 

140.  The  future  of  special  steels    -  -      80 

141.  Iron  and  tungsten  81 

142.  Iron  and  copper  -      02 

CHAPTER  VIII. 
THE  METALS  OCCURRING  BUT  SPARINGLY  IN  IRON. 

145.  Zinc,  tin,  lead,  titanium         -  -     G4 

146.  Arsenic,  antimony,  bismuth,  vanadium  85 

147.  Molybdenum    -  -     08 

148.  Nickel  and    cobalt  GG 

149.  Aluminium       -  -GO 

A,  Wootz  67 

B,  Mitis  castings    -  -     87 

C,  Aluminium  in  commercial  iron    - 

150.  Mercury                                                                       -           -  -     89 

151.  Platinum,  palladium,  rhodium,   osmium-iridium,   gold,   silver,      89 
Metals  of  the  alkaline  earths,  potassium  and  sodium  -  89 

CHAPTER  IA. 

IRON  AND  OXYGEN. 

155.  Oxides  of  iron                                                                       -  -     90 

156.  Oxygen  in  commercial  iron                                                        -  91 

157.  Effect  of  oxygen  on  iron                                                       -  -     91 

158.  Oxygen  in  molten  iron  91 
Discussion  of  methods  of  determinization,  and  of  their  results     -     02 
Spiegel  reaction  method,  hydrogen  method,  Tucker's  method  02 

159.  Oxygen    with    carbon  -     94 

160.  Corrosion  of  iron   -  94 


Section. 

101.  lnfluer.ce  of  surface  exposure  pyrophorpism 


Page. 
-      95 

162.  "           tempera  tuve  95 

163.  "            different  mc.'.in  -      95 

A,  In  general,  Calvin':,  experiments  9"> 

B,  Subaerial  ruslii  ;;         -  -      06 

C,  Subaqueous  ruitteg  90 

D,  Sewa.n'  96 

E,  Sulphurous  acid  97 

164.  Influence  of  the  compo  .ition  of  the  iron,  structure,  size  -      97 

165.  Cast-iron  vs.  steel  and  wrought  iron     •  98 
!!iii.  Steel  vs.  wrought-iron  98 

A,  Small  scale  tests    -  99 

B,  In  actual  practice         -  -    100 
Discussion  of  opinions  101 

100.  A,  best  vs.  common  wrought-iron  -     102 

167.  Influence  of  difference  of  potential        -  102 

A,  Galvanizing     -  102 

B,  Segregations  102 

C,  Magnetic  oxide  •    102 

D,  Copper,  brass,  etc.  103 

E,  Iron  on  iron    -  -    103 

168.  Protective  coatings    -  -    104 

CHAPTER  X. 

NITHOOEN.  HYDROGEN,  CARBONIC  OXIDE. 

170.  Their  condiUon  in  iron 

172.  Iron  and  nitrogen 

173.  Nitrogenized  iron 

171.  Nitrojen  in  commercial  iron 

IRON    AND    HYDROGEN. 

175.  Summary 

176.  The  presence  of  hydrogen  in  iron 

A,  Its  absorption  - 

B,  It  is  usually  present 

C,  Parry's  results  - 

D,  Saturation  point    - 

F,  Ammonia  from  steel   - 

178.  Influence  of  hydrogen  0:1  the  physical  properties  of  iron 

A.  Non-nascent  hydrogen 

B,  Nascent  hydrogen  - 
Contact  with  zinc,  heating 

Rest;  cold-working;  quant. ty  of  hydrogen  absorbed 

180.  Deoxidation  by  hydrogen 

IRON  AND  CARBCNn  OXIDE. 

181.  Sumn.ary 

182.  Reduction  and  oxidation  by  carbonic  oxide  anJ  acid    - 

183.  Influence  of  temperature  on  the  reactions  1  ctwrcn  the  oxides 

of  carbon  and  of  iron 

184.  Influence  of  the  proportion  of  iron  to  carbon     - 

185.  Carb  ,a  deposition 

A,  Deposition  on  metallic  iron 

B,  Influence  of  carbonic  acid      -  -  - 

C,  Iron  oxide  att  v;ks  deposited  carbon 

D,  Carbonic  acid  attacks  deposited  carbon 

E,  Nature  of  thsse  actions    - 

F,  Influence  of  structure 

G,  Influence  of  speed  of  current 

188.  D:>33  carbonic  oxi  le  exist  a^  such  in  iron? 

A,  Troost  and  Hautefeuille    - 

B,  Tarry 

C,  Bessemer    • 

189.  Other  cases      -  - 

190.  Apparent  absorption  of  carbonic  oxide 

191.  Influence  of  carbonic  oxida  on  the  physical  properties  of  iron    - 

CHAPTER  XI. 

THE   ABSORPTION   AND  ESCAPE   OF  GAS  FROM   IRON. 

200.  Classification  of  gases  according  to  time  of  escape 

201.  Conditions  of  the  escape  of  gas  -  - 

A,  Scattering  and  rising  - 

B,  Piping 

202.  What  classes  of  iron  scatter  and  rise?        -  -  - 

A,  Influence  of  temperature 

B,  "  "  composition  and  of  additions 

C,  "  '•  process  of  manufacture    - 

D,  "  "  pressure 

E,  "  "  agitat  Ion  and  solidification 

F,  Protracted  escape     --.,.. 


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127 
127 
127 
128 
129 
130 
130 
130 


TABLE    OF    CONTENTS. 


IX 


Section. 

20:i.  Extraction  of  gas  in  vacuo 

205.  Quantity  of  gas  evolved 

A,  In  the  spiegle  reaction    - 

B,  In  solidifying 

C,  On  boring  under  water 

D,  On  heating  in  vacuo 

206.  Quantity  of  gas  absorbed 

207.  The  composition  of  the  gas  evolved 

A,  In  general 

B,  The  carbonic  oxide  group    • 

C,  The  hydrogen  group 

208.  Composition  of  gases  extracted  on  boring  and  in  vacuo 

210.  What  causes  blowholes': 

211.  The  mechanical  theory 

212.  The  reaction  and  solution  theories 

DISCUSSION  : 

213.  Evidence  from  the  composition  of  the  gas 

214.  Evidence  from  analogy  - 

A ,  Temperature  and  solvent  power 

B,  Protracted  and  deferred  escape 

C,  Resemblance  of  ice-bubbles  - 

215.  Rationale  of  the  action  of  silicon 

216.  Reaction  an  insufficient  cause  of  blowholes 

217.  Rationale  of  changes  in  the  composition  of  the  gases 

218.  Source  of  the  hydrogen  and  nitrogen 

219    Reaction  possibly  an  important  cause  of  blowholes  - 

220.  Resume 

CHAPTER  XII. 

TH3  PREVENTION  OF  BLOWHOLES  AND  PIPES. 

222.  Shape  and  position  of  blowholes 

223.  Contraction  cavities    - 

221.  Piping;  the  position  of  the  pipe 

225.  The  volume  of  the  pipe 

226.  Surface  cracks,  snakes,  internal  cracks,  flat  dies 

227.  Sinking-heads 

Hot-top  sinking-head,  Boultons,  Hinsdales 

228.  Agitation  during  solidification 

229.  Liquid  compression 

A,  \Vhitworth's     - 

B,  Daeleii's;  C,  Williams' 

D.  Billings;  E,  Hinsdale;  F,  Bessemer 
G,  Krupp;  H,  Cazaiat;  I,  Jones 
J,  Chilling  the  ingot-top 

230.  Effect  of  liquid  compression 
Evidence     - 

231.  Exhaustion 
~:12.  Slow  cooling 

233.  Chemical  additions     - 

234.  Descending  mould-bottom 
••.':!"].  Dead-melting  or  killing 

CHAPTER  XIII. 

STRUCTURE  AND  RELATED  SUBJECTS. 

230.  In  general 

MICROSCOPIC  STUDY  OF  POLISHED  SECTIONS. 

237.  General  phenomena 

23M.  The  com  oi;ents  of  iron  described    - 

A,  Ferrite 

B,  Cementite 

C,  Pearlyto 

D,  Hardenite 

E,  Sorbite 

F,  slag;  G,  Other  substances 
H,  The  residual  compound    • 

233.  Other  evidence  of  composite  structure 

FRACTURE. 
240.  In  general 

212.  Brinuell's  carbon  studies 
24o.          "         fracture  studies 
244.  Details  of  fractures 
215.  Certain  features  of  the  change  of  fracture 

246.  Influence  of  the  rate  of  cooling 

A,  Small  bars 

B,  Large  masses 

247.  Effect  of  forging 


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Section.  i"age. 

•J  I*.  <  Hher  views  on  changes  of  fracture  177 

A,  Metcalf  -    177 

B,  Chernoff  177 

249.  Discussion  of  Chernoff's  views  -    1 78 

250.  Methods  of  heat-treatment;  annealing  cast  in:  s:  Coffin's  rail- 

process     - 

Thermo-tenaion  ;  Clemandot's  process  ;  Chernoff's  process         •    180 
Coilin's  axle-process   -  -         1s! 

To  find  Vaud  W  -181 

CHAM.KS  til.1  CRYSTALLIZATION,  ETC. 

2-">i.  Governing  crystallization    • 

Recrystallization  182 

2."i;s                             on  alow  cooling  from  the  melting  point  182 

Columnar  ingot -structure    -  183 

251.  Recrystallization  on  reheating  slowly-cooled  metal  -  184 

A,  On  long  heating  184 

B,  At  V  184 

C,  At  W:  1,  Polished  sections;  2,  Coflin's  weld  184 

3,  Coffin's  bend:  4,  Thermal  phenomena  185 

255.  Recrystallization  on  reheating  ijticr.chid  sU  el  185 

256.  "               dining   slow    cooling  from  W:    recaleseeiice    185 
A,  Rise  of  temperature  -  185 

C,  L  xpansion  185 

D,  Coffin's  bend  186 

E,  Magnetic  properties,  etc.  186 

257.  Thermal  phenomena  during  heating  and  ccoling  187 
257A.  Discussion    -  188 

Osmond's  theory  1£9 

Discussion  -  190 

258.  Recrystallization  at  high  temperatures  after  forging  192 

A,  Distortion  in  cold-working    -  -      193 

B,  "    hot        "  193 
The  grain  of  hot-forged  iron  equiaxed  -      193 

'D,  Lengthwise  vs.  crosswise  properties  of  iron  193 

259.  Change  of  crystallization  in  the  cold  -      194 
Fibre  in  iron  and  steel   -  194 

260.  Influence  of  vibration  and  shock    -  186 

261.  Change  of  crystallization,  etc.,  in  the  cold,  while  at  rest  199 
201 A  •  Persistence  of  crystalline  form  200 

262.  Overheating  ai. d  turning: 

A,  Phenomena      -  200 

B,  Rationale     - 

264.  Segregation  202 

265.  Causes  of  segregation        -------- 

266.  What  elements  segregate  most  ?  205 
£67.  Special  features  of  tegregation 

268.  Prevention  of  heterogeneouinefs 

How  much  segregation  is  usual  ?  209 


CHAPTER  XIV. 

COLD-WORKING,     HOT-WORKING,    WELDING. 

269.  Cold-working  in  general 

270.  Effect  on  the  several  properties  in  detr.il  : 

The  elastic  limit         --------- 

Density,  resilience  and  stiffness     .- 

271.  Different  forms  of  cold-working 

272.  Rationale  of  cold-wcrking 

273.  Resemblance  between  effects  of  quenching  and  of  cold-working 
1C6   274.  Does  cold-working  affect  iron  like  other  metals '( 

166  WKiE-DRAVriKG. 

167  275.  In  general 

168  \  276.  Pointing  and  pickling 

277.  Lubrication:  Dry  coating,  water  coating,  salt 
Wet  coaling,  lacquer 

Dry  vs.  wet  drawing 

278.  Drawing     ------ 

Draw-plates     ----------- 

279.  Annealing 

280.  Examples  of  practice 

281.  Protective  coatings    - 

282.  Tests  for  wire 

COLD-ROLLING   AND  CCLD  DP.AWING. 

283.  Cold-rolling     - 

284.  Cold-drawing 

Cold-rolling  and  cold-drawing  compared     - 


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103 

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16.") 


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210 

213 

214 
215 
217 
218 
219 

220 
221 
221 
222 
2£2 
222 
223 
224 
?25 
226 
226 

226 

227 
228 


TABLE    OF    CONTENTS. 


PUNCHING  AND  SHEARING. 

Section. 

285.  Effect  of  punching 

286.  Shearing     - 

287.  Discussion         -  - 

288.  Rationale  of  the  effects  of  puncking 
288A.  Practice  as  to  punching 

289.  Other  forms  of  cold- u-ork:  Frigo  tension,  Cold-hammering  - 
Hammer-hardening,  Dean's  process 

290.  Blue-shortness 

291.  Th  3  treachery  of  »teil 

29.2.  Mysterious  cases;  Lividia,  Maginais 

2J3.  Apparently  normal  failures:  Discussion 

291.  The  trustworthiness  of  steel 

295.  The  eHect  of  work 

293.  Relation  between  thickness  and  strength,  etc.: 

A,  Ingot-iron 

B,  Ingot-steel 

C,  Weld-iron 

297.  Relation  between  thicknes3  of  iagot,   etc.,   and   strength  of 

pieces  rolled  from  it 

298.  Rationale  of  the  effect  of  wor  j: 

299.  Hammering  vs.  rolling 

300.  Welding 

301.  Welding  power  cf  different  irons 

A,  Ingot  vs.  weld-iion   -  -  . 

B,  Effect  of  composition  on  welding 

Welding  unlike  irons     -  -  . 

302.  Welding  methods:  Scarf,  V,  butt,  split,  temperature,  fluxes 

303.  Electric  welding: 

A,  Thomson's  process 

B,  Bernardo's  process 

304.  Density 

305.  Dilatation:  the  floating  of  cold  iron 

Tlie  composition  of  steel  for  many  purposes    - 

CHAPTER  XV. 

DIRECT  PROCESSES. 

310.  Possibilities  of  the  direct  process      - 
Competition  with  scrap-iron 

313.  Competition  with  the  blast-furnace  - 

314.  Discussion:  Fuel  - 

Cost  of  installation      -  ... 

315.  Difficulties  of  the  direct  process 

A,  Sponge-making  processes 

B,  Balling  processes 

C,  Steel-melting-heat   processes 

316.  Classification  by  mode  of  heating 

317.  The  future  of  direct  processes 

DESCRIPTION  OF  DIRECT  PROCESSES. 

318.  Catalan  process    - 

31  .  American  bloomary  process 

320.  Osmund  furnace  -  - 

321.  StCckofen 

322.  Husgafvel's  high  bloomary        -  ... 

323.  Its  economic  features 

324.  Nyhammar  bloomaty 

325.  Gurlt's  process 

326.  Cooper's  and  Westman's  processes 

327.  Tourangin's  process    - 

328.  Laureau's  process      -  -  ... 

329.  Bull's  process 

330.  Lucas'  process  - 
3:51.  Conley's  process  - 

330.  Chenot's  process 

333.  Blair's  process 
Yates,   Tro  ca    Clay 
Routon,  Wilson,   Rogers 

334.  Sch;nidha:r.mer't  process     - 

335.  Du  Puy's  process  - 
337.  Mushet's  process 

338A.  Siemens'  and  Ponsards'  retort  processes 

339.  Thoma,  Harvey,  Ger'.iardt 

340.  Ex'nes  or  Carbon  Iron  Company's  procas^ 

341.  Siemens'  rotator  process  :  Siemens'  cascade  furnace 

342.  Leckie's  direct  procsss     - 

343.  F.  Siemens'  process 

344A.  Eustis'  direct  process;  B.  Ireland's  direct  process 


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288! 


CHAPTER  XVI. 

CHARCOAL-HEARTH  PROCESSES. 

Section. 

346.  In  general 

347.  Product,  reason  for  existence 

348.  Classification 

349.  Single-smelting  process    - 

350.  Lancashire-hearth  process    • 
851.  South  Wales  process 

352.  Swedish  Walloon  process 
S53.  Franche-Comte  process 

354.  Treating  scrap-iron  in  charcoal-hearths 

355.  Making  steel  in  charcoal-hearths 


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CHAPTER  XVII. 

T:IS  COTCIB:,E  STEEL  PROCESS. 

356.  Varieties         .....  . 

357.  Compared  with  other  processc.j 
S58.  Crucibles  : 

Graphite  crucibles,   life,   use,    manufacture 

Clay  crucibles  :    Preparation  in  Sweden,  in  Britain 
C"9.  Furnaces  :   Sheffield  c.ike,  American  anthracite,  Siemcrs 

Nobel's  petroleum  furnace 

Repairs 

Comparison  of   furnaces 

860.  Charging         -  ... 

36!.  The  process 

Melting  .... 

Killing      - 

Teeming  -  ... 

Grading  .... 

Labor  .... 

302.  Length  of  operation 

363.  Loss  of  iron    -  ... 

364.  Mate-rials  - 

365.  Uniformity    - 
3C6.  The  Mitis  process 

3G7.  Cost  of  the  crucible  process 

CHEMISTRY   OP   THE   CRUCIBLE    PROCESS. 

3i'i8.  In  general        -  -  ... 

Absorption  of  silicon 

369.  Absorption  of  carbon 

370.  Absorption  of  manganese,  sulphur,  etc. 

CHAPTER  XVin. 

APPARATUS  FOR  THE  BESSEMER  PROCESS. 

371.  Tli  _>  arrangement  of  the  plant  outlined 
37  ?.  Operations  classified 

370.  Position  oi  the  cupolas 

A,  For  discharging  debris 

B,  For  delivering  to  the  converters 
37-1.  Weighing  the  converter-charge 

375.  General  arrangement  of  vessels,  pit  and  cranes    - 

376.  Number  of  vessels,  cranes,  etc.,  reeded:  discussion    - 

377.  Application  of  discussion      -  ... 

1,  Number  of  vessels  - 
Maximum  ,,utput  of  American  mills 

2,  Size  of  vessels        -  - 

3,  Number  of  casting-cranes 

4,  Number  of  sets  of  mould 

5,  Number  of  ingot-cranes 

378.  Capacity  of  casting  pit    -  -  -  - 

379.  Klcinbcssemcrei :  Large  vs.  small  Bessemer  plants 
380    Arrangement  of  vessels,  etc. :  detailed  discussion 

A,  Advantage  of  raising  the  vessels 

B,  Vessels  side  by  side,  instead  of  opposite 

381.  Forsyth's  plan 

382.  Other  plans:  Northeastern,  converging-axed,  Eochum,  Harris- 

burg 

Diverging-axed.  Joliet 
3    Other  forms  of  casting  pit 

1,  Casting-pit  suppressed 

2,  •'      removed  from  vessels 

3,  Auxilliary  pits 

4,  Straight  pits  ... 

5,  Annular  pits     ... 


293 
297 

293 
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301 
303 
302 
302 
304 
304 
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308 
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310 
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315 


316 
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320 
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322 
323 
324 
324 
324 
324 
325 
326 
328 
329 
330 
331 

333 
334 
334 
334 
335 
335 
335 
337 


TABLE    OF    CONTENTS. 


XI 


Section. 

884.  Minor  arrangements 

385.  General  arrangement  of  tracks,  etc. 

380.  Position  of  heating-furnaces,  etc. 

3H7.  The  several  levels 

38H.  The  Bessemer  converters 

380.  Bessemer's  early  vessels 

390.  Converters  classified 

391.  Fixed  vs.  rotating  vessels 

392.  Side  vs.  bottom-blowing 

393.  Internnl  blowing 

:i!H.  Straight  vs.  contracted  shells 
:i!).r>.  Excentric  vs.  concentric-  noses 
39(i.  Size  of  vessel-nose 

397.  Details  of  the  construction  of  converters 
llolley's  shell-shifting  device 

398.  The  bottom      - 

399.  Size  of  the  tuyere  openings 

400.  Rotating  mechanism 

401.  Joint  between  shell  and  bottom 

402.  Shell-linings,  preparation 

403.  "        '•         wear,  skulling 
404-   Preparation  of  bottom,  life,  etc 


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Section.  Pasrc. 
405.  Special  forms  of  converters                                                           -         35(5 

40G.  The  Clapp-GriHiths  vessel  -    356 

407.  Robert's  vessel  357 
Laureau's  vessel  -    35S 

408.  Davy's  portable  vessel  :!5s 

409.  Ladles  -    358 

410.  Caspersson's  converter-ladle        -  360 

APPENDIX  I— SPECIAL  STEELS. 

413.  Manganese-steel  -  361 
413A.  Effects  of  small  quantities  of  manganese  :!<ir> 

414.  Silicon-steel  365 

415.  Chrome-steel  :!«•; 
41 G.  Tungsten-steel  368 

417.  Copper-steel  -  368 

418.  Titanium-steel  369 

419.  Nickel-steel    •  369 

APPENDIX  II— ANTI-RUST  COATINGS. 

420.  Experiments  by  R.  W.  Lodge  and  the  author  372 

APPENDIX  m— LEAD-QUENCHING. 

421.  Experiments  of  Chatillon  &  Commentry  373 


TABLE  OF  CONTENTS. 


Chapter.  Page. 

1.  :  Classification  and  Constitution  of  Steel  -                                                               1 

II. :  Carbon  and  Iron,  Hardening,  Tempering,  and  Annealing  4 

III.  :  Iron  and  Silicon  -                                                             36 

IV". :  Iron  and  Manganese  -                                                      42 

Y.  :  Iron  and.  Sulphur  -  ...                                     48 

VI. :  Iron  and  Phosphorus  -                                                                        -  54 

VII.  :  Chromium,  Tungsten,  Copper  -                                     7.i 

VIII.  :  The  Metals  Occurring  but  Sparingly  in  Iron  -                                    .84 

IX.  :  Iron  and  Oxygen  -  90 
X. :  Nitrogen,  Hydrogen,  Carbonic  Oxide  -                             105 
XI. :  General  Phenomena  of  the  Absorption  and  Escape  of  Gas  from  Iron  125 
XII.  :  The  Prevention  of  Blowholes  and  Pipes  ...                 140 
XIII  :  Structure  and  Related  Subjects  163 
XIV.  :  Cold  Working,  Hot  Working,  Welding  .            .                 210 
XV. :  Direct  Processes     -  -                       -           259 

XVI.  :  Charcoal -Hearth  Processes  2b9 

XVII.  :  The  Crucible  Process  296 

XVIII.  :   Apparatus  for  the  Bessemer  Process  -  -                 316 

Appendix. 

I.  :  Special   Steels  ....            361 

II. :  Anti-Rust  Coatings  .           .                 872 

III.  :  Lead-Quenching    -                                    ...  .....            373 


LIST     OF     ILLUSTRATIONS. 


Figure. 
1.  Influence  of  silicon  on  the  saturation-point  for  carbon 


<;  temperature  on  the  condition  of  carbon 

3.  "  carbon  on  tensile  strength 

4.          '      "        "  "         Gatewood    - 

5.  "         "        "      "    ductility     - 

6.  "  silicon  on  tensile  strength  and  ductility 

7.  "  manganese  on  tensile  strength 

8.  "  phosphorus  on  tensile  strength  and  ductility 

9.  Andrews  on  rusting        ......... 

10.  Influence  of  temperature  on  the  action  of  carbonic  oxide  and 

carbonic  acid        .,»....--... 

11.  Gases  escaping  from  iron    - 

12.  Scattering  of  steel  ingots        ..... 

13.  Rising  of  steel  ingots 

14.  Proportion  of  carbonic  oxide  in  gas  escaping  from  steel 

15.  Conjectured  solubility  of  gas  in  iron 

16.  Muller's  boring  apparatus  for  gas 

17.  18.  Blow-holes     - 

19.  Central  cavities  in  ingots        ........ 

19  A  to  19  D.  Microscopic  intrusions  in  blow-holes 

20.  Position  of  blow-holes     --------- 

25.  Large  vug  crystals 

26.  Dendrites  from  a  blow-hole         ....... 

27.  28.  Columnar  structure  of  ingots 

29,  30,  31.  Crystals  from  cavities  in  ingots       - 

32.  Growth  of  blow-holes     --------- 

34.  Contraction  of  iron  during  solidification 
35  to  40.  Piping  in  steel  ingots     - 

41.  Internal  and  external  cracks  in  ingots       - 

42.  Hot-top  sinking-head      --------- 

42A.  Boulton's  casting  arrangement        ------ 

43.  Whitworth's  liquid-compression  apparatus 
44,45.  Daelen's        "  "  " 

46.  Williams'  "  "  "  ,       .       .       -       - 

47.  Hinsdale's          "  "  " 

48.  Gas-tight  joints  for  ingot-molds 

49.  Unusually  high  combinations  of  tensile  strength  and  elongation 

50.  Unusually  high  combinations  of  elastic  limit  and  elongation 

51.  Slow  cooling  vs.  blow-holes 

52.  Microscopic  appearance  of  meteoric  iron 


Page. 

-  9 
10 

-  14 
15 

-  16 
39 

-  47 
68 


"  wrought-iron 

"  Bessemer  steel  ingot 

"  gray  cast-iron 

"  blister-steel 

"  white  cast-iron 


53  to  55. 

56. 

57. 

68. 

59. 

60.  Condition  of  combined  carbon 

61.  Brinnell's  fracture-studies 

62.  Effect  of  temperature  on  size  of  grain  - 

63.  Heat-treatment  methods  :  Chernoff's  views 
63A.  Microscopic  appearance  of  ateel  ingot 

64  to  67.  Columnar  crystals  in  steel  ingots 

68.  Fracture  of  ingot     -        -        -        -        - 

69.  Coffin's  experiment 

70.  The  after-glow  or  recalescence 

71.  Retardations  in  heating  and  cooling  - 

72.  Experiments  in  quenching      -        -        - 
73  to  77.  Fractures,  etc.,  of  cold-worked  iron  - 

78.  Stress  in  chilled  castings         -        -        - 

79.  Fracture  of  burnt  steel 

80  to  84.  Segregation 


119 
125 
126 
126 
133 
137 
142 
146 
146 
146 
147 
148 
148 
148 
148 
148 
149 
150 
152 
154 
154 
155 
156 
156 
156 
157 
159 
160 
162 

-  164 
165 

-  165 
166 

-  166 
166 

-  170 
171 

-  176 
178 

-  182 
183 

-  183 

-  185 

-  186 
187, 188 

-  191 
193 

-  200 

-  201 

-  204 


Figure. 

85.  Allen's  agitator    ....... 

86.  Strain  diagrams  of  cold  worked  iron      -       -        - 

87.  Local  cold  working      ....... 

88.  Strain  diagrams  interrupted  ------ 

89.  "  "          of  hot-  and  of  cold-rolled  iron 

90.  Influence  of  cold  working  on  strength  and"  ductility    - 

100.  Effect  of  wire-drawing  on  tensile  strength 

101.  Draw-bench     --------- 

102.  Draw-plate  -       -        - 

103.  Annealing-pot         -       -       - 

104.  Scale-removing  machine     - 

105.  Galvanizing  plant 

106.  Pincers  for  removing  zinc 

107.  108.  Tests  for  wire 

109,  110.  Billings  cold-drawing  apparatus 

111,  112.  Flow  of  iron  in  punching 

113,  Local  effect  of  punching     - 

114,  114  A.  Punching  strengthens  locally      - 

115,  116.  Conical  vs.  cylindrical  punching 

117.  Blue-worsing  strengthens  iron  locally  - 

118.  Spontaneous  cracks  in  steel 

118 A.  Influence  of  reduction  on  tensile  strength  and  ductility  - 
118B.  Influence  of  the  finishing-temperature  on  the  size  of  grain 

119.  Welds 

121.  Thomson's  electric  welding  machine  -        -        -        - 
121  A.  Bernardos'  electric  welding         - 

123.  Carbon  and  density      -       -       -       - 

124.  Tensile  strength  and  density 

125.  Density  of  melting  cast  iron 

126.  Morrell's  gas-furnace       - 

131.  Catalan  hearth     -       -       -       -       . 

132.  American  bloomary        .       -       -        - 

133.  Husgafvel's  high  bloomary 

134.  Gurlt's  furnace        ... 

135.  Cooper's  and  Westman's  Processes 
135 A.  Tourangin's  furnace     -       -       - 

136.  137.  Blair's  sponge-making  furnaces 

138.  Wilson's  furnace     ------ 

140.  Schmidhammer's  furnace    -       -       - 

141.  Siemens'  retort  furnace 

144.  Siemens'  rotator  -       -        -        - 

145.  Siemens'  cascade  furnace 

146.  F.  Siemens'  furnace  for  direct  process 

147.  148.  American  Lancashire-hearth 
149.  Swedish  Walloon  hearth  - 
150, 151.  Crucibles 

152.  Sheffield  crucible  shaft  furnace 

153.  American  anthracite  shaft  furnace  for  crucibles  . 

154.  Siemens  crucible  furnace 

155.  Notel's  petroleum  furnace  for  crucibles 

156.  157.  Pittsburgh  crucible  melting  house 
158.  Ingot  mold  for  crucible  steel 

159  to  162.  Tongs  for  the  crucible  process 

163.  Cross  section  of  Joliet  Bessemer  plant 

164.  Plan  of  Bethlehem  Bessemer  plant 

165.  Gordon,  Strobel  and  Laureau's  plant,  plan 

166.  Old  standard  British  Bessemer  plant,  plan  and  section 

167.  Homestead  Bessemer  plant,  plan 

168.  South  Chicago  Bessemer  plant,  plan 

169.  New  Forsyth  10-ton  plant,  plan 


Page. 
209 

-  212 
212 

-  213 
215 

-  216 
216 

-  223 
224 

-  224 
225 

-  226 
226 

-  226 
227 

-  228 
230 

-  232 
233 

-  236 
239 

-  245 
247 

-  252 
254 

-  255 
256 

-  256 
258 

-  264 
269 

-  270 
272 

-  275 
276 

-  276 
279 

-  232 
282 

-  283 
286 

-  288 
288 

289,  291 
290 

-  300 
300 

-  801 
301 

-  302 
303 

-  305 
305,  306 

-  316 
319 

-  327 
328 

-  331 
332 

-  333 


XIV 


LIST     OF     ILLUSTRATION'S. 


Figure. 

170.  Northeastern  Bessemer  plant,  plan 

171.  Harrisburg  Bessemer  plant,  plan 

172.  Diverging-axed  Bessemer  plant,  plan 

173.  Joliet  Bessemer  plant,  plan  -        -        - 

174.  Phoenix  Bessemer  plant,  plan  and  section 

175.  Two-pit  Forsyth  Bessemer  plant,  plan 

176.  Bochumer  Verein  Bessemer  plant,  radial  straight  pits 
173A.  Peine  Bessemer  plant,  straight  pits,  plan  - 

177.  Edgar  Thomson  Bessemer  plant,  plan  and  section 
178  to  187.  Bessemer's  early  vessels 

188  to  189.  Early  Swedish  vessels 

191.  Early  Swedish  vessel       - 

192  to  199.  Modern  Bessemer  converters  - 

201.  Anatomy  of  Bessemer  converter    - 

202.  South  Chicago  10-ton  vessel,  removable  shell 


Page. 

Figure. 

Page. 

333 

204  to  206,  New  15-ton  vessel 

-    346,  347 

-    334 

2)7.  Holley's  shell  shifting  device 

347 

334  j  208.  Bottom  joint  of  Bessemer  converter      - 

-    348 

•    334   209.  Bethlehem  Bessemer  converter  with  hood,  cylinder,  etc  - 

349 

335 

210.  Durfee's  wing  piston  for  Bessemer  converter 

-     350 

-    :535 

211.  Holley's  old  conical  bottom  for  Bessemer  converters 

350 

iglit  pits                      336 

212  to  214.  Bottoms  with  bricks 

354 

-    336 

215.  Bottom  drying  arrangement  - 

-    355 

tion                              338 

216.  Clapp-Grifliths  Bessemer  converter 

856 

-    340 

217  to  218.  Robert-Bessemer  converter 

-    l!.')7 

340 

219.  Davy's  portable  Bessemer  converter 

888 

-    341 

220.  Steel  casting  ladle  - 

-    358 

342 

221  Ladle  for  cast  iron 

359 

-    341 

222.  Caspersson's  converter  ladle   - 

360 

346 

226  to  228.  Strain  diagrams  of  manganese  steel 

362 

LIST     OF     TABLES. 


No.  Page. 

1.  Silicon  and  carbon  9 

2.  Carbon  found  in  Fe,C  per  100  of  total  carbon  present  12 

3.  Effect  of  carbon  on  tensile  strength       ...  13 

4.  Summary  of  Gatewood's  carbon  results  14 

5.  Effects  of  carbon  on  tensile  strength  16 

6.  Effect  of  carbon  on  elongation  16 
6A.  Tensile  strength  and  elongation          ------  17 

7.  Modulus  of  elasticity  of  ingot  metal  as  affected  by  the  percent- 

age of  carbon 17 

7A.   Compressive  strength  as  influenced  by  carbon      ...  17 

8.  Percentage  of  excess  ( -t- )  or  deficit  ( — )  of  elastic  and  ultimate 

tensile  strength  and  of  elongation  of  unannealed  and  of 
hardened  iron  and  steel  forgings  above  those  of  the  same 
iron  when  annealed  ---------18 

9.  Percentage  of  excess  of  tensile  strength,  etc.,  of  unaunealed 

and  of  oil-hardened  unforged  castings  over  those  of  the  same 
casting  when  annealed  --------19 

10.  Percentage  of  excess  of  tensile  strength,  etc.,  of  hardened  iron 

and  steel  forgings  over  those  of  the  same  material  when  un- 
annealed ------  .....  go 

11.  Effects  of  tempering        -        ...  22 

12.  Temperatures,  etc.,  for  tempering  steel    -        -  23 

14.  Influence  of  the  temperature  of  annealing  26 

15.  Effects  of  annealing  as  influenced  by  varying  cross-section     -  26 

16.  "               "                   "            "    the  percentage  of  carbon  -  27 
16A.  Gain  (+)  or  loss  ( — )  of  tensile  strength,  etc.,  due  to  hardening 

plus  annealing  per  100  of  those  of  the  steel  before  hardening  23 

17.  Siliciferous  rails  of  at  least  tolerable  quality  33 

18.  Effect  of  silicon  on  tensile  strength  and  elongation                  -  39 

19.  Silicon  steels 40 

20.  Spiegeleisen  and  ferro-manganese  43 

21.  Manganese  and  forgeableness  45 

22.  "      sulphur  in  steel  known  or  believed  to  have  forged 

at  least  tolerably  well        ........  43 

22A.  Fusion  of  cast-iron  with  ferrous  sulphide  49 

23.  Desulphurization  in  cupola  melting  51 

24.  Sulphurous  rail  steel       ---------53 

25.  Good  rails  with  high  phosphorus  but  low  sulphur  54 
25A.  composition,  etc.,  of  pure  phosphates  and  silicates  57 

26.  Dephosphorization  vs.  slag  basicity  -----  53 
26A.    Absorption  of    phosphorus     from  phosphates  by  metallic 

iron,  etc.       -----------59 

26B.  Dephosphorizing  power  of  slags    -  59 

27.  Effect  of  phosphorus  on  tensile  strength  and  elongation  68 

28.  Phosphoric  steels  C9 

29.  Trenton  phosphoric  steels,  1869  71 

30.  Phosphorus  in  various  irons  and  steels      -        -        -  74 

31.  Composition  of  ferro-chrome                                                           -  76 

32.  Chrome  steel       -        -  76 
33A.  Forging  temperatures  of  Brooklyn  chrome  steel  78 
32B.  Properties  of  special  steels  -----                -        _  gi 

33.  Ferro-tungsten     -- 81 

34.  Tungsten  steel 81 

34A.  Forging  properties  of  tungsten  steel  82 

35.  Effect  of  copper  on  hot-malleableness   -  83 

36.  Tin  iron  alloys     -  85 

37.  Alloys  of  iron  and  aluminium        ...  87 

40.  Percentage  of  ferric  oxide  in  iron  scale  91 

41.  Oxygen  in  commercial  iron  and  uncarbonized  steel  92 

42.  Oxygen  in  oxygenated  Bessemer  metal,  as  inferred  from   the 

spiegel  reaction ---93 


No.  Page. 

43.  Oxygen  with  carbon,  etc.,  in  iron 94 

44.  Loss  of  iron  by  corrosion  in  pounds  per  square  foot  of  surface 

per  annum    --                                        .       ....  94 

45.  Calvert's  experiments  on  rusting       -  96 

46.  Combined  carbon  and  rapidity  of  corrosion                          -        -  97 

47.  Parker's  and  Andrew's  experiments  on  rusting       ...  97 
47A.  Relative  corrosion  of  wrought-iron  and  steel,  small  scale 

tests 99 

4TB.  Corrosion  by  acidulated  water 100 

47C.  Relative  corrosion  of  wrought-iron  and  steel    -  101 

47D.  Steel  and  iron  vessels  classed  at  Lloyd's  Register     ...  102 

47F.  Corrosion  of  galvanized  and  tinned  iron,  etc.        ...  104 

48.  Influence  of  iron  scale:  corrosion  in  confined  cold  sea- water    -  103 

49.  Ratio  of  the  apparent  rate  of  corrosion  of  the  naked  portion  of 

scale-bearing  to  that  of  scaleless  discs 103 

54.  Gas  obtained    by    boring  cold  steel,  iron,  etc.,  under  water, 

etc. ...  ice 

55.  Gas  escaping  from  hot  iron  before,  during,  and  shortly  after 

solidification 107 

56.  Gases  evolved  from  iron  while  heated  in  vacuo  -                -       -  108 

57.  Absorption  of  gases  by  iron        -       -                                -       -  109 

58.  Nitrogen  in  commercial  iron         .......  109 

59.  Nitrogenized  iron  obtained  by  heating  in  ammoniacal  gas  109 

60.  Maximum  hydrogen  found  by  several  observers  in  solid  iron  pre- 

viously untreated    ---------  no 

60A.  Analysis  of  Parry's  results,  specimens  heated  24  hours  or  more  112 

61.  Influence  of  exposure  to  nascent  hydrogen                  ...  115 

63.  Results  of  Bell's  experiments  on  calcined  Cleveland  ore         -  117 
03.  Temperatures    which  limit  the  action  of  carbonic  oxide  and  car- 
bonic acid    --.------..  H8 

64.  Removal  of  oxygen  per  100  of  original  by  carbonic  oxide        -  118 

65.  Reduction,  oxidation,  and  carbon  deposited  by  carbonic  oxide 

and  acid       -----------  119 

66.  Influence  of  temperature  and  structure  of  carbon  impregnation.  121 

67.  Influence  of  structure  and  of  speed  of  current  on  reduction  and 
carbon  impregnation  by  pure  carbonic  oxide        ....  133 

08.  Carbonic  oxide  in  commercial  iron  previously  untreated       -  124 

69.  Influence  of  previous  exposure  to  carbonic  oxide  on  the  evolu- 

tion of  that  gas  in  vacuo      ------..  135 

70.  Gases  of  steel  classified  according  to  time  of  escape       -       -  126 
70A.  Recarburizing  reactions  in  the  Bessemer  process     -        -        -  128 

71.  Behavior  of  iron  before  and  during  solidification     -       -       -  139 

72.  Influence  of  temperature  and  length  of  exposure  on  the  volume 

and  composition  of  gas  extracted  in  vacuo       -       -       -       -  181 

73.  Gases  obtained  by  boring  with  sharp  drill         -        -       -       -  132 

75.  Dominant  types  of  composition  of  gases  evolved  by  iron    -       -  133 

76.  Recarburizing  additions  which  immediately  check  the  escape 

of  gas  though  apparently  causing  the  oxidation  of  carbon  -  139 

78.  Sinking  head  and  croppings,  etc.,  from  top  of  steel  ingots  and 

castings,  rejected  for  unsoundness    ------  153 

79.  High  combinations  of  strength  and  ductility           ...  igj 

80.  Composition  and  properties  of  unforged  steel  castings        -       -  162 

81.  Minerals  which  compose  iron              ----..  154 

82.  Composition  of  slap  in  weld  iron          ------  igg 

83.  Analysis  of  the  influence  of  slag  on  the  properties  of  weld  iron, 

and  on  its  percentage  of  carbon      ---...  jgg 

84.  General  summary  of  tracture  changes                 -  173 

85.  General  scheme  of  Brinnell's  fractures      -----  173 

86.  Metcalf's  views  on  the  influence  of  the   quenching    tempera- 

ture on  the  fracture,  etc.                                                     -       -  177 

86A.  Influence  of  Clemandot's  process  of  compression  hardening  180 


xvi 


LIST    OF    TABLES. 


No.  Page. 

87.  Effect  ot  Coffin's  process  on  size  of  grain 

87A.  Retardations  in  the  heating  and  cooling  curves  of  iron  -  187 

88.  Influence  of  the  direction  of  rolling     -        -        -        -        -        -  194 

88A.  Influence  of  direction  of  forging  from  Maitland's  data       -  195 

88B.  Patience  of  iron  under  repeated  bending        -                -        -  199 

89.  Effect  of  rest  on  cast-iron  guns             ------  200 

91.  Effect  of  repose  on  the  properties  of  12  groups  of  steel  specimc  n  ;  COJ 

92.  Burning  and  oxidation                                                                      •  201 

93.  Silicon  and  silica  in  different  parts  of  a  burnt  cracible  steel  bar  202 

94.  Similarity  of  composition  of  different  parts  of  a  heat  of  steel      -  203 

95.  Uniformity  in  open-hearth  steel                                                  -  203 

90.  Segregation  in  steel  and  cast-iron                                   -  206 

97.  Composition  of  Pennsylvania  steel  rail                                           -  208 

98.  Stratification  of  phosphorus  and  manganese    •  208 

99.  Crusts,  etc.,  on  cast  iron         --------  208 

100.  Influence  of  cold-working  on  the  properties  of  iron         -        -  210 

101.  Influence  of  stretching  beyond  the  elastic  limit  on  the  modulus 

of  elasticity,  elastic  limit,  etc.,    and    modifications  of   this 

influence  by  rest  and  further  treatment    -----  211 

102.  Influence  of  twisting  on  tensile  strength  of  wrought  iron  and 

soft  steel          .-.---               ....  212 

103.  Effects  of  cold  bending  and  annealing          -----  212 

104.  Increase  of  tensile  strength  by  rest  214 

105.  Decrease  of  density  on  wire  drawing    ------  214 

106.  The  effects  of  successive  draughts  in  wire  drawing         -        -  216 

107.  Illustrating  the  depth  to  which  the  effect  of  cold-rolling  extends  216 

109.  Dilation 218 

110.  Effects,  etc.,  of  cold-working  compared  with  those  of  hardening 

and  of  cold- working  other  metals          -----  220 

111.  Persistence  of  the  salt  coating  in  wire  drawing           ...  333 

112.  Birmingham  wire  gauge           -------  223 

113.  Resistance  of  wire  to  drawing       -------  333 

114.  Some  details  of  wire  drawing  in  an  American  mill         -        -  223 

115.  Composition  of  wire  and  mint  dies        ------  333 

116.  Examples  of  general  procedure  in  wire-drawing    •        -        -  225 

117.  Reduction  in  drawing  gun  wire            -  226 

118.  Bendings  required  by  the  German  government  for  rope  wire  226 

119.  Trains  for  cold  rolling  at  an  American  mill                          -        -  227 

120.  Cold  rolling  at  an  American  mill  (concluded)          -  227 

121.  Experiments  in  cold  rolling  44-inch  steel  bars     -  227 
121  A.   Punching:  Its  effects  and  their  removal  by  reaming  and  by 

annealing      ---------         -  229 

122.  Effects  of  punching        -                                                                  -  229 

123.  Effect  of  punching  and  subsequent  reaming  on  soft-ingot  steel  230 

124.  Percentage  of  elongation  of  holes  when  drifted  till  the  metal 

begins  to  crack 230 

125.  Effect  of  shearing  and  cold  hammering,  and   of  subsequent 

annealing  on  soft  ingot  sueel              ------  330 

126.  Properties  of  strips  from  previously  punched  steel  plates,  the 

strips  cut  at  various  distances  from  the  punched  holes    -        -  231 

127.  Restoration  by  riveting      --.--.-.  033 

128.  Effect  of  previous  cold  and  blue-heat  treatment  on  flexibility 

(endurance  of  repeated  bending)        -                                -        -  235 

129.  Effect  of  cold  and  blue-heat  treatment  on  tensile  properties    -  235 

130.  Effect  of  blue  and  cold  work  on  ductility  as  inferred  from  drift- 

ing          235 

131.  Relation  between  thickness  and  physical  properties  of  iron  and 

steel  bars,  plates,  etc.    --------  242 

132.  Influence  of  the  early  vs.  the  late  reductions  on  the  physical 

properties  of  ingot  iron                                                                  -  243 

133.  Influence  of  work  or  reduction  on  the  properties  of  iron  243 

134.  Influence  of  work  or  reduction  on  the  properties  of  iron             -  243 

135.  Influence  of  the  proportion  of  carbon  on  the  increase  of  tensile 

strength,  etc. ,  due  to  forging,  etc.        -----  044 

136.  Improvement  of  wrought-iron  F  with  diminishing  size      -        -  244 

137.  Influence  of  the  initial  thickness  of  the  ingot  from  which  they 

were  rolled  on  the  properties  of  steel  plates        -  245 

138.  Influence  of  thickness  of  ingot  on  properties  of  steel  plates        -  245 

139.  Influence  of  the  initial  thickness  of  the  pile  from  which  they 

were  rolled  on  the  properties  of  wrought-iron  bars    -        -  246 

139 A.  Normal  and  cool  work                                                                   -  246 

140.  Influence  ot  work  on  the  proportion  of  slag  in  weld  iron      -  246 

141.  Annealing  vs.  forged  steel      -        -                248 

142.  Properties  of  an  unforged,  heat-treated  steel  gun  tube  -  248 
148.  Increase  of  tensile  strength,  etc.,  on  forging  and  rolling  Fagesta 

steel  from  3  x  3  to  1|  X  by  -}  inch,  measured  in  percentages 

of  the  tensile  strength,  etc.,  of  the  3  x  3  bar    -        -       -       -  249 


No.  Page. 

1 14.  Absolute  excess  (or  deficit)  of  the  tensile  strength  of  hammered 

Bessemer  steel  bars  over  that  of  similar  but  rolled  bars  249 

145.  Properties  of  steel  plates  from  rolled  and  from  hammered  slabs    249 

146.  Strength  of  welded  section  in  percentage  of  that  of  the  un- 

welded  metal 251 

147.  Composition  of  welding  and  of  non-welding  steels    -  -        251 

148.  Strength  of  electrically-welded  joints 255 

149.  Specific  gravity  of  steel  257 

150.  Composition  of  steel        -  ...    258 

152.  Heat  required  for  making  20  kg.  of  pig  iron  and  sponge  contain- 

ing the  same  quantity  (18'6  kg.)  of  iron,  from  Cleveland  ore    262 

153.  Direct  processes  classified  by  mode  of  heating        ...         266 

154.  General  scheme  of  the  direct  processes  -    268 

155.  Catalan  hearth  practice  269 

156.  American  bloomary  practice  -    270 

157.  Composition  of    American  bloomary  iron        -  -        270 
157A.  History  of  the  American  bloomary  establishments  reported 

in  1884  and  1887  271 

158.  Stiickofen  practice 

159.  Composition  of  blooms  from  Husgafvel  high  bloomaries  27S 

160.  The  Husgafvel  furnace  and  its  work  273 

161.  Results  obtained  in  the  Nyhammar  bloomary  275 
162    Chenot's  process  278 
162A.  Loss  in  the  open-hearth  steel  process,  using  iron  sponge        -    280 

163.  Blair's  process    -        -  281 
163B.  Eames  or  Carbon  Iron  Company's  process  -                                 -    285 

164.  Diary  of  Siemens'  direct  process       -        -  287 

165.  Details  of  Siemens'  direct  process  -    287 

167.  Composition  and  properties  of  charcoal-hearth  iron  290 

168.  Production  of  blooms  in  charcoal-hearths     - '      -        -  -    292 

169.  Age  of  United  States  charcoal-hearths  292 

170.  Cost  of  making  charcoal-hearth  iron     -        -  -    292 

171.  Economic  features  of  charcoal-hearth  processes  292 

172.  Economic  features  of  the  crucible  process,  facing  page  -    296 

173.  Composition  of  slag  of  crucible  process  297 

174.  Materials  used  in  cracible  making         -  -    299 

175.  Size  and  cost  of  American  crucibles 299 

176.  Composition  of  crucibles  -         301 

177.  Operations  in  Mitis  process,  time  of  •    309 

178.  Cost  of  crucible  process      -  ^         310 
179,180.  Chemical  changes  in  crucible  process  311,  312 

181.  Influence  of  crucible  composition  on  silicon-absorption  313 

182.  Influence  of  carbon-content  on  sihcon-absortion          -  313 

183.  Influence  of  length  of  killing  on  silicon-absorption  313 

184.  Influence  of  manganese  on  carbon-  and  silicon-absorption          -    313 

185.  Influence  of  carbon  on  carbon-  absorp:  ion        -        ...         314 

186.  Ferromanganese  and  steel  lose  more  manganese  than  mangani- 

ferous  steel          ----------    3jg 

187.  Influence  of  carbon  on  loss  of  manganese  -  316 

188.  Time  occupied  in  pouring  iron  into  Bessemer  vessel  -        -    320 

189.  Time  occupied  by  vessel-manoeuvres  -        -        -        -        -    321 

190.  Time  occupied  by  casting-crane  manoeuvres      -  321 

191.  Time  occupied  in  teaming,  etc.       -        -  -    322 

192.  Time  occupied  by  manoeuvres  of  ingot-cranes  -        -        -        -       332 

193.  The  foregoing  tables  condensed      -------    332 

194.  Maximum  output  of  American  Bessemer  mills         -  323 

195.  Estimated  capacity  of  a  single  casting-pit     -  -    325 

196.  Leading  dimensions  of  Bessemer  plants    -  329,  330 

197.  198.  Area  of  tuyere-holes        -  -    348,  3-19 

199.  Vessel-linings  and  bottoms  -------        351 

200.  Ultimate  composition  of  refractory  materials  for  Bessemer  process  352 

201.  Number  and  output  of  Clapp-Griffiths  vessels    -  356 

202.  Refractory  mixtures  for  the  Bessemer  process       -  -    359 

203.  Use  of  Caspersson's  converter-ladle    ------       360 

£06  to  209.  Properties  of  manganese-steel  -     361  to  364 

210.  Composition  of  f  erro-silicon    --------   385 

210A.  Slag  made  with  silico-spiegel  -  ...        355 

211.  Properties  of  silicon-steel         -  -  366 
211A.  Composition  of  siliciferous  steels     ------        366 

212.  Composition  of  ferro-chrome          ---....    3(jg 
213  to  215.     Composition  and  properties  of  chrome-steel  366,  367 

216.  Properties  of  tungsten- steel    -        -  -        -    368 

217.  Properties  of  copper-steel  -        369 
218  to  220.  Properties  of  nickel-steel      -                        ...    370,  371 
220A.  Corrosion  of  nickel-steel           -------        371 

221.  Corrosion  of  iron  with  protective  coatings    -----   372 

222.  Effect  of  lead  and  other  quenching 373 


^ 

(  UNIVERSITY 


THE    METALLURGY    OF    STEEL 


CHAPTER     I. 
CLASSIFICATION  AND  CONSTITUTION  OF  STEEL. 


§  1.  METALLURGY. — The  art  of  extracting  metals  from 
their  ores  and  other  combinations  and  of  fashioning 
them. 

STEEL  has  (1)  a  specific  sense,  and  (2)  in  English  and 
French  a  generic  sense  which  harmonizes  poorly  with  its 
specific  meaning. 

(A)  In  its  SPECIFIC  SENSE  steel  is  a  compound  of  iron 
possessing,  or  capable  of  possessing,  decided  hardness 
simultaneously  with  a  valuable  degree  of  toughness  when 
hot  or  when  cold,  or  both.  It  includes  primarily  com- 
pounds of  iron  combined  with  from  say  0-30  to  2  per  cent 
of  carbon,  which  can  be  rendered  decidedly  soft  and  tough 
or  intensely  hard  by  slow  and  rapid  cooling  respectively, 
and  secondarily  compounds  of  iron  with  chromium,  tung- 
sten, manganese,  titanium,  and  other  elements,  compounds 
which  like  carbon  steel  possess  intense  hardness  with 
decided  toughness. 

This  specific  sense  was  formerly  the  sole  one,  in  all 
lands ;  it  is  the  legitimate  and  dominant  one  to-day  in 
Teutonic  and  Scandinavian  countries,  and  it  would  be  in 
this  country  also,  could  the  little  band,  which  stoutly 
oppose:!  the  introduction  of  the  present  anomaly  and  con- 
fusion into  our  nomenclature,  have  resisted  the  momentum 
of  an  incipient  custom  as  successfully  as  they  silenced  the 
arguments  of  their  opponents. 

The  following  scheme  classifies  iron  in  accordance  with 
this  specific  meaning : 

Classification  of  International    Committee  of  1876,  of  the  American  Institute 
of  Mining  Engineers. 


MALLEABLE. 

NON-MALLEABLE. 

Jast  whca  molten 
into  a  malleable 
mass. 

Can  not  be  hardened 
by  sudden  cooling. 
IRON. 

Can  be  hardened  by 
sudden  cooling. 
STEEL. 

Cast-iron. 

Ingot  iron. 
Flusseisen. 
Ferfondu. 

Ingot  steel. 
Fluss  Stahl. 
Acier  fondu. 

Aggregated    from 
pasty      particles 
without      subse 
qurat  fusion. 

Weld  iron. 
Sweisseisen, 
Per  soude\ 

Weld  steel. 
Schweiss  Stahl 
Acier  soud^. 

(B)  GENEIJIC  SENSE. — While  these  species  are  univer- 
sally recognized  they  are  not  usually  grouped  in  accord- 
ance with  the  above  scheme  in  English  speaking  countries 
and  France,  where  "  steel  "  is  used  genetically  to  include 
not  only  the  species  "steel,"  but  "ingot  iron,"  as  well. 
Most  of  the  "boiler-plate  steel"  of  to-day  and  much 
structural  material,  which  is  unquestionably  steel  in  its 
now  established  generic  sense,  belong  to  the  species 
"ingot  iron."  So  firmly  has  this  sense  of  the  word 
become  established  that  unfortunately  it  were  vain  to 

OTTDOSe  it. 


Freedom  from  intermingled  slag,  etc.,  is  not  only,  I  be- 
lieve, a  better  recognized,  but  intrinsically  a  more  valuable 
basis  for  discrimination  between  weld  and  ingot  metal,  as  it 
implies  the  possession  of  definite  properties,  than  LTolley'  s 
histoiical  basis  of  having  been  cast  when  molten  into  a 
malleable  mass  ;  since  metal  which  is  not  metallic  when 
cast  may,  by  subsequent  treatment,  be  made  to  resemble 
=o  closely  that  which  is  as  to  justify  classing  them 
together.  We  should  recognize  inherent  properties  rather 
than  the  accident  of  birth  or  previous  conditions. 

"Iron"  and  "steel"  are  employed  so  ambiguously 
and  inconsistently,  that  it  is  to-day  impossible  to  arrange 
all  varieties  under  a  simple  and  consistent  classification. 
The  following  scheme  expresses  the  current  meanings  as 

accurately  as  may  be  : 

/  / £^  3 ) 

Present  American  and  British  Classification. 


MALLEABLE. 


Is  free  from  sla^, 
etc. 


Contains  slag  or 
similar  matter. 


Can  not  be  hard- 
ened by  sudden 
cooling,  AND 
contains  inter- 
mingled slag  or 
similar  matter. 
IRON. 


Yv'rought  or 
Weld  iron. 


Can  be  hardened  by  sud- 
den cooling,  OR  is  both 
malleable  and  bard,  OR 
is  free  from  intermixed 
slag  and  similar  matter. 

STEEL. 


Ingot  iron        Ingot  steel. 


Weld  steel. 


NON-MALLEABLE 


Cast-iron. 


Highly  carbureted  non-siliciferous  non-malleable  cast- 
ings are  to-day  rendered  malleable  by  semi-decarburi- 
zation  and  are  'then  called  steel  castings  ;  this  is  just  if 
they  resemble  castings  of  similar  composition  and  initially 
malleable  more  closely  than  they  resemble  cast-iron  ;  their 
malleableness,  freedom  from  slag,  etc.,  and  their  power  of 
being  hardened  then  entitle  them  to  be  called  steel.  Ordi- 
nary malleable-iron  castings  can  hardly  be  embraced  in 
this  scheme,  but  form  a  separate  division. 

The  attempt  to  call  mitis  castings  "wrought-iron,"  is 
to  be  deprecated ;  it  can  only  more  hopelessly  confuse 
matters.  They  are  clearly  ingot-iron. 

Steel  is  cross-classified  in  many  ways  ;  for  example,  after 
the  element  which  gives  the  iron  its  increased  hardness,  as 
carbon, — tungsten, — chromium-steel,  etc.;  according  to  the 
hardness  or  degree  of  carburization,  as  mild  steel,  hard 
steel,  etc.;  according  to  the  mode  of  manufacture,  as  open- 
hearth,  crucible  steel,  etc.,  and  otherwise. 

§  2.  THE  CONSTITUTION  OF  STEEL  is  somewhat  obscure. 
The  former  view  that  nitrogen  or  other  gases  played  an 
essential  part  in  its  nature  has,  probably,  no  important 
supporters. 


THE    METALLURGY    OF    STEEL. 


I  conceive  it  to  consist  (A) 'of  a  matrix  of  iron  which  is 
sometimes  (as  in  ingot-iron  and  annealed  steel),  compar- 
atively, or  even  quite  pure,  and  sometimes  (as  in  hardened 
steel,  manganese  steel,  etc.)  chemically  combined  with 
a  portion,  or  even  the  whole  of  the  other  elements  which 
are  present,  probably  in  indefinite  ratios,  its  mechanical 
properties  being  greatly  affected  by  them ;  and  (B)  of  a 
number  of  independent  entities  which  we  may  style 
"minerals,"  chemical  compounds  of  the  elements  present, 
including  iron,  which  crystallize  within  the  matrix,  and 
by  their  mechanical  properties,  shape,  size,  and  mode  of 
distribution,  also  profoundly  affect  the  mechanical  prop- 
erties of  the  composite  mass,  though  probably  less  pro- 
foundedly  than  do  changes  of  corresponding  magnitude 
in  the  composition  of  the  matrix.  This  conception  is  based 
on  the  following  phenomena  and  analogies. 

When  a  crystalline  rock,  consisting  let  us  say  of  a 
mixture  of  quartz,  mica,  and  feldspar  is  fused,  its  con- 
stituents which,  prior  to  fusion,  had  existed  as  separate 
entities,  coalesce,  and  form,  apparently,  one  homogeneous 
magma.  Just  as  an  ordinary  aqueous  solution  may  be 
regarded  as  a  single  complex  chemical  combination,  each 
element  of  which  is  directly  combined  with  every  other 
one  present,  so  such  a  fused  magma  may  be  regarded 
as  a  single  polybasic  silicate  of  iron,  lime,  magnesia,  etc. 

[In  the  common,  narrow  view,  solutions  are  not  chemical 
combinations,  because  the  most  familiar  chemical  unions 
(1)  occur  in  definite  proportions,  (2)  are  attended  with 
thermal  or  electric  phenomena,  and  (3)  yield  a  product 
whose  physical  properties  differ  widely  from  those  of  its 
components,  while  solutions  occur  in  all  ratios,  usually 
without  marked  thermal  and  electric  phenomena,  and 
yield  products  whose  properties  are  intermediate  between 
those  of  their  components.  Many  philosophic  chemists, 
however,  believing  with  Hegel  that  the  identification  of 
different  substances  with  the  formation  of  a  new  one  is  the 
essence  of  chemical  union,  and  that  the  three  common 
characteristics  I  have  mentioned  are  simply  accidents  of 
certain  familiar  chemical  unions,  consider  solutions  as 
true  chemical  unions,  though  less  stable  than  many  of  the 
typical  ones.  They  believe  that  in  solutions,  though  the 
chemical  force  is  not  the  overwhelming  one,  though  it 
does  not  dominate  the  purely  physical  forces,  such  as  co- 
hesion, as  completely  as  in  the  more  stable  chemical 
unions,  yet  it  is  always  present.  They  point  out  that 
many  solutions  exhibit  some  one  at  least  of  the  three 
characteristics  of  the  common  stable  chemical  unions  to  so 
marked  a  degree  as  to  lead  us  to  believe  that  on  further 
examination  most  and  perhaps  all  solutions  will  be  found 
to  exhibit  some  of  them  ;  and  that  the  apparent  absolute 
homogeneousness  of  solutions  in  itself  suffices  to  distin- 
guish them  from  mixtures,  for  apparently  absolutely  no 
concentration  by  gravity  occurs  in  them. 

(1)  Thus,  though  solutions  occur  in  many  ratios,  they 
probably  do  not  in  all,  since  some  solutions,  if  diluted 
beyond  a  certain  degree,  cease  to  be  homogeneous,  separ- 
ation by  gravity  occurs,  they  become  mixtures.  More- 
over, if  we  regard  all  the  components  of  a  single  crystal 
as  mutually  combined,  then  many  strong  undoubted  typi- 
cal chemical  combinations  occur  in  continuously  varying 
indefinite  ratios,  as  in  the  co-crystallization  of  antimony 
and  zinc,  of  ferrous  and  cupric  sulphates,  of  gold  and  tin, 
in  homogeneous  well-defined  crystals. 


(2)  Many  solutions  do  exhibit  marked   thermal  phe- 
nomena ;  witness  the  evolution  of  heat  on  mixing  sul- 
phuric acid  and  water  ;  its  absorption  when  sal-ammoniac 
is  dissolved. 

(3)  It  is  the  fact  of  the  unlikeness  of  the  compound  to  the 
mean  of  its  components,  not  the  degree  of  that  unlikeness, 
which  should  be  regarded  as  the  prominent  characteristic 
of  chemical  compounds.     But  many  solutions  are  strik- 
ingly unlike  the  mean  of  their  components.     Thus  the 
specific  gravity  of  many  saline  solutions  is  far  greater 
than  the  mean  specific  gravity  of  salt  and  dissolving 
water  ;  some  salts  indeed  dissolve  without  at  all  increas- 
ing the  volume  of  the  water.     In  other  cases,  dilution 
causes  vivid  chromatic  changes  ;    for  example,   brown 
cupric  chloride  forms  with  a  little  water  an  emerald  green 
liquor ;  with  more  water,  it  turns  blue.    If  these  solutions 
be  admitted  to  be  chemical  unions,  how  can  we  bar  out 
the  rest,  which  certainly  are  true  identifications  of  differ- 
ent substances,  and  which  may,  on  close  examination, 
prove  to  possess  the  familiar  but  non-essential  character- 
istics of  the  stronger  compounds  ?    If  we  admit  solutions, 
how  can  we  exclude  fused  alloys,  slags,  molten  rocks 
when  homogeneous  ?  That  each  contains  distinct  separable 
entities  when  solidified,  does  not  show  that  it  does  when 
molten.] 

When  such  a  fused  magma  as  I  have  described  solidi- 
ties, its  properties  will  depend  very  greatly  on  the  condi- 
tions under  which  solidification  occurs,  and  probably  on 
other  conditions  now  unguessed.  These  properties  are  in- 
fluenced not  alone  by  the  mineral  species  which  form  dur- 
ing solidification,  but  by  the  shape  and  size  of  the  indi- 
vidual crystals,  by  the  degree  of  cohesion  between  the  adja- 
cent crystals  of  dissimilar  minerals,  and  by  the  manner  in 
which  they  are  interlaced ;  in  short,  by  structure.  Now,  not 
only  does  the  structure,  but  the  very  nature  of  the  minerals 
themselves  depend  on  unknown  conditions.  We  cannot  tell, 
for  instance,  whether  a  given  lot  of  CaO,  AL03,  NaaO,  and 
Si02,  will  form  oligocase  or  a  mechanical  mixture  of  anor- 
thite  and  quartz  (the  composition  of  some  oligoclase  differs 
from  that  of  some  anorthite  only  in  having  a  little  more 
silica) ;  whether  a  given  lot  of  CaO,  MgO,  and  SiOs,  will  form 
hornblend,  or  pyroxene  (they  are  often  of  identical  com- 
position). Many  other  cases  could  be  cited  of  minerals  ol 
identical  composition,  but  different  physical  properties : 
opal  and  quartz,  calcite  and  aragonite,  and  the  defines, 
which,  though  of  identical  composition,  include  very  dis- 
similar compounds,  (1)  the  wax-like  ozocerite,  (2)  the  liquid 
pittoliums,  and  (3),  olefiant  gas  itself.  It  is,  moreover, 
impossible  to  predict  what  changes  in  the  mineral  species 
which  compose  a  crystalline  rock,  and  in  the  form  and  ar- 
rangement of  their  crystals,  will  be  effected,  into  what 
new  minerals  its  component  elements  will  be  induced  to 
rearrange  themselves,  by  a  given  change  in  its  ultimate 
composition. 

The  ultimate  composition  of  a  crystalline  rock  may  in- 
deed give  us  a  rough  idea  of  its  physical  properties.  A 
highly  siliceous  rock  will  be  specifically  light  and  prob- 
able hard  and  vitreous  ;  a  rock  containing  much  lead,  no 
matter  what  the  state  of  combination  of  that  lead  may  be, 
will  ordinarily  be  heavy.  The  addition  of  magnesia  and 
ferric  oxide  might  be  shown  by  experience  to  change  the 
hard  feldspar  to  the  soft  cleaving  mica.  But  it  is  clear  that 
any  attempt  at  an  accurate  prediction  of  the  physical 


CONSTITtTTION    OF     STEEL. 


properties  of  ;i  crystalline  rock  from  its  ultimate  composi- 
tion must  be  futile.  They  must  either  be  ascertained  by 
direct  test,  or  inferred  from  a  study  of  its  proximate  coin- 
position,  which  must  be  determined  by  whatever  means 
are  available,  and  of  the  arrangement  of  its  component 
minerals,  the  size,  etc.,  of  their  individual  crystals,  etc. 

In  the  present  state  of  our  knowledge  it  seems  probable 
that  the  conditions  in  a  solidifying  steel  ingot,  and  per- 
!nps  in  many  other  alloys  and  similar  compounds,  resem- 
ble those  iu  a  solidifying  crystalline  rock.  For  we  find 
that  the  chemical  condition  of  the  components  of  the 
solidified  steel  and  the  size  and  probably  the  shape  and 
arrangement  of  its  individual  crystals  are  affected  accord- 
ing to  now  unknown  laws  by  changes  in  its  ultimate 
composition,  and  by  the  conditions  which  precede  and 
accompany  its  solidification  and  cooling. 

The  influence  of  the  conditions  of  cooling  on  the  chemical 
condition  of  the  components  of  the  solid  steel  is  well  exem- 
plified by  the  case  of  carbon.  If  a  highly  carbureted  steel 
is  long  exposed  to  a  high  temperature  while  cooling,  graph- 
ite crystallizes  out  as  a  distinct,  readily  recognized  "mine- 
ral," if  I  may  so  speak  ;  if  the  molten  steel  be  cooled  with 
sufficient  rapidity,  no  graphite  is  formed,  but  the  whole  of 
the  carbon  passes  into  a  condition  in  which  it  renders  the 
metal  brittle.  If  we  cool  the  steel  slowly  from  a  red  heat, 
most  of  the  carbon  forms  a  carbide,  probably  of  definite 
composition,  Fe3C,  which,  distributed  uniformly  in  mi- 
nute crystals  through  the  matrix  of  iron,  strengthens  and 
hardens  the  mass,  but  much  less  than  does  the  carbon 
when  in  the  condition  induced  by  sudden  cooling. 

These  variations  in  the  condition  of  carbon  are  accom- 
panied by  closely  corresponding  variations  in  its  chemical 
behavior  on  the  application  of  solvents.  So  too,  if  we  may 
judge  from  marked  differences  in  its  behavior  under  the 
action  of  solvents  and  from  apparently  closely  correspond- 
ing differences  in  the  mechanical  properties  of  the  metal 
which  contains  it,  not  only  is  the  chemical  condition  of 
phosphorus  different  in  different  steels,  but  that  of  differ- 
ent portions  of  phosphorus  in  the  same  piece  of  steel 
differs  greatly.  Similar  differences  probably  exist  with 
the.  other  elements  found  in  steel. 

The  influence  of  the  conditions  of  cooling  on  the  struct- 
ure of  steel  is  readily  recognized.  Slow,  undisturbed 
cooling  induces  coarse  crystallization  ;  if  the  metal  be 
vigorously  hammered  during  slow  cooling,  the  structure 
becomes  much  finer  ;  if  the  cooling  be  sudden,  extremely 
fine  structure  results.  That  other  and  now  unguessed 
conditions  profoundly  alter  both  the  mineral  species  and 
the  structure  of  steel,  and  that  changes  in  ultimate  com- 
position modify  both,  species  and  structure  of  steel,  as  of 
crystalline  rock,  in  most  complex  ways,  is  indicated  by 
the  utterly  anomalous  relations  between  the  ultimate  com- 
position and  the  mechanical  properties  of  steel.  This 
anomalousness,  which  has  pu;:zled  so  many,  is  readily 
explained  by  the  close  resemblance  between  the  conditions 
of  the  formation  of  rock  and  of  ingot,  which  not  only 
shows  us  why  we  do  not  discover  these  relations,  but  that 
in  all  probability  we  never  can  from  ultimate  composition. 
The  lithologist  who  attempted  to-day  to  deduce  the  me. 
chanical  properties  of  a  granite  from  its  ultimate  composi- 
tion would  be  laughed  at.  Are  our  metallurgical  chemists 
in  a  much  more  reasonable  position  ? 

The  complex  wny  in  which  slight  changes  in  ultimate 


composition  may  induce  disproportionate  changes  in  the 
proximate  composition  of  the  mineral  species  making  up 
the  solid  steel,  and  through  them  its  mechanical  proper- 
ties, is  readily  seen  on  reflection.  If  between  the  elements 
of  the  molten  mass  there  exists  a  certain  balance  which 
just  permits  the  formation  of  certain  compounds  during 
solidification,  the  introduction  of  a  minute  quantity  of  a 
certain  element,  say  manganese,  might  just  upset  this  bal- 
ance and  give  rise  to  the  formation  of  quite  a  different  set 
of  compounds,  which  might  have  radically  different  effects 
on  the  properties  of  the  metal.  While,  were  the  original 
composition  somewhat  and  perhaps  but  slightly  different, 
then  the  addition  of  the  same  quantity  of  manganese 
might  not  in  the  least  alter  the  kind  or  proportion  of  the 
different  mineral  species  which  make  up  the  solid  mass. 

If,  pointing  out  that  -02  per  cent  phosphorus  sensibly 
alters  the  ductility  of  steel,  you  a^k  how  this  effect 
can  be  due  to  so  minute  a  quantity  of  a  simply  inter- 
mingled mineral,  I  answer:  (1)  That  we  have  just 
seen  how  minute  changes  in  ultimate  composition 
may  profoundly  alter  the  proximate  composition.  One 
per  cent  of-  salt  distributed  through  gneiss  would  de- 
stroy its  weather  resisting  powers  ;  5  per  cent  of  mica 
would  give  it  strong  cleavage  ;  so  5,  or  even  1  per  cent 
of  a  mineral  whose  presence  in  steel  might  be  due  to  an 
addition  of  say  '02  per  cent  of  phosphorus,  might  pro- 
foundly alter  its  properties.  AVe  note  among  the  hydro- 
carbons compounds  whose  physical  properties  differ 
greatly,  yet  whose  ultimate  composition  is  very  similar, 
nay  even  identical.  (2)  That  if  0'0002  per  cent  of  iodine 
gives  starch  liquor  a  perceptible  color  it  is  not  surprising 
that  100  times  as  large  a  quantity  of  phosphorus  should 
perceptibly  affect  the  properties  of  the  iron  matrix  with 
which  we  may  fancy  that  it  directly  combines.  (3)  That 
even  so  minute  a  quantity  of  phosphorus  as  '02  per  cent 
may  so  affect  the  conditions  of  solidification,  for  example 
by  altering  the  fluidity  of  the  matrix  at  some  critical 
temperature  at  which  crystallization  occurs,  as  to  greatly 
affect  the  size,  shape  and  mode  of  arrangement  of  the 
crystals  of  some  of  the  minerals  present,  and  of  the 
matrix  itself. 

If  now  it  is  asked  why,  if  these  so-called  minerals  form 
in  steel  during  solidification,  we  never  see  them,  I  reply 
(1),  that  the  component  minerals  of  many  crystalline  rocks 
are  only  discernible  under  the  microscope,  and  even  then 
only  because  they  happen  to  be  moie  or  less  transparent, 
to  differ  from  each  other  in  color,  and  to  have  crystalline 
forms  which  have  been  accurately  determined  by  the 
study  of  large  crystals ;  (2)  that  we  have  hardly  begun  to 
look  for  them  in  steel ;  (3),  that  under  favorable  circum- 
stances, we  do  find  what  appear  to  be  distinct  minerals  in 
steel  (graphite,  Fe3C,  TiC  in  definite  crystals)  and  to  so 
great  an  extent  as  to  render  it  probable  that  these  or  simi- 
lar minerals  usually  exist,  but  that  being  opaque,  so  nearly 
alike  in  color,  and  in  such  minute  and  iiniformly  dis- 
tributed particles,  they  escape  observation.  la  considering 
segregation,  we  shall  see  that  when  steel  contains  con- 
siderable quantities  of  manganese,  phosphorus,  sulphur, 
etc.,  what  are  probably  distinct  minerals,  perhaps  even  of 
definite  chemical  composition,  form,  now  concentrating 
in  the  center  of  the  ingot,  now  liquating  from  its  exterior 
according  to  the  existing  conditions. 

If  these  views  be  correct,  then,  no  matter  how  accurate 


THE     METALLURGY     OF     STEEL. 


uud  extended  our  kuowh-'dgc  <;!.'  ultimate  composition,  and 
lio-.v  vast  the  statistics  on  wliiclionr  inferences  are  based, 
if  we  attempt  to  predict  mechanical  properties  from 
them  accurately  we  become  metallurgical  Wigginses.  For 
while  we  may  predict  that  siliceous  rocks  will  usually  be 
vitreous,  July  hot,  April  rainy,  and  phosphoric  steel 
brittle,  yet  when  we  go  farther  and  predict  accurately,  we 
state  what  is  not  inferable  from  our  premises.  It  may, 
and  sometimes  does,  snow  in  July  ;  Christmas  may  be 
warmer  than  Easter  ;  the  more  siliceous  may  be  less  vit- 
reous than  the  less  siliceous  rock;  and  the  more  phosphoric 
steel  tougher  than  the  less  phosphoric  one. 

And  here  it  may  be  observed  that  the  intimate  knowl- 
edge which  the  public  and  many  ncn-metallurgical  engi- 
neers attribute  to  metallurgists  as  to  the  effects  of  com- 
position on  physical  properties  has,  I  believe,  no  existence 
in  fact.  Many  steel-metallurgists  persuade  themselves 
from  wholly  insufficient  data  that  they  have  discovered 
the  specific  quantitative  effects  of  this  or  that  element ;  in 
other,  and  I  trust  few  cases,  in  metallurgy  as  in  medi- 
cine, the  charlatan  feigns  profound  knowledge,  dread- 
ing the  effect  on  his  client  of  acknowledged  though  una- 
voidable ignorance.  Many  an  experienced  steel-maker 
has  confidently  assured  me  of  such  and  such  specific  ef- 
fects, producing  when  challenged  a  few  analyses  uncon- 
sciously culled  from  those  which  opposed  his  view,  and 
shown,  on  comparison  with  a  larger  number,  to  be  with- 
out special  significance. 

When  we  confront  him  with  cases  which  upset  his 
theory,  he  calmly  replies  that  if  we  had  only  determined 
the  sulphur  as  well,  all  would  have  been  clear  ;  if  by  bad 
luck  this,  too,  is  known,  he  thinks,  probably,  that  nitrogen 
or  carbonic  oxide  may  affect  matters ;  or  possibly  he 
attaches  great  weight  to  oxygen,  which  he  can  always  fall 
back  on,  triumphantly  remarking  that  when  we  can  deter- 
mine this  element  the  problem  will  be  solved. 

Again,  it  it  is  our  ignorance  of  the  effects  of  the  rare  met- 
als, titanium,  vanadium,  or  what  not.  And  if  all  these  and 


all  gases  were  full}-  known  he  would  piobably  sigh  for  exact 
:irlcimination.s  of  some  millionths  of  osmium,  boron,  or 
rubidium.  Certain  he  is  that  chemistry  can  explain  all  if 
you  will  only  give  him  time.  So  it  may,  but  not  the 
chemistry  that  he  knows  ;  ultimate  analysis  never  will ; 
proximate  analysis  may,  but  by  methods  which  are  not 
yet  even  guessed  at,  and  in  the  face  of  fearful  obstacles. 

How  often  do  we  look  for  the  coming  of  the  master 
mind  which  can  decipher  our  undecipherable  results  and 
solve  our  insoluble  equations,  while  if  we  will  but  rub  our 
own  dull  eyes  and  glance  from  the  petty  details  of  our  phe- 
nomena to  their  great  outlines  their  meaning  stands  forth 
unmistakably  ;  they  tell  us  that  we  have  followed,  false 
clues,  and  paths  which  lead  but  to  terminal  morasses.  In 
vain  do  we  flounder  in  the  sloughs  and  quagmires  at  the 
foot  of  the  rugged  mountain  of  knowledge  seeking  a  royal 
road  to  its  summit.  If  we  are  to  climb,  it  must  be  by 
the  precipitous  paths  of  proximate  analysis,  and  the 
sooner  we  are  armed  and  shod  for  the  ascent,  the  sooner 
we  devise  weapons  for  this  arduous  task,  the  better. 

By  what  methods  ultimate  composition  is  to  be  deter- 
mined is  for  the  chemist  rather  than  the  metallurgist  to 
discover.  But,  if  we  may  take  a  leaf  from  lithology,  if 
we  can  sufficiently  comminute  our  metal  (ay,  there's  the 
rub  !),  by  observing  differences  in  specific  gravity  (as  in 
ore  dressing),  in  rate  of  solubility  under  rigidly  fixed 
conditions,  in  degree  of  attraction  by  the  magnet,  in 
cleavage,  luster,  and  crystalline  form  under  the  micro- 
scope, in  readiness  of  oxidation  by  mixtures  of  gases  in 
rigidly  fixed  proportions  and  at  fixed  temperatures,  we 
may  learn  much. 

Will  the  game  be  worth  the  candle?  Given  the  proxi- 
mate composition,  will  not  the  mechanical  properties  of 
the  metal  be  so  greatly  influenced  by  slight  and  undeter- 
minable changes  in  the  crystalline  form,  size,  and  arrange- 
ment of  the  component  minerals,  so  dependent  on  trifling 
variations  in  manufacture,  as  to  bo  still  only  roughly 
deducible  ? 


CHAPTER     II. 
CARBON  AND  IRON. — HARDENING,  TEMPERING,  AND  ANNEALING. 


§  3.  Iron  combines  with  carbon  in  all  proportions  up  to 
about  seven  per  cent,  absorbing  it  readily  when  in  contact 
at  or  above  a  red  heat  with  carbonaceous  matter,  such  as 
charcoal,  graphite,  and  even  diamond,  or  with  cast-iron, 
or  steel.  About  4'6  per  cent  of  carbon  appears  sufficient 
to  saturate  pure  iron.a 

The  presence  of  manganese  raises  the  point  of  satura- 
tion of  carbon  in  iron,  while  silicon  lowers  it.  Sulphur  is 
thought  to  lower  the  saturation  point  for  molten  iron,  but 
rather  to  raise  that  for  solid  iron — i.e.,  to  diminish  the 
total  carbon  which  iron  can  take  up,  but  to  increase  the 
proportion  of  that  total  carbon  which  during  cooling  re- 
mains chemically  combined,  in  both  these  ways  opposing 
the  formation  of  graphite. 


n  Rammelsberg  (Metallurgical  Review,  I.,  p.  176)  is  said  to  have  found  in 
Wootz  7'867  per  cent  carbon  wholly  combined,  0-136  silicon,  and  O'OOS  sulphur. 
But  this  is  surely  an  error. 


Carbon  has  a  remarkable  power  of  diffusing  itself 
through  iron,  tending  to  become  uniformly  distributed, 
not  only  through  the  different  portions  of  a  given  piece  of 
iron,  but  between  separate  pieces  of  iron  which  are  in 
contact  with  each  other.  Thus  Bell b  raised  the  percent- 
age of  carbon  contained  in  wrought-iron  from  0"04  to  0'39 
by  heating  it  in  contact  with  cast-iron.  Abel, c  by  heat- 
ing steel  disks  O'Ol  inch  thick  between  wrought-iron  plates 
reduced  their  carbon  from  about  1  per  cent  to  0"1.  This 
diffusing  power  of  carbon  is  not  confined  to  iron.  Mars- 
den*1  states  that  amorphous  carbon  in  impalpable  powder 
in  contact  with  porcelain  at  a  temperature  above  redness 
gradually  diffuses  into  the  porcelain  and  ultimately  per- 
meates it  throughout.  These  facts,  of  course,  clear  up 

b  "  Principles  of  the  Manufacture  of  Iron  and  Steel,"  p.  160. 

«  Iron,  1883,  I.,  p.  76. 

d  Jour.  Iron  and  Steel  List.,  1881, 1.,  p.  233. 


CHEMICAL    CONDITION    OF    CARBON. 


B 


the  mysteries  which  formerly  hung  aboiit  the  cementation 
of  steel. 

§  4.  THE  TOTAL  CAKBOX,  or  Saturation  Point  for 
Carbon. — The  quantity  of  carbon  -with  which  molten  iron 
can  combine  (=  combined  -f-  graphitic  carbon  of  the 
solidified  iron),  depends  chiefly  on  the  percentage  of  silicon, 
sulphur,  and  manganese  which  it  contains.  The  former 
two  elements  lower  the  saturation  point  for  carbon,  while 
manganese  raises  it. 

Chemically  pure  iron  can  app  urently  only  combine  with 
about  4'C3  per  cent  of  carbon.  Thus  E.  Riley  a  exposed 
pure  iron  imbedded  in  charcoal  for  two  cLivs  to 
a  steel-melting  temperature.  It  absorbed  only  a  little 
more  than  4  per  cent  carbon  ;  4'63  was  the  highest  per- 
centage of  carbon  that  either  Dick  or  IIochstatterb 
obtained  by  melting  sometimes  pure,  sometimes  nearly 
pure  iron,  with  an  excess  of  carbon  in  Percy's  laboratory. 
That  this  is  about  the  point  of  saturation  with  almost 
pure  iron  is  suggested  by  the  fact  that  when  in  these  ex- 
periments the  iron  contained  this  amount,  its  upper  sur- 
face was  covered  with  graphite  apparently  extruded  be- 
fore solidification,  even  when  the  iron  was  rapidly  cooled. 

§  £>.  MANGANESE  raises  the  point  of  saturation  for  carbon 
—that  is,  permits  higher  total  carbon.  Thus  ferro-man- 
ganese  (see  Table  20)  of  ten  contains  above  5  '5  per  cent,  and 
occasionally  7  per  cent.  Ledebur0  considers  that,  with 
increasing  manganese,  the  saturation  point  for  carbon 
rises  as  follows  : 


Manganese lOtoSO 

Corresponding  saturation  point  for  carbon. 5 


55 


50 
6 


6f, 
0-3 


80 
7 


7.3 


§  6.  SILICON  probably  lowers  the  saturation  point  for 
carbon.  Thus,  in  Fig.  1  we  note  that  the  total  carbon  for 
those  irons  which  are  apparently  saturated  with  it  (/.  e. 
those  which  have  the  highest  "total  carbon"  spots  for 
given  silicon)  closely  follow  the  broken  line  C  +  £f  Si  =  6. 

As  12  and  23  are  the  atomic  weights  of  carbon  and 
silicon,  we  may  believe  with  Stockman*1  that  silicon  ordi- 
narily displaces  carbon  atomically  from  irons  already  satur- 
ated with  it.  Yet  the  above  formula  does  not  represent 
absolute  saturation,  since  we  find  that  in  Nos.  28  and  29  in 
Table  1,  the  value  C  +  \  f  Si  rises  to  7'08  and  7'39.  In  No. 
11,  in  Table  20,  this  value  reaches  7'02. 

Thus  sulphur  and  manganese  oppose  each  other,  the  one 
lowering,  the  other  raising  the  saturation  point  for  carbon, 
This  is  illustrated  by  Nos.  20,  25,  £4  and  26,  Table  1,  which 
though  rich  in  manganese  have  only  3  per  cent  jc.rbon  or 
less,  while  in  non-siliciferous  ferro-manganese  the  carbon 
usually  runs  up  to  4,  5  or  even  6  per  cent. 

§  7.  SDLPIIUB  in  large  quantity  appears  to  lower  the 
saturation  point  for  carbon.  Thus  Weston  e  adding  small 
quantities  of  FeS  to  graphitic  cast-iron  with  4'5  per  cent 
C,  obtained  irons  whose  carbon,  always  much  less  than  in 
the  initial  iron,  fell  as  their  sulphur  rose,  thus : 


Sulphur 2-13 

Carbon 3'17 


I -68 
3L90 


1-313  (?) 
3-60 


That  the  sulphur  by  its  presence  actually  expelled  car- 
bon is  indicated  by  the  fact  that  graphite  separated  from 
the  iron  apparently  while  molten,  in  certain  cases  floating 
on  its  surface. 


a  Jour.  Iran  and  Steel  Inst.,  1S77, 1.,  p.  163. 

b  Percy  :  "  Iron  end  Steel,"  p.  113-111. 

c  •'  Handbuch  der  Eisenhuttenkunde,"  p.  233. 

d  Stahl  und  Eisen,  1883,  IV.  ;  Jour.  Iron  and  St.  Inst.,  1883,  pp.  415,  7CO. 

e  Percy:  "Iron  and  Steel,"  p.  135. 


That  moderate  amounts  of  sulphur  (0*45  percent),  do  not 
necessarily  lower  the  sal  urat  i<  ;n  point  for  carbon,  is  shown 
by  Karsten's  experiment.  Melting  gray  iron  (with  3'31  of 
graphite  and.  •<;•_'."'>  combined  =3*94 total G and '03 per oentS) 
with  sulphur,  part  of  the  iron  united  with  the  sulphur  to 
form,  a  sulphide  which  did  not  coalesce  with  the  remainder 
of  the  iron :  the  carbon  of  the  latter,  by  the  elimination 
of  part  of  its  iron,  rose  to  5 '488  C  (wholly  combined), 
though  its  sulphur  had  risen  to  0-45  per  cent.  It  is  ii;;t 
probable  that  the  high  carbon  content  of  this  iron  wr.s  due 
to  the  presence  of  a  large  quantity  of  manganese,  for  the 
carbon  of  the  initial  iron  was  almost  wholly  graphitic; 
had  it  been  manganiferous  its  carbon  would  hav^  been 
combined.  It  appears  that  therefore  0'45  per  cent  S  had 
actually  raised  the  saturation  point  for  C.  (For  the  effect 
of  sulphur  on  the  condition  of  carbon  see  §  20.) 

§  8.  THE  CONDITION  OF  CARBON  IN  IKON. — Carbon  may 
exist  in.  iron  (A)  mechanically  mixed  with  it  as  graphite, 
or  (B)  in  chemical  combination  with  the  iron,  or  (C)  in 
chemical  combination  with  some  third  element  contained 
in  the  iron,  or  (D)  in  solution,  if  we  admit  that  solution 
differs  from  combination. 

A.  GKAPIIITE  occurs  most  characteristically  in  highly 
carburized  cast-iron,  long  exposed  to  a  temperature  ap- 
proaching fusion.     As  its  tenacity  is  very  low,  it  has  little 
influence  on  the  physical  properties  of  the  iron  beyond 
destroying  its  continuity,  thus  lowering  its  tensile  and 
compressive  strength  and  ductility. 

B.  CHEMICALLY  COMBINED  WITH  IRON. — Carbon  exists 
in  combination  with  the  iron  in  at  least  two  perfectly 
distinct  modifications.      Let  us  first  review  the  evidence 
which  shows  that  they  are  really  distinct. 

Evidence  of  Two  Conditions  of  Combination  of  Carbon, 

and  Iron, 

§  9.  CHEMICAL  EVIDENCE. — Faraday  in  1822  first  showed 
that  steel,  which,  when  suddenly  cooled,  dissolved  com- 
pletely in  hydrochloric  acid,  when  annealed  left  a  car- 
bonaceous residue  when  thus  dissolved.' 

Caron  obtained  like  results.  Rinman,  in  Ifc65,  observ- 
ing that  the  quantity  of  carbon  remaining  undissolved 
when  one  and  the  same  steel  was  attacked  by  cold  HC1  dif- 
fered greatly,  being  greatest  in  unworked  steel,  and  small- 
est in  hardened  steel  (which  sometimes  yielded  little  or 
no  carbonaceous  residue)  named  the  carbon  which  dis- 
solved hardening  carbon,  because  chiefly  found  in  har- 
dened steel,  and  that  which  did  not  cement  carbon,  because 
he  found  it  chiefly  in  cement  or  blister  steel. 

Karsten*  recognized  that,  in  addition  to  the  condition 
of  graphite  and  that  of  combination  seen  in  hardened  steel, 
carbon  existed  in  a  third  state,  which  he  regarded  as 
a  polycarbide  of  unknown  composition.  From  his  de- 
scription of  its  properties  and  the  conditions  under  which 
it  was  formed,  it  is  probable  that  his  polycarbide  was 
identical  with  Rinman' s  cement  carbon. 

Abel,  whose  results  are  by  far  the  most  valuable,  by 
dissolving  different  steels  in  a  ''chromic"  soluticn  (ob- 
tained by  adding  sulphuric  acid  to  an  aqueous  solution  of 
potassium -bichromate),"  whether  after  annealing,  harden- 
ing,  or  tempering,  obtained  varying  quantities  of  a  heavy, 


*  Percy  :  "Iron  and  Gtec!.'' 

B  Idem,  p.  128. 

h  Iron,  1883,  I.,  p.  70,  and  1885,  I.,  p.  115. 


8 


THE    METALLURGY     OF     STEEL. 


gray-black,  spangly  carbide  of  iron  as  a  carbonaceous 
insoluble  residue,  attracted  by  the  magnet,  and  of  nearly 
constant  composition,  closely  approaching  that  of  the 
formula  Fe3C.  The  steels  examined  were  almost  free  from 
graphite.  The  proportion  of  the  total  combined  carbon 
found  in  this  insoluble  carbide  varied  from  4 '7  per  cent  in 
hardened  steel  to  92'8  per  cent  in  certain  annealed  steel, 
/.  e.,  in  hardened  steel  nearly  all  the  carbon  was  soluble 
in  his  chromic  solvent,  in  annealed  steel  hardly  any  of  it 
was.  Unannealed  steel  yielded  slightly  less  Fe3C  than  that 
which  had  been  annealed,  while  tempered  steel  yielded  an 
amount  intermediate  between  that  of  hardened  and  that 
of  annealed  steel,  the  proportion  of  carbide  in  tempered 
steel  being  in  general  higher  the  more  strongly  and  the 
longer  the  steel  had  been  heated  before  tempering. 

The  carbide,  whose  composition  wras  similar,  not  only 
in  the  same  steel  after  different  treatment  (hardening, 
annealing  and  tempering),  but  in  different  steels  as  well, 
contained  a  small  quantity  of  water  (carbon-hydrate?), 
say  0'77  to  3 '23  per  cent,  probably  arising  from  the 
partial  decomposition  of  the  carbide  by  the  chromic  sol- 
vent. 

The  carbide  Fe  3  C  is  dissolved  by  hot  HC1  nearly,  or  per- 
haps quite  completely.  The  impossibility  of  discrimin- 
ating sharply  between  it  and  the  small  quantity  of 
graphite  (?)  with  which  it  is  mixed,  together  with  the 
slight  decomposition  of  the  carbide  itself  by  the  chromic 
solvent  by  which  it  is  separated  from  the  mass  of  the  iron, 
are  probably  the  chief  causes  of  the  slight  variations 
observed  in  its  composition.  When  obtained  by  means 
of  a  chromic  solution  whose  strength  was  not  so  great  as 
to  largely  decompose  the  carbide  itself,  it  contained  from 
6 '39  C  to  8 '09  C,  a  varying  proportion  of  which  was  proba- 
bly graphite.  Fe3C  should  contain  6'57  C. 

Muller,  on  dissolving  Bessemer  steel  in  dilute  sulphuric 
acid,  obtained  a  carbide  of  iron  as  a  pyrophoric  residue 
containing  6 '01  to  7'3S  per  centC,  and  thus  closely  resem- 
bling Abel's  Fe3C. 

Muller' s  carbide  residue,  however,  only  contained  from 
19  to  73  per  cent  of  the  total  carbon  of  the  steel,  while 
Abel's  had  a  much  larger  proportion,  and  differed  from 
Muller' s  in  not  being  pyrophoric.8 

To  sum  up,  many  investigators  have  distinguished  two 
modifications  of  combined  carbon,  a  more  and  a  less 
readily  soluble  modification.  Both  clearly  differ  from 
graphite  in  being  soluble  in  boiling  hydrochloric  acid. 
The  less  soluble  of  the  two  is  insoluble  or  partly  so  in 
dilute  cold  acids,  sulphuric,  hydrochloric,  and  according  to 
Woodcock,  in  nitric,  as  well  as  in  Abel' s  chromic  solution. 
The  more  readily  soluble  of  the  two  dissolves  completely 
in  these  solvents.  To  fix  our  ideas,  I  shall,  after  Einman, 
provisionally  call  the  more  soluble  hardening  carbon,  as  il 
predominates  in  hardened  steel,  and  the  less  soluble,  ce- 
ment carbon,  and  I  shall  speak  of  the  combination  between 
cement  carbon  and  iron  as  Abel's  carbide,  Fe3C.  In  adopt- 
ing these  names  as  those  best  known,  I  recognize  fully 
that  each  of  these  modifications  may  actually  comprise 
several  yet  undistinguished  varieties,  and  that  the  less 
readily  soluble  portions  obtained  by  different  experiment 
ers  and  by  different  solvents  may  not  be  i  dentical.  Still, 
each  of  these  two  modifications  has  strongly  distinctive 


haracteristics,  and,  if  it  be  subdivisible  into  varieties,  the 
varieties   of  each   species   possess  in  common  a  similar 
hemical  behavior,  and  similar  effects  on  the  properties  of 
the  iron  which  contains  them. 

So,  too,  I  adopt  the  formula  Fe3C  provisionally,  recog- 
nizing that  the  cement  carbon  which  it  contains  may  not 
xist  in  the  iron  as  Fe3C,  but  merely  in  a  condition  which 
on  solution  yields  Fe3C,  but  that  none  the  less  it  differs 
in  this  respect,  as  in  its  comparative  insolubility,  from 
hardening  carbon. 

§  10.  MICROSCOPIC  EVIDENCE.' — -With  a  power  of  G50 
linear,  Sorby,b  a  very  trustworthy  observer,  finds  in 
unhardened  steel  a  mass  of  crystals,  say  0.001  inch  in 
diameter,  with  their  faces  covered  with  fine  stria?,  say 
oJ-inr  inch  apart,  due  to  the  fact  that  each  crystal  is 
composed  of  minute  parallel  layers  of  two  wholly  dif- 
ferent substances,  a  softer  one  in  layers  about  roimr 
inch  thick,  and  a  very  hard,  brittle  one,  in  layers 
about  Toi'inr  inch  thick,  interstratified  with  the  first :  and 
he  has  apparently  completely  satisfied  himself  by  very 
prolonged  investigation  that  the  materials  which  compose 
these  alternate  layers  are  of  widely  different  physical 
properties.  His  very  brief  paper  does  not  give  his  evidence 
in  detail,  but  he  says  (apparently  as  a  sample  of  it)  "in 
partially  decarbonized  white  cast-iron"  these  "plates 
are  sufficiently  thick  to  show  perfectly  well  that  the 
hard  plates  are  continuous  with  portions  of  the  original 
hard  white  constituent,  and  the  soft  plates  continuous 
with  the  soft  malleable  iron  free  from  carbon,  produced 
by  decarbonization.  These  two  substances  differ  greatly." 

The  soft  layers  he  regards  as  composed  of  soft  car- 
bonless iron :  we  may  provisionally  regard  the  hard 
ones  as  composed  of  Fe3C  ;  and  for  brevity,  I  shall  refer 
to  them  by  this  name,  recognizing  that  they  have  not 
yet  been  directly  proved  to  be  Fe3C.  He  finds  that  at  a 
very  high  temperature  these  components  unite  to  form 
an  intermediate  compound  (/.  e.,  the  C  becomes  hardening 
C  ?),  which  by  long  exposure  to  a  lower  but  still  high 
temperature  (annealing)  splits  up  again  into  the  former 
parallel  layers,  or  if  exposed  long  enough  to  this  tem- 
perature they  ' '  segregate  into  comparatively  thick  and 
irregular  plates"  (of  Fe3C?)  "and  aggregations  of  pure 
Fe ; "  while  if  suddenly  cooled  (as  in  hardening)  from  a 
very  high  temperature,  the  intermediate  compound  appar- 
ently has  not  time  to  split  up,  at  least  he  finds  no  evi- 
dence that  it  has,  and  no  trace  of  what  I  have  supposed 
to  be  Fe3C.  Apparently  this  intermediate  compound, 
formed  at  a  high  temperature,  split  up  at  a  lower 
one,  but  retained  undecomposed  by  sufficiently  rapid 
cooling,  is  Fe  united  with  hardening  C.  The  hard  plates 
(Fe3C)  are  absent  from  practically  carbonless  iron,  and 
increase  in  quantity  Tinder  like  conditions  as  the  com 
bined  carbon  increases. 

§  11.  ACCORD  OF  CHEMICAL,  MICROSCOPIC,  AND  PHYSI- 
CAL PHENOMENA. — Microscopic  and  chemical  evidence 
here  agree  in  detecting  a  substance  (Fe3C)  absent  from 
wr-ought  and  ingot-iron  and  hardened  steel,  found  in 
greatest  quantity  in  annealed  steel,  clearly  differing  from 
pure  Fe,  from  the  Fe  and  C  of  hardened  steel,  and  from 
graphite.  Considering  now  steel  of  say  1  per  cent  total 
combined  carbon  in  its  hardened,  tempered,  and  annealed 


i  Iron,  1885, 1.,  p.  116,  and  Zeit.-Ver.  Deutsch.  Ingen.,  XXII.,  385,  1878. 


b  Journal  of  the  Iron  and  Steel  Institute,  1886,  p.  143. 


THE    CONDITION    OF    CARBON    IN    IRON. 


states,  together  with  ingot  iron,  we  may  condense  the  re- 
sults of  observations  into  the  following  table  • 


PRODUCT. 

Chemical  analysis  shows 

Microscope  shows 

Physical   tests 
show    hard- 
ness       and 
strength. 

l'Y:,C. 

Combination    of     Fe 
with  hardening  C. 

Fe3C? 

Other  iron 

Hardened  stool  . 
Tempered    "   . 
Annealed     "   . 
Softest              I 

o-o 

7'5± 
15-0  ± 
\  almost 
j  none. 

Fe. 
99 

93 

85 

99-95 

c.  • 

1 
0-5 
0 

0-05 

Sum" 
100 
93-5 

85 

100 

0 

88  ± 

0 

100 

"(if± 
100 

highest 
next  highest 
much  lower 

lowest 

Ingot-iron  .  .  .  f 

These  four  products— (1)  hardened,  (2)  tempered,  (3)  an- 
nealed steel,  and  (4)  ingot  iron,  are  composed  of  four  ele- 
ments, sometimes  singly  present,  sometimes  mixed,  viz.: 

1.  Pure  carbonless  iron,  very  soft. 

2.  Fe3C,  reported  by  Sorby  as  very  hard  and  brittle. 

3.  A  compound  of  Fe  with  hardening  0  in  the  ratio  of 
about  00  :  1,  almost  the  sole  component  of  hardened  steel, 
naturally  supposed  to  be  very  hard  and  strong. 

4.  A  similar  compound  with  the  ratio  92  Fe  :  0-5  C  — 
99-43  Fe  :  0'54  G.  Having  only  about  half  the  hardening  C 
which  the  preceding  compound  has,  it  is  naturally  sup- 
posed to  be  much  less  hard  aud  strong. 

Now  HARDENED  STEEL,  composed  almost  solely  of  com- 
pound 3,  should  be,  as  it  is,  extremely  hard  and  strong. 
TEMPERED  STEEL,  a  mixture  of  92 '5  per  cent  of  the  much 
softer  and  weaker  substance,  No.  4,  as  matrix  with  7 '5  per 
cent  of  the  hard  brittle  substance,  No.  2,  should  be,  as  it  is, 
much  less  strong  and  hard,  the  presence  of  only  7'5  per 
cent  of  the  hard  Fe3C  by  no  means  compensating  for  the 
reduced  strength  and  hardness  of  the  matrix. 

ANNEALED  STEEL,  consisting  of  a  matrix  of  soft  carbon- 
less iron,  which  constitutes  85  per  cent  of  the  mass,  with 
15  per  cent  of  the  hard  brittle  Fe3C  crystallized  within  it, 
should  be,  as  it  is,  still  much  softer  and  weaker,  as  even 
15  per  cent  of  Fe3C  mechanically  interspersed,  no  matter 
how  hard  we  may  suppose  it,  could  not  be  expected  to 
bring  up  the  strength  and  hardness  of  ingot  iron  to  that 
of  tempered  steel.  Fifteen  percent  of  quartz  disseminated 
through  steatite  can  not  bring  the  hardness  of  the  whole 
up  to  that  of  feldspar,  though  it  certainly  will  raise  it, 
as  a  comparatively  small  amount  of  tough  hornblende  in 
granite  raises  the  toughness  of  the  mass  sensibly. 

SOFT  INGOT  IRON,  finally,  should  be,  as  it  is,  the  softest 
and  weakest  of  all,  for  it  consists  almost  solely  of  sub- 
stance 1,  pure  carbonless  iron.  This  remarkable  accord 
between  the  results  of  chemical,  microscopic,  and  physical 
examination  ;  the  wonderful  difference  between  the  physi- 
cal properties  of  hardened  and  unhardened  steel,  corre- 
sponding as  it  does  to  such  marked  differences  in  the 
characters  of  their  respective  components  as  revealed  by 
the  microscope,  and  in  the  chemical  behavior  of  their  com- 
bined C ;  the  correspondence  between  the  intermediate 
strength  of  tempered  steel  and  the  chemical  behavior  of 
its  combined  C ;  the  chemical  and  the  almost  certain 
microscopic  isolation  of  a  definite  compound  of  Fe  with 
C  found  copiously  in  annealed  steel,  but  practically  absent 
from  hardened  stesl  and  soft  iron  ;  these,  taken  together, 
leave  in  my  mind  no  shadow  of  a  doubt  that  we  have  in 
steel  at  least  two  distinct  states  of  combination  of  carbon 
which  exercise  widely  different  effects  on  the  properties 
of  the  metal.  The  supposition  that  the  brittle  Fe3C  is 


a  This  is  the  sum  of  the  hardening  carbon  plus  the  iron  united  with  it  and 
excludes  the  FeaC. 


simply  mechanically  mixed  with  the  remainder  of  the  iron 
is  wholly  compatible  with  the  malleableness  of  the  whole ; 
we  have  a  parallel  case  in  a  copper  ingot  which  Percy  de- 
scribes," which  was  malleable,  though  it  contained  22  per 
cent  of  tungsten,  which  he  states  was  certainly  simply 
mechanically  diffused  through  the  copper. 

§  12.  EVIDENCE  OF  OTHER  COMBINATIONS  OF  CARBON 
WITH  IRON.— Dudley"  in  certain  cast-irons  distin- 
guishes besides  graphite  two  forms  of  carbon,  one 
combined  with  iron  to  form  a  gray  carbide,  the  other 
.apparently  quite  distinct  from  this  carbide.  To  the 
latter  he  gives  the  name  strength  carbon.  Unfortu- 
nately he  has  neither  determined  the  quantity  nor 
the  composition  of  this  carbide.  Whether  either  of  the 
forms  of  combined  carbon  which  he  distinguishes  are 
identical  with  those  distinguished  by  Abel  in  steel  is  un- 
certain. As  they  have  not  been  recognized  in  steel,  they 
are  not  of  especial  moment  for  our  present  purpose. 

The  endeavors  of  several  investigators  to  prove  the  ex- 
istence of  other  definite  combinations  of  iron  and  carbon 
have  not  been  supported  by  sufficient  evidence  to  com- 
mand general  acquiescence.  Tuuner  (Ledebur,  Handbuch, 
p.  240),  regarded  the  combined  carbon  as  in  the  condi- 
tion of  Fe4C,  which  in  iron  with  but  little  carbon  was 
mixed  with  pure  iron.  Gurlt  regarded  gray  cast-iron  as 
an  octocarbide  mixed  with  graphite,  and  white  cast-iron 
as  a  tetracarbide,  formed  at  a  low  heat  and  resoived  at  a 
higher  one  into  octocarbide  and  graphite. 

§  13.  COMPOUNDS  OF  C  WITH  ELEMENTS  OTHER  THAN 
IRON. — S.  A.  Ford  on  dissolving  cast-iron  in  boiling  HC1 
in  an  atmosphere  of  CO3  obtains  a  flocculent  yellowish 
residue,"  decomposed  by  hot  potash  solution  with  separa- 
tion of  a  black  varnishlike  mass  (separated  carbon  ?).  He 
regards  it  as  a  compound  of  carbon  and  silicon. 

Shinier, d  on  dissolving  cast-iron  in  HC1,  finds  in  the 
residue  minute  non-magnetic  cubes,  usually  perfect,  y-jVs  to 
T^T  inch  thick  ;  Sp.  Gr.  5'1  ;  soluble  in  HN03 ;  unaffected 
by  HC1,  (apparently)  by  strong  boiling  caustic  potassa,  and 
by  prolonged  heating  at  bright  redness  in  H  ;  and  consist- 
ing of  TiC,  with  12  per  cent  of  apparently  mechanically 
mixed  foreign  matter. 

§  14.  THERMAL  RELATIONS  OF  THE  COMPOUNDS  OP  CAR- 
BON AND  IRON. — Osmund's  e  results  indicate  that  when 
iron  and  carbon  unite  heat  is  evolved,  as  in  the  formation  of 
so  many  other  chemical  compounds.  They  suggest,  though 
equivocally,  that  more  heat  is  evolved  when  carbon  com- 
bines with  iron  in  the  cement  state  than  when  it  unites 
with  it  in  the  hardening  state.  Troost  and  Hautefeuille'  s ' 
results  appear  to  directly  contradict  these,  and  indicate 
that  the  combination  of  iron  and  carbon  is  attended  by 
absorption  of  heat,  as  in  the  formation  of  explosive  com- 
pounds. The  matter  appears  to  need  further  investiga- 
tion. Osmund's  results  are  as  follows : 

RISE  OP  TEMPERATURE,  ON  DISSOLVING  IRON. 


Percentage  of  carbon. 

Absolute  rise  of  tem- 
perature in  de- 
grees centigrade . . 

Rise  of  temperature  , 
relative  to  that  of  -; 
the  annealed  state.  ( 


Annealed 

Cold-forged  . . 

Hardened 

Annealed 

Cold-forged  . 
Hardened   . . . 


0-17 
3-151 


0-54 

2-111 

2-3073-018 

2-3333-056 

1 

1-045 

1-0521-084 


1-17  tool  steel. 


1.419 


I  white 
1  cast-iron 


1-632 
1 


-1-150 


a  Journal  of  the  Iron  and  Steel  Institute,  1885,  Vol.  I.,  p.  34. 

b  Trans.  Am.  Inst.  Mining  Engineers,  XIV.,  1886,  p.  798. 

c  Idem,  XIV.,  1886,  p.  939. 

d  Idem,  1887,  XV. 

e  Uomptes  Rendus,  C.,  1885,  pp.  1328,  1231. 

t  Metallurgical  Review,  Vol.  I.,  p.  177. 


THE    METALLURGY    OP    STEEL. 


Both  in  annealed  and  hardened  steel  the  higher  the  car- 
bon the  less  heat  is  evolved  when  the  metal  is  dissolved 
in  a  calorimeter,  lience  it  is  inferred  that  splitting  up  the 
union  between  iron  and  carbon  causes  an  absorption  of 
heat,  and  consequently  that  their  union  had  been  accom- 
panied by  evolution  of  heat. 

In  each  case  the  hardened  metal,  with  its  carbon  largely 
in  the  hardening  state,  gives  out  more  teat  than  when 
annealed,  and  with  its  carbon  chiefly  in  the  cement  condi- 
tion. Thi3  might  be  thought  to  imply  that  the  passage  of 
carbon  from  the  cement  to  the  hardening  state  was  accom- 
panied by  absorption  of  heat,  were  it  not  (1 )  that  the  heat 
evolved  by  cold-forged  steel  exceeds  that  evolved  by 
annealed  steel  almost  as  much  as  that  evolved  by  hardened 
steel  does  ;  and  Abel  lias  shown  that  cold-forging  does  not 
cause  carbon  to  pass  to  the  hardening  state :  and  (2)  that 
the  excess  of  heat  evolved  from  hardened  over  that 
evolved  from  annealed  steel  is  far  from  being  pro- 
portional to  the  percentage  of  carbon.  In  case  of  cold- 
forged  steel  this  excess  is  the  same  whether  0'17  or  0-54 
per  cent  C  is  present,  and  in  the  case  of  hardened  steel  it 


is  only  GO  per  cent  greater  with 
cent  C.     These  anomalies  suggest 


17  than  with  0'54  per 
that  the  variations  in 


the  evolution  of  heat  caused  by  hardening,  annealing, 
etc.,  are  due  to  some  other  effect  than  the  variations  in 
the  condition  of  carbon. 

Troost  and  Hautefeuille  found  that  carburetted  iron 
evolved  more  heat  when  dissolved  than  iron  nearly  free 
from  carbon. 

§  15.  THE  DISTRIBUTION 


OF  THE  CARBON  between  the 


CEMENT  vs.  HARDENING  CARBON. — The  conditions 
under  which  carbon  passes  from  the  cement  to  the  harden- 
ing condition  and  back  are  so  complex  that  the  influence 
of  the  total  percentage  of  carbon  on  the  proportion  of 
the  combined  carbon  which  passes  into  the  cement 
and  the  hardening  state  respectively  is  masked  by  the 
influence  of  other  variables.  It  probably  cannot  be  traced 
without  further  experimental  evidence.  The  softness  of 
graphitic  cast-iron  suggests  that,  when  the  total  carbon 
is  very  high,  the  combined  carbon  passes  rather  into  the 
cement  than  the  hardening  state.  The  graphite  indeed 
lessens  the  strength  and  hardness  of  the  iron  as  a  whole, 
but  we  can  hardly  ascribe  to  it  the  softness  of  the  indi- 
vidual crystals  which  we  observe  ;  these  it  simply  encom- 
passes. But  the  occurrence  of  the  carbon  in  such  iron  in 
the  cement  state  may  be  due  to  other  causes  than  the 
total  percentage  of  carbon  ;  for  example,  to  the  presence 
of  silicon,  slow  cooling,  etc. 

§  17.  EFFECTS  OF  SILICON,  SULPHUR  AND  MANGANESE 
ON  THE  PROPORTION  OF  GRAPHITE  TO  TOTAL  COMBINED 
CARBON. — In  general,  silicon  forces  carbon  out  of  combina- 
tion and  into  the  graphitic  state  ;  manganese  and  sulphur 
(and  perhaps  phosphorus)  have  the  opposite  effect,  favoring 
the  retention  in  the  combined  state  of  all  the  carbon  which 
the  iron  contains. 

§  18.  SILICON  appears  not  only  to  oppose  the  union  of 
carbon  with  molten  iron,  bat  (at  least  when  present  in 
quantities  exceeding  1'37  per  cent)  to  oppose  to  a  still 
higher  degree  its  union  with  solid  iron,  to  force  the  carbon 
out  of  combination  and  into  the  graphitic  state.  Graphitic 
cast-irons  generally  contain  much  silicon ;  if  this  be  re- 
moved they  become  white,  and  their  graphite  is  converted 
into  combined  carbon.  Thus,  in  the  Bell-Krupp  purifying 
process  (pig  washing),  if  a  highly  graphitic  iron  be  melted 
and  brought  in  contact  with  iron-oxide,  nearly  the  whole 
of  its  silicon  is  oxidized  before  any  considerable  percent- 
age of  carbon  has  been.  If  the  iron  be  removed  and 
allowed  to  solidify  after  biit  a  brief  contact  with  the  oxide, 
it  is  found  to  have  become  perfectly  white. 

In  the  old  finery  process  the  same  conversion  of  gray 
into  white  iron  occurs.  It  may  be  observed  in  the  Bessemer 
process,  in  which  the  iron,  after  it  hao  been  blown  but  a 
few  minutes,  during  which  much  of  its  silicon  but  very 
little  of  its  carbon  is  removed,  becomes  white.  A  spiegel 
with  5'39  per  cent  Mn  and  0-37  Si,  which  Percy  melted 
in  a  clay  crucible,  took  up  2 '9 1  per  cent  Si  from  the  cru- 
cible and  became  gray." 

If  we  examine  cast-irons  which  are  tolerably  well  satu- 
rated with  carbon  and  silicon  we  find  that,  as  the  silicon 
rises  the  total  carbon  (which  is  the  percentage  with  which 
the  iron  combines  when  molten)  falls,  while  the  combined 
carbon  (the  percentage  which  the  iron  is  able  to  retain  in 
combination  after  solidifying)  falls  still  more  rapidly,  at 
least  when  the  silicon  exceeds  1'37  percent.  Hence  the 
ratio  of  graphite  to  combined  carbon  rises  rapidly  with  the 
rising  silicon,  so  rapidly  indeed  that,  for  a  while,  the  ab- 
solute percentage  of  graphite  actually  rises,  in  spite  of  the 
decline  in  the  total  carbon,  though  later  the  graphite  in 
turn  declines.  Some  of  these  effects  may  be  traced  in 
cent  carbon  we  can  still  find  graphite,  but  the  amount  is  Table  1  and  Fig.  1.  We  may  consider  them  under  two 
small,  while  the  separation  of  graphite  from  ingot  iron  heads,  (A)  Turner's  results  and  (B)  the  others.  Consider- 
would  probably  be  difficult  if  not  impossible.  ing  the  latter  first,  we  note  that  passing  in  Table  1  from 

b  Akermaii :  Engineering  and  Mining  Journal,  I.,  1875,  p.  888. 


graphitic,  cement,  and  hardening  conditions,  /.  e.,  the  pro- 
portion of  the  total  C  found  in  each  state,  depends  chiefly, 
1,  on  the  total  amount  of  carbon  present ;  2,  on  the  con- 
ditions under  which  the  iron  has  been  exposed  to  a  high 
temperature  and  subsequently  cooled ;  3,  on  the  presence 
of  certain  other  elements,  notably  sulphur,  silicon,  and 
manganese;  4,  perhaps  on  other  imperfectly  understood  con- 
ditions. Akerman,  Caron  and  Barba  consider  that  pressure 
causes  carbon  to  pass  from  the  cement  to  the  hardening 
condition  even  at  low  temperatures  ;  but  this  conclusion  is 
not  warranted  by  their  evidence,  and  is  strongly  opposed  by 
Abel's"  demonstration  that  in  ordinary  cold-rolled  steel 
almost  all  the  carbon  is  in  tho  cement  state  in  spite  of  the 
enormous  pressure  which  arises  in  cold  rolling.  (See  §  56.) 

IN  GEXERAL  the  formation  of  graphite  is  favored  by  a 
high  total  percentage  of  carbon,  by  long  exposure  to  a 
very  high  temperature  (say  1,500°  C.),  and  by  the  pres- 
ence of  silicon ;  and  it  is  opposed  by  the  presence  of 
sulphur  and  manganese.  The  formation  of  cement  carbon 
is  favored  by  slow  cooling,  and  that  of  hardening  car- 
bon by  rapid  cooling,  from  a  red  heat. 

§  16.  EFFECT  OF  TOTAL  PERCENTAGE  OF  CARBON. — 
GRAPHITE  vs.  COMBINED  CARBON.  Under  like  conditions, 
the  more  carbon  is  present  the  larger  apparently  is  the 
proportion  of  the  total  which  escapes  from  combination 
and  becomes  graphitic.  Witness  the  readiness  with  which 
under  favorable  conditions  70  per  cent,  and  even  occa- 
sionally 90  per  cent  of  the  total  carbon  becomes  graphitic 
in  highly  carburetted  cast-iron.  In  steel  with  say  1  per 


»  Trans,  Institution  Mechanical  Engineers,  1881,  jj.  696. 


INFLUENCE    OF     OTHER    ELEMENTS     ON    THE    CONDITION     OF     CARBON. 


TABLE  1.— SILICON  AND  CARBON. 


c 
1 

a 
2 

c 
3 

a 
4 

c 
5 

a 
6 

a 

7 

a 

8 

a 
9 

a 

10 

c 
11 

c 

12 

a 
13 

d 
14 

a 
15 

h 

16 

r<> 

1-90 

1-85 

1-71 

0-56 

0-68 

0-80 

0-20 

0'37 

0-79 

0'38 

o-io 

0'24 

0-60 

1  62 

1-19 

1-43 

1'81 

1"66 

2'59 

Total  carbon  

;>••;» 

1'98 

5-79 

2-00 

5-69 

2-09 

2-21 

3-18 

1-87 

223 

4-68 

i-66 

2'01 

8-86 

2-03 

:(•:(« 

0-12 

0'19 

0'43 

0'45 

0-87 

0-96 

1-37 

l-.Mi 

8-61 

2-96 

3-30 

:(•:<.-> 

3'92 

4-58 

4-74 

5-1:5 

Manganese  

70-10 

0-1  .' 
0-3!; 

68-64 

0-21 

e-33 

T).*>o 

<  ,'  .  <> 

0-88 

0-33 

0-:i( 

0-60 

0-28 

0-7." 

c-ro 

o:>,l 

141  1 

48-20 

0-84 
0-33 

27-13 

0-95 
0-30 

0-77 
1'12 

C'OC 

0'05 

0-04 

01  . 

0-03 

OQ.j 

004 

0-03 



0"05 

0'17 

h 

17 

h 

13 

b 
10 

d 

£J 

a 
Cl 

c 

22 

d 
,'.3 

c 
24 

b 
25 

d 
26 

a 

27 

& 

e 
29 

& 

391 

0'71 

o-oo 

0-58 

0-38 

()•<«) 

0-69 

0 

0 

8-68 

;  »-,SS 

S'38 

1  '48 

1-94 

1-12 

0-60 

o 

o 

'.',     ':','.! 

2  '88 

2'96 

3-01 

1'86 

242 

2'13 

2-72 

l",l! 

1-74 

1-81 

0-79 

o 

o 

5-13 

5'47 

5-92 

6-72 

7'33 

8-33 

8-81 

9-19 

9-80 

9-75 

9-80 

15-10 

1538 

20 

23 

o-so 

1'54 

1-C9 

!25-70 

1-GO 

2-11 

•28-s:) 

24-30 

1-20 

30-14 

1  '.15 

3-43 

1-12 

0-60 

0  14 

029 

0-11 

0-21 

0-11 

Sul?>hur.  .. 

0-33 

0-04 

0-03 

0-03 

0-02 

0-04 

009 

a,  T.  Turner,  Jonr.  Iron  and  St.  Inst.,  1886,  I.,  p.  174  ;  6,  Zaboudsky,  Idem,  1884,  T.,  p.  298  ;  c,  Mem,  1883,  II.  jj.  780  ;  d.  Stockman,  Idem,  18aS.  I.,  p.  415  ; 
e,  Percy,  Idem,  1877,  1.,  p.  1G4  ;  /,  Lawrence  Smilh,  Idem,  1880,  I.,  p.  038  ;  </,  E-  Hi-ey,  M''"',  13&-,  I-,  !'•  131  ;  h,  E.  Hart,  Am.  Inst.  Min.  Engrs.,  V.,  p.  164. 


left  to  right,  the  silicon  gradually  increases  ;  the  combined 
carbon  diminishes  ;  the  total  carbon  diminishes  after  the 
silicon  reaches  0  per  cent ;  the  graphite  at  first  increases 
as  the  combined  cnrbrn  diminishes,  but  later  on  as  the 
total  carbon  in  turn  diminishes  the  graphite  declines. 

The  effects  thus  caused  by  increasing  silicon  do  not  ap- 
pear here  with  perfect  regularity,  since  they  are  in  some 
cases  obscured  by  those  of  manganese  and  other  variables 
which  will  shortly  be  referred  to.  In  Fig.  1  these  results 
are  graphically  shown.  In  each  instance  in  which  both 
total  and  combined  carbon  are  given,  I  have  joined  their 
spots  with  a  line,  whose  length  indicates  the  percentage  of 
graphite  present ;  this,  in  irons  approximately  saturated 
with  carbon  and  silicon  probably  reaches  a  maximum  with 
about  4  to  5  per  cent  Si.  In  Fig.  1  the  graphite  evidently 
declines  as  the  silicon  rises  above  6  per  cent. 

•  FIG.  1.    INFLUENCE  OF  SILICON  ON  THE  SATURATION  POINT  FOR  CARBON, 

•  The  total  carbon  Is  indicated  by  the  dots  (»)  and  by  the  upper  ends  of  the  vertical  lines; 

(•combined  "    "        "        "  "crosses  U)  "    "    "   lower    "     "    °       "          " 
"  graphite,  the  difference  between  the  total  and  the  combined  carbon,  Is  Indicated  by 
the  length  of  the  vertical  lines. 


'  PERCENTAGE  OF  SILICON.  ' 


TUI:NEU'S  RESULTS. — By  melting  together  in  various  pro- 
portions cast-irons  whose  compositions  (including  total  C) 
were  closely  alike,  excepting  that  one  was  rich  in  silicon, 
while  the  other  had  but  little,"  Turner  obtained  a  series 
of  irons  in  which  silicon  was  practically  the  only  variable. 
Unlike  the  other  results  here  given,  Turner's  throw  no 
light  on  the  effect  of  silicon  on  the  total  quantity  of  carbon 
which  iron  will  take  up,  since  his  irons  were  far  from  satu- 
rated with  carbon  ;  but  they  show  the  effect  of  varying 
percentages  of  silicon  on  the  distribution  of  carbon  be- 
tween the  graphitic  and  combined  states  in  irons  whose 
t  >tal  carbon  is  practically  constant. 


»  J  vr.  Iron  and  Steel  Inst ,  1880.  I.,  p.  174, 


The  curve"  in  Fig.  1  shows  his  results,  which  indicate 
that  as  silicon  rises  from  0  to  1  per  cent  the  percentage  of 
carbon  held  in  combination  rises  ;  but  that  as  silicon  rises 
from  1  per  cent  to  about  6  per  cent  it  causes  the  carbon  to 
become  more  and  more  largely  graphitic  ;  and  finally,  that 
as  it  rises  from  about  5  per  cent  to  about  10  per  cent  the 
proportion  of  carbon  remaining  in  combination  again  in- 
creases ;  but  as  this  final  apparent  rise  of  combined  carbon 
is  due  wholly,  or  nearly  so,  to  a  single  instance  (No.  27), 
little  weight  should  be  attached  to  it,  especially  as  we  find 
that  the  total  carbon  in  the  other  instances  continues  to  de- 
cline regularly  as  the  Si  rises  from  5  per  cent  to  10  percent. 

Had  Turner  added  silicon  to  an  iron  initially  saturated 
with  carbon,  even  the  smallest  addition  would  probably 
have  diminished  the  total  carbon  and  have  caused  the  for- 
mation of  graphite.  His  results  are,  however,  valuable  as 
showing  that  when  the  total  carbon  is  far  below  the  point 
of  saturation  the  addition  of  moderate  quantities  of  silicon 
may  actually  increase  the  proportion  of  that  carbon  which 
remains  in  combination  ;  the  silicon  may  rise  from  '19  to 
•96  per  cent  without  increasing  the  proportion  of  carbon 
which  becomes  graphitic. 

§  19.  MANGAJSKSE  promotes  the  union  of  carbon  with 
iron  both  in  the  molten  and  solid  states.  Thus  we  find 
that  highly  manganiferous  cast-irons  (spiegel  and  ferro- 
manganese)  not  only  contain  much  more  carbon  than 
others,  but  that  their  carbon  is  ordinarily  almost  wholly 
in  combination.  Thus  silicon  and  manganese  oppose  each 
other  ;  the  former  lowers,  the  latter  raises  the  saturation 
point.for  carbon  in  molten  iron,  •{i.  e.,  the  maximum  attain- 
able total  C),  as  well  as  the  saturation  point  in  solid  iron, 
i.  e.,  the  proportion  of  carbon  which  can  remain  combined 
during  solidification  and  cooling.  Whether  under  given 
conditions  a  cast-iron  of  given  total  carbon  becomes  graph 
itic  or  white  on  solidification  depends  greatly  on  the  relative 
proportions  of  carbon,  silicon,  and  manganese  which  it 
contains.  Thus  Pourcel  obtained  cast-iron  with  15  per 
cent  Mn,  but  actually  gray  (i.  e.,  graphitic),  owing  to  the 
presence  of  a  large  percentage  of  silicon,  though  had 
the  silicon  been  absent  a  much  smaller  percentage  of 
manganese  would  have  sufficed  to  make  the  iron  perfectly 
white  (/.  e.,  to  have  held  all  the  carbon  in  combination). 

Conversely     Ledebur0    affirms   that  with  60  per   cent 


bThis  is  a  "  first  derived  curve"  which  I  have  obtained  from  Turner's  results 
by  taking  them  in  groups  of  three  (1st,  2d,  3d,  then  2d,  3d,  4th,  etc.),  and  plot- 
ting  the  center  of  gravity  i.l'  each  group. 

c  "  TTandbin  b  der  Eisenhiittenkunde,"  p.  230. 


10 


THE    IMETALLURGY    OF     STEEL. 


Mn,  iron  may  contain  about  5  per  cent  C,  wholly  in 
combination,  even  in  the  presence  of  more  than  2  '5  per 
cent  Si,  a  quantity  which  but  for  the  manganese  would 
render  the  greater  part  of  the  carbon  graphitic. 

§  20.  SULPHUR,  though  it  appears  like  silicon  to  lower 
the  saturation  point  for  carbon  in  molten  iron,  and  thus 
to  lower  the  total  carbon,  yet  like  manganese  prevents 
the  formation  of  graphite  ;  from  which  we  may  infer  that, 
while  silicon  lessens  the  power  of  carbon  to  unite  with 
iron  even  more  in  the  solid  than  in  the  molten  state,  so 
that  part  of  the  carbon  taken  tip  by  the  molten  iron  is 
separated  out  as  graphite  on  the  solidification  of  silicifer- 
ous  irons,  sulphur  limits  the  power  of  molten  quite  as  much 
as  of  solid  iron  to  combine  with  carbon,  so  that  the  whole 
of  the  carbon  taken  up  by  a  sulphurous  iron  when  molten 
is  retained  in  combination  during  solidification. 

The  effect  of  sulphur  in  preventing  the  formation  of 
graphite  is  illustrated  by  the  common  observation  that 
while  white  cast-iron  has  often  more  than  0  3  per  cent  S, 
we  rarely  find  more  than  0*15  per  cent  S  in  gray  iron,  and 
it  is  stated  that  the  sulphur  in  No.  la  Bessemer  cast-iron 
cannot  exceed  -05  to  '07  per  cent.  I  have,  however,  anal- 
yses of  No.  I  iron  with  0'12,  0*13,  (C14,  and  even  018 
per  cent  S. 

Since  the  high  blast-furnace  temperature  and  the  refract- 
ory calcareous  slags  which  accompany  the  formation  of 
graphitic  cast-iron  at  once  increase  (by  temperature) 
the  amount  of  silicon  and  diminish  (by  basicity  of  slag) 
the  amount  of  sulphur  which  passes  into  the  cast  iron, 
and  since  the  presence  and  absence  of  a  considerable 
amount  of  silicon  in  gray  and  white  irons  respectively 
suffice  to  account  for  the  separation  of  graphite  from  the 
one  and  the  retention  of  the  carbon  in  combination  in  the 
other,  it  might  be  thought  that  sulphur  did  not  directly 
prevent  the  carbon  of  white  iron  from  becoming  graphitic, 
but  that  the  presence  of  sulphur  and  the  freedom  from 
graphite  of  white  iron  merely  resulted  from  a  common 
cause,  namely,  the  condition  of  the  blast-furnace.  But 
that  sulphur  may  directly  prevent  the  formation  of 
graphite  and  cause  the  retention  of  all  the  carbon  in  the 
combined  state  is  indicated  by  experiments  of  Karsten, 
and  of  Smith  and  Weston  in  Percy's  laboratory,  in  which 
adding  sulphur  to  graphitic  gray  iron  turned  it  white, 
the  carbon  in  general  passing  wholly  into  combination. 
In  one  case  the  iron  contained  5 '49  per  cent  of  combined 
carbon,  together  with  u-446  per  cent  S.  The  presence  of 
silicon  of  course  limits  the  power  of  sulphur  to  retain 
carbon  in  the  state  of  combination. 

§  21.  PHOSPHORUS  is  thought  to  prevent  the  separa- 
tion of  graphite,  but  to  a  much  less  degree  than  sulphur 
and  manganese. 

§  22.  CKMENT  vs.  HARDENING  CARBON. — It  is  not  yet 
possible  to  distinguish  the  effects  of  silicon,  manganese, 
siilphur,  and  phosphorus  on  the  proportion  of  the  com- 
bined carbon  which  passes  into  the  cement  and  the  har- 
dening conditions  respectively  ;  indeed,  it  is  not  unlikely 
that,  when  these  elements  are  present  in  considerable 
quantity,  they  form  ternary  or  even  more  complex  com- 
pounds with  part  of  the  iron  and  carbon,  so  that  part,  or 
possibly  all,  of  the  carbon  is  neither  in  the  cement  nor 
the  hardening  condition  as  now  understood. 

§  23.    THK   EFFECT  OF  TEMPERATURE   ox  THE  CON 


DITION  OF  CARBON.— The  graphite-forming  tendencies 
appear  to  reach  a  maximum  at  a  temperature  approaching 
whiteness,  the  tendencies  to  form  cement  carbon  at  a 
temperature  near  dull  redness  ;  while  where  these  tenden- 
cies fall  to  their  minima,  the  tendencies  to  form  harden- 
ing carbon  seem  to  reach  two  corresponding  distinct 
maxima,  one  at  or  above  a  white  heat,  and  a  second  at  a 
rather  low  yellow  heat,  the  W  of  Brinnell.  They  appear 
to  l.e  complementary  to  the  graphite- form  ing  tendencies 
at  very  high  temperatures,  and  to  the  cement-forming  ten- 
dencies at  lower  ones.  The  existence  of  these  two  maxima 
suggests  that  what  we  call  hardening  carbon  may  really 
comprise  two  or  more  distinct  compounds,  all  considerably 
harder  than  pure  iron,  and  hence  not  easily  distinguished, 
from  each  other.  Each  of  the  supposed  maxima  of  ten- 
dencies to  form  hardening  car'- on  may  be  simply  the 
maximum  tendency  to  form  some  one  of  these  as  yet  undis- 
tinguished compounds. 

The  accompanying  attempt  to  sketch  the  relative 
strength  of  the  tendencies  to  form  graphite,  hardening 
and  cement  carbon  at  different  temperatures,  far  from  at- 
tempting accuracy,  is  necessarily  conjectural.  It  may 
serve  to  elucidate  a  working  hypothesis  which  places  the 
facts  thus  far  observed  in  an  easily  remembered  scheme. 


100 

z 


CEMENT  CARBON  FE3  C. 


w 


p 

STRAW 


X 

COLD 


»Ri!ey:  Jour.  Iron  and  St.  lust.,  1874, 1.,  p.  107, 


Fig.  2.— Supposed  influence  of  temperature  on  the  relative  strength  of  the 
tendencies  to  form  graphite,  hardening,  and  cement  carbon. 


In  melted  iron  all  the  carbon  must  be  present  in  solu- 
tion or  combination,  or  partly  in  each  condition.  AVere 
any  of  it  present  as  graphite  it  would  rise  to  the  surface  on 
account  of  its  lower  specific  gravity,  and  would  be  found 
concentrated  there  on  solidification  ;  whereas  it  is  nearly 
uniformly  distributed  through  the  iron  after  solidifying, 
showing  that  the  graphite  is  formed  after  solidification  has 
set  in.  This  appears  to  be  often  imperfectly  understood, 
since  we  hear  metallurgists  speaking  of  the  oxidation  of 
graphite,  as  distinguished  from  combined  carbon,  in  the 
Bessemer  process.  It  is  utterly  inconceivable  that  graphite 
should  exist  as  such  in  molten  iron  ;  indeed,  it  would  be 
hard  to  frame  definitions  of  chemical  combination  and  solu- 
tion which  would  not  between  them  necessarily  include  all 
the  carbon  in  molten  iron  ;  and  carbon  in  either  combina- 
tion or  solution  can  be  no  more  properly  spoken  of  as 
graphite  than  can  the  carbon  in  beef.  If  further  evidence 
be  needed,  witness  the  way  in  which  graphite  separates 
from  molten  iron  when  it  is  supersaturated  with  carbon 
(as  by  the  introduction  of  silicon) ;  the  graphite  here  rises 
to  the  surface  of  the  molten  metal  as  "  kish." 

§  24.  THE  TENDENCY  TO  THE  FORMA':~ON  OF  GRAPHITE 
appears  to  reach  a  maximum  at  a  temperature  N  slightly 
below  fusion.  Witness  the  formation  of  graphite  when 
highly  carbureted  cast-iron  is  slowly  cooled ;  that  is,  when 
it  occupies  a  long  time  in  passing  through  the  range  of 


EFFECT  OF  TEMPERATURE  ON  THE   CONDITION  OF   CARBON. 


11 


temperature  most  favorable  to  the  formation  of  graphite, 
aud  the  conversion  of  white  into  graphitic  gray  cast-iron 
by  prolonged  exposure  to  a  temperature  slightly  below 
fusion. 

[Karsten  indeed  states  that  white  cast-iron  can  only  be 
rendered  graphitic  by  superheating  far  above  its  melting 
point,  with  subsequent  slow  cooling.  This  is,  however, 
opposed  to  common  experience  and  to  the  statements  of 
many  distinguished  observers.  Forquignon,  a  by  expos- 
ing white  iron,  whose  carbon  was  wholly  combined,  to  a 
temperature  of  about  1000  degrees  C.  in  vacuo  for  several 
days,  converted  the  greater  part  of  its  carbon  into  graphite, 
the  total  percentage  of  carbon  being  unaltered.  Bell,"  by 
heating  white  iron  in  a  hot-blast  oven  for  thirteen  days 
raised  its  graphite  from  0'374  to  1 -79  per  cent,  the  total 
carbon  being  nearly  unchanged.  ] 

The  net  tendency  to  form  graphite  rather  than  com- 
bined carbon  appears  to  be  stronger  at  this  temperature 
N  than  at  either  higher  or  lower  ones,0  since  by  either 
raising  or  lowering  the  temperature,  part  of  the  graphite 
formed  at  temperature  N  may  unite  chemically  with  the 
iron.  Thus  if,  after  rendering  cast-iron  highly  graphitic 
by  prolonged  exposure  to  a  temperature  somewhat  below 
fusion,  we  further  raise  its  temperature,  the  graphite  re- 
combines,  so  that  by  the  time  it  is  melted  the  carbon  is 
again  wholly  combined.  Whether  the  recombination  oc- 
curs suddenly  when  a  certain  temperature  is  reached,  or 
whether  every  increment  of  temperature  is  accompanied 
by  a  corresponding  degree  of  recombination  of  carbon,  is 
not  known  ;  but  analogy  points  to  the  latter  as  the  more 
probable  supposition. 

That  this  recombination  occurs,  at  least  in  part,  before 
fusion,  is  shown  by  the  fact  that  graphitic  cast-iron  with 
but  little  combined  carbon  (the  combined  C  in  No.  1  gray 
iron  is  occasionally  as  low  as  0'30  per  cent)  has  a  vastly 
lower  melting  point  than  graphiteless  steel  with  the  same 
percentage  of  combined  carbon.  The  melting  point  of  the 
iron  can  not  be  lowered  by  the  carbon  while  graphitic 
(graphite,  infusible  itself,  is  an  inert  foreign  body),  but 
only  on  its  passing  into  combination  and  thus  increasing 
the  percentage  of  combined  carbon,  which  must  evidently 


a  Journal  of  the  Iron  and  Steel  lust.,  1884,  p.  626. 

l>  "  Principles  of  the  Manufacture  of  Iron  and  Steel,"  p.  159. 

o  According  to  this  view ,  if  graphitic  cast-iron,  saturated  with  graphite  by 
long  exposure  to  temperature  N,  were  suddenly  cooled  from  N  by  immersion  in 
water,  it  should  be  more  graphitic  than  if  wo  allowed  it  to  cool  slowly  from  this 
point,  since  the  sudden  cooling  should  preserve  the  chemical  constitution  and  pre- 
vent the  subsequent  recombination  of  graphite.  This  at  first  seems  opposed  to 
experience,  since  suddenly  cooling  graphitic  iron  from  even  a  temperature  as  low 
as  N  is  known  to  lower  its  grade,  to  make  it  more  close  grained.  But  this  objec- 
tion is  more  apparent  than  real.  From  Bell's  researches  it  is  probable  that  sudden 
cooling  from  N,  while  it  makes  the  grain  of  the  cast-iron  closer  and  makes  it  look 
less  graphitic,  does  not  diminish  the  amount  of  graphite  it  contains  seriously,  if 
at  all. 

The  grade  of  iron  is  not  dependent  solely  on  its  composition,  but  also  on  its  rate 
of  cooling.  Witness  Bell's  experiment  of  allowing  a  large  mass  of  iron  to  cool 
slowly.  The  interior  which  cooled  very  slowly  was  mottled,  the  edges  white, 
while  certain  portions  were  gray  ;  yet  the  percentage  of  both  combined  and  graph- 
itic carbon  was  practically  constant  throughout  the  block.  Indeed,  white  iron  has 
occasionally  more  graphite  than  No.  1  gray  iron  :  thus  Bell  reports  instances  in 
which  white  iron  had  2 '3  per  cent  graphite,  while  No.  1  iron  had  only  2'10  per 
cent. 

In  the  second  place,  under  ordinary  conditions  the  cast-iron  cools  so  rapidly 
from  the  melting  point  to  N  that  sufficient  time  is  not  given  for  the  graphite-form- 
ing tendencies  to  completely  assert  themselves,  so  that  by  the  time  the  iron  is 
cooled  down  to  N  it  is  far  from  being  saturated  with  graphite.  Hence,  in  ordi- 
nary slow  cooling  below  N,  say  from  N  to  O,  graphite  would  continue  forming  to 
a  considerable  further  extent  without  reaching  the  somewhat  lower  percentage 
corresponding  to  saturation  at  O;  while  this  further  separation  of  graphite  would 
be  checked  if  the  iron  were  very  suddenly  cooled  from  N 


commence,  in  the  case  of  a  comparatively  fusible  cast-iron, 
with  initially  only  0*30  combined  C,  at  a  temperature  far 
below  the  melting  point  corresponding  to  this  degree  of 
carburization. 

On  the  other  hand,  if  an  iron,  saturated  with  graphite 
by  long  exposure  to  temperature  N,  be  long  exposed  to  a 
somewhat  lower  temperature,  say  O,  part  of  its  graphite 
is  apparently  changed  into  combined  carbon/  Indeed 
wrought-iron  may  be  carburized  by  long  heating  in  contact 
with  cast-iron  or  even  steel,  which  play  the  role  of  the 
charcoal  of  the  cementation  furnace. 

The  passage  of  carbon  from  the  graphitic  to  the  com- 
bined state,  and  the  reverse,  comparatively  rapid  at  elevated 
temperatures,  becomes  mneii  slower  as  the  temperature 
descends  towards  redness  ;  and  it  is  stated  that  it  can  not 
take  place  below  a  red  heat,"  at  least  in  case  of  cast-iron. 

Superheating  beyond  the  melting  point  indirectly  favors 
the  formation  of  graphite  during  solidification,  since  the 
superheated  metal,  in  cooling  in  the  mold  down  to  the 
melting  point,  raises  the  temperature  of  its  walls  so  that 
the  metal  after  solidification  cools  more  slowly  than  it 
otherwise  would,  that  is,  it  remains  for  a  longer  time  at 
temperatures  near  N.  A  high  blast-furnace  temperature 
also  indirectly  favors  the  formation  of  graphite  during 
solidification  by  increasing  the  percentage  of  silicon  in 
[the  cast-iron,  and  usually  by  diminishing  that  of  sulphur. 
Whether  at  a  temperature  far  above  the  melting  point  the 
chemical  condition  of  the  carbon  becomes  altered  in  a  way 
that  directly  increases  its  readiness  to  become  graphitic 
during  solidification,  i.  e.,  whether  an  iron  melting  at 
1600  degrees,  superheated  to  2000  degrees,  and  again 
cooled  to  1700  degrees  before  pouring  into  its  mold, 
would  become  more  graphitic  on  solidification  than  it 
would  had  it  been  initially  cast  into  that  same  moJd  at 
1700  degrees  without  previous  superheating,  is  not  clear, 
though  it  is  clear  from  Bell's'  experiments  that  this  su- 
perheating in  certain  cases  permanently  raises  the  grade  of 
the  iron.  He  superheated  white  cast-iron  far  beyond  its 
melting  point :  it  became  gray.  On  remelting  and  rapidly 
cooling  it  still  remained  gray. 

§23.  EFFECT  OF  TEMPERATURE  ON  THE  RELATIVE  PRO- 
PORTIONS OF  CEMENT  AND  HARDENING  CARBON. — We  may 
obtain  considerable  information  as  to  the  distribution  of 
carbon  between  the  cement  and  hardening  states  at  dif- 
ferent temperatures  by  examining  iron  which  has  been 
cooled  from  those  temperatures  so  suddenly  as  to  give 
little  time  for  change  of  chemical  condition ;  i.  e.,  by  pre- 
serving the  chemical  status  quo. 

In  Table  2  I  have  condensed  Abel's  more  important 
results  bearing  on  this  question.  It  gives  the  percentage 
of  the  total  carbon  found  as  Fe2C  (plus  an  insignificant 
quantity  of  graphite)  in  different  steels  after  different 
treatment. 

We  here  note  that  in  annealed  steel  practically  all  the 
carbon  is  in  the  cement  state,  while  in  hardened  steel 
hardly  any  of  it  is,  from  which  we  infer  that  it  is  in  the 
hardening  state.  In  tempered  steel  an  intermediate  pro- 


d Percy :  "Iron and  Steel,"  p.  127. 

e  Akerman  :  Journal  cf  the  Iron  and  Steel  Inst.,  1879,  p.  508. 

t  Journal  of  the  Iron  and  Steel  Inst.,  1871,  p.  297.  Be!l,  however,  goes  too 
far  in  inferring  that  the  quantity  of  graphite  and  combined  carbon  do  not  affect 
the  grade  of  iron.  They  clearly  do  not  exclusively  control  Jt,  but  it  is  exceedingly 
probable  that  they  affect  it ;  that  is,  the  grade  ii  a  function  of  composition  jointly 
with  other  variables.  (Bell  :  "  Manufacture  of  Iron  and  Steel,"  p.  158.) 


12 


THE    METALLURGY    OF    STEEL. 


TABLE  2.— CARBON  FOUND  AS  FE3C  PER  100  OP  TOTAL  CARBON  PRESENT. 


CONDITION  OF  STEEL. 


Dannemora  blister  steel. 
(C,  0-91  to  0-94;  Si, 
0006,  Mn,  0-009.) 


Annealed 

Unannealed 

Previously  hardened  steel  tem- 
pered at  a  blue  heat 

Do,  after  15  minutes  exposure 
to  a  blue  heat 

Do.,  after  6  hours  exposure  to  a 
blue  heat 

Do.,  tempered  at  a  straw  heat. . 

Do.,  after  15  minutes  exposure 
to  a  straw  heat 

Do.,  after  6  hours  exposure  to  a 
straw  heat 

Hardened  steel 


Ingot  steel.     (C,0'995to 
1-12). 


87-4  to  92-8 
81 '5  to  95 -8 

16-1  to  31-9 


33-8  to  59'2;  aver.46'5 


87-5 

15-4  to  22-0 
4 1-9  to  42-9 

30-3  to  32-5 

34-2  to  36-0 
4-7 


I  average 
33-0 


average 
"     30-9 


portion  is  in  the  cement  state,  and  on  the  whole  rather 
more  in  blue  than  in  straw -tempered  steel,  which  har- 
monizes with  the  greater  softness  of  the  former.  Further, 
after  prolonged  exposure  to  a  tempering  heat,  whether 
blue  or  straw,  we  find  more  cement  carbon  than  after  brief 
exposure,  which  indicates  that  the  passage  of  carbon  from 
the  hardening  to  the  cement  state  is  not  instantaneous  at 
these  temperatures. 

In  melted  iron  and  steel  the  carbon  is  probably  in  a 
state  closely  related  to  hardening  carbon,  since  on  sudden 
cooling  from  fusion  we  find  it  chiefly  in  the  hardening 
state. 

At  temperatures  below  fusion  the  tendency  to  form 
hardening  carbon  rapidly  diminishes,  as  shown  by  the 
formation  of  graphite  ;  but  we  infer  that  it  again  increases 
as  the  temperature  falls  below  O  (Fig.  2),  reaching  a  max- 
imum at  W,  again  diminishing  as  the  temperature  descends 
to  V,  and  below  this  remaining  nearly  constant.  That 
it  rises  as  the  temperature  falls  from  N  to  O,  we 
infer  from  the  gradual  recombination  of  part  of 
the  graphite  formed  at  N,  if  the  iron  be  long  ex- 
posed to  O.  That  it  reaches  a  maximum  at  W  and 
again  diminishes,  we  infer  from  the  fact  th-)t  steel 
hardened  at  W  has  all  or  nearly  all  of  its  carbon  in  the 
hardening  state,  but  that  if  after  exposing  steel  to  a  red 
heat  we  cool  it  to  any  temperature  T,  at  or  'below  V,  so 
slowly  that  the  carbon  has  ample  time  to  distribute  itself 
between  the  hardening  and  cement  states  in  the  propor- 
tions corresponding  to  equilibrium  for  T,  and  then  suddenly 
cool  it  from  T,  we  find  its  carbon  in  the  cement  state  (as 
inferred  from  the  fact  that  the  steel  is  then  almost  as  soft 
as  if  thoroughly  annealed),  no  matter  how  violent  the 
cooling  be. 

Conversely,  if  we  quench  previously  annealed  steel 
bars  of  identical  physical  properties  from  successively 
higher  temperatures  we  find  that  they  do  not  (as  Chernoff 
has  shown),  become  materially  harder  than  when  annealed, 
until  a  temperature  V  is  reached  ;  but  as  the  quenching 
temperature  rises  above  V,  the  resulting  hardness  in- 
creases abruptly,  quickly  reaching  a  maximum. 

I  have  verified  this  statement  experimentally  by  heat- 
ing one  end  of  a  previously  annealed  steel  bar  to  dull  red- 
ness, the  remainder  being  heated  by  conduction  from  the 
hot  end.  It  was  exposed  for  about  four  hours  to  practi- 
cally uniform  conditions,  as  all  but  the  hot  end,  which 
was  kept  by  a  constant  flame  at  constant  temperature,  was 
buried  in  lime.  The  bar  was  then  quenched  in  a  very  rapid 
stream  of  water.  Examining  the  hardness  by  the  method 
of  indentation,  I  found  that  the  portions  which  had  not 


been  visibly  red-hot  were  not  appreciably  harder  than 
the  cool  end,  which  had  not  been  materially  heated  (it 
hardly  felt  warm  in  the  hand),  and  which  was  therefore 
still  annealed 

Now  if,  at  any  temperature  materially  below  redness, 
any  important  proportion  of  the  carbon  tended  to  pass 
into  the  hardening  state,  it  would  clearly  have  done  so  in 
some  portion  of  my  bar,  since  each  successive  portion  of 
the  bar  was,  immediately  before  quenching,  exposed  for 
hours  to  a  temperature  practically  constant  for  each  such 
portion,  but  progressively  diminishing  as  we  pass  from 
portion  to  portion,  and  from  the  hot  towards  the  cool  end 
of  the  bar,  and  embracing  every  degree  of  temperature  be- 
tween redness  and  70°  F.  On  quenching,  I  should  have 
found  some  portion  of  my  bar  harder  than  the  annealed 
end;  as  I  did  not,  I  infer  that  there  is  no  such  ten- 
dency. 

Slightly  varying  the  experiment,  I  leisurely  heated  one 
end  of  a  steel  bar  to  whiteness,  the  remainder  being 
heated  by  conduction.  On  quenching  it,  and  determining 
its  hardness  by  indentation,  I  found  that  where  the  tem- 
perature had  been  below  V.  (which  is  in  the  neighborhood 
of  dull  redness),  the  steel  was  not  measurably  harder 
than  when  annealed  ;  but  that  as  the  quenching  tempera- 
ture rose  above  V,  the  hardness  increased  very  abruptly, 
quickly  reaching  glass  hardness,  so  that  I  was  unable  to 
effect  any  indentation  with  an  exceedingly  hard  knife- 
edge.  By  carrying  the  pressure  high  enough,  the  glass- 
hard  steel  bar  would  fly  violently  in  pieces,  but  without 
being  visibly  indented ;  the  knife  edge  was  not  visibly 
affected. 

Other  phenomena  indicate  an  important  chemical  change 
at  a  temperature  between  W  and  V.  Iron  undergoes  a  very 
sudden  expansion  at  or  in  the  neighborhood  of  this  range, 
and  its  thermo-electric  behavior  is  abnormal ;  moreover, 
"the  temporary  magnetism  of  saturated  iron  at  this  tem- 
perature suddenly  vanishes  from  a  foregoing  very  large 
value."  a 

Am  I  asked  to  reconcile  the  hypothesis  that  the  carbon 
tends  throughout  the  range  of  temperature  between  V 
(Fig.  2)  and  X  to  pass  with  equal  completeness  into  the 
cement  state  with  the  fact  that  blue-tempered  is  softer 
lhan  straw-tempered  steel  ?  I  reply  that,  though  the  ten- 
dency exists  throughout  this  range,  it  is  held  in  check  by 
what  we  may  term  chemical  inertia  or  viscosity  ;  that  at 
60  degrees  this  tendency  is  as  completely  checked  as  is 
the  tendency  of  hydrogen  and  oxygen  to  combine  ;  that 
when  we  raise  the  temperature  and  relax  this  viscosity  the 
carbon  does  actually  pass  into  the  cement  state,  and  the 
more  fully  the  more  completely  we  relax  it;  i.  e.,  the 
higher  we  raise  the  temperature.  When  we  reach  a  straw 
heat,  viscosity  is  so  far  relaxed  that  a  considerable  portion 
of  the  carbon  previously  imprisoned  in  the  hardening 
state  is  able  to  pass  into  the  cement  state,  and  our  steel  is 
greatly  softened.  At  a  blue  heat  still  more  of  the  carbon 
is  able  to  overcome  chemical  inertia,  and  our  steel  is  still 
farther  softened,  while  just  below  visible  redness  this 
viscosity  appears  to  completely  depart  and  the  carbon 
passes  wholly  into  the  cement  state.  This  hypothesis 


aBarus  and  Strouhal,  "Bulletin  U.  8.  Geological  Survey,"  No.  14,  p.  99; 
Tait,  Trans.  Boy.  Soc.  Edinburgh,  XXVII.,  1872-3,  p.  1:35  ;  Gore,  Phil.  Mag., 
XXXVII.,  p.  59,  1869  ;  Ibid.,  XL.,  p.  170,  1870  ;  Baur,  Wie.  Ann.,  XI.,  p.  408, 
1880. 


EFFECTS  OF  CARBON  ON  THE  MECHANICAL  PROPERTIES  OF  IRON. 


13 


harmonizes  with  the  fac1:  that  though  hardened  steel  is 
softened  by  heating  to  temperatures  below  redness,  and 
the  more  so  the  higher  this  temperature  be  (provided  it 
does  not  exceed  V.),  yet  annealed  steel  is  not  hardened  by 
such  heating,  whether  followed  by  sudden  or  slow  cooling. 
For  the  softening  of  hardened  steel  by  this  heating  means 
that  its  carbon  passes  into  the  cement  state  ;  the  fact  that 
annealed  steel  is  not  hardened  by  this  treatment  means 
that  carbon  in  the  cement  state  remains  there  :  both  point 
to  the  cement  state  as  the  one  towards  which  the  carbon 
tends  at  these  temperatures. 

That  the  transfer  of  carbon  from  the  hardening  to  the 
cement  state  may  occur  at  very  low  temperatures  is  sug- 
gested by  the  reported  fact  that  table  knives a  gradually 
lose  their  hardness  if  they  are  habitually  washed  in  hot 
water.  It  is  the  experience  of  many  that  razors  used 
cold  last  for  a  greater  number  of  years  than  those  which 
are  habitually  heated  for  shaving,  though  for  other  reasons 
the  razor  while  hot  may  cut  better  than  when  cold. 

The  views  I  have  given  harmonize  with  Jarolimek's 
observation  that  steel  may  be  somewhat  hardened  by 
quenching  from  a  red  heat  in  molten  zinc,  which  melts  at 
752  degrees  F.,  but  not  as  much  as  if  quenched  in  water  ; 
while  steel  thus  hardened  is  again  annealed  by  prolonged 
immersion  in  melted  zinc. 

After  exposing  steel  to  temperature  W,  and  allowing  its 
carbon  to  pass  completely  into  the  hardening  state,  if  we 
could  cool  it  absolutely  instantaneously  we  would  retain 
all  its  carbon  in  that  state  ;  the  steel  would  acquire  its 
maximum  theoretical  hardness.  Cooling  can  never  be 
instantaneous;  more  or  less  carbon  will  pass  into  the 
cement  state,  towards  which  it  tends  at  temperatures 
below  V,  the  steel  will  lose  something  of  its  maximum 
theoretical  hardness,  and  it  will  lose  the  more,  roughly 
speaking,  the  slower  this  cooling  be.  Cooled  in  water, 
which,  thanks  to  its  low  boiling  point,  high  specific  heat, 
conductivity,  and  mobility,  cools  the  steel  very  suddenly, 
it  loses  very  little,  it  acquires  nearly  its  maximum  theo- 
retical hardness.  Cooled  in  air  it  loses  much,  for  the  air, 
thanks  to  its  low  specific  gravity,  specific  heat  and  con- 
ductivity, cools  it  but  slowly.  Momentarily  immersed 
in  molten  zinc  and  immediately  withdrawn,  and  its  cooling 
finished  in  air,  it  cools  with  intermediate  rapidity,  and 
hence  has,  when  cold,  an  intermediate  degree  of  hardness, 
because  the  zinc,  thanks  to  its  high  specific  gravity  and 
high  thermal  conductivity,  for  an  instant,  though  hot, 
withdraws  heat  very  rapidly — more  rapidly  than  air — 
from  the  steel,  which  is  so  much  hotter.  Prolonged  im- 
mersion in  molten  zinc,  however  (i.e., prolonged  exposure 
to  a  temperature  near  V),  enables  the  carbon  to  pass  largely 
to  the  cement  state  ;  the  steel  becomes  softer  than  after 
the  previoiis  momentary  immersion  followed  by  air  cool- 
ing ;  it  is  softened  by  the  very  medium  which  had  partially 
hardened  it. 

§  26.  EFFECTS  OF  CARBON  ON  THE  MECHANICAL 
PROPERTIES  OF  IKON.  IN  GENERAL. — For  given  propor- 
tion between  the  percentages  of  graphitic,  cement,  and 
hardening  carbon,  as  the  carbon  increases  the  tensile 
strength,  elastic  limit,  elastic  ratio,  and  compressive 
strength  increase  within  limits  ;  the  fusibility,  hardness, 
and  hardening  power  increase,  perhaps  without  limit  ; 
while  the  malleableness  and  ductility,  both  hot  and  cold, 


and  the  welding  power  diminish,  apparently  without 
limit.  The  modulus  of  elasticity  appears  nearly 
independent  of  the  percentage  of  carbon,  at  least  within 
the  limits  carbon  zero  to  carbon  2 -00  per  cent. 

For  reasons  given  in  §  2,  it  is  not  to  be  expected  that  mere 
equality  in  the  carbon  content  would,  even  were  the 
composition  otherwise  identical,  insure  like  mechanical 
properties,  nor  that  like  changes  in  composition  would 
entail  like  changes  in  these  properties.  Yet  we  might 
reasonably  hope  that,  since  carbon  influences  them  so 
greatly,  the  innumerable  published  observations  might 
have  enabled  us  to  determine  accurately  its  average 
effects.  Unfortunately  this  is  far  from  being  the  case.  Its 
average  effects  hav.e  been  determined  independently  by 
many  observers,  some  of  whom  have  deduced  them  from 
very  extended  data.  Their  results  are  dishearteningly  dis- 
cordant. 

§  27.  TENSILE  STRENGTH. — Though  we  have  more  in- 
formation on  the  effects  of  carbon  on  tensile  strength  than 
on  the  other  properties,  yet  even  here  our  results  are  very 
conflicting. 

The  views  of  several  writers  are  summed  up  in  the 
following  table : 

TABLE  3.— EFFECT  OF  CARBON  ON  TENSILE  STRENGTH,  e 


Writer. 

Kind  of  steel. 

Tensile  strength.    Lbs.  per  sq.  inch. 

T  -  43, 
T  —  60 

368  +  25, 
900  +  70 
800  +  60 
370  (1  +  ( 
825  (1  + 
300  +  10( 
•2  to  -3 

70,000 
•6  to  -7 

100,000 
1  to  1-1 

100,000 

601C  +  5 
000  C. 
000  C. 

& 

),OOOC. 
•3  to  -4 

76,000 
•7  to  '8 

109,000 
1-1  to  1-2 

60,000 

1,302  C2. 
•4  to  -5 

as.ooe 

•8  to  -9 
117,000 

Thurston  a 

Annealed      "    *  
Bessemer      "    

T  =  50, 
T  =  6l, 

T  =  52, 
T  =  45. 
•10  to  -3 

65,000 
•5  to  -6 

91,000 
•9tol- 

117,000 

Bausebinger  a.  ... 
Weyrauch  a  
Salom  b                . 

Gatewoodc  

When  carbon  is  from  .  . 
It      increases       tensile 
strength  at  the  rate  of 
When  carbon  is  from  .  . 
It      increases      ten?ile 
strength  at  the  rate  of 
When  carbon  is  from  .  . 
IB      increases      tensile 
strength  at  the  rate  of 

a  Ledebur  :  "  Handbuch  der  Eisenhuttenkunde,"  p.  646. 


aThurston  :  "  Materials  of  Engineering,"  II.,  p.  420-1.  b  Trans.  American 
Inst.  Mining  Engineers,  XIV. ,  p.  127.  c  Asst.  Naval  Constructor  R.  Gatewood, 
private  communication,  d  Annates  des  Mines,  1879,  p.  339.  e  C  =  the  percent- 
age of  carbon  present.  (Minimum  values. 

These  formulae,  as  may  be  seen  in  Fig.  3,  where  their 
curves  are  plotted,  are  very  discordant.  Comparing  them 
with  each  other,  and  with  about  1500  cases,  which  I 
have  plotted  (many  of  which  are  given  in  Fig.  3),  and 
which  are  gathered  from  many  sources,  the  more  firmly 
rivets  the  conviction  that  ultimate  composition  can  no  more 
in  steel  than  in  lithology  or  organic  chemistry  be  an  accu- 
rate and  trustworthy  index  of  physical  properties,  since 
in  the  one  as  in  the  others  we  find  identical  ultimate  com- 
position with  very  different  properties. 

Thus  I  find  that  with  the  same,  or  nearly  the  same 
carbon,  the  tensile  strength  varies  in  one  case  from  47,000  to 
137, 000  pounds  per  square  inch;  in  another  from  43, 000  to 
135,000,  and  in  a  third  from  79,000  to  170,000 ;  nor  do  I 
find  any  difference  in  the  other  variables  sufficient  to 
account  for  these  enormous  discrepancies.  Nor,  if  we 
go  a  step  farther  and  almost  completely  eliminate  other 
variables,  do  we  find  concordant  results.  Thus  Gatewoodb 
reports  three  sets  of  most  valuable  results,  whose  salient 
features  I  have  grouped  in  the  following  table. 

In  each  of  these  three  sets  of  tests  the  conditions  appear 
to  have  been  fairly  constant,  the  only  important  variable 
being  the  carbon.  The  compositions  were  in  other  respects 
nearly  constant,  if  we  except  the  variations  in  manganese 
(which  I  shall  endeavor  to  show  has  probably  little  effect 

b  Op  cit. 


14 


THE    METALLURGY    OF    STEEL. 


160,1X10 


180,000 


HO.OdO 


13M*iO 


7 


100,01111 


B 

E 

fe 


90,000 


SOJHill 


EO,OOI) 


855 

•  =Chlef  ly  Bessemer  Steel. 

0— Crucible  Steel. 

v  "Open  Hearth  Steel. 

*=Steel  Castlngs.usually  uutempered. 

C=Bauschtnger's  formula. 

D=Thurston's  formula. 

TABLE  4. — SUMMARY  OF  GATEWOCD'S  CARBON  RESULTS. 


olio  i1S5  090" 

PERCENTAGE  OF  CARBON. 


FIG.  3. 


w 

E=Gate wood's  formula. 
H=Salom's  formula, 
J  — Weyrauch's  formula. 
L=Average  after  ' 


STEEL. 

Number  of  heats. 

Composition  . 

Physical   properties. 

Carbon. 

Manganese,  i  Phosphorus. 

Maximum. 

Minimum. 

Maximum. 

Minimum. 

Average. 

Average. 

Average  Increase  (  +  )   or  De- 
crease (—  )   per   1    per  cent 
carbon. 

T  e  n  s  i   1  e 

strength. 
Pounds  per 
square  inch. 

Elongation. 
Per  cent. 

Chester.  .. 
Norway.. 
Camhria.. 

130 
339 
120 

•22 
•31 
•24 

•10 
•11 
•09 

•73 
•64 
•90 

•20 
•17 
•18 

38 
•38 
•45  + 

•05 
•06 
•085  ± 

+  138,750 
+   41  900 
4.   65,500 

—  43-5 
—  78 
—13-3 

on  the  tensile  strength),  as  were  the  methods  of  testing  and 
of  preparing  the  test  pieces.  The  inferences  from  these  sets 
of  observations,  among  the  most  valuable  ever  presented 
in  view  of  their  number  and  the  constancy  of  their  con- 
ditions, should  be  concordant ;  they  are  utterly  discordant. 


Thus  the  effect  of  carbon  on  tensile  strength  indicated 
by  the  Cambria  results  is  50  per  cent  greater,  and  that  in- 
dicated by  the  Chester  tests  over  200  per  cent  greater  than 
that  of  the  Norway;  its  effect  on  elongation  is  nearly 
twice  as  great  in  the  Cambria  and  more  than  five  times  as 
great  in  the  Chester  as  in  the  Norway  steel.  I  hold  that 
these  results  indicate  either  a  degree  of  carelessness  and 
ignorance  in  the  conduct  of  these  tests  hardly  credible  in 
these  well  (and  in  two  cases  admirably)  ordered  establish- 
ments, and  on  the  part  of  the  apparently  intelligent  in- 
spectors ;  or,  more  probably,  in  view  of  like  differences  in 
the  effects  of  carbon  deduced  from  the  enormous  mass  of 
results  published  by  other  observers,  that  the  effects  of 
carbon  are  not  quantitatively  constant. 

In  Fig.  4  Gatewood's  results  are  graphically  repre- 
sented. While  between  the  Cambria  and  the  sinuous  Nor- 


EFFECT  OF  CARBON  ON  THE  MECHANICAL  PROPERTIES  OP  IRON. 


°T 


=  Cambria, 


FIG.  4. 


4=4  =Chester,  Heat  Nos.  670  a  767. 
5=Curre  derived  from  4. 


/^Chester. 


way  curve,  whose  sinuosities  have  been  artificially  reduced 
by  derivation,  there  is  an  approach  to  parallelism,  both 
are  abruptly  crossed  by  the  Chester  curve.  As  each  of  these 
latter  curves  represents  a  greater  number  of  heats  than 
the  Cambria,  they  rudely  shake  our  faith  in  it.  Curve  4, 
which  I  have  derived  from  the  results  obtained  at  Chester 
after  a  change  of  personnel  had  removed  apparent  causes 
of  discrepancy,  is  more  nearly  parallel  with  the  others  than 
the  original  Chester  curve,  but  it  implies  an  increment  of 
73,812  pounds  tensile  strength  per  square  inch  per  in- 
crease of  one  per  cent  carbon,  or  nearly  twice  as  much  as 
is  implied  by  the  Norway  curve. 

The  most  important  lesson  of  these  results  is  that  we 
must  use  the  most  extreme  caution  in  drawing  inferences 
even  from  extended  data  as  to  the  effects  of  composition 
on  physical  properties. 

The  Cambria  curve  is  so  smooth  that,  representing  as  it 
does  130  results,  even  the  experienced  observer  would  be 
tempted  to  rely  on  its  teachings.  Yet  here,  as  in  so  many 


( similar  cases,  if  we  extend  our  observations  they  over- 

'  throw  our  apparently  well  established  conclusions  ;  these, 

!  then,  should  be  considered  authoritative  only  when  based 

on  an  enormous  number  of  observations,  on  steel  from 

many  sources  and  made  under  different  conditions,  since 

coincidences  between  composition  and  properties  often  re- 

'  suit,  not  from  the  causal  relation  between  them,  but  from 

some  common  unsuspected  cause,  whose  effects  may  be 

eliminated  by  comparing  steel  produced    by    different 

methods  and  under  different  conditions. 

In  Fig.  3  we  note  that  the  spots  lie  in  a  band  which 
rises  and  rapidly  widens  as  the  carbon  rises  till  it  reaches, 
say,  1  per  cent.  The  comparatively  few  cases  whose  carbon 
is  between  1  and  1*5  per  cent  indicate  that  the  tensile 
strength  reaches  its  maximum  with  carbon  about  1  per 
cent,  which  accords  with  common  observation.  The  for- 
mulse  of  Thurston,  Gatewood  and  Salom  run  fairly  through 
the  most  thickly  dotted  region,  Thurston' s  being  too  high 
for  low  carbon  steel  (ingot  iron),  while  Salom' s  is  too  low 


16 


THE    METALLURGY    OF    STEEL. 


for  carbon  below  (V10.  Troilius'  figures  are  rather  high, 
and  those  of  Weyrauch  and  Bauschinger  much  too  low 
except  for  low  carbon  steel. 

While  we  cannot  accurately  quantify  the  effects  of  car- 
bon, I  believe  that  for  ordinary  unhardened  merchantable 
steel,  the  tensile  strength  is  likely  to  lie  between  the  fol- 
lowing pretty  wide  limits  : 

TABLE  5.— EFFECTS  OF  CAHBON  ON  TENSILE  STRENGTH. 


Carbon.  Percent 

n-.j 

o-io 

0-15 

0-20 

0-80 

0-40 

0-50 
110,000 

0-CJ 
120,000 

0-80 

1-00 

1-80 

f,=     Upper 
g  g.     Limit... 

66,000 

70,000 

75,000 

80,000 

90,000 

100,000 

150,000 

170,1  

118,000 

~  7    Lower 
,     §3     JJmlt... 

50,000 

50,000 

55,000 

60,000 

065,00 

70,000 

75,000 

80,000 

90,000 

90,000 

90,000 

§  28.  DCCTILITT. — The  effects  of  the  percentage  of  car- 
bon on  the  elongation,  for  our  purposes  the  most  available 
measure  of  ductility  because  the  most  frequently  re- 
corded, are  obscured  by  other  variables  even  more  strik- 
ingly than  are  its  effects  on  tensile  strength.  Thus  we  find 
that  in  exceptional  cases  the  elongation  varies  from  2 '3  to 
32  per  cent  with  constant  carbon  ;  in  another  case  from  0* 
to  29-3  per  cent ;  nor,  if  we  turn  from  exceptional  cases  to 


ing  when  C  is  below  0-5  per  cent ;  (B)  when  it  io  be- 
tween 0'5  per  cent  and  1  per  cent.  Above  1  per  cent 
the  elongation  diminishes  very  slowly.  The  following 
table  gives  the  upper  and  lower  limits  which,  judging 
from  these  instances,  we  are  likely  to  meet : 

TABLE  6. — EFFECT  OF  CARBON  ox  ELONGATION. 


Elongation.  . 


By  formula 

Usual  upper  limit 

Usual  lo\vt-r      "    


0-10 


26-4 
29-0 
17-5 


0-20 

24-6 
85-S 

15-0 


o-ac 

0-40 

0-50 

21-G 

a-o 

12-0 

17-4 

•-TO 

IS- 

'  '  7-5' 

6-4S 
10-0 


0-70 


0-80 


.V04      4-0& 
7-5        6-0 
2'5  |     1-5 


Deshayes,  from  study  of  an  enormous  number  of  Euro- 
pean steels,  proposes  the  formulae  n — 

Elongation  =  35  —  30  C,  and 

Elongation  =  42  —  36  C,  (here  C  =  the  percentage  of 
carbon),  for  the  percentage  of  elongation  measured  in  7 "8 
and  3*9  inches  respectively. 

There  is  little  in  the  results  I  have  plotted,  either  as  to 
elongation  or  tensile  strength,  to  support  the  popular  be- 
lief that  the  properties  of  Bessemer  steel  correspond  with 
those  of  open-hearth  steel  of  lower  carburization,  which 
I  incline  to  regard  as  a  superstition,  though  without  more 
prolonged  study  of  our  statistics,  we  can  not  wholly  dis- 


CD' 

• 

o 

u 

• 

, 

* 

=>  — 

CO 

l&s 

S 

• 

;;«•.•  " 

efcj* 

u  » 

?N 

LESEN 

D. 

fc    20 

MA, 

«»        ' 

. 

vi-E  c°s 

"« 

.^HJ^ 

'         ©' 

»  a 

0 

v  =  Open  Hearth  Steel. 

•-  •  ,  ; 

*             "t 

fc  "  ;:  ^s 

>.     * 

© 

O  =  Crucible  Steel, 

O 

,*vjV 

""          : 

V          4 

% 

* 

O 

+  =  Unforged  Steel  Castings,  occasionally  oil  hardened. 

z    ._ 

VWV  V    V 

V      " 

,•    * 

r\ 

0  =  Bessemer  Steel  made  in  Clapp-Grif  fiths  Converters. 

C 

v 

»' 

v  • 

**  \ 

. 

T  =  Average  of  tests  for  f  our  U  .  S.  Vessels,  Gatewood. 

f  » 

» 

V 

,*  e 

^ 

. 

B 

H 

^  \T 

9 

T 

0 

111 

e  + 

f  V 

4+»  ?•• 

*     v 

, 

0 

• 

'-v>^Ci 

'''^ 

V           , 

z 

v  ;, 

'.-,.;.  '•^•"., 

S»i_V 

v   *  »• 

e  . 

e 

i 

Q 

f 

B    »'      V 

•rr^T 

3  . 
1              ' 

—  -«. 

•  ! 

i 

s. 

. 

E 

m 

3 

0                 0:iO            0.80            0.30            0.10            0.50            O.CO            0:70            0.80            0 

BO            IW            1,10            1.80            1.80            1. 

10            1.00             1.6              1. 

Carbon  <£.                                                                                            FIG.     5. 

ordinary  ones,  do  we  find  a  closer  approach  to  uniformity 
in  elongation  than  in  tensile  strength.  Thus  in  the  Chester, 
Norway,  and  Cambria  lots  of  steel  investigated  by  Gate- 
wood,  and  already  referred  to  under  tensile  strength,  we 
find  that  the  loss  of  elongation  per  increase  of  -01  per  cent 
carbon  is  '425,  -078  and  0'133  per  cent  respectively.  (See 
Table  4.)  I  have  plotted  the  results  of  over  a  thousand  de- 
terminations with  elongation  as  crdinate,  carbon  as  ab- 
scissa, as  shown  in  Fig.  5.  We  note  that  the  thickly 
dotted  region  lies  in  a  broad  band,  gradually  declining  as 
the  carbon  increases,  its  width  showing  that,  where  carbon 
is  below  0-5,  the  elongation  for  given  carbon  in  common 
merchantable  steel  often  varies  by  20  per  cent  of  the  initial 
length.  With  increasing  carbon  the  elongation  at  first 
declines  slowly,  say  from  C  0'  to  C  0'2  percent,  then  more 
rapidly  till  the  carbon  reaches  say  0-5  per  cent,  and  after 
this  it  again  declines  more  slowly.  I  find  that  the  empirical 

formulae  (A) :  E  -  33  —  60  (C8  +  0-1) ;  and 

(B) :  E  =  12  —  11-9  8  VC  —  0'5 
(In  which  E  =  per  cent  elongation  in  8"  and  C  =  per  cent  carbon) 

give  curves  plotted  in  the  diagram  and  running  well 
through  the  most  thickly  dotted  region,  (A)  apply - 


credit  it.  The  many  cases  in  which  the  elongation  and  ten- 
sile strength  of  crucible  steel  fall,  the  one  above,  the  other 
below  the  limits  usual  in  Bessemer  and  open-hearth  steel 
for  given  carbon,  give  color  to  the  less  often  expressed 
belief  that  the  properties  of  crucible  steel  of  given 
carburization  correspond  to  those  of  Bessemer  and 
open-hearth  steel  of  lower  carburization.  I  also  notice  a 
fact  which  has  not  heretofore  been  brought  to  my  atten- 
tion, that  the  elongation  and  tensile  strength  of  steel 
castings  of  given  carbon,  like  those  of  crucible  steel,  cor- 
respond with  those  of  Bessemer  and  open-hearth  steel  of 
lower  carbon.  While  this  may  be  due  to  plotting  an 
insufficient  number  of  cases,  it  occurs  to  me  that  this 
similar  behavior  of  crucible  steel  and  of  steel  fastings  may 
be  due  to  their  both  containing  more  silicon  than  Besse- 
mer and  open-hearth  steel,  silicon  opposing  the  effects  of 
carbon."  The  greater  freedom  from  phosphorus  of  cruci- 
ble steel  and  often  of  steel  castings  is  another  possible 
explanation. 

a  Annales  des  Mines,  1879,  p.  339. 

»  Miiller,  J.  I.  and  S.  I.,  1882,  I.,  p.  374,  concludes  that  Si  has  an  effect 
opposite  to  that  here  suggested,  raising  the  tensile  strength. 


INFLUENCE    OF    CARBON    ON    THE    PHYSICAL    PROPERTIES. 


17 


§  28A.  ELONGATION  AND  TENSILE  STRENGTH. — I  here 
insert  a  table  showing  the  usual  upper  and  lower  limits  of 
tensile  strength  for  given  elongation  in  steel : 

TABLE  6A.— TENSILE  STRENOH  AND  ELONGATION. 


Kliin^'ation.  PIT  cent  

4 

6             8       |     10 

12          14 

ir, 

18 

1  -n:tl      limits    of    tensile  ( 

I'PIK'I 

150,000 

[88,001 

[80,000122.000 

ii.vxx 

lllVHk'i 

lOi.lKKI 

1)3,000 

>tp'iiL'Ui.  l.bs.  persq.  in.  / 

I,<i\\rt 

110,111111 

KfJ.IXK 

M,000|  85.000 

80,00 

7.VKHI 

7:),iKK' 

54,000 

20            22       1     24       1 

26           2S      1 

80      1 

82 

T'Mlal   lilllils   ill'   trriMlr   stlvllffth.  | 

Upper,  i 

08,000 

88,000    80,000 

77,000 

74,000 

71.000 

70.000 

l.hv   ptT  M|.  ill  

.  .  .  (    Lower.) 

.MI.IJOI)   86,0001  !W,(*N>! 

51.000 

M.OOfll 

50,0001 

rO.IK.II 

§  29.  MODULUS  OF  ELASTICITY. — The  effect  of  carbon 
on  the  modulus  is  probably  very  slight.  Deshayes,"  from 
an  analysis  of  a  great  number  of  cases,  concluded  that  the 
modulus  was  constant  for  all  steel,  under  identical  condi- 
tions of  previous  mechanical  treatment,  etc. 

In  Table  7  I  have  condensed  the  results  of  many  obser- 
vations and  of  the  values  given  by  different  authorities  for 
the  modulus.  While  apparently  only  based  on  52  cases 
it  really  represents  a  much  greater  number,  since  in  cer- 
tain cases  a  given  unit  of  the  52  represents  the  average  of 
many  results. 

Omitting  one  apparently  abnormal  case  (reported  by 
Cloud  45, 000, 000  pounds)  we  find  that  the  average  modulus 
is  practically  the  same  for  each  of  the  groups  arbitrarily 
made. 

Certain  writers  believe  that  the  modulus  rises  slightly 
as  the  carbon  increases  from  0,  reaching  a  maximum  with 
carbon  0'30  toO'35,  and  again  declining  as  the  carbon  rises 
above  0-35 ;  but  if  there  is  any  such  variation  it  is  so  slight 
as  to  be  of  no  importance. 

When  the  carbon  passes  some  point  now  unknown  the 
modulus  begins  to  decline,  since  we  find  it  much  lower  in 
cast-iron  than  in  steel. 

TABLE  7.— MODULUS  OF  ELASTICITY  OF  INOOT  METAL  AS  AFFECTED  BY  TUB  PERCENTAGE  OF 

CARBON. 


Abbot  gives  the  modulus  and  other  physical  properties" 
of  10  steel  castings.  If  we  may  infer  their  carbon  from 
either  their  tensile  strength  or  elongation,  the  very  consider- 
able variations  in  the  modulus  are  but  faintly  influenced 
by  the  degree  of  carburization.  If  we  number  them  accord- 
ing to  their  moduli,  No.  1  having  the  highest,  then,  taken 
in  the  order  of  tensile  strength,  they  stand  thus  :  3,  1,  2. 
10,  4,  7,  5,  6,  9,  8,  the  modulus  being  on  the  whole 
rather  higher  in  those  with  highest  tensile  strength.  If 
arranged  in  the  order"  of  elongation,  the  first  having  the 
highest  elongation,  they  stand  thus :  5,  3,  1,  9,  4,  10,  2,  7, 
6,  8.  Those  with  the  highest  modulus  have  on  the  whole  the 
highest  elongation,  yet.the  highest  modulus  but  one  ac- 
companies an  elongation  of  only  2  per  cent.  Arranged  in 
order  of  their  elastic  limit  they  stand  thus :  3,  1,  2,  4,  7, 
6,  10,  f,,  8,  9. 

§  BO.  The  roMPRKssivE  STRENGTH  rises  with  increasing 
carbon  within  limits  at  present  unknown.  From  Kirk- 
aldy's  data,  I  have  calculated  (Table  7A)  the  effect  of 
increments  of  carbon  on  elastic  and  ultimate  eompressive 
strength.  The  results  are  so  harmonious  as  to  inspire 


Percentage  of    excess  of 
eompressive       strength 
over  that  of  steel  of  0'3 

Compressive 
strength.       Lbs. 

carbon. 

DESCRIPTION. 

S3 

<*>. 

Number. 

Carbon. 

I! 

Jl 

•f  Length  = 
^  diameter 

fj 
Pr  ct. 

3  Length  = 
r^  diameter 

Length  =  1 
diameter. 

"Length  =  1 
diameters. 

1.  . 
a.  . 

3.    . 

ft 

Ultimate 
eompressive     • 
strength. 

1-2 

0-9 
06 
03 

40 
43 
29 
0 

63 
44 
39 
0 

115 
106 
79 
0 

102,173 
95,207 

84,827 
47,513 

4.    . 
5.   . 
6.   . 

•8||f 

lali 

i 

Elastic 
eompressive     • 
strength. 

09 
0-6 
0-3 

64 
61 
54 
0 

51 
40 
37 
0 

52 
43 
30 
0 

53 
44 
31 
0 

64,000 
02,666 
60,000 
39,000 

61,666 
58,000 
52,666 
40,666 

C  0  to  0-15 

CO'15toO-25 

C    0'25  to  0-35 

C  0-35  to  0-75 

C  0-75  to  1-00 

Cl'OOtol'26 

No.  of  l-asr:-,.. 

Maximum.  .  . 
Minimum  .    . 

A  venifre     .  .  . 

14 

T.bs    per 
sq.  ill. 

30,135,000 
22,000,000 

27,407.000 

12 
Lbs.  per 
sq.  in. 

S7.  300,000 
24,576,000 

28,327,000 

4 
Lbs.  per  sq  in. 

(45.000.000  ?1  a 

so.75o.ono  b 

24,850.000 
(3i,7li2,0fl«?)a 
28.683.000    b 

8 
Lbs.  per 
sq.  in. 

31.859,340 
23,558,000 

27.500,000 

6 
Lbs.  persq.  in. 

2\2'23,000 
23,000,000 

26,011.000 

8 
Lbs.  per 
stj.  in. 

31,839,650 
25,266,000 

23,292,500 

a,  including  one  abnormal  case.    b.  omitting  one  abnormal  case. 

confidence,  though  the  data  are  so  scanty  that  inferences 
from  them  can  not  be  considered  conclusive. 

(1.)  While  the  eompressive  strength  increases  constantly 
for  all  lengths  as  the  carbon  rises  to  1-2,  it  increases  most 
rapidly  with  the  rise  from  C  0-3  to  C  0'6  per  cent.  In  some 
cases  the  eompressive  strength  is  but  little  greater,  and  in 
one  case  actually  less  with  C  1*2  than  with  C  0-9  per  cent. 

(2.)  The  longer  the  piece  (/.  e.,  the  greater  the  ratio  of 
length  to  diameter)  the  greater  in  general  is  the  gain  of 
ultimate  eompressive  strength  with  increasing  carbon  ; 
while  the  gain  of  elastic  eompressive  strength  seems  to  be 
about  the  same  for  one  length  as  for  another. 

TABLE  7A.— COMPRESSIVE  STRENGTH  AS  INFLUENCED  BY  CARBON. 


§  31.  THE  HARDNESS  of  steel,  as  measured  by  its  resist- 
ance to  abrasion  or  by  the  indentation  made  by  given 
pressure  on  given  indenting  knife  edge,  etc.,  rises  with 
rising  carbon,  and  especially  as  the  percentage  of  carbon  in 
the  hardening  state  increases  ;  it  certainly  continues  to  in- 
crease beyond  that  degree  of  carburization  which  cor- 
r.  sp'onds  with  the  maximum  tensile  strength  and  prob- 
ably beyond  that  corresponding  with  maximum  eom- 
pressive strength,  as  measured  by  the  resistance  of 
columns  to  bulging,  buckling  and  skewing.  Steel, 
wire-dies  of  1 '7  per  cent  C  wear,  according  to  Aletcalf," 
much  more  rapidly  than  those  of  2 '37  or  2  89  per  cent  C, 
while  tensile  strength  appears  to  reach  its  maximum  with 
about  1  per  cent  C. 

I  know  of  no  data  which  enable  us  to  quantify  the 
effects  of  carbon  on  hardness. 

§32.  THKFCSIBILITY  increases  with  the  carbon,  probably 
without  limit.  It  is  generally  stated  that  graphitic  iron 
has  a  higher  melting  pointd  than  graphiteless  iron  of 
otherwise  identical  composition,  and  identical  total  car- 
bon. It  is  probably  more  accurate  to  say  that  graphitic 
iron  melts  at  the  same  temperature,  but  more  slowly,  as  at 
the  melting  point  of  graphiteless  iron  the  graphite  of 
graphitic  iron  probably  gradtially  completely  combines, 
so  that  the  iron  eventually  becomes  graphiteless  and  melts. 

HARDENING,   TEMPERING,    AND  ANNEALING. 

§33.  DEFINITIONS. — 1.  STEEL  is  HARDENED  (in  the  spe- 
cific sense  of  the  word)  by  sudden  cooling  from  a  high  tem- 
perature, usually  at  or  above  redness,  e.  p.,  by  plunging 
it  in  water,  oil,  etc. 

2.  To  temper  (to  qualify,  to  soften)  in  its  specific  sense 
means  to  mitigate,  to  partly  remove,  to  moderate  the  ef- 
fects of  previous  hardening.  It  is  usually  performed  by 
gently  reheating  the  previously  hardened  steel,  but  to  a 


11  Annril'K  rf«x  Mines.  1879,  p.  342. 
Trans.  Am,  Inst.  Mining  engineers,  XIV.,  p.  :;53,  1886. 


o  Timm.  Am  Inst.  Mining  Engineers,  IX.,  p.  549. 
d  Ledebur  "  Handbuch,"  p.  340. 


18 


THE    METALLURGY    OF     STEEL. 


TABLE  8.— PERCENTAGE  or  EXCESS 


(+)  OB  DEFICIT  ( — )  OP  ELASTIC  AM>  ULTIMATE  TENSILE  STRENGTH    AND  OK   ELOX<;\TIOX  or  UXANXEALED  AND   op   HARDENED  IRON  AND  .SI 

FOEGIKG8    AMOVE  THOSE  OP  TI1E  BAME  lEON   WHEN    ANNEALED. 


1. 

1 

fc 

n. 

1 

«2. 
B 

rt 

III. 
c. 

IV. 
Si. 

Y. 

Mn. 

YI. 

p. 

Y1I. 
DESCRIPTION. 

Yin. 

Quenching- 
tempera- 
ture. 

Per  cent  of  excess  of  ultimate 
tensile  strength. 

Per  cent,  of  excess  of  elongation. 

P.  c.  excess  of  elnstii 
tensile  strength. 

Properties  of  the. 
annealed  steel. 

In  the  unan-  £< 
nealed  steel.  ." 

X.       XI.      XII.    XIII. 

"When  hardened  in 

XIY. 

i| 

st 

«s 

nB 

XV.    XYI.XYII.XYIII. 

"\Vhon  hardened  in 

xix 

§1 

s  — 
3  <° 

«3 

£13 
a> 

g* 

XX.    XXI. 

When  hard- 
ened i:l 

Tensile 
strength 

§  c 

Elastic? 
limit. 

Watei 

Coal 

t:ir. 

Tal- 
low. 

Oil. 

Water 

Coal 
tar. 

Tal- 
low. 

Oil. 

Water 

Oil. 

a: 

a  „- 
5]"" 

0-5 
1 
2 
8 

4 

5 
6 

7 
8 

9 

10 

11 

12 

18 
14 
14-5 
15 
16 
17 
18 

19 

20 
21 

ca 

23 
24 
25 
26 
27 
28 

29 

il  M 
S 
8 
S 

H 
H 

"i 

»! 
» 

H 

1C 

N 
8 
H  M 
8 
K 

S 

•07 
•07 
•07 
•08 

%® 

•15 
•14® 
•23 
•20 
•10® 
•30 
•10® 
•80 
•17® 
•22 
•33 

•40? 

•40? 
•42 
•89 

•78 
1-00? 

1-22 

Norway  wrought-iron  
Charcoal-hearth  iron  

Full  redness 
Rednesa  .  . 

+6-3 

|? 

+  41 

5-8 

64,200 

47..%! 
44.ST7 

22  ; 
•9 

19 
32  2 
16-( 
33 

11-6 
29'9 

S2M 
19 

22 
11-9 

31-2 

7 
7-7 
10 
15 

5-f 
2-7 
T-8 
9-2 
8'3 
12-5 
11-8 
20 
12-5 

25,18(1 

20,306 

28,128 

2S.116 
26,554 

46,144 

79 

11                        (t              !< 

tt 

+  40 
+  76 
+  23 

-t-53 

i    4S 

47 

44,61)3 
52,540 
58,510 

4D.41C, 
4li,730 

54,244 
59,214 

55,096 
61,269 

82166 
79,620 

77,000 
92,900 
96,891 
151,716 
119,172 
J'iV.iTS 
106,002 

123.165 
118,221 
113,533 
122,282 
101,421 
102,809 
116,763 
101,422 
103,64V 

•01® 
•02 

•02 
•02® 
•04 

•05® 
•12 

•41 
•09® 
•10 

•02® 

•03 

•03 
•01® 
•02 

Average  of  5  Bessemer  steels 
Open-hearth  steel  

Average  2  open-hearth  steels 
Puddled  iron 

Not  stated.. 
Red  heat... 
Not  stated  .  . 

+  2 
—  4 

+  3 

—  5 

—  56 

+  •* 

+51 

Brine 
+  43 

+M 

2 
+11 

—  30 
-  45 

Brine. 
—  88 

29 

f) 

'  ::r, 

•1)2® 
•03 
•02® 
•1)4 
•02® 
•03 

•15® 
•27 
•09® 
•86 
•14® 
•27 

•03 

•02 
•03 

Average  of  5  Bessemer  steels 
"         2  open-hearth  ** 

Not  stated., 

Rednesa  .  .  . 
High 

+11 
+  5 

+  c 
-i-37 

+  66 
+  65 

+  42 
4-  55 
19 

15 

M 

+17 
+12 
+  2 

+32 
+31 

+21 

8 

51 



—  8 
12 

—  40 
32 

Homogeneous  metal.  °Dai-s 

: 

-58 
45 
-14 

100 

S9 

33 

5 

-35 

38 

+20 



Bessemer  steel  
Pittsburgh  open-hearth  steel 

Redness.  ... 
Yellow  

—11 

+80 
+27 

- 

-33 

MT'J 

Lgg 

High 

°6 

h76 

100 

53 

+40 
+13 

+50 
+14 

h55 
-29 
-79 

—  22 
—  18 

—  65 
—  80 

-65 
-50 

—78 

H 

offlj 

Hi^h  

baO 

Low  
Not  stated 

+  « 

r24 
-71 

+  20 

—38 
98 

-65 

—96 
—97-5 
61 

U                     (t 

" 

[-57 

Rivet  steel  

frt 

i 

-78 

70 

M 

;     .. 

7j 

52 

ii 

n 

-41 
-58 

8 

1 

15 

« 

25 

100 

Steel  .  .                            -j 

Redness  .... 
Strongly 
Heated  

+71 

+119 
+14 

69,000 

NOTE.— For  references,  see  end  of  Table  ID. 


very  much  lower  temperature  than  that  employed  in  har- 
dening, and  then  cooling  generally  suddenly,  but  some- 
times slowly.  I  bhall  use  the  word  exclusively  in  this  sense, 
though  it  is  often  and  not  incorrectly  employed  generic- 
ally  t  j  designate  any  sudden  cooling,  whether  from  an 
excessively  high  or  a  moderate  temperature. 

3.  Annealing. — While  tempering  somewhat  moderates 
the    effects  of    previous    hardening,   annealing  aims  to 
nearly  completely  eliminate  them,  as  well  as  to  remove  the 
stresses  caused  by  previous  cold  working.     It  is  ordi- 
narily effected  by  slow  cooling  from  a  high  temperature, 
at  or  above  redness.     Thus  steel  is  in  its  hardest  and  most 
brittle  state  when  hardened,  in  its  softest  and  toughest 
when  annealed,  and  in  an  intermediate  condition  when 
tempered. 

4.  Quenching  may  be  employed  to  designate  generic- 
ally  any  sudden  cooling. 

I  will  describe  first  for  those  who  run  the  methods  and 


effects  of  quenching  and  annealing,  and  then  seek  the 
rationale  of  these  operations  for  those  who  think. 

§  34.  METHODS  AND  EFFECTS— HARDENING.— The  general 
effect  of  hardening  is  to  increase  the  hardness,  to  raise  the 
elasticlimit,  to  diminish  the  ductility  and  specific  gravity, 
and,  if  the  cooling  be  not  extremely  sudden,  to  raise  the 
tensile  strength.  It  is  said  to  raise  the  modulus  of  elas- 
ticity. 

The  degree  to  which  these  properties  are  affected  de- 
pends chiefly  (A)  on  the  temperature  from  which  cooling 
occurs,  (B)  on  the  composition  of  the  steel,  and  (C)  on  the 
rapidity  of  cooling,  which  in  turn  depends  chiefly  (C\),  on 
the  shape  and  size  of  the  piece,  and  (C2)  on  the  medium 
employed  for  hardening. 

APPARENT  EXCEPTIONS  to  the  statement  of  the  effects 
of  hardening  just  mideare  found  in  quenching  previously 
cold-rolled  and  cold-drawn  steel,  and  previously  unforged 
and  unannealed  steel-castings. 


ADDENDI-M  TO  TAHI.B  S.— Percentage  of  excess,  etc.,  of  tensile  strength,  etc.,  of  open  hearth  fire-box  plate  steel  of  five  sixteenths  inch  thickness,  when  unannealed  and  when  hardened  o 
the  same  nii-tal  when  annealed.  Carbon.  I. -.2  per  cent ;  manganese,  0  36  per  cent ;  silicon,  O'OOS  per  cent;  phosphorus,  0- 035  per  cent ;  sulphur,  0-017  per  cent.  Test  strips  were 
plate  ot  open-hearth  tire-box  steel,  all  1%  ineh  wide  by  30  inches  long,  one  cud  extending  uninjured  above  testing  machine  grips,  which  were  subsequently  bent. 


ver  these  of 
re  all  from  one 


1  Number.  ." 

II. 

jj 

I 
B 
ii 

III. 
C. 

IV. 

Si. 

V. 

Mn. 

VI. 
P. 

VII. 
DESCRIPTION. 

VIII. 

(quenching 
tempera- 
ture. 

Percentage  of  excess  of  tensile 
strength. 

Percentage  of  excess  of  elonga- 
tion. 

P.  c.  excess  of  elastic 
tensile  strength. 

Properties  of  the 

annealed  stfi-l. 

In  the  nnan-j- 
nealed  steel,  r' 

X.       XI.     XII.    XIII- 

When  hardened  in 

XIV. 

a   • 

g  S 

vjr 
—  £ 
"1 
£  a 

XV.  XVI.  XVII.  XVIII- 

When  hardened  in 

In  tlic  nnan-X 
nealed  steel.  ^ 

XX. 

When 

elle- 

Water 

XXI. 

hard- 
lin 

Oil. 

XXII. 

Tensile 
strengtb 

XXIII. 

c 
.2 
a 

M 

c 
_o 

XXIV 

Klastio 
limit. 

Water 

Brine. 

Coal 
tar. 

Oil. 

Water 

Brine. 

Coal 
tar. 

Oil. 

29-5 

Calculated  from  A.  E. 
Hunt's  data,  in  the  dis- 
cussion of  a  paper  on 
"  Steel,"  etc.,  by  W.  Met- 
calf,  b  nerican  :->ociety  of 
Civil  Engineers.  April  4, 
1887. 

Dark  orange 
Medium  " 
Bright     " 
Lemon  
Light  lemon 
Low  white. 
Scintillating 
white.  .    . 

—10 

+16 
+1S 
—  6 
+12 
+29 
+31 

-34 

+32 
-,-38 

+32 
-32 

+  3 

4-  8 

-|-24 

—  4 

—31 
—34 

—28 
—31 
—47 

—47 
—58 
—50 
-52 
—  54 

—18 
-16 
—27 
—40 
—48 
—  SI 

—93 

—  1 

+30 
+40 
+37 
-4-54 

+83 
+15 

+\* 

+21 
+24 

4* 

+19 

6-2,100 

30-4 

1 

32.6W 

+28 
-36 

—67 
—92 

—48 
-94 

METHODS    OF    HARDENING      TEMPERING    AND     ANNEALING. 


TABLE  NO.  9. 

PERCENTAGE    OK  EXCESS    OF   TENSIIJC    STRENGTH,    ETC.      OF   UNANNEALED  AND  OF  OIL   HARDENED  UNFORCED  CASTINGS     OVER    THOSE    OF    THE    SAME     CASTINGS 

WHEN     ANNEALED. 


I. 

11. 

a 
g 

£ 
& 

c. 
III. 

Si. 
IV. 

Mn. 
V. 

Description. 
VI. 
UNFORGED  CASTINGS. 

Quenching 
temper- 
ature. 

Per   cent   excess  of 
tensile    strength. 

Per    cent  excess  of 
elongation  . 

Per      cent      excess 
of  elastic    tensile 
strength. 

Properties  of  the  annealed 
casting. 

VII. 

vnr. 

i 

1 
I 

& 

IX. 

« 

_g 

3 

1 

o 

X. 

5| 

» 

-i 
«ii 

ISS 

o 

XI. 

tj 

1 
a 
a 

§ 
& 

XII. 

'5 

.a 

! 

o 

XIII. 

^ 
a  bo 

_,"'» 

^3      rz 

•2-sf 
o  a  s 
o  «s  3 
0 

xrv. 

1 

a 
t> 

XV. 

*§ 

a 

1 

xvi. 
_•>, 

°1 

O  *2*     • 

•  ^  ^^  *O 
05   _._ 

S'gl 

8*§ 
o  . 

Tensile 
strength. 
Pounds 
per  square 
inch. 

Elonga- 
tion. 

Elastic 
limit. 
Lbs. 
per 
square 
inch. 

30 
31 
3d 
33 

34 
35 
36 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
40 
CO 
51 
52 
53 
54 
55 
56 

p 
p 
p 

E 
E 
U 
E 
E 
E 
E 
IT 
P 
P 
P 
P 
P 
P 
P 
E 
P 
P 
P 
E 
E 
II 
U 

•18± 
•18± 
•18± 
•26 
•26 
•30 
•33 
•42 
•42 
•45 
•50 
•50  ± 
•50  ± 
•50  ± 
•50  ± 
.50  ± 
50  ± 
.50± 
55 
56  ± 
56  ± 
56  ± 
•63 
•63 
•77 
•96 

•20 
•31 
23 
•36 
•36 

•30+! 
•27 
•27 
35 

•39± 
•39  ± 
•39  ± 
•39  ± 
•39  ± 
39  ± 
•39  ± 
•40 
•34  ± 
•34  ± 
•34  ± 
•55 
•55 
•46 
•63 

•43 

•63 
•61 
•41 
•41 

•48'  ' 
'75 
'75 
I'l 

•88± 
•88  ± 
•88  ± 
•88  -t 
•88  ± 
•88  ± 
•88  ± 
1-05 
•94  ± 
•94  ± 
•94  ± 
•95 
•95 
•67 
•64 

Cherry  red. 
tt        tt 

Not  stated. 

it          u 

+  26 
+   9 
+  31 

—47 

+  64 
+  32 
-•  48 

69,987 
71,545 
64,960 
69,864 
66,080 
70,112 
76,964 
103,660 
103,518 
105,080 
96.544 
103,891 
108,371 
113,792 
113,075 
107,385 
110.947 
99,568 
103,660 
103,107 
103,107 
103,824 
111,470 
103,660 
84,000 
78,176 

28.50 
24-30 
26-7 
28  -5 
36'5 
34-0 
21-5 
9-8 
14-0 
175 
8-6 
9-0 
11-5 
7-7 
113 
9-3 
79 
81 
98 
6-2 
4-0 
13-0 
70 
7  '5 
1-5 
1-3 

33,995 
33,846 
28,448 
33,370 
37,364 

((                                    U                                    U 

ft                          ft                          it 

Terre  Noire  castings  

tt         (i         t  r 

-34 

—27 

"^'4 
+  1 

+   6 
+  5 
-23 
—15 
—19 
+   1 

+  15 
+  16 

-55 
—48 
33 

—39 

—14 

-18 
—10 

+  33 
+  62 

Not  stated. 

K        i 

it        t 

(C                 1 

Cherry  red 

it         * 

tt        * 
tt         t 
«t         * 
•i        « 
«(         t 
Not  stated. 
Cherry  red 

tl       rf       4 

it          t 

Not  stated. 

tt       tt 

+  25 
+  1 

+  5 
+  15 

—31 

—84 
—77 
—84 
76 

—49 
—  tt 

—11 
—  6 

+  74 
+   5 
+   5 
+  32 

28,684 
35,926 
52,398 
48,280 

U                                     It 

tt                       ft 

U                                    ft 

—14 
—54 

—15 

—10 



+  9 

+  18 
+  11 
+  1 
+  11 
+  2 
+  7 
+  6 
+  9 
+  17 
+  9 
+  47 
+  53 

19 

+  40 
+  33 
+27 
+  31 
+  38 
+  13 
+  24 
+  14 
+    7 
+  13 
0 
+  51 
+  45 

47,645 
51.530 
51.900 
51,206 
48,384 
51,306 
48,305 
35,926 
54,432 
51,475 
51,475 
51,830 
41,748 

It                      tt 
(f                       tt 
tf                      tt 

tt                                    cf 
tf                                    (1 
t                                    ft 
1                                     tt 
t                                    tt 
t                   t                 tt 
t                   t                tt 
f                   t                 (f 

52 

+   1 
—36 

35 

5 

—14 

—20 

—59 



—34 
—  10 

0 

+70 
—  6 
-90 

—87 

—34 
—23 
—  2 

—83 
—72 
—100 

—13 
—19 

(t                 tt                 tt 

+   6 

—100 

NOTE. — For  references  see  end  of  table.    Excesses  +  ;  Deficits  — . 

NOTE.— The  percentages  of  increase  of  elongation  columns  XI.  to  XIII. ,  are  per  100  of  elongation  of  the  unannealcd  piece,  not  per  100  of  its  length. 


The  net  result  of  highly  heating  them  (say  to  a  cherry 
red),  with  subsequent  quenching  is  usually  to  soften  and 
toughen  them,  often  with  a  great  increase  of  tensile 
strength.  (Thus  the  numbers  in  column  X.  of  Table  9  are 
invariably  algebraically  larger  than  the  corresponding 
numbers  in  col.  VIII.:  those  in  col.  XIII.  are  algebra- 
ically larger  than  the  corresponding  ones  in  col.  XL,  with 
three  exceptions,  doubtless  due  to  experimental  errors, 
or  to  heterogeneousness  of  the  steel).  But  this  is  because 
the  coarse  structure  of  the  castings  and  the  brittleness 
which  cold-workinggives  iron  and  other  metals  depart  when 
the  metal  is  heated  ;  and  the  brittleness  which  quenching 
causes  is  less  intense  than  that  which  previously  existed. 

In  Tables  8,  9, 10,  11,  and  16A I  have  analyzed  the  results 
of  many  experiments  on  hardening;  this  enables  me  to 
present  its  specific  quantitative  effects  more  fully  I  believe 
than  has  heretofore  been  done." 

A.  TENSILE  STRENGTH. — In  general,  moderately  rapid 
cooling  raises  the  tensile  strength.  Violent  cooling  may 
lower  it,  especially  in  the  case  of  high-carbon  steel  and 
when  the  quenching  temperature  is  high. 

a.  WATEK-HARDENING  cools  steel  very  rapidly.  With 
low-carbon  steel  (say  with  carbon  below  0'5  per  cent) 
water-hardening  from  a  moderate  temperature  raises  the 
tensile  strength  greatly  (see  cases  1  to  14,  and  71;  in  these 
13  cases  the  tensile  strength  is  raised  on  an  average  47 
per  cent).  Water-hardening  low^carbon  steel  from  a  high 
temperature,  however,  in  the  only  case  I  have  met  (No.  12) 
lowers  the  tensile  strength  (by  19  per  cent). 

Water-hardening  high-carbon  steel  (with  C  above,  say, 
0^-75  per  cent),  whether  from  a  high  or  low  temperature, 
either  lowers  the  tensile  strength  (see  cases  16,  23,  and  75, 
in  which  it  is  lowered  by  from  25  to  58  per  cent) ;  or  at 

"See  also  addendum  to  Table  8. 


most  raises  it  very  slightly  (case  76,  in  which  it  is  raised 
by  2  per  cent). b 

(b)  OIL  HARDENING  almost  invariably  raises  the  tensile 
strength,  even  when  the  quenching-temperature  and  the 
carbon  are  both  high,  sometimes  more  than  doubling  it. 

In  62  cases  of  oil-hardening  which  I  have  analyzed  the 
tensile  strength  is  raised  on  the  average  35$,  and  is  low- 
ered in  only  one  of  them  (Xo.  76)  ;  in  this  a  high-carbon 
steel  (1*12$  C)  is  quenched  from  a  very  high  temperature. 

If  both  the  carbon  and  the  quenching  temperature  be 
low,  water-hardening  may  give  slightly  higher  tensile 
strength  than  oil-hardening.  (See  case  5.)  But  in  the 
great  majority  of  cases  oil-hardening  gives  much  higher 
tensile  strength  than  water-hardening.  In  4  cases  (Nos. 
12,  16,  19,  and  29)  in  which  the  eame  steel  is  oil-hardened 
from  both  high  and  low  temperatures,  I  find  that  where 
the  carbon  is  moderately  low  the  high  quenching-tem- 
perature gives  the  greatest  tensile  strength  ;  where  the 
carbon  is  high  (1'22$)  low-temperature  quenching  gives 
the  highest  tensile  strength. 

Coal  tar  and  tallow  in  cases  17,  18,  and  19  raise  the  ten- 
sile strength  less  than  oil. 

These  facts  appear  to  point  to  the  conclusion  that  to  get 
the  highest  tensile  strength  with  very  low-carbon  steel  we 
must  cool  rapidly,  quenching  in  water  from  a  high  temper- 
ature ;  for  steel  of  say  0'4  C  we  must  harden  more  moder- 
ately, using  oil,  but  still  a  rather  high  quenching  temper- 
ature ;  for  high-carbon  steel  (say  1  '25$)  we  must  cool 
gently,  from  a  low  temperature  and  in  oil. 

b  This  statement  refers  only  to  the  cases  which  I  have  met.  I  do  net  mean  to 
imply  that  water-hardening  never  greatly  increases  the  tensile  strength  of  high- 
carbon  steel  ;  indeed,  it  would  probably  largely  increase  the  tensile  strength  of 
pieces  of  large  cross-section,  even  if  their  car'jon  were  decidedly  high,  and  es- 
pecially if  the  quenching  temperature  were  low,  since  they  cool  comparatively 
slowly  even  in  cold  water.  The  following  paragraphs  are  written  in  the  same 
spirit. 


20 


THE    METALLURGY    OF    STEEL. 


TABLE  10. 
PSBOSNTACB:  or  EZOESS  OF  TENSILE  STRENGTH,  ETC.,  OF  IIAIIDENEU  IRON  AUD  STEEL  FOUGINGS  OVER  THOSE  OF  THE  SAMS  ?:ATEIUAL.  waEN 


Somber. 

I 

q, 

Temperature  fr.  j  1  1  1 
•which  quenched. 

Pt-r  (-cut  Increase  of  tensile 
strength. 

Increase  of  eloiiytition   per 
100  of  the  donation  <>1 
the  uriannealed  bar. 

Per  cent  increase  of  elas- 
tic tensile  strenyl  h. 

Properties  of  Die  unanuealiM 
Steel. 

Quenched  ri 

Quenched  In 

Quenched  in 

Tensile 
strength 

Ibs.  per 
sq.  in. 

Elon- 
gation 
per 
cent. 

Elastic 
limit 
Ibs.  per 
eq.  in. 

Water.         |      C>a 

"VTatcr. 

Oil. 

TVatcr. 

Oil. 

57 
53 
53 
80 
61 
63 
63 
64 
65 
63 
67 
63 
69 
70 
71 
73 

73 

74 
75 

73 

T 
T 
B 

ir 

A 
A 
A 
B 
IT 
H 
H 
B 
A 
A 
H 
H 

N 
0 
S 

S 

•01 
•03± 
•1 
•15 
•27 
•31 
•31 
•34 
•35? 

•o;? 

•40? 
•41 
•45 
•47 
•49 
•71 

•87 
1-05 

1-05 

1-16 

Wot  stated. 

tt 
it 
tt 

i 

i 

it 
tt 

tt 
tt 
tt 
tt 
tt 

1C 

(  Slightly   heated 
1  Strongly      " 

+  7'8 
+  38-5 

_ia 

51,202 

J>           essemer  Suee  

55 

63,900 
56,000 
51,520 
79,804 
84,774 
78,384 
74,300 
77,952 
78,4CO 
92  515 

+  33 
+  26 
+  36 
+  33 
+  30 
+  13 
+  39 
+  37 

—4 

+  83 
+  81 
+  16 
+  17 
+33 

34' 
32-5 
24' 
25-25 
23-5 
20- 
7-4 
18-7 
21' 

23,000 
24,640 
51,404 
53,676 
47,426 
35,800 
36,900 
36,960 

Terre  Noire  ste-J  

+  23- 

—43 

—13 
—45 

-44 
+  14 

+  ^4 

4!         *'      open-hearth  steel.  .  . 



—26 

+  15 
+45 

—31 

+  17- 

+  50 
+  33 
+  47 
+62 
+  60 
+77 

+  39 

+  39 
+48 

—79 

—95 
—30 

+  100 
+  58 
+  108 
+  80 
+  161 

+  190 

+44 

73,800 
73,556 
8<5,76S 
67,200 
87,360 

109,760 
145,400 
97,783 
139,84" 

23- 
24-5 
21-4 
24'8 

10- 

S'4 
5-5 
3-9 
4-6 

81,300 
37,346 
44,804 
33,600 
40,320 

44,800 
88,810 

Terre  Noire  open-hearth  steel  
it         ti         <t         «         »t 

Terre  Noire  

—51 

+73- 
)  broke    in  ( 
/•  quench-  J. 
\       ing       j 

—90 
1  broke    in  ( 
>  quench-  •< 
)        ing       ( 

—  5ri 
—60 

-88 
+  13 
-100 

+  100 
]  broke    in  ( 
f  quench-  -< 
}        ing       ( 

it           t; 

It              c( 

-(58-+) 
+  2' 

—100 
—100 

TTchntius  si?el,  Wikmanshyttan.  .  . 

-(<Ji+) 

—100 

IToTE. — Excesses  + ,  deficits  — .  • 

REFERENCES  TO  TABLES  8,  9,  AND  10. 

A,  Akerman,  Jour,  of  the  Iron  and  Steel  Institute,  1879,  II.,  p.  539.  B,  W.  Armstrong,  Engineering,  1883,  II.,  p.  354.  D,  Dellvik,  Jour.  Iron  and  Steel  Inst., 
1379,  IL,  p.  538.  E,  Euverte,  Jour.  Iron  and  Steel  Inst.,  1877, 1.,  p.  245.  H,  Hunt.  Trans.  Amer.  Inst.  Mining  Engineers,  XII.,  p.  311.  K,  Kiraldy,  "  Experi- 
ments on  Wrought  Iron  and  Steel,"  1866,  p.  164.  N,  "  Proc.  U.  8.  Naval  Institute,"  X.,  p.  561.  O,  "  Report  of  U.  S.  Senate  Select  Committee  on  Ordnance  and 
War  Ships,"  1886,  p.  310.  P,  Holley,  Metallurgical  Review,  II.,  p.  230,  May,  1878.  S,  Styffe,  Iron  and  Steel,  Sandberg's  Translation,  p.  1S7.  T,  Tetmajer,  Jour. 
oftheIronandSteelInst.,188S,Il.,ip.700.  TJ,  Spencer  and  Sons,  Jour,  of  the  Iron  and  Steel  Inst.,  1883, 1.,  p.  304.  ?  After  the  percentage  of  carbon  indicates 
that  it  is  not  given  by  the  authority  quoted,  but  is  simply  inferred  from  the  tensile  strength.  V,  It  is  probable,  but  not  certain,  that  the  casting  was  slightly  reheated 
after  cooling  in  oiL  H  TI,  Experiments  by  the  Author. 


(B)  ELONGATION, — Analyzing  81  recorded  cases  (some 
water,  some  oil-hardened),  I  find  that  60  of  them  lose  25$ 
or  more  of  their  elongation  on  hardening,  35  lose  50$  or 
more,  and  13  of  them  lose  90$  or  more.     In  each  of  19 
cases  of  water-hardening  the  elongation  is  considerably 
lowered,  the  mean  loss  being  60$  (of  the  original  elonga- 
tion). In  52  out  of  56  cases  of  oil-hardening  the  elongation 
is  lowered,  but  on  the  whole  considerably  less  than  by 
water-hardening ;   the  mean  loss  of  elongation  by  oil- 
hardening  is  45$.     In  only  one  out  of  seven  cases  in  which 
the  effect  of  both  water  and  oil-hardening  on  the  same  steel 
i".  given  does  the  oil-hardening  reduce  the  elongation  more 
than  water-hardening.     The  elongation  of  steel  high  in 
carbon  is  on  the  whole  reduced  by  hardening  rather  more 
than  that  of  steel  low  in  carbon.   But  in  the  cases  which  1 
have  collected  the  loss  of  ductility  by  high-carbon  steel  on 
hardening  exceeds  the  loss  which  low-carbon  steel  under- 
goes much  less  than  is  generally  supposed.     Thus  in  34 
cases  in  which  the  C  is  0  '40$  or  below,  the  mean  loss  of 
elongation  by  hardening  is  41$ ;  in  47  cases  whose  C  is  be- 
tween 0'4$  and  V16$  the  mean  loss  of  elongation   by 
hardening  is  40$. 

Cases  2,  3,  4,  6,  8,  9,  10,  and  CO,  whose  C  does  not  ex- 
ceed 0'30$,  each  lose  40$  or  more  of  their  elongation  on 
hardening.  Case  2,  with  only  0-07$  C,  loses  79$  of  its 
elongation. 

Hardening  from  a  high  temperature  generally,  though 
not  invariably,  lowers  the  elongation  more  than  low-tem- 
perature quenching. 

(C)  THE  ELASTIC  LIMIT  is  almost  invariably  raised  by 
hardening,  and  usually  more  than  the  tensile  strength  is. 
In  examining  44  recorded  cases  I  do  not  find  one  in  which 
the  elastic  limit  is  lowered  by  hardening,  and  but  one  in 
which  it  is  not  raised.     In  these  44  cases  the  effect  of 
hardening  on  the  tensile  strength  is  also  determined.      In 
29  of  them  the  elastic  limit  is  raised  more  than  the  tensile 
strength,  being  raised  on  the  average  by  47$  while  the 


tensile  strength  in  the  same  cases  is  raised  on  the  average 
by  only  32$. 

On  the  whole  hardening  appears  to  raise  the  elastic 
limit  of  high  rather  more  than  that  of  low  carbon  steel, 
though  by  no  means  invariably.  Thus  in  20  cases  whose 
C  is  0-4  $  or  less  the  mean  elevation  of  elastic  limit  is  42$ ; 
in  24  cases  with  C  above  0'40,  the  mean  elevation  is  50$  ; 
yet  cases  59  and  60,  with  C  O'l$and  0 '15$ respectively, 
have  their  elastic  limit  raised  by  oil-hardening  F3$  and  81  $. 

D.  HARDNESS. — While  we  have  little  quantitative  in- 
formation as  to  the  effects  of  hardening  ca  tr:o  hardness 
of  steel,  we  may  say  roughly  that  the  higher  the  initial 
temperature,  the  more  rapid  the  cooling  and  the  higher 
the  percentage -of  carbon,  the  harder  does  the  steel  be- 
come. The  effect  of  varying  temperatures  is  illustrated 
by  Metcalf  s  experiment."  One  end  of  a  steel  bar  is 
heated  to  dazzling  whiteness,  the  remainder  being  heated 
by  conduction  from  the  hot  end.  If  it  be  quenched  in 
water  with  its  different  portions  thus  at  different  temper- 
atures, we  find  that  the  part  which  had  been  scintillatingly 
hot  will  now  scratch  glass,  and  has  a  coarse,  very  lustrous, 
yellowish  fracture.  That  which  was  simply  white-hot  is 
nearly  as  hard  as  glass,  with  a  coarse  but  less  yellow 
fracture.  Those  which  had  been  at  a  high  yellow,  an 
orange,  and  a  high  red-heat  are  successively  softer  and 
tougher,  with  successively  finer  fractures,  which  are  in  all 
three  fiery.  That  which  had  been  at  a  cherry -red  heat  is 
very  strong  and  much  less  brittle  than  the  preceding,  with 
the  finest  fracture  of  all;  it  is  well  hardened,  e.  ff.,  for 
cutting  tools,  though,  of  course,  requiring  subsequent 
tempering.  That  which  had  shown  a  low-red  color  is 
tougher  and  softer  yet,  but  still  hard  enough  for  tap- 
teeth  ;  its  edges  show  a  very  fine  fracture,  its  center  is 
somewhat  coarser.  The  portion  which  had  not  been  visi- 
bly red-hot  is  not  materially  hardened,  and  is  conse- 
quently softer  than  any  of  the  others,  and  has  the  same 


a  Metallurgical  Review,  I.,  p.  246. 


METHODS  OF  HARDENING,  TEMPERING  AND  ANNEALING. 


fractuiv  as  the  unharclened  steel,  which  is  decidedly 
coarser  than  that  of  the  portion  quenched  from  cherry- 
redness. 

Extending  Metcalf  s  experimont  to  lower  temperatures 
and  quantitatively  determining  the  hardness  of  the  differ- 
ent portions  of  the  bar  by  the  method  of  indentation,  I 
found  that  the  hardness  was  not  measurably  above  that 
of  the  annealed  steel  until  the  quenching-temperature 
reached  a  point  in  the  neighborhood  of  a  dull  red,  but  that 
passing  above  this  point  the  hardness  A'  ery  suddenly  in- 
creased, soon  reaching  an  apparent  maximum. 

While  the  ductility  and  tensile  strength  are  somewhat 
more  affected  by  a  given  quenching  in  high  than  in  low- 
carbon  steel,  the  hardness  proper  is  incomparably  more 
affected  in  the  former  than  in  the  latter.  Indeed,  a 
quenching  which  in  high-carbon  steel  replaces  decided 
toughness  with  glass-hardness,  does  not  sensibly  increase 
the  hardness  proper  of  ingot  and  weld  iron. 

Thua  on  quenching  wrought-iron  from  a  white  heat  I 
was  unable  to  detect  quantitatively  by  the  method  of  in- 
dentation any  increase  of  hardness,  though  its  ductility 
was  somewhat  impaired,  and  though,  as  we  see  in  Table 
8,  its  tensile  strength  may  be  affected  by  quenching  nearly 
as  much  as  that  of  high  carbon  steel. 

§  35.  CONDITIONS  OF  HARDENING.  A.  TEMPERATURE.— 
The  specific  effects  of  different  quenchirig-temperatures 
on  the  properties  of  steel  have  already  been  indicated.  It 
is  thought  that,  at  least  in  the  case  of  tool  steels,  the 
best  general  results  are  obtained  by  employing  the  low- 
est quencliing-temperature  which  suffices  to  give  the  re- 
quired hardening,  as  needlessly  high  temperatures 
impart  a  coarseness  of  structure  and  consequent  brittle- 
ness  which  can  not  be  wholly  effaced  by  subsequent  treat- 
ment, while  no  compensating  advantage  accrues.  In 
general,  the  hardness  proper  is  not  increased  unless  the 
queuching-temperature  be  at  least  as  high  as  a  dull 
cherry -red  heat ;  and  it  is  stated  that  the  lower  the  car- 
bon the  higher  must  the  quenching- temperature  be  to 
produce  decided  hardening.  Thus  tool  steels  with  say  \% 
C  often  require  only  a  low  red-heat  for  quenching  ;  gun- 
steels  with  say  0'4$  C  are  said  to  acquire  the  most  ad- 
vantageous hardening  by  quenching  from  a  salmon  or  even 
a  strong  yellow  heat.  (Of.  Pp.  175,  191,  bottom.) 

Quenching  from  lower  temperatures,  however,  probably 
affects  the  tensile  strength  and  apparently  diminishes  the 
ductility,  though  much  less  than  high- temperature  quench- 
ing. 

B.  HEATING  FOR  HARDENING. — The  method  used 
should  depend  largely  on  the  shape,  size  and  number  of 
the  pieces  to  be  heated.  The  smith's  forge,  though  largely 
used,  is  far  from  advantageous.  Molten  lead  appears  to 
afford  the  most  uniform  heating,  but  its  use  is  insalubri- 
ous. Small  pieces  may  be  heated  in  a  reverberatory  fur- 
nace, by  contact  with  hot  iron  of  appropriate  shape,  in  a 
gas  flame,  etc.  Where  many  small  pieces  are  to  be 
hardened  they  may  be  inclosed  in  an  iron  pipe,  box  or  pan 
filled  with  charcoal  dust,  and  placed  in  a  smith's  forge, 
a  reveberatory  furnace,  etc.  A  pan  or  open  box  offers  the 
advantage  that  the  pieces  can  be  stirred  about  and  thus 
heated  uniformly. 

Large  pieces  must  of  course  be  heated  in  reverberatory 
furnaces,  often  of  shapes  specially  adapted  to  the  pieces 
to  be  heated  ;  e.  g. ,  long  gun  tubes  are  heated  one  at  a 


time  in  very  narrow  rectangular  vertical  furnaces,  in  which 
a  single  tube  stands  on  end.  One  side  of  (he  furnace  is 
hinged  so  that  the  tube  may  be  very  rapidly  removed 
sidewise,  to  be  immediately  plunged  in  a  deep  tank  of  oil. 

C.  RAPIDITY  AND  MEDIA  OF  COOLING. — In  general  the 
more  rapid  the  cooling  the  harder  and  more  brittle  i.s  the 
steel  ;  rapidity  of  cooling  up  to  a  certain  point  increases 
the  tensile  strength,  but  if  the  cooling  be  exceedingly 
rapid  the  tensile  strength  maybe  very  greatly  lower.  •<!, 
and  the  steel  may  even  be  broken  by  the  hardening  itself. 
Apparently  the  lower  the  carbon  the  more  rapid  and 
violent  should  the  cooling  be  to  give  the  highest  tensile 
strength. 

The  hardness  and  brittleness  of  hardened  steel  are  influ- 
enced far  more  by  the  rapidity  with  which  the  steel  cools 
from  a  cherry -red  heat  to  490°  C.  than  by  the  rapidity  of 
cooling  below  400°  C.,  though  the  latter  is  not  without 
influence  on  the  resulting  hardness.  Thus  red-hot  steel  is 
somewhat  hardened  by  brief  immersion  in  melted  zinc 
(zinc  melts  at  412°  C.),  followed  by  moderately  rapid  cool- 
ing in  the  air,  while  if  the  steel  be  left  immersed  in  the 
zinc  the  hardness  thus  acquired  is  again  lost. 

Mercury  cools  stesl  with  the  greatest  rapidity  ;  water, 
rapeseed  oil,  tallow  and  coal-tar  follow  in  the  order  here 
given.  Urine  and  brine  are  said  to  cool  steel  more  rapidly, 
and  soapy  water  less  rapidly  than  pare  water.  A  thin 
layer  of  oil  on  the  surface  of  the  wafcr  retards  the  cooling. 
Oil-hardening  almost  always  gives  both  higher  tensile 
strength  and  higher  elongation  than  water-hardening. 
But  it  must  be  remembered  that  even  oil  hardened  steel 
has  almost,  if  not  quite,  invariably  lower  elongation  t'.ian 
the  same  steel  when  annealed,  and  in  an  overwhelming 
majority  of  cases  even  lower  elongation  than  when  unan- 
nealed. 

For  castings  and  most  forgings  of  steel  with  less  than 
0'76$  C,  such  as  guns,  m.iriu3  sliafts,  and  armor  plate, 
tensile  strength  is  more  important  than  hardness,  hence 
they  are  habitually  hardened  in  oil.  For  cutting  tools, 
hardness  is  more  important  than  strength,  hence  they  are 
ordinarily  hardened  in  water.  Ones  heated  the  pieces 
should  be  promptly  quenched  ;  there  should  be  plenty  of 
the  cooling  medium,  so  that  its  temperature  may  not  be 
considerably  raised  by  the  heat  it  receives  from  the  steel ; 
the  piece  should  be  moved  about  in  the  bath.  This  not 
only  hastens  the  cooling  by  exposing  the  steel  to  fresh 
portions  of  the  bath,  and  by  mechanically  removing  the 
steam  from  the  surface,  but  also  equalizes  the  rate  of  cool- 
ing of  the  different  portions  of  the  piece.  For  large  pieces 
a  running  stream  may  be  needed  for  these  ends,  and  Jaro- 
limek  advises  a  spray  of  water  for  hardening,  as  giving 
the  greatest  hardness  with  the  smallest  consumption  of 
water.  When  large  pieces  (gun  tubes,  castings,  etc.) 
are  to  be  cooled  in  oil,  the  oil  may  be  cooled  by  worms 
or  water  jackets,  through  which  cold  water  circulates,  as 
a  running  stream  of  oil  might  be  inconvenient. 

Clearly,  under  otherwis3  like  conditions,  a  more  rapidly 
cooling  medium  will  be  needed  to  produce  a  given  rapidity 
of  cooling  in  thick  than  in  thin  pieces.  For  instance^ 
while  to  attain  given  stiffness,  thin  springs  (e.  g.,  those  of 
locks),  are  hardened  by  quenching  in  oil  from  a  cherry- 
red,  thick  springs  are  given  a  similar  stiffness  and  hard- 
ness by  water-hardening,  as  water  abstracts  heat  far  more 
rapidly  than  oil ;  while  those  of  intermediate  thickness 


22 


THE    METALLURGY    OP     STEEL. 


are  given  like  qualities  by  quenching  in  water  covered  with 
a  film  of  oil,  which  abstracts  heat  with  a  rapidity  inter- 
mediate between  that  of  oil  and  water. 

§  36.  PRECAUTIONS. — If  we  plunge  a  red-hot  cylinder 
of  steel  into  water,  the  exterior  at  first  cools  much  more 
rapidly  than  the  interior:  the  outer  shell  is  in  the 
position  of  a  thin,  highly  heated  cylinder  slipped  over  a 
cold  inner  cylinder,  which  it  is  barely  able  to  contain 
while  hot.  The  outer  cylinder  is  strained  and  may  be  burst 
by  its  own  contraction,  resisted  by  the  interior  which  it  is 
unable  to  compress.  If  we  have  a  square  rod,  instead  of 
a  cylindrical  .one,  the  resistance  of  the  interior,  which 
cools  and  contracts  comparatively  slowly,  to  the  initially 
rapid  contraction  of  the  exterior,  may  cause  the  exterior 
to  bulge,  to  become  convex  to  approach  the  cylindrical 
shape,  in  which  the  ratio  of  surface  to  volume  reaches  the 
minimum.  If  we  have  an  unsymmetrical  piece  (e.  g.,  an 
eccentric),  the  more  rapid  early  cooling  of  the  outside  may 
warp  it  out  of  shape. 

In  these  cases  cracking,  convexing  and  warping  are  due 
to  the  fact  that,  immediately  after  immersion,  the  exterior 
cools  more  rapidly  than  the  interior.  With  pieces  of  other 
shapes  similar  cracks,  distortions,  warpings  may  arise 
from  the  endeavor  of  the  more  slowly  cooling  portions  to 
cool  and  contract  after  the  more  rapidly  cooling  ones  have 
already  become  cool  and  rigid.  In  short,  we  must  endeavor 
to  avoid  dissimilar  rates  of  cooling  and  contraction  in  differ- 
ent portions  of  the  piece.  These  may  be  partially  or  even 
wholly  guarded  against  by  the  following  expedients : 

A.  BY  ACCELERATING  THE  COO:  ING  OF  THE  MOBK  SLOWLY 

COOLING  PARTS;  e.  g.,  we  may  dish,  panel,  or  perforate  the 
central  portions  of  thick  fiat  pieces  ;  and  we  may  perforate 
cylindrical  and  prismatic  pieces  longitudinally,  or  cut 
longitudinal  furrows  on  their  surfaces,  in  each  case  aiming 
to  hasten  the  cooling  of  the  central  portion  of  the  piece. 
When  one  portion  of  the  piece  is  much  thicker,  and  hence 
tends  to  cool  more  slowly  than  the  rest,  we  may  dip  that 
portion  into  the  cooling  medium  first. 

B.  BY   RETARDING  T11K  COOLING  OF  THE  MOKE  RAPIDLY 

COOLING  PARTS  ;  e.  ff.,  to  the  periphery  of  flat  pieces,  and 
to  other  portions  which  tend  to  cool  too  fast,  we  may, 
before  hardening,  fit  pieces  of  iron,  or  even  wire  gauze  ; 
the  scale  from  rolling  or  forging  purposely  left  on  such 
pieces  has  a  similar  but  of  course  milder  effect.  When, 
as  in  eccentrics,  holes  occur  in  the  periphery  of  flat  pieces, 
there  is  great  liability  to  cracking,  since  the  outer  rim  is 
then  in  the  condition  of  a  band  shrunk  upon  a  cylinder 
and  nearly  filed  through  at  one  point ;  the  contractility 
of  the  band  is  here  resisted  by  such  a  small  area  of 
cross-section  that  fracture  is  likely  to  occur.  So,  too, 
when  sharp  re-entering  angles  occur  on  the  exterior  of 
a  "piece,  it  is  apt  to  crack,  just  as  a  piece  of  cloth 
tears  across  where  notched.  So,  too,  where  holes 
occur  near  the  inner  border  of  annular  and  similar 
pieces,  or  where  re-entering  angles  (key-seats,  etc.)  occur 
on  their  inner  border,  fracture  is  likely  to  occur.  Such 
holes,  notches,  re-entering  angles,  etc.,'  should  be  avoided 
as  far  as  possible,  and  where  they  occur  it  is  important  to 
retard  the  cooling  of  the  metal  immediately  surrounding 
them,  as  by  inserting  in  the  hole  or  nick  a  piece  of  hot  j 
fire-clay  or  iron,  by  wrapping  wire  in  the  corners  of  key- 
seats,  etc.,  before  hardening,  etc. 

C.  BY   VARYING  INITIAL  TEMPERATURES. — In  certain 


cases,  such  as  taps,  we  may  heat  the  more  rapidly  cooling 
portion  (here  the  exterior)  to  a  somewhat  higher  tempera- 
ture than  the  interior,  to  partially  equalize  their  tempera- 
tures during  cooling.  And  in  general  the  more  slowly 
cooling  portions  should  certainly  not  be  initially  hotter 
than  the  more  rapidly  cooling  parts,  as  this  would  exag- 
gerate the  contraction  which  they  undergo  after  the  lat- 
ter have  become  cold  and  rigid.  Per  contra,  we  must 
carefully  avoid  overheating  and  burning  the  corners  and 
thin  portions  of  the  piece,  as  the  steel  may  thus  be  readily 
and  irreparably  injured. 

IN  PARTIAL  DIPPING,  where  only  a  portion  of  the  piece 
is  to  be  hardened,  it  should  be  moved  up  and  down  in  the 
water.  Otherwise,  an  aggravated  case  of  aBliochronous 
cooling  arises,  as  we  have  a  sharp  line  of  demarcation  at  the 
water's  surface  between  the  immersed  and  rapidly  cooling 
parts  and  the  non-immersed  and  slowly  cooling  ones. 

DIRECTION  OF  IMMERSION. — Long  and  narrow  or  thin 
pieces  should  be  immersed  lengthwise ;  otherwise  the 
aeliochronous  contraction  will  warp  the  piece ;  e.  g., 
if  a  thick  rod  be  immersed  not  lengthwise,  but  sidewise, 
the  side  first  immersed  cooling  and  contracting  first  will 
become  concave  for  the  instant ;  the  upper  side  cooling 
and  contracting  after  the  first  has  become  cold,  will  not 
exactly  compensate  for  this  initial  curvature,  and  the  piece 
when  cold  will  still  be  somewhat  curved. 

§  38.  TEMPERING. — Hardened  steel  is  too  brittle  for 
most  purposes  ;  hence  it  is  generally  .somewhat  toughened 
by  tempering,  by  slightly  re-heating  it.  The  higher  the 
temperature  to  which  the  steel  is  heated  in  tempering  the 
tougher  does  it  become,  with  a  corresponding  loss  of  hard- 
ness, but,  at  least  in  certain  cases,  with  considerable  gain 
in  tensile  strength.  Steel  when  tempered,  though  much 
more  ductile  than  when  hardened,  is  far  less  ductile  than 
when  annealed. 

TABLE  11.— EFFECTS  OF  TEMPERING. 


Hardened  in  watei*  •] 

Open-  hearth     steel 
of  0-15  C.a 

Cast    steel  of  I'OO 
±  C.b 

Tensile 
strength. 
Lbs.  per 
sq.  in. 

Elonga- 
tion ;,. 

Tensile 
strength 
Lbs.   per 
sq.  ill. 

Elonga- 
tion. 

72,760(6 
76,690 
66,385 

25-@ 
25-75 
S7- 

90,049 

100,98  l 
104,888 

112,119 
121,716 

o- 
o- 

0-7 
0-7 

7-0 

"          "  blue  heat  ^ 

59,79C(£ 
60,580 
58,000® 
58,430 

}* 

^36-5 

a  A.  E.  Hunt,  in  Transactions  Am.  Inst.  Mining  Engineers,  XII,  p.  311. 
b  Kirkaldy  experiments  on  wrought-iron  and  steel,  p.  165. 

§  39.  HEATING  FOR  TEMPERING. — The  hardened  steel 
must  be  re-heated  uniformly.  If  slowly  heated  the  steel 
is  said  to  become  tougher  than  if  rapidly  heated,  without 
corresponding  loss  of  strength  and  hardness.  Though  the 
smith's  forge  is  largely  used  for  heating  steel  for  temper- 
ing it  is  utterly  unfitted  for  this  purpose.  According  to 
the  size  and  shape  of  the  piece  to  be  tempered  we  may  heat 
it  by  contact  with  hot  iron  bars,  plates,  rings,  etc.,  or  by 
radiation  from  them ;  on  the  surface  of  melted  lead  or 
other  fusible  metal ;  in  hot  sand,"  in  burning  charcoal,  in 
reverberatory  furnaces,  etc.  When,  as  in  the  case  of  drills, 
only  the  point  is  hardened  and  tempered,  after  hardening 
the  still  hot  shank  heats  the  point  by  coneluction. 

In  all  these  cases  the  temperature  of  the  steel  is  indi- 


Ede  :  the  Treatment  of  Steel,  Miller,  Metcalf  &  Parkin,  p.  69. 


OTHER    METHODS    OF     HARDENING    AND    TEMPERING.       g  41. 


23 


cated,  with  sufficient  accuracy  for  practical  purposes,  by 
the  color"  of  the  film  of  oxide  which  forms  on  the  surface 
of  the  steel  (see  Table  12),  which  on  this  account  must  be 
brightened  before  it  is  re-heated,  and  the  steel  must  be 
withdrawn  from  the  heat  the  instant  the  desired  tint  ap- 
pears, lest  it  become  too  hot  and  hence  too  soft. 

TABLE  12.— TEMPERATURES,  ETC.,  FOB  TEMPEUII.G  STEEL. 


Oxide  tint. 

Tempera- 
ture. 

Appearance  of 
oil  bath.b 

Corresponding  uses  o: 
the  tempered  stue!. 

£-3  s 

^1  = 

a,       ft 
£     '" 

**M 

•asa& 
o  fr-sT* 
•» 

Cent 

Fah. 

White  

Tungsten  steel.  c 
HARDEST. 
Lancets. 

Tungs- 
ten steel 

l-5#c 
1'3-Jc 

0'9e 
0'8~ 

220 
230 

288 

243 

255 
260 
265 

S76 

277 

428 
446 

450 
469 

491 
500 
509 
530 
53i 

Straw  

Golden  yellow  

i 

t 
i 

Brown  

First  smoke. 

straments.    engrav. 
ings,t>   tups,b   dies  b 
cuttersb  

Re.  zors,   penknives, 
hammers,  d      taps, 
reami'rs  and  dies,  for 
wrought   and    cast- 
iron,  copper,  brass, 
etc.,*  cold  chisels  for 

Cold   chisels,    shears, 
scissors,  hatchets. 

Axes,      planes,     lal  he 
tools  for  copper.  <l 

Table    knives,     lar^e 
shears,  wood   tuiu 
ing     and      cutting 
tools,  d  cold    ch'sejs 
for  soft  cast  iron.d 
Cold  cbiselsforbrass.d 

Swords,  coiled  springs. 
Fine  saws,  augers,  etc. 

Brown,      dappled 
wilk  purple  

Purple  

Strong  darksmoke 

Abundant     black 
smoke. 

Violet  

\     Bright  blue  

288 
293 
804 

316 

550 
559 
580 

600 

*  Full  blue  
Dark  blue  

Jan    be    lighted, 
but  does  not  con- 
tinue to  burn.  . 

land  and  pitsaws,co!d 
chisels  for  wrouRBt- 
iron  and  copper,  d 

Spiral  springs,  b 
Jlockmnkei-s'     p  u  r  - 
poses,  b        SOFTEST. 

Just  visibly  red  iu 
the  dark  

eights     spontane- 

Burns  rapidly.... 

b  Ede  :  Treatment  of  Steel,  Miller,  Metcalf  and  Parian,     c  BSker  :  Journ   Iron 
nud  Steel  lust.,  1880,  I.,  p.  334.    dThurston:  Materials  of  Engineering,  II.,  p. 
3126. 

When  many  pieces  are  to  be  similarly  tempered  they 
are  advantageously  heated  in  oil  or  tallow,  the  behavior 
of  the  oil  then  roughly  indicating  the  temperature  (see 
Table  12). 

Thus  Ede  recommends  that  springs  of  ell  kinds, 
immersed  in  oil  or  smeared  with  it,  be  heated  till  the  oil 
burns  on  them  with  a  white  flame,  when  they  are  imme- 
diately quenched  in  cool  oil.  If  they  are  heated  in  the 
oil,  it  is  necessary  to  remove  them  from  it  to  ascertain 
whether  they  are  hot  enough  to  permit  the  oil  to  burn 
persistently  on  their  surfaces,  i.  e  ,  to  "blaze." 

The  temperatures  appropriate  for  tempering  for  various 
purposes,  and  the  indications  by  which  they  are  recog- 
nized are  given  in  Table  12.  They  vary  considerably  with 
different  steels,  in  a  way  imperfectly  understood.  The  ox- 
ide tints  too  are  said  to  differ  with  different  steels,  and  it 
is  not  unlikely  that  a  long  exposure  to  a  given  tempera 
ture  produces  a  deeper  tint  than  a  brief  one;  e.  g.,  a 
golden-yellow  may  indicate  either  a  brief  exposure  to  243° 
C.,  or  a  longer  exposure  to  say  230°.  But  this  loo  is  prob- 
ably of  little  practical  moment,  as  the  toughening  effect  of 

a  If  steel  be  heated  in  vacuo,  these  colored  films  do  not  form,  which  indicates 
that  they  are  of  oxije.  (Roberts  :  Traus.  Inst.  Mechanical  Engineers,  1881,  p. 
710.) 


a  given  temperature  appears  to  increase  with  the  length 
of  exposure  to  that  temperature. 

If  the  tempered  piece  be  too  hard,  that  is,  if  it  has  not 
been  heated  strongly  enough,  it  may  be  further  softened 
by  re-heating  to  a  slightly  higher  temperature,  and  with- 
out repeating  the  hardening  proper.  If,  however,  it  be  too 
soft,  that  is,  if  it  has  been  too  highly  heated  in  tempering, 
it  must  be  hardened  again  by  sudden  cooling  from  a  high 
temperature  (e  f/.,  a  cherry-red  heat). 

§  40.  COOLING.—  Ede  b  states  that  the  properties  of  steel 
are  the  same  whether  rapidly  or  slowly  cooled  after  heat- 
ing for  tempering,  i.  e.,  the  tempering  is  due  to  the 
reheating,  not  to  the  subsequent  cooling  ;  but  as  a  matter 
of  convenience  the  tempered  steel  is  usually  promptly 
cooled  in  water  or  oil.  My  preliminary  experiments  indi- 
cate that  steel  slowly  cooled  from  a  blue  heat  is  slightly 
tougher  than  if  suddenly  cooled.  Drills,  etc.,  whose  points 
are  heated  for  tempering  by  conduction  from  the  hct 
shank  of  the  drill,  must  of  course  be  plunged  in  water  the 
moment  that  their  point  shows  the  desired  temper,  as 
otherwise  the  point  would  become  overheated  by  conduc- 
tion. 

§  41.  OTHER  METHODS  OF  HARDENING  AND  TEMPEH- 
ING.— The  ordinary  method  here  described  may  seem  ir- 
rational in  that  it  first  gives  the  steel  undesirable  hard- 
ness and  brittleness,  part  of  which  has  to  be  subsequently 
removed.  Its  advantage  is  that  it  employs  readily  recog- 
nized and  regulated  temperatures  and  rates  of  cooling,  so 
that  the  degree  of  hardness  obtained  is  fairly  under  con- 
trol. By  the  oxide  tints  the  temperature  reached  in  tem- 
pering may  be  very  closely  controlled,  and  if  the  temper- 
ature from  which  the  steel  is  initially  hardened  can  not  be 
so  closely  recognized,  this  is  of  slight  importance,  since 
the  effect  of  considerable  variations  in  this  temperature  is 
slight.  Two  of  its  disadvantages  are  (A)  that  the  violent 
cooling  employed  in  hardening  often  cracks  costly  pieces, 
and  (B)  the  subsequent  tempering  chiefly  softens  the  ex- 
terior, which  in  the  case  of  cutting  tools  needs  the  greatest 
hardness.  Hence  plans  for  dispensing  with  subsequent 
tempering  by  directly  hitting  the  desired  degree  of  hard- 
ness by  the  hardening  operation  itself,  which  gives  the  ex- 
terior the  greatest  hardness,  leaving  the  interior  somewhat 
tougher,  have  been  proposed. 

They  all  appear  to  have  two  serious  disadvantages.  1st, 
the  degree  of  hardness  cannot  be  so  nicely  regulated  by  a 
single  operation  as  by  hardening  combined  with  subse- 
quent tempering.  2nd,  we  apparently  obtain  a  higher 
combination  of  strength  with  ductility  by  hardening  fol- 
lowed by  tempering  than  is  attainable  with  a  single  opera- 
tion, since  the  tempering  does  not  appear  to  lessen  the 
tensile  strength  and  hardness  imparted  by  the  preceding 
hardening  as  much  as  it  restores  the  ductility  wrhich  the 
hardening  had  removed.  On  account  of  these  drawbacks 
they  have  met  with  little  favor  even  for  cutting  tools ; 
while  for  softer  steels,  e.  f/.,  for  ordnance,  armor  plate, 
castings,  etc.,  they  seem  still  less  fit  ted,  since  here  their 
advantage  of  giving  the  exterior  greater  hardness  than  the 
interior  counts  for  naught. 

A.  C.U:ONC  recommended  hardening  not  in  cold  but 
in  warm  water,  which  would  cool  the  steel  more  slowly, 
and  harden  it  less  violently.  But  this  does  not  appear  to 


b  Treatment  of  Steel,  Miller,  Metcalf  &  Parkin,  p.  69. 
c  Metallurgical  Review,  I.,  p.  158. 


24 


THE    METALLURGY    OF    STEEL. 


give  uniform  results,  as  the  degree  of  hardness  acquired  is 
influenced  by  the  size  and  shape  of  the  piece,  the  rapidity 
with  which  it  is  moved  under  the  water  and  by  other 
variables  little  under  control,  more  than  by  the  tempera- 
ture of  the  water. 

B.  INTERRUPTED  COOLING  is  recommended  by  Jaroli- 
mek.a    Observing  that  the  degree  of  hardness  depends 
chiefly  on  thy  rapidity  with  which  the  steel  passes  from  a 
red  heat  to  one  slightly  below  redness,  while  tempering 
depends  on  exposure  to  a  much  lower*  temperature,  he 
would  harden  by  immersing  the  red-hot  steel  in  the  com- 
paratively dense  center  of  a  spray  of  water  till  the  red  color 
disappeared,  then  allow  it  to  cool  at  a  comparatively  slow 
but  (as  he  claims)  controllable  rate,  by  removing  it  to  the 
outer  and  rarer  portions  of  the  spray,  or  if  it  be  very  small 
and  would  cool  very  rapidly,  by  removing  it  completely, 
so  that  it  may  cool  in  the  air. 

C.  ORDINARY  HARDENING  WITHOUT  SUBSEQUENT  TEM- 
PERING is  employed  for  uses  which  demand  great  hardness 
but  for  which  toughness  is  not  needed,  e.  g.,  where  friction 
alone  is  to  be  resisted.     Thus  hardened  steel  bushings,  b 
rings,  collars,  plug  gauges  as  well  as  lathe  tools  °  for  cut- 
ting very  hard  cast-iron  and  unannealed  steel  may  be  used 
un  tempered. 

In  other  cases  where  great  stiffness  is  required,  as  in 
some  spiral  springs  which  must  sustain  a  heavy  load  but 
which  require  but  little  play,  the  desired  hardness  and 
stiffness  may  be  attained  by  hardening  alone  without  sub- 
sequent tempering,  by  employing  a  steel  lower  in  car- 
bon than  would  be  suitable  were  it  to  be  tempered  after 
hardening. 

§  42.  GUN  TOBES  and  jackets  are  generally  oil-hardened, 
though  i  t  is  said  that  Krupp'  sf  are  not.  The  quenching  tem- 
perature varies  from  a  blood-red  (Woolwich*),  to  a  strong 
yellow  heat  (Terre-Xoiree),  a  salmon  heat  being  employed 
in  the  best  American  practice.  The  higher  the  carbon  and 
the  more  the  piece  has  been  forged  before  hardening  the 
lower  should  the  quenching  temperature  be.  In  the  Eus- 
sianf  practice  it  is  said  that  the  piece  is  left  but  from  10 
to  15  minutes  in  the  oil ;  at  Terre-Xoire,  and  I  believe  at 
Woolwich,  and  in  the  best  American  practice  it  is  allowed 
to  cool  in  the  oil,  which  is  sometimes  cooled  by  circulation. 

Usually  the  hardened  tube  or  jacket  is  next  tempered 
by  heating  it  to  a  temperature  which  varies  from  500° 
Fahr.  (Woolwich),  to  a  cherry-red  (Terre-N"oire),  the 
tempering  temperature  being  generally  highest  where  the 
hardening  temperature  has  been  highest,  i.  e.,  where  the 
carbon  is  lowest.  At  Woolwich  the  jackets  are  tempered 
in  the  act  of  shrinking  them  upon  the  tube,  and  it  is  said 
that  the  tubes  are  not  tempered,  except  in  as  far  as  they 
are  heated  by  the  contact  with  the  hot  jackets.  To  re- 
move the  brittleness  due  to  hardening,  the  piece  is  almost 
invariably  either  subsequently  annealed  or  tempered. 

In  shrinking  the  coils  upon  the  tubes  at  Woolwich  d  the 
jacket  is,  according  toMaitland,  heated  to  500°  or  600°  F., 
and  slipped  over  the  tube,  the  shrinkage  in  the  case  of 
IS'.O"  guns  varying  from  0  to  -j-^  of  the  diameter.  The 
upper  end  of  the  jacket  is  kept  hot  by  a  ring  o'f  gas  or  a  hot 


a  Metallurgical  Review,  I.,  p.  158. 
b  Ede,  Op.  cit. 

c  Tburston  :  Materials  of  Engineering,  II.  p.  336. 
<t  Maitland:  Jour.  Iron  and  Steel  Inst.,  1881,  II.,  pp.  433-6. 
••  J'oim-el:  Op.  Cit.  P.,  1882,  IL,  p.  513. 
BeiwJt:  Proceedings  U.  S.  Naval  Inst,,  X.,  p.  561, 


cylinder  of  iron,  while  the  other  end  is  cooled  by  a  ring 
of  water,  which  is  gradually  raised  as  the  cooling  pro- 
ceeds. This  is  done,  lest  both  ends  of  the  jacket  should 
simultaneously  cool  and  grip  the  tube,  since  then  its 
subsequent  contraction  would  subject  the  jacket  to 
abnormal  longitudinal  tensile  stress. 

The  initial  oil-quenching  of  gun  tubes,  etc.,  is  frequently 
spoken  of  as  tempering  or  even  toughening,  but  as  in  the 
cases  which  I  have  observed,  the  tensile  strength  is  raised 
and  the  elongation  is  lowered  by  this  quenching,  it  ap- 
pears to  me  a  true  hardening  and  not  a  tempering.  (See 
Cases  13,  65,  66,  and  67,  Tables  8,  9,  10.)  The  tempera- 
ture at  which  the  hardened  tube  or  jacket  is  tempered  is 
usually  governed  by  an  examination  of  its  physical  proper- 
ties. If,  after  hardening,  it  appears  abnormally  hard,  the 
tempering  temperature  is  raised  higher  than  would  other- 
wise be  desirable.  If  it  appears  unexpectedly  soft  it  is  less 
strongly  reheated  for  tempering.  The  reheated  piece  is  at 
some  works  again  suddenly  cooled  (e.  ff.,  Terre-Xoire, 
where  it  is  reimmersed  in  oil,  in  which  it  is  allowed  to 
cool).  In  others  it  cools  slowly,  which  naturally  renders 
it  somewhat  softer  and  tensilely  weaker  than  when  sud- 
denly cooled. 

§43.  HARDENING  SPECIAL  STEELS. — Mushet's  "spe- 
cial" (tungsten)  steel,  Park  Bro.  &  Co.'s  "imperial" 
steel,  Miller,  Metcalf  &  Parkin's  "hardened"  steel,  and 
Hadfield's  "manganese"  steel  are  used  for  cut;ing-toolr; 
without  previous  quenching  of  any  kind.  The  steel  is 
forged  at  a  strong  red  heat  to  the  desired  shape  and  then 
allowed  to  cool  slowly  in  the  air;  after  grinding  on  an 
emery  wheel  (it  is  hardly  cut  by  a  file)  it  is  ready  for 
use.  Chrome  steel  is  quenched  in  water  from  dull  red- 
ness. See  further  §§  86, 138  and  139. 

§  45.  ANNEALING  effaces  more  or  less  completely  the 
effects  of  previous  hardening ;  it  increases  the  ductility 
and  specific  gravity,  and  it  generally  lowers  the  elastic 
limit.  As  gentle  hardening  raisjs  the  tensile  strength 
while  violent  hardening  may  lower  it,  so  annealing,  while 
it  generally  lowers  the  tensile  strength,  may  raise  it,  if  it 
has  been  previously  lowered, by  violent  hardening  or  other- 
wise. Annealing  removes  hardness  and  brittleness  arising 
from  cold  working  and  aelio<>hronousg  contraction  (as  in 
steel  castings)  as  effectually  as  those  caused  by  quenching. 
Important  steel  castings  are  generally  thoroughly  annealed 
in  this  country.  It  is  sometimes  specified  that  steel  marine 
boiler  and  ship  plates  shall  be  annealed.  The  most  careful 
of  marine  boiler  makers  (e.  g  ,  Cramp  &  Sons)  anneal  boiler 
plates  after  severe,  but  not  after  light  flanging,  etc.  Loco- 
motive and  stationary  boiler  plates  are  not  annealed  in 
this  country,  even  after  the  most  severe  punishment,  e.  g., 
flanging,  punching,  drifting,  etc.  In  European  ship-yards 
steel  was  formerly  very  largely  annealed  after  undergoing 
any  trying  work.  Annealing  appears  to  be  much  less 
frequently  resorted  to  to-day.  (Cf.  p.  179.) 

HEATING  TOR  ANNEALING. — The  steel  should  be  heated 
uniformly,  and  to  this  end  without  direct  contact  with 
the  flames. 

TEMPERATURE  FOR  ANNEALING. — The  most  advanta- 
geous temperature  for  all  kinds  of  steel  appears  to  be  a 
bright  cherry-red,  or  for  tool  steels  (with  say  \%  C)  per- 


8  I  susgect  the  adjective  aeliochronous  or  aeliotachic  to  express  the  fact  that  the 
cooling  and  contraction,  evenaf  equal  in  amount,  occur  at  different  rates  in  dif- 
ferent portions  of  the  piece. 


METHODS     AND     EFFECTS     OF     ANNEALING. 


25 


hup:;  a  slightly  lower  one.  If  the  steel  be  long  exposed 
to  a  much  higher  temperature  (say  a  light  red  or  orange 
In-lit)  it  assumes  a  coarsely  crystalline  structure,  which  it 
retains  on  cooling,  and  its  toughness  and  strength  are 
greatly  impaired.  High-carbon  steels  (e.  g.,  tool  steel) 
appear  to  assume  this  crystalline  structure  at  a  much  lower 
temperature  than  steels  with  less  carbon. 

COOLING. — The  more  slowly  the  steel  is  cooled,  within 
reasonable  limits,  the  softer  and  tougher  does  it  in  general 
become.  But  slow  cooling  from  a  cherry -red  to  a  tem- 
perature slightly  below  visible  redness  increases  the 
toughness  and  softness  far  more  than  slowness  of  cooling 
from  this  temperature  down.  Hence  for  many  purposes 
which  do  not  demand  extreme  toughness  it  suffices  to  cool 
the  steel  slowly  till  the  red  color  disappears  and  then 
quench  it  in  water.  Indeed  low-carbon  steel  which  has 
been  rendered  hard  and  brittle  (e.  g.,  by  cold-rolling  or 
drawing,  by  punching,  shearing,  etc  ),  and  steel  castings, 
may  be  rendered  far  less  hard  and  brittle  by  simply  heat- 
ing to  redness' and  quenching,  especially  if  oil -quenched, 
but  still  usually  less  ductile  than  if  slowly  cooled. 

It  is,  however,  probable  that  phosphoriferous  steels 
acquire  their  greatest  ductility  by  only  moderately  slow 
cooling.  Thus  Styffe*  gives  an  instance  in  which  weld 
iron,  with  0'26^  P,  is  much  tougher  as  well  as  somewhat 
stronger  after  quenching  in  water  than  even  after  ordi- 
narily slow  cooling,  in  the  former  case  having  a  tensile 
strength  of  66,769  Ibs.,  and  an  elongation  of  2,%  against 
a  tensile  strength  of  61,758  Ibs.,  and  an  elongation  of  only 
G'5%  after  ordinary  cooling. 

A  thorough  annealing  may  be  obtained  by  cooling  the 
heated  steel  in  ashes,  lime,  or  other  slow  conductor  of 
heat,  or  by  permitting  it  to  cool  slowly  in  the  furnace  in 
which  it  is  heated,  by  drawing  its  fire  and  closing  all  aper- 
tures.  Many  important  steel  castings  are  thus  annealed. 
At  many  American  works,  however,  boiler  and  ship- 
plates,  etc.,  are  annealed  (?)  by  heating  them  (often  under 
conditions  which  insure  irregular  heating)  to  a  red  heat, 
then  allowing  them  to  cool  on  the  mill  floor,  exposed  to 
draughts,  and  often  in  contact  with  cold  iron  plates  ;  in 
view  of  this  the  incredulity  of  many  engineers  about  the 
benefits  of  annealing  is  hardly  surprising.  Indeed,  un- 
less to  remove  really  violent  stresses  (e.'  g.,  after  punch- 
ing and  shearing  very  thick  pieces  with  rather  high  car- 
bon) annealing  should  not  be  resorted  to,  unless  it  can 
be  performed  carefully,  as  it  may  simply  exaggerate  the 
effects  of  previous  rapid  cooling  and  cool-rolling  which  it 
aims  to  remove  :  (e.  g.,  in  case  21  of  Table  16  the  tensile 
strength  is  actually  higher  and  the  elongation  lower  after 
the  annealing  than  before ;  yet  on  carefully  annealing 
steel  of  the  same  kind,  case  No.  20,  idem,  it  became 
softer  and  tougher. 

§  46.  QUANTITATIVE  EFFECTS  OF  ANNEALING.  A. 
HARDENED  STEEL.— The  effects  of  annealing  hardened 
steel  are  almost  exactly  the  reverse  of  those  of  hardening 
annealed  steel ;  and  as  most  of  the  quantitative  effects  of 
hardening,  detailed  above,  refer  to  the  difference  between 
the  tensile  strength  and  ductility  in  the  hardened  and  an- 
nealed states  respectively,  it  is  not  necessary  to  repeat 
them  here.  The  reader  is  referred  to  the  preceding  para- 
graphs, and  to  Tables  8  and  9. 

B.  UNIIARDENED  STKEL  — The  rolling  and  hammering 

»  Iron  and  Steel,  p.  133,  No.  34  ;  and  j>.  136,  Nos.  33  to  35, 


of  steel  is  often  finished  at  so  low  a  temperature  as  to 
considerably  raise  its  tensile  strength  and  diminish  its 
ductility,  and  these  effects  are  often  reinforced  by  the 
comparatively  rapid  cooling  which  it  undergoes  after 
leaving  the  rolls  or  hammer,  under  exposure  to  draughts 
of  air  and  often  in  contact  with  cold  plates.  These  effects 
are  largely  removed  by  annulling,  which  thus  increiis.-s 
the  ductility  and  diminishes  the  tensile  strength  of  ordi- 
nary commercial  steel  like  those  of  hardened  steel,  but  to 
a  much  lower  degree,  which  varies  greatly,  depending  as 
it  does  not  alone  on  the  efficiency  of  the  annealing,  but 
more  especially  on  the  degree  to  which  these  properties 
had  previously  been  affected  by  cool  forging  and  rapid 
cooling. 

The  efficiency  of  the  annealing  depends  chiefly  (!},  on 
the  annealing  temperature,  and  (2)  on  the  rapidity  of 
cooling,  and  hence  on  the  cooling  medium.  The  effect  of 
cool-forging  and  rapid  cooling  depends  chiefly  on  (3)  the 
cross  section  of  the  steel,  since  thin  pieces  not  only  are 
finished  at  a  lower  temperature  but  cool  more  rapidly 
after  leaving  the  rolls  than  thick  pieces,  and  (4)  on  the 
percentage  of  carbon. 

1.  ANNEALING-TEMPERATURE. — The  higher  the  anneal- 
ing temperature,  if  it  be  not  so  high  as  to  give  rise  to 
crystalline  structure,    the  more  efficient  it  is.     Thus  in 
Table  14,  annealing  the  same  steel  from  a  bright  cherry -red 
affects  the  ultimate  and  elastic  tensile  strength  about  5(1% 
more,  and  the  ductility  about  twice  as  much  as  annealing 
from  a  dark  cherry-red.     Steels  of  1  per  cent  and  of  'J2 
per  cent  carbon  appear  to  acquire  their  highest  ductility 
when  annealed  from  bright  cherry-redness  and  from  an 
crange  color  respectively.     With  higher  annealing  tem- 
peratures both  tensile  strength  and  ductility  decline  :  if 
even  ingot  iron  be  slowly  cooled  from  scintillating  white- 
ness its  ductility  may  be  almost  wholly  destroyed. 

2.  RAPIDITY  OF  COOLIXG. — In  the  same  table  we  note 
that  lime-cooling  affects  the  tensile  strength  and  elastic 
limit  much  more,  and  the  ductility  on  the  whole   some- 
what more  than  cooling  in  oil,  which  is  a  much  better 
conductor  of  heat  than  lime,  and  cools  the  steel  faster. 
The  intrinsic  value  of  the  steel,  if  we  may  measure  it  by 
the  product  of  the  tensile  strength  into  the  elongation,  is 
somewhat  greater  after  the  slower  lime-annealing  than 
after  oil-cooling,   though  this  might  not  hold  true  v/ith 
pieces  of  other  cross-sections  and  of  different  carbon. 

3.  CROSS  SECTION. — Since  thin  steel    becomes    colder 
while  being  forged  and  cools  more  rapidly  after  forging 
than  thicker  steel,  we  should  naturally  expect  to  find  that 
the  stresses  set  up  by  cool  forging  and  rapid  cooling  would 
be  greater  in  thin  than  in  thick  steel,  and  hence  that  the; 
former  would  be  more  affected  by  annealing.     And  as  re- 
gards tensile  strength,  this  is  apparently  the  case.     Thus, 
comparing  together  Cases  1  with  6,  2  with  7,  3  with  8,  and  4 
with  9,  in  Table  16,  we  note  that  the   tensile  strength  of 
the  former  of  each  pair  (representing  2-inch  square  bars) 
is  diminished  by  annealing  more  than  that  of  the  latter 
(which  represents  the  average   of  2-inch  square  and  of 
larger  bars). 

So  too  in  Table  15  we  see  that,  with  a  rough  approach 
to  uniformity,  the  smaller  the  cross-section  of  the  finished 
piece  the  more  the  tensile  strength  is  lowered  by  anneal- 
ing. But  as  regards  ductility  we  find  the  very  opposite. 
Thuo  in  Table  15  columns  C  and  D  we  see  that  the  thicker 


26 


THE    METALLURGY     OF     STEEL. 


TABLE    14. 

INFLUENCE  OF  THE  TEMPERATURE  OF  ANNEALING.      INCREASE   (  +  )    OR  DECREASE    (— )    03  TENSILE  STRENGTH,    ETC.,   CAUSED  BY   ANNEALING, 

PEE   100  OF  ORIGINAL. 


Steel  of  0'30  per  cent  carbon  

Initial  (unannealed). 

Tensile    strength. 
Lbs.  per  sq  .  in.      ! 

Elastic  limit, 
jbs.  per  sq.  iu. 

Elongation  Re< 
Per  cent. 

luction  of  area. 
.Per  cent. 

74,950 

43,330 

20 

33 

Percentage  of  increase  on  annealing. 

—    6 
—  16 
—  23 

—     6 
—  18 
—  29 

+  15 

+  40 

-i    !<0 

+    9 

+  26 
+  51 

Calculated  from  A.  F.  Hill's  data  •<         "            "     dark  cherry-red  

(         "            "      bright        "         

EFFECT    OF  DIFFERENT  ANNEALING  MEDIA. 

Initial  (unannealed). 

Tensile  strength.        Elastic  limit. 
Lbs.  per  sq.  in.        Lbs.  per  sq.  in 

Elongation. 
Per  cent. 

Reduction  of  ar 
Per  cent. 

ea.     Efficiency. 
Number. 

93,300                      50,180 

15-3 

30 

1,425,960 

Percentage  of  increase  on  annealing. 

—  14                        —  17 
—  11                        —    9 

.     +  49 
+   32 

+  39 
+  36 

+  25 
+   17 

Calculated  from  A.  P.  Hill's  data,  annealed  from  dark  cherry-red,  in  |  Q™e  

TABLE  15. 

EFFECTS  Of  ANNEALING  AS  INFLUENCED  BT  VARYING  CROSS  SECTION.        CALCULATED  FROM  KIRKALDY'S  DATA,  "EXPERIMENTS  ON   FAGERSTA  STEEL,"  SERIES   C1  C2 

C",  AND  B1  B2  B3  AND  B4. 
Increase  ( H  )  cr  decrease  (— )  of  tensile  strength,  elongation,  etc.,  caused  by  annealing  ordinary  Bessemer  steel  bars,  per  100  of  the  original. 


A 

B 

C 

D 

E 

No. 

Size  of  Bars. 

Tensile  Strength. 

Elastic  Limit. 

Elongation.     . 

Reduction  of  Area. 

Efficiency  Number. 

H 

R 

n         R 

H 

R 

R 

H 

R 

1 

a 
s 

Mean  of  results  cbiainc-1  with 
steel  of  1-0,   0-5,  and  0-15  per 

K"*K" 

l"xl" 

WxlW" 

—15-1 
—  8-7 
—  3-5 

—18- 
—  6- 

—  3- 

—  1C- 
—13- 
-13- 

+   27- 
+    11- 
+   65- 

—    6- 

—    7- 
+   40- 

+   25- 
+   33- 

+   78- 

+     9- 

+     2- 
+   59- 

—  16- 
-  13- 

+    39' 

4 

cent  C. 

2"x3" 

—  2-7 

—   o* 

—14- 

+   75- 

+   60- 

+   94- 

+   72- 

+   22- 

5 

au"x2}<i" 

—  7-6 

—  3' 

—18- 

+  111- 

+  160- 

+  289- 

+  107- 

+  153- 

6 

3"x3" 

—  £-9 

—  4- 

—15- 

+  188- 

+    97- 

+  164- 

+  184- 

+   87- 

7 

3"x2" 

—77 

+   45- 

+   57- 

+   33- 

8 

3"  x  3" 

G'4 

+   64' 

+   96- 

+   54- 

9 

4"x4" 

—2-7 

+   38- 

+   43- 

+   34- 

10 

5"  x  5" 

—4-7 

+   22- 

+   46- 

^     15- 

11 

6"  x  6" 

—0-3 

+  189  -a 

+  169-a 

+  109.a 

NOTE. — The  percentages  of  increase  of  elongation  and  cf  reduction  cf  area,  cols.  C  and  D  are  per  100  of  elongation,  etc.,  of  the  unannealed  steel,  and  not  per  ICO 
of  its  length,  etc. 


"  =  tioso  figures  r.ro  exaggerated  by  ore  r.kEcrrr.cl  rcrult. 


fi  =  hammered. 


R  =  rolled. 


the  steel,  the  more  does  annealing  increase  its  elongation 
and  contraction.  Since  then,  thick  pieces  have  their  ten- 
sile strength  diminished  less  and  their  ductility  increased 
more  by  annealing  than  thin  ones,  our  data  suggest  that 
annealing  benefits  thick  more  than  thin  pieces,  an  impor- 
tant conclusion,  which  I  have  not  hitherto  seen  set  forth. 
The  effect  of  annealing  on  the  elastic  limit  appears  to  be 
independent  of  the  cross  section. 

4.  CARBON. — Under  apparently  like  conditions,  the  ten- 
sile strength  is  sometimes  lowered  more  in  high  than  in 
low-carbon  steel,  while  as  often  the  low-carbon  steel  is 
the  most  affected.  Thus,  in  Cases  1  to  10  of  Table  16,  the 
high-carbon  steel  is  the  most  affected.  In  Cases  11  to  18, 
the  low-carbon  steel  i3  rather  more  affected  than  the  high, 
while  in  Cases  23  to  26  the  low-carbon  steel  has  its  tensile 
strength  and  elastic  limit  in  every  case  affected  more  than 
high-carbon  steel.  But,  almost  without  exception,  under 
like  conditions,  the  higher  tha  carbon  the  more  the  ductility 
is  increased  by  annealing,  the  effect  of  the  annealing  on 
the  ductility  generally  rising  very  rapidly  with  increasing 
carbon.  Thus,  in  Table  16,  the  higher  is  the  C,  under  like 
conditions  the  higher  algebraically  are  the  numbers  in 
columns  6  and  7.  Since,  then,  with  increasing  carbon 
the  effect  of  annealing  in  raising  the  ductility  rises  more 
rapidly  and  constantly  than  does  its  effect  in  lowering  the 
tensile  strength,  it  f  Hows  that,  if  we  may  measure  the 
intrinsic  value  of  steel  by  the  product  of  its  tensile  strength 
into  its  elongation,  the  higher  the  carbon  the  more  bene- 
ficial in  general  is  annealing.  I  am  not  aware  that  this 


deduction  has  heretofore  being  pointed  out.  Thus, 
in  all  the  comparable  cases  in  Table  16,  writh  one 
exception,  due  in  turn  to  a  single  abnormal  observation, 
the  higher  the  carbon  the  greater  algebraically  is  the  per- 
centage of  increase  of  the  efficiency  number.*1 

The  few  cases  given  in  columns  IX.  and  XIV.  of  Table 
8  throw  little  light  on  these  questions,  as  the  other  varia- 
bles vary  so  much  as  to  mask  the  effects  of  varying  C, 
while  in  each  set  of  cases  in  Table  16  we  have  practically 
constant  conditions. 

5.  HAMMERING  vs.  ROLLING — Comparing  in  Table  16 
the  figures  of  cases  11  to  1 4  (hammered)  with  the  corre- 
sponding ones  of  cases  15  to  18  (rolled  steel),  we  note  that 
in  the  majority  of  cases  the  hammered  steel  is  affected  by 
annealing  more  than  the  rolled  steel.  But  this  is  no  doubt 
chiefly,  perhaps  wholly  due  to  the  fact  that  this  particu- 
lar hammer  worked  more  slowly  than  these  particular 
rolls,  hence  finished  the  piece  at  a  lower  temperature,  and 
thus  induce  to  a  greater  degree  those  effects  which  an- 
nealing removes.  This  does  not  necessarily  indicate  that 
hammered  steel  is  in  general  more  affected  by  annealing 
than  rolled  steel,  except  in  so  far  as  hammers  in  general 
may  work  more  slowly  than  rolls.  It  points  to  no  oc- 
cult difference  between  the  effects  of  the  hammer  and  the 
rolls. 

§  47.  UNFORGKD  STEEL  CASTINGS. — The  cases  before  us 
show  how  the  coarse  structure  and  the  stresses  which 
exist  in  unannealed  castings  weaken  them,  besides  very 


a  Efficiency  number  —  elongation  x  tensile  strength,  pounds  per  squure  mch. 


THE    RATIONALE    OF  HARDENING    AND    ANNEALING. 


TABLE  16. — EFFECTS  OF  ANNEALINQ  AS  INFLUENCED  BY  THE  PERCENTAGE  OF  LV. 


DESCRIPTION  OF  STEEL. 

Increase  (  +  )  or  decrease  (  —  )  of  tensile   strength,   etc.  .  caused  by  anneal- 
ing, per  100  of  the  original. 

Properties  of  the  steel  before  annealing. 

No. 

Per  cent 
Carbon. 

Tensile 
strength. 

Elastic 
limit. 

Elonga- 
tion. 

Reduction 
of  area. 

Efficiency 
number. 

Tensile 
strength. 
Lbs.  jx?r 
Lq.  ia. 

Elastic 
limit. 

Elonga- 
tion. 
Per 
cent. 

Rccuc- 
tLn. 
Per 
cent. 

Two-inch  cqv.aro  Fagersta  Bessemer  steel  bars  J 

1 
2 
3 

<t 
5 

•80 
•GO 
•40 
•20 

13-7 
—  6-3 
5'6 

—29- 
—  2-9 
—  7-0 
—  6-0 
—11-3 
—22-3 
—  4-4 
—  7-1 
—  8-2 
—11-86 
—23-6 
—20-4 
—39-5 
—24-5 
—23-3 
—  8-6 
—10-9 
—14-3 

-t     ICO- 
+     25- 
+        6- 
—        1-3 

+      45- 

+    vo- 

+    110-d 
+      SI- 
+      16' 

+  150- 
+    63- 
+     9-8 
+     4'(i 
+    57-6 
+    70- 
;  186-4 
+    43- 
+   49- 

+  11C- 

+    17- 
+      0-7 
—     7-3 

98,024 
97,887 

75,013 
59,940 

66,500 
47,700 
39,300 
35,200 

2-3 
10-2 
17-9 
22-5 

33 
28-4 

5:..  -5 
613 

Average  of  the  four  preceding  

—  6-0 
—  7-6 
—  7-1 
—  1-5 
—  4-1 
—  3-7 
—  4-13 
—  3-3 
—  6-9 
—11-6 
—  7-2 
—  5-0 
-  3-7 
—  6-8 
5-0 

Average  of  results  from  6-inch  square  ingots  ( 
and    bars  5  ia.,  4  in.,  3  in.,  and  3  ij.  square  J 
hammered  from  them.     Fagersta  Bessemer  1 
steel"     .                                 [ 

6 
7 
8 
9 
10 

•80 
•60 
•40 
•20 

+   58- 
+  110-7 
+   16- 
+    13- 

75,959 
75,639 
05,001 
56,401 
68,350 
99,333 
81,307 
60,834 
80,421 
105,784 
79,470 
56,843 
80,699 
66,500 

C3,457 
41,743 
31,943 
27,800 
38,736 
73,383 
48,850 
40,633 
54,289 
67,900 
39,283 
28,317 
45,167 

Average  of  remits  from  bars  3  in.,  2%  in.,  21 
in.,  IJ^iu.  ,  1  in.,  and  %  in.   square,   ham-- 
merod  from  Fagersta  Bessemer  steel  ingots  a.  ( 

11 
12 
1C 

14 

1-00 

o-co 

0-15 

+      88- 
+      13- 

•f        5- 

+   50- 
+   28- 
+   21- 

+  189- 
+   29- 
-     2- 

2'6 
13-1 
20- 
11-9 
3-1 
11-5 
36-2 
13-6 
28-05 
19-95 

6-2 

3<;-8 

55-8 
Sl-4 
6-7 
20-6 
50-4 
279 

Average  of  results  from  bars  similar  to  tho  Ir.st  ( 
set  (Nos.  11  to  14),  butrolled  instead  of  being/ 
hammered**..                          ( 

15 
16 
17 

IS 

1-00 
0-EO 
0-15 

+      58- 
+        3- 
+        3- 

+   75- 
-1-   69- 
+   20- 

+  140- 
+   15- 
—     3- 

Five  lots  cf  Chester  open-hearth  (  Maximum.  . 
steel  plates,  0'48  andO'74  inches/  Minimum  .  . 
thick.    Gatewood,  p.  131  b  (  Average  
Three   care"ully   annealed    open-hearth    steel  I 
plates.    Idem,  p.  105  b  | 

10 

0-145 
0-145 
0-145 
0-18  to 
0-26 

0-90± 

0-50 
0-40 
0-30 
0-50 
0-40 
0-30 

o-oo 

040 
0-30 

—  7-43 
—  1-58 
—  5-17 
—  4-7  to 
—  8-5 

+   5- 

—  6- 
—13- 
—22' 
+  13- 
+  14- 
+  23- 
—  1- 

—  3- 

—  3- 

+      23-16 
+        2-68 
+      13-52 
+        6-3  to 
+        8-4 

4- 

+      23- 
+      29- 

+    si- 

+    131- 

+  101- 

+      79- 
+  1057- 
+   518- 
+  394' 

10 
10 

£3 
2J 

£1 

SO 
23 
84 

25 
35 
25 
20 
23 
26 

63,067 

+     0-lto 
+     5- 

Steel  plates  representing  90  per  cent  of  251 

Steel  bar-.  1-5x0-5x13  inches,  caloul-.ted  f  rom  ( 
A.  F.  Hill's  data  c  ..  -j 

—14- 
15- 

+    15- 
-1-    13- 

—     7- 

97,300 
90,900 
76,400 
83,930 
75,400 
69,376 
91,810 
87,560 
85,380 

56,700 
49,300 
43,100 
49,960 
4t,2CO 
31,290 
71,680 
64,180 
63,720 

13- 
17- 

iJ-1- 
5-3 
C-3 
11-3 
0-7 
S3 
C'4 

Steel  bars,  previously  hardened  by  shearing  j 
from  plates  c  .  .  .  | 

—35' 
+  19- 
+  35- 
+  43- 
9- 

Steel  bars,  previously  hardened  by  cold  ha-r-  j 

—19- 
—37- 

( 

NOTE. — The  percentage  of  inc>  ea?o  of  elongation  and  of  reduction  of  area,  columns  6  and  7,  are  per  100  of  the  elongation,  etc.,  of  the  unannenlerl  steel,  and  not  per 
1 00  of  ita  length.  Tteso  results  ai e  calculated  by  the  author  from  the  data  given  by  the  following  writers  :  a  Kirkaldy,  "  Experiments  on  Fager&ta  Steel."  l>Oa.L- 
frood,  "Reportof  the  Naval  Advisory  Board  on  Mild  Steel."  U.  S.  Navy  Department,  1886.  c  A.  F.  Hill,  Transactions  of  the  American  Institute  of  Mining  Engi- 
neers, XI. ,  p.  348,  1883.  a  these  two  results  are  exaggerated  by  one  abnormal  case.  Except  where  specified  the  steel  was  in  the  ordinary  condition,  and  had  under- 


gone  no  treatment  after  leav.'n 


results  are  exagger 
the  rolls  or  hammer. 


greatly  diminishing  the  ductility.  Thus  in  columns 
VIII.,  XL,  and  XIV.  of  Table  9  we  see  that  the  elonga- 
tion of  the  unannealed  casting  is  always,  and  its  elas- 
tic limit  and  tensile  strength  are  almost  always  below 
those  of  the  same  casting  when  annealed. 

Moreover,  we  observe  that  as  the  carbon  increases  ('/.  e., 
as  we  pass  down  the  columns)  there  is  on  the  whole  a 
decided  decrease  in  the  algebraic  value  of  the  numbers 
in  columns  VIII.  and  XL;  «'.  e.,  the  higher  the  carbon  the 
more  are  both  tensile  strength  and  elongation  increased 
by  annealing,  which  means  that  in  castings  as  in  forgings 
annealing  is  the  more  beneficial  the  higher  is  the  carbon. 

PUNCHED  AND  SIIEARKD  STEEL. — The  stresses  in 
punched,  sheared  and  flanged  boiler-plate  steel  are 
greatly  relieved  by  simply  heating  to  redness  and  quench- 
ing in  oil  or  boiling  water,3  but  perhaps  less  than  by  slow 
cooling.  Cases  25  and  26,  Table  16,  show  a  greater  increase 
of  efficiency  number  on  annealing  '50  carbon  than  '30 
carbon  steel.  This  agrees  with  the  observation  made  con- 
cerning the  effect  of  annealing  on  other  high  vs.  low-carbon 
steel.  The  effects  of  annealing  on  punched  and  sheared 
steel  will  be  discussed  with  the  effects  of  punching,  etc. 

EFFECT  OF  ANNEALING  ON  TUB  MODCLUS  OF  ELAS- 
TICITY.— The  indications  are  at  present  not  only  meager, 
but  contradictory.  On  the  one  hand,  it  is  stated  that 
hardening  raises  the  modulus,  which  would  imply  that 
annealing  should  lower  it ;  and  analyzing  Kirkaldy' s  re- 
sults on  10  plates  of  0'15  C  we  find  that  annealing  lowers 
it  from  37,300,000  to  32,260,000  Ibs.,  or  by  say  14$.  On  the 
other  hand,  from  an  examination  of  results  obtained 
with  Cambria  steel  (C  '09@'24)  Gatewoodb  concludes  that 


a  Barnaby:  Jour.  Iron  and  Steel  lust.,  1883,  I.,  p.  208-9. 

1'  Rept.  TJ.  S.  Naval  Advisory  Bd.  on  Mild  Steel,  1886,  p.  136. 


the  modulus  of  this  steel,  in  the  condition  in  which  it  or- 
dinarily leaves  the  rolls,  is  raised  by  about  1,000,000  Ibs. 
by  annealing. 

§  48.  NUT  EFFECT  OF  HARDENING  PLI  s  ANNEX- 
ING.— Though  annealing  counteracts  the  effects  of  harden- 
ing it  does  not  necessarily  obliterate  them,  and,  while 
giving  the  metal  even  greater  ductility  than  it  had  before 
hardening,  it  may  not  completely  remove  the  increase  of 
tensile  strength  conferred  by  hardening,  so  that  by 
judiciously  managing  these  two  operations  we  may 
simultaneously  increase  both  tensile  strength  and  ductility. 
This  is  illustrated  in  Table  16  A.  Here  in  one  instance  we 
have  a  simultaneous  gain  of  33^  in  tensile  strength,  25  % 
in  elongation  and  77  %  in  reduction.  The  cases  here  given 
all  represent  steel  forgings.  Steel  castings,  whose  tensile 
strength  and  ductility  are  lowered  by  coarse  structure  and 
internal  stress,  might  undergo  a  still  greater  simultaneous 
gain  of  tensile  strength  and  ductility  when  hardened  and 
subsequently  annealed. 

THE  RATIONALE  OF  HARDENING  AND  ANNEALING. 

§  49.  IN  THE  PREVALENT  VIEW  sudden  cooling  affects 
the  physical  properties  of  steel  by  preserving  the  chemi- 
cal condition  which  existed  at  a  red  heat. 

The  following  discussion  recognizes  in  addition  certain 
purely  physical  effects  of  sudden  cooling,  to  which  in  com- 
mon with  its  chemical  features  it  ascribes  the  changes  in 
the  properties  of  the  metal.  The  changes  in  hardness 
proper  it  ascribes  mainly  to  chemical,  those  in  tensile 
strength  and  ductility  jointly  to  chemical  and  ph-  sical 
origin.  Let  him  pass  it  by  who  seeks  easy  reading  ;  my 
feeble  light  can  but  faintly  illumine  these  obscure 
depths. 

I  recognize  three  distinct  proximate  effects  of  sudden 


THE    METALLURGY     OF    STEEL. 


TABLE   16   A.-GAIN  (+)  OR   Loss   (— )   OF  TENSILE   STRENGTH,  ETC.,   DUE  TO   HARDENING   PLUS  ANNEALING  PEB  100  OF  THOSE  OF  THE  STEEL  BEFOHB 

HARDENING. 


Gain  of  tensile  strength. . . 

Gaiu  of  elongatior 

Gain  of  reduction  of  area. 
Gain  of  efficiency  number. 
Original  tensile  strength . . 

Original  elongation 

Original  reduct  ion  c  if  area . 


—    1-2 

+  47- 

+  113- 

+    40- 

8S,7C9 
16-6 
22-56 


+      9-2 
+    35- 

i  102- 

+    47- 
74,722 
18- 
23-61 


—      1-6 
+    52- 
+  153- 
+    49- 
82,053 

17- 

19-59 


+  11- 

+  44' 

+  82- 

+  00- 

70,129 
16 -B 
25-30 


+    a- 

+    95- 

+  145- 

+    99- 
89,656 
1 1  -5 
16-83 


+  13- 
+  11- 
1  83- 
+  25- 
78.144 

19" 

21-85 


+ 15- 
+  28- 
+  86- 
+  47- 
83.850 

17- 

22-56 


+  10- 
+  32- 
+  71- 
+  45. 
82,709 

17- 

24-31 


+  33- 
+86- 

+  77- 
4  <•(•,- 
7'.i.5:> 
16-6 
22-80 


+  26- 

—28' 

— 21' 

-11- 
81J31I 
88-5 
37-53 


+  16' 
—  4- 

i  :i:s- 
+  11- 

97,539 
17' 

20-72 


+      7-     +     8-     +    8- 

+    10-     +  16-     +    5- 

f       8-     +  09-     +  47- 

+     18-      +  25-     +  1H- 

100,;-59  95,008  94,100  89,000 
15-  12  '5       19-5 

29-72       13-0      32-0 


t-  20- 

+     3- 

+  44- 

24- 


18-5 
27-0 


+     13- 
+     30- 
-h  158- 
+     47' 
8<>,13S 
11* 
12-9 


Proc.  U.  S.  Naval  Inst.,  No.  40,  1887,  pp.  OS  and  118. 


Gain  and  less  of  elongation  and  of  reduction  of  area  are  per  100  of  the  elongation  and  reduction  of  the  unhar- 
dened  steel,  and  not  per  100  of  its  dimensions. 


cooling.  Others,  Neptune-like,  may  perturb  our  phe- 
nomena. Superimposed  they  produce  resultant  effects  on 
each  mechanical  property,  and  the  ratio  which  the  re- 
sultant for  one  (e.  g.,  tensile  strength)  bears  to  that  for 
another  (e.  g.,  hardness"),  under  different  cor.ditions  dif- 
fers very  greatly,  not  merely  in  amount  but  actually  in 
sign.  Our  present  data  do  not  permit  us  to  determine  the 
value  of  each  proximate  effect  quantitatively ;  I  merely 
seek  their  signs  and,  where  possible,  a  roiagh  estimation 
of  their  relative  values. 

Hardening  differs  from  annealing  essentially  in  being  a 
more  rapid  cooling.  A  rapid  cooling  may  affect  the  physi- 
cal properties  of  steel, 

(1.)  By  maintaining  in  the  cooled  steel  the  chemical 
condition  of  the  metal,  and  especially  that  of  its  carbon, 
which  existed  at  a  high  temperature  ;  this  should  increase 
its  hardness  and  tensile  strength  but  lower  its  ductility. 

(2.)  By  causing  the  outside  to  cool  much  faster  than  the 
inside,  which  may  act  in  two  ways  : 

(A.)  By  setting  up  stresses  which  if  moderate  increase 
the  tensile  strength,  but  if  intense  lower  it,  and, 
whether  slight  or  severe,  lower  the  ductility. 
By  compressing  the  exterior  they  may  increase 
the  superficial  density  and  hardness. 
(B.)  By  causing  a  pressing  or  kneading  together  of 
the  different  layers,  somewhat  resembling  that 
of   forging,   which  should  increase  both  the 
tensile  strength  and  ductility. 
(3.)  By    preventing    the    coarse    crystallization  which 
occurs  when  the  metal  is  long  exposed  to  a  high  tempera- 
ture, and  perhaps  by  breaking  it  up  in  some  measure  if 
already  acquired.     In  this  way  both  tensile  strength  and 
ductility  should  be  increased. 

The  following  table  sums  these  effects  up,  -{-  indicating 
that  a  property  is  increased,  —  that  it  is  diminished  by 
sudden,  as  compared  with  slow  cooling  : 

EFFECTS  OP  SUDDEN  COOLING. 


PROXIMATE  EFFECTS. 

Ultimate  effects  on  the  physical 
properties  of  steel. 

Tensile 
strength. 

Ductility. 

Hardness. 

1. 
3. 

3. 

It  preserves  the  chemical  status  quo 

+ 

± 
+ 
+ 

+ 

+ 

+ 

+ 
+  ? 
? 

It  causes  dissimilar  rates  of  contraction  : 
A.  These  set  up  stresses  „  

B.  They  knead  the  particles  together  

It  prevents  coarse  crystallization  

Annealing,  i  e.,  slow  cooling,  by  offering  the  opposite 
set  of  conditions,  effaces  more  or  less  completely  all  the 
effects  of  sudden  cooling,  except  (2  B. )  those  due  to  the 
kneading  together  of  the  particles,  which  it  is  probably 
powerless  to  remove. 


1 1n  this  discussion  I  use  hardness  in  its  strictest  sense  of  power  to  resist  indenta- 
tion, which,  though  usually  accompanied  by  rigidity  and  brittleness,  stands  in  no 
fixed  relation  to  them. 


None  of  the  proximate  effects  diminishes  hardness  ; 
hence  steel  is  always  harder  when  quickly  than  when 
slowly  cooled.  But  the  signs  in  the  ductility  and  len- 
sile  strength  columns  are  sometimes  -f,  sometimes  — ; 
hence,  sudden  cooling  renders  steel  stronger  or  weaker, 
tougher  or  more  brittle,  according  to  the  special  con- 
ditions of  the  case.  It  is  certain  that  the  relation  be- 
tween the  effects  of  sudden  cooling  on  tensile  strength, 
ductility  and  hardness  respectively  differ  greatly  with, 
the  special  conditions  of  cooling,  i.  e.,  the  shape  and 
size  of  the  piece,  its  percentage  of  carbon,  the  tempera- 
ture from  which  quenching  occurs,  the  cooling  medium, 
etc.  Hence,  while  the  usual  effect  of  sudden  cooling  is 
to  make  steel  stronger  and  more  brittle,  it  may,  under 
exceptional  conditions,  render  it  at  once  weaker  and 
more  brittle,  and  under  others  at  once  stronger  and 
tougher  than  if  slowly  cooled.  And  while  slow  cooling 
usually  renders  steel  tougher  and  tensilely  weaker,  it  may, 
under  exceptional  conditions,  render  it  both  weaker 
and  more  brittle,  and  under  others  both  tougher  and 
stronger. 

Let  us  now  consider  in  detail  these  proximate  effects 
of  sudden  cooling  and  their  relations  to  its  ultimate 
effects. 

§  50.  SUDDEN  COOLING  AFFECTS  THE  MECHANICAL 
PROPERTIES  OF  STEEL  BY  PRESERVING  THE  CHEMICAL 
STATUS  QUO. 

In  §§  23-25  I  gave  reasons  for  believing  that  at  or  about 
cherry -redness  the  carbon  of  steel  passes  almost  wholly 
into  the  hardening  state,  combining  with  the  whole  of  the 
matrix  of  iron  present  to  form  a  compoiind  which,  when 
cold,  is  intensely  hard  and  much  stronger  arid  more  brittle 
than  pure  iron,  and  which  is  preserved  by  sudden  cooling. 
Hence  quenching  from  redness  hardens,  strengthens 
makes  brittle.  That  at  a  lower  temperature,  V5  it  tends 
to  pass  into  the  cement  state,  crystallizing  within  the 
matrix  of  iron  as  a  definite  carbide,  Fe3C,  giving  the 
composite  mass  a  degree  of  hardness,  strength  and  brittle- 
ness  intermediate  between  those  of  hardened  steel  and  of 
pure  iron  ;  hence  slow  cooling,  implying  long  exposure  to 
temperatures  near  V,  softens,  toughens,  weakens.  That 
at  temperatures  below  Vthis  tendency  remains,  but  that, 
if  by  sudden  cooling  the  carbon  has  been  imprisoned  in 
the  hardening  state,  it  is  prevented  by  chemical  inertia 
from  escaping  into  the  cement  state  as  long  as  the  meta^ 
remains  cold  ;  yet  that  this  inertia  is  gradually  relaxed,  the 
change  to  the  cement  state  gradually  occurs,  and  the 
hardness,  strength  and  brittleness  due  to  quenching  from 
redness  are  gradually  more  and  more  completely  removed 
as  the  suddenly  cooled  steel  is  reheated,  till,  when  V 
is  reached,  their  removal  is  complete.  Chemistry 
thus  explains  much,  but,  as  I  shall  now  try  to  show,  not 
all. 


THE    RATIONALE    OF    HARDENING    AND    ANNEALING. 


29 


§  61.  SUDDEN  COOLING  AFFECTS  THE  PHYSICAL  PROPER- 
TIES OF  STEEL  BY  CAUSING  DISSIMILAR  RATES  OF  CON- 
TRACTION. 

I.  Tiiuoumi  CAUSING  INTI-.KNAL  STRESSES. — Let  us  con- 
sider these  stresses  and  their  effects  on  (A)  specific 
gravity,  (B)  tensile  strength,  (C)  ductility,  and  (D)  hard- 
ness. 

A.  EFFECT  ON  SPECIFIC  GRAVITY. — Consider  a  round 
bar  while  being  quenched.  The  exterior  first  cools,  con- 
tracts, becomes  rigid,  its  dimensions  being  determined  by 
the  size  of  the  still  comparatively  hot,  expanded,  mobile 
interior.  The  resistance  of  the  interior  1o  the  return  of 
the  exterior  to  the  dimensions  which  it  had  before  heat- 
ing act5  on  that  exterior  precisely  as  a  tensile  stress 
does  on  a  body  at  constant  temperature.  If  very  power- 
ful it  strains  it  beyond  its  elastic  limit,  it  takes  a  per- 
manent set,  it  is  permanently  distended.  The  stress  may 
exceed  the  ultimate  strength  of  the  outer  layers,  which 
then  crack,  the  piece  breaks  in  hardening.  The  interior 
continues  to  contract ;  its  adhesion  to  the  now  rigid  dis- 
tended exterior  prevents  its  own  complete  return  to  its 
initial  dimensions  ;  it  may,  in  it?  struggle  to  reach  them, 
somewhat  compress  the  exterior,  but  not  enough  to  efface 
the  distention  previously  caused.  The  piece,  as  a  whole, 
remains  somewhat  enlarged,  its  specific  gravity  is  lowered. 

The  final  state  of  external  compression  and  internal 
tension  is  readily  verified  by  slitting  a  hardened  steel  bai- 
rn two,  lengthwise,  in  a  planing  machine ;  each  half  be- 
comes curved,  concave  on  the  planed  side. a 

That  the  low  specific  gravity  of  hardened  steel,  while 
perhaps  in  part  due  to  the  preservation  by  sudden  cooling 
of  chemical  combinations,  which  are  lighter  than  the  com- 
posite mass  of  iron  plus  the  carbide  FesC  of  which  an- 
nealed steel  mainly  consists,  is  largely  due  to  mechanical 
distention,  is  further  indicated  by  the  experimer.ts  of 
Barus  and  Strouhal.  On  progressively  removing  annular 
layer  after  layer  from  the  exterior  of  a  hardened  steel 
bar,  3  cm.  in  diameter,  whose  sp.  gr.  after  hardening  was 
7 '7744,  the  sp.  gr.  of  the  residual  core  increased  with  sur- 
prising regularity,  as,  by  the  removal  of  more  and  more 
of  the  shell  it  was  permitted  to  contract  further  and  fur- 
ther, until,  when  its  diameter  had  fallen  to  1'38  cm.,  or  a 
little  less  than  half  its  initial  size,  its  sp.  gr.  had  risen  to 
7'8009,  or  approximately  half  way  towards  that  which  it 
had  before  hardening,  which  had  been  7 "8337. b 

After  the  cooling  has  progressed  slightly  and  the  out- 
side has  contracted  more  than  the  still  comparatively 
slowly  cooling  and  disproportionally  distended  interior,  it 
is  no  longer  able  to  contain  it  and  at  the  same  time  to  pre- 
.serve  its  original  shape.  It  is  therefore  shortened  and 
bulged,0  thus  slightly  approaching  the  spherical  shape,  in 


a  Use  o£  Steel,  Barba,  Hohey,  p.  10.     I  have  verified  this  experimentally. 

The  internal  distortion  and  consequent  stresses  set  up  in  large  steel  castings  by 
the  difference  in  the  rates  of  cooling  arid  contraction  of  their  different  portions  (a 
difterence  which,  thanks  to  the  high  melting-point  of  the  metal,  and  the  compara- 
tively low  temperature  of  the  mould,  may  be  very  great),  are  sometimes  so  ex- 
treme that  tbepirticles  of  tho  metal,  even  with  the  mobility  which  they  acquire  at 
a  full  red  heat,  may  not  be  able  to  travel  and  to  flow  far  enough  to  completely 
efface  them.  A  large  casting  from  which  much  cutting  has  to  be  do^e,  even  if  care- 
fully annealed  before  the  cutting  begins,  will  often  spring  much  out  of  shape  when 
part  of  tha  metal  has  been  cut  away,  proving  the  existence  even  after  annealing  of 
internal  stresses,  whose  equilibrium  is  destroyed  by  cutting  away  a  portion  of  the 
metal  which  had  sustained  them.  Honce  the  importance  of  annealing  such  pieces 
after  rough  machining. 

bAm.  Jour,  of  Science  XXXI.,  p.  386;  Jour.  Iron  and  St.  Inst.,  1886,  I., 
p.  37S. 

«  Journal  Iron  and  Steel  Inst.,  1879,  II.,  p.  428,  Caron,  Barba,  op.  fit.,  p.  10. 


which  the  minimum  of  exterior  holds  the  maximum  of 
interior;  and  this  distortion  is  not  wholly  effaced  by  the 
subsequent  contraction  of  the  interior.  I  have  elsewhere 
offered,  with  confirmatory  experiments,  this  explanation 
of  the  shortening  and  the  increase  in  diameter  of  round 
bars  on  sudden  cooling.d 

B.  EFFECT  ON  TKNSILE  STRENGTH. — Studying  the  effect 
of  sudden  cooling  on  the  tensile  strength  of  a  round  bar, 
we  may,  for  our  present  purpose,  consider  it  as  composed 
of  a  nest  of  concentric  cylindrical  spiral  springs,  firmly, 
but  not  absolutely  rigidly  attached  to  each  other  at  many 
points  along  their  length.     If  to  an  annealed  bar,  which 
in  this  view  would  consist  of  such  a  nest  of  springs  initi- 
tially  free  from  internal  stress,  we  apply  a  powerful  longi- 
tudinal tensile  stress,  grasping  as  usual  the  skin  of  the 
bar  (i.  e.,  the  outermost  spring),  owing  to  the  pliancy  of 
the  interstratal  connections  the  outer  spring  must  clearly 
bear  an  undue  proportion  of  the  stress,  and  indeed  each 
spring  will  bear  a  slightly  greater  proportion  than  the  one 
next  within  it.    This  will  cause  the  system  to  break  down 
piecemeal  under  a  stress  which  would  be  impotent  if  uni- 
formly resisted  by  all  the  springs.     This  effect  is  more 
readily  grasped  if  we  conceive  a  very  thick  short  bar,  e.  g., 
a  disk  6  feet  in  diameter  and  6  inches  long,  subjected  to 
stress  parallel  with  its  axis  and  applied  to  its  circumfer- 
ence. 

A  suddenly  cooled  bar  in  this  view  consists  of  such  a  set 
of  springs,  but  with  the  outer  ones  in  initial  compression, 
the  inner  ones  in  tension,  owing  to  the  residual  stress  due 
to  contraction  at  dissimilar  rates.  Extraneous  tensile 
stress  applied  by  grasping  the  outer  spring  (as  happens 
when  such  a  bar  is  pulled  apart  in  the  testing  machine),  is 
not  resisted  by  the  outer  springs  until  they  have  elongated 
by  as  much  as  they  were  initially  compressed,  the  inner 
springs  meanwhile  supporting  the  whole  extraneous  stress 
in  addition  to  their  initial  residual  stress.  This  condition, 
the  opposite  of  that  in  the  annealed  bar,  tends  to  favor 
the  outer  springs  at  the  expense  of  the  inner  ones.  Resi- 
dual stress,  then,  if  moderate,  should  increase  the  tensile 
strength  of  the  system,  by  tending  to  equalize  the  stress 
borne  by  the  several  springs,  through  counteracting 
the  effects  of  interstratal  yielding ;  and  when  it  becomes 
just  intense  enough  to  exactly  balance  them,  the  tensile 
strength  should  reach  its  maximum,  again  declining  as 
with  still  more  sudden  cooling  the  still  more  powerful 
residual  stress  throws  an  excessive  proportion  of  stress  on 
the  inner  springs. 

C.  EFFECT  ON  DUCTILITY. — While  the  effect  of  stress 
on  ductility  may  not  be  so  readily  traced,  yet  the  simile  of 
the  springs  may  at  least  partially  explain  it.      When 
extraneous  tensile  stress  is  applied  to  the  outermost  of  such 
a  nest  of  connected  concentric  springs  initially  free  from 
stress,  and  thus  resembling  an  annealed  bar,  the  outer 
spring  first  reaches  its  elastic  limit,  undergoes  permanent 
elongation,  breaks  ;   the  particles  which  connect  it  with 
the  next  inner  spring  similarly  permanently  elongate,  then 
break,  then  the  next  spring  elongates  and  breaks,  etc. 
After  the  outer  spring  breaks  (and  it  may  break  at  many 
points  in  its  length),  its  broken  fragments,  still  transmit- 
ting the  stress  to  the  intact  springs  within  it,  are,  owing 
to  the  elongation  which  each  of  these  undergoes  both  before 
and  after  its  individual  rupture,  progressively  drawn  apart 

dTracs.  Am.  Inst.  Mining  Engineers,  XIV.,  p.  400. 


THE    METALLURGY    OP    STEEL. 


more  and  more  up  to  the  instant  when  the  final  parting  of 
the  last  spring  occnrs,  so  that  part  of  the  elongation  of 
each  spring  is  superadded  to  that  of  those  outside  it,  and 
the  system,  as  a  whole,  is  greatly  elongated. 

So,  too,  as  the  fragments  of  each  broken  spring  are 
drawn  apart  longitudinally,  the  remaining  area  of 
cross-section  of  the  system  is  simply  that  of  the  still 
unbroken  inner  springs,  and  we  get  great  reduction  of 
area. 

If,  however,  as  in  the  case  of  a  bar  of  hardened  steel, 
the  inner  springs  are  under  such  initial  tensile  stress 
that  they  break  simultaneously  with  the  outer  ones,  we 
have  none  of  the  cumulative  action,  the  superadding  of 
the  elongation  of  one  layer  to  that  of  the  next  which 
occurs  with  our  annealed  bar ;  we  get  but  little  elonga- 
tion, and,  since  the  final  area  is  not  diminished  by 
the  drawing  asunder  of  successive  outer  layers,  but  little 
reduction  of  area.  Nor,  if  the  initial  stresses  be  so  severe 
that  the  inner  springs  break  before  the  outer  ones,  will 
the  elongation  of  the  system  be  increased  by  the  addi- 
tion of  the  elongation  of  one  spring  to  that  of  another, 
such  as  arises  when  the  outer  spring  breaks  first,  as  is 
clear  on  reflection.  If  the  tensile  stress  were  applied 
through  the  inner  spring,  then  as  the  fracture  gradually 
extended  outward  from  spring  to  spring  the  two  fragments 
of  each  broken  spring  would  continue  to  transmit  the  ten- 
sile stress  to  the  spring  next  outside  them,  and,  being 
always  under  tensile  stress,  they  might  be  continually 
drawn  farther  and  farther  apart,  and  the  final  fracture 
might  be  deeply  cup-shaped.  But  as  the  stress  is  trans- 
mitted along  the  outer  spring,  there  is  nothing  to  draw 
apart  the  fragments  of  the  successively  broken  inner 
ones  ;  their  elongation  is  not  superadded  to  that  of  the 
outer  one,  and  the  total  elongation  of  the  piece  is  sim- 
ply that  of  the  outer  spring,  which  breaks  last. 

A  simile  pushed  too  far  always  misleads.  This  one 
may,  I  hope,  portray  certain  features  of  what  occurs  dur- 
ing rupture,  not,  of  course,  with  complete  accuracy,  yet 
closely  enough  to  facilitate  our  present  study.  Dissatis- 
fied with  it,  I  offer  it  for  lack  of  a  better. 

D.  EFFECT  ON  HARDNESS. — The  state  of  violent  com- 
pression in  which  the  exterior  of  a  quenched  bar  is  left  may 
be  expected  to  force  its  particles  more  closely  together,  and 
thus  to  partially  account  for  the  hardness  of  the  external 
layers.  The  powerful  compression  which  steel  undergoes 
in  cold-forging  does  actually  harden  its  exterior. 

To  test  this  I  had  one  portion  of  an  unhardened  steel 
bar  of  If"  diameter  reduced  to  f "  diameter  when  cold,  by 
a  single  draught  through  a  die  (Billings  cold-drawing  pro- 
cess). A  portion  of  the  same  bar  which  had  not  been  thus 
treated,  was  accurately  turned  to  the  same  diameter.  The 
hardness  of  the  cold-drawn  portion,  as  measured  by  inden- 
tation, was  very  perceptibly  greater  than  that  of  the 
turned  portion.  I  doubt  whether  the  difference  could  be 
detected  by  the  file. 

II.  DISSIMILAR  BATES  OF  CONTRACTION  PRODUCE  A 
KNEADING  EFFECT. — The  different  rates  at  which  the  con- 
centric layers  of  a  steel  bar  contract  during  sudden  cooling, 
owing  to  their  different  rates  of  cooling,  must  occasion 
more  or  less  insterstratal  motion,  rubbing  together,  inter- 
lacing, pressure,  tension  ;  and  since  we  find  that  such 
internal  motion,  whether  as  in  kneading  dough,  putty  or 
clay,  arising  chiefly  from  compression  ;  or,  as  in  forging 


metals,  from  both  compression  and  tension;"  or,as  in  pulling 
molasses  candy,  chiefly  from  tension,  appears  to  increase 
the  intermolecular  cohesion,  to  raise  both  tensile  strength 
and  toughness,  we  may  reasonably  ascribe  to  this  feature 
of  sudden  cooling  a  strengthening  and  toughening  effect. 
And  if  by  more  thorough  interlacing  it  increases  the  inter- 
molecular  cohesion,  the  resistance  to  displacement,  we 
may  suppose  that  this  increases  the  hardness  as  measured 
by  indentation. 

§  52.  SUDDEN  COOLING  vs.  COARSE  CRYSTALLIZATION. 
Though  as  explained  in  §  243,  p.  172,  as  we  heat  steel  far- 
ther and  farther  above  W  its  grain  grows  coarser  and 
coarser,  yet  on  heating  it  to  W  itself  pre-existing  crystal- 
lization is  broken  up,  and  the  grain  becomes  very  fine  or 
even  porcelanic.  During  slow  cooling  from  W,  however,  a 
certain  amount  of  crystallization  occurs.  So,  too,  forging 
areaks  up  crystallization  more  or  less  completely  :  but  if 
forging  cease  while  the  temperature  is  considerably  above 
W,  crystallization  again  sets  in,  and  tends  to  become  the 
coarser  the  higher  the  temperature.  Sudden  cooling, 
whether  after  heating  to  W  or  after 'forging,  in  that  it 
shortens  the  exposure  to  temperatures  at  which  crystal- 
lization occurs,  limits  crystallization,  and  crystallization 
clearly  lessens  both  strength  and  ductility,  the  more  so 
the  coarser  it  becomes.  This  effect  of  sudden  cooling  is 
especially  marked  where  the  crystallizing  tendency  is 
strongest,  'e.  g.  in  large  masses  and  in  phosphoric  iron. 
In  some  phosphoric  irons  the  tendency  to  coarse  crystal- 
lization is  so  strong  that  they  are  actually  tougher  after 
sudden  than  after  slow  cooling.  (See  §§  45  and  126.)  In 
sudden  cooling  interstratal  movements  must  arise,  since 
neighboring  layers  must  cool  and  contract  at  very  differ- 
ent rates,  and  forging  must  cause  similar  interstratal 
movements.  These,  like  the  agitation  of  any  solidifying 
crystallizing  mass,  should  not  only  prevent  the  formation 
of  large  crystals  with  extended  surfaces  of  weak  cohesion, 
but  even  break  them  up  when  once  formed. 

§  53.  EFFECTS  OF  TEMPERING  AND  ANNEALING. — Let 
us  now  consider  how  the  effects  of  sudden  cooling  which 
have  just  been  discussed  are  removed  or  weakened  by 
tempering  and  annealing,  and  how  the  latter  operation 
removes  the  effects  of  cold-working. 

1.  CHEMICAL  ACTION. — As  explained  in  §§  23  and  50,  the 
heating  which  occurs  in  tempering  and  annealing  relaxes 
chemical  inertia  so  as  to  permit  the  carbon  to  pass  from  the 
hardening  state,  in  which  it  has  been  previously  imprisoned 
by  sudden  cooling,  to  the  cement  state,  to  a  degree  which, 
within  limits,   increases  with  the  temperature  reached ; 
hence,  the  higher  this  heating  the  softer  the  steel  becomes. 

2.  REMOVAL  OF  THE  EFFECTS  OF  CONTRACTION  AT  DIS- 
SIMILAR RATES. — We  have  seen  that  contraction  at  dis- 
similar rates,  owing  to  sudden  cooling,  should  produce 
two  quite  distinct  mechanical  effects,  (A)  internal  stresses, 
(B)  a  kneading  or  forcing  together  of  the  particles  of  the 
metal.     There  is  both  reason  to  expect  that  cold-forging, 
punching,  etc.,  should,  and  evidence  that  they  do,  pro- 
duce both  these  effects,  though  not  in  the  same  relative 
proportion.     Cold-working  in  moderation,  as  in  cold-roll- 
ing and  wire-drawing,  increases  the  tensile  strength  very 


a  That  forging  acts  very  largely  by  tension  is  suggested  by  the  fact  that  cold- 
forging  makes  iron  lighter  and  not  denser.  Langlcy  found  that  repeated  cold- 
hammering  lowered  the  specific  gravity  of  a  steel  bar  from  7"828  to  7'817  and  then  to 
7'780  ("The  Treatment  of  Steel,"  p.  42.)  So,  too,  in  a  case  reported  by  Percy 
( Journ.  Iron  and  St.  Inst.,  1886, 1.,  p.  63),  cold-drawing  appears  to  have  lowered  the 
specific  gravity  of  wire  from  7 -8402 ±  to7'8H2. 


THE    RATIONALE    OF    HARDENING    AND    ANNEALING. 


31 


greatly  while  lowering  the  ductility.  In  excess,  as  in 
punching  and  shearing,  it  lowers  both  tensile  strength  and 
ductility,  sometimes  wholly  destroying  the  latter.  As 
shown  in  §  51,  these  are  the  results  which  should  be  ex- 
pected from  the  stresses  which  sudden  cooling  should  set 
up,  which  from  the  nature  of  the  case  should  closely  resemble 
those  of  cold  forging,  which  must  leave  the  exterior  in  a 
state  of  compression,  the  interior  in  one  of  tension. 

A.  REMOVAL  OF  INTERNAL  STRESS. — The  action  of  tem- 
pering and  annealing  in  removing  internal  stress  can,  I 
think,  be  most  readily  grasped  by  regarding  the  metal  not 
as  an  ideal  solid,  but  merely  as  an  extremely  viscous  liqiiid, 
approaching  the  condition  of  lead  or  of  molasses  candy. 
A  remembrance  of  the  readiness  with  which  cold  steel 
flows  under  the  action  of  car  wheels,  of  the  punch,  etc., 
may  help  us  to  grasp  this  idea.  If  the  particles  of  the 
metal  be  subjected,  even  when  cold,  to  sufficient  stress, 
they  may  yield  to  it  and  flow,  and  thus  diminish  the  stress. 
Just  as  in  the  case  of  molasses  candy,  this  flow  may  con- 
tinue until  the  stress  is  so  far  relieve!  that  it  just  fails  to 
produce  any  further  flow,  when  the  particles  gradually 
come  to  rest  in  equilibrium  under  the  maximum  stress 
which,  with  their  existing  viscosity,  they  can  sustain 
without  How  ;  or,  if  the  stress  and  the  flow  which  it  induces 
exceed  a  certain  amount,  the  viscosity  of  the  metal  exceeds 
its  cohesion,  and,  unable  to  flow  farther,  it  breaks.  Evi- 
dently, the  more  we  heat  either  candy  or  steel  the  less 
viscous  does  it  become,  the  more  readily  does  it  yield  to 
stress,  whether  external,  as  that  of  hammering,  etc.,  or 
internal,  as  that  induced  by  previous  sudden  cooling  or 
cold-forging.  If  hardened  or  cold-forged  steel  be  heated 
to  a  red  or  yellow  heat  (say  900°  to  1100°  C.)  its  viscosity 
is  so  much  diminished,  its  particles  become  so  mobile  that 
they  flow  under  the  stress  which  they  had  defied  when 
cold,  and  almost  completely  relieve  and  efface  it.  If  we 
would  avoid  setting  up  new  stresses  in  place  of  those 
which  we  have  dispelled  we  must  allow  our  steel  to  cool 
so  slowly  that  its  different  portions  will  contract  practi- 
cally uniformly  :  our  steel  becomes  annealed  :  but  it  is 
clear  that  the  true  annealing,  the  relief  of  stress,  was  ef- 
fected by  the  heating,  and  that  the  slow  cooling  is  merely 
to  avoid  undoing  the  annealing  already  accomplished. 

If  the  hardened  or  cold- worked  steel  be  heated,  not  to  a 
red  but  merely  to  a  straw-heat  (say  230°  C.),  its  particles 
are  rendered  mobile,  but  far  less  so  than  by  the  much 
higher  heating  employed  for  annealing :  if  heated  a  little 
higher  than  a  straw-heat,  say  to  blueness  (290°  C.),  they 
become  still  somewhat  more  mobile.  This  increased 
mobility  relieves  previously  induced  stresses,  and  the 
brittleness  which  they  had  caused  is  thus  removed  to  a 
greater  or  less  degree  as  the  temperature  reached  be  higher 
or  lower :  the  steel  is  tempered.  The  temperature  to 
which  steel  is  heated  for  tempering,  though  it  suffices  to 
relieve  the  more  intense  stresses,  is  so  low,  and  hence  the 
contraction  which  occurs  when  the  tempered  steel  is  again 
cooled  is  so  slight,  that,  even  if  the  steel  be  suddenly 
cooled  no  serious  stresses  are  likely  to  arise. a  Hence 
rapid  cooling  is  usually  employed  for  convenience. 


a  That  slight  stress  may  arise  even  in  quenching  from  100°  C.  is  indicated  by  an 
experiment  of  Langley's.  (The  Treatment  of  St3el,  p.  43.)  A  cold-hammered 
steel  bar  was  heated  to  100"  C.  and  slowly  coolal ;  its  sp.  gr.  then  was  7  816. 
When  again  heated  to  100  and  quenched  in  cold  water  its  sp.  gr.  fell  to  7-790,  but 
It  rose  again  to  7'817  on  again  heating  to  100,  and  cooling  slowly.  Other  triuls 
gave  closely  similar  results, 


As  heating  hardened  steel  softens  and  toughens 
it  by  transferring  carbon  to  the  cement  state,  it  may 
appear  superfluous  to  call  in  the  relief  of  stress  simitl 
taneously  effected  to  help  explain  annealing ;  but 
in  §  54  cogent  reasons  are  given  for  believing  that  both 
the  chemical  effect  of  sudden  cooling  and  its  physical 
effect  in  causing  stress  give  strength  and  brittleness.  And 
the  same  reasoning  indicates  that  both  the  chemical  and 
physical  effects  of  reheating  contribute  powerfully  to  its 
weakening  and  toughening  effect. 

B.  REMOVAL  OF  THE  EFFECT  OF  THE  KNEADING  ACTION. 
—As  shown  in  §  54,  the  effect  of  the  kneading  action  due 
to  dissimilar  rates  of  contraction  is  probably  not  wholly, 
if  at  all,  removed  by  subsequent  annealing. 

3.  REMOVAL  OF  THE  EFFECT  OF  HARDENING  ON  CRYSTAL- 
LIZATION.— See  §  52. 

4.  THE  TEMPERATCRE  AT  "WHICH  ANNEALING  BEGINS.— 
Annealing  appears  to  begin  at  surprisingly  low  tempera- 
tures.   The  gradual  deterioration  of  cutlery  even  at  tem- 
peratures below  100°  C  is  referred  to  in  §  25.     So,  too,  the 
thermo-electric  power, b  which  appears  to  increase  so  con- 
stantly as  stress  diminishes  that  it  has  been  regarded  as 
an  index  of  stress  (indeed,  they  may  stand  in  the  causal 
relation),  increases  even  when  steel  is  exposed  to  a  tem- 
perature no  higher  than  66°  C.,  though  very  gradually. 
During  three  hours  of  exposure  to  this  temperature  the 
rise  of  the  thermo-electric  power  continues  at  an  almost 
constant  rate.     At  100°  C.  it  rises  more  rapidly,  rising  as 
much,  in  ten  minutes  at  this  temperature  as  it  increases  in 
three  hours  at  66°.  At  185°  C.  the  rise  is  still  more  abrupt, 
and  at  330°  it  rises  so  abruptly  as  to  seem  to  jump  instantly 
to  its  maximum.     At  each  temperature  there  is  a  maxi- 
mum, or  normal  thermo-electric  power,  and  hence,  prob- 
ably, a  maximum  degree  to  which  stress  is  relieved,  which 
during  continued  exposure  to  that  temperature  are  ap- 
proached asymptotically.     The  higher  the  temperature 
the  higher  is  the  normal  (maximum)  thermo-electric  power, 
the  lower  is  the  corresponding  normal  state  of  stress  which 
is  thus  approached,  and  the  more  rapidly  are  they  ap- 
proached, *.  e.,  the  faster  ar.d  more  fully  is  stress  effaced. 

The  stresses  due  to  sudden  cooling  appear  (as  already 
explained)  to  lower  the  density.  Langley  found  that  the 
density  of  steel,  slightly  lowered  by  quenching  from  100° 
C.,  was  restored  by  re-exposure  to  100°  with  subsequent 
slow  cooling. a 

Similar  changes  occur  in  other  metals  at  low  tempera- 
tures ;  thus  Matthiessen  and  Barus  and  Strouhal"  found 
that  the  conductivity  of  hard-drawn  silver  and  G  erman 
silver  was  changed,  from  which  it  is  inferred  that  the 
stress  due  to  hard-drawing  was  diminished,  by  continued 
boiling  in  water. 

It  is  not  certain  how  far  the  changes  effected  at  these 
low  temperatures  are  due  to  relief  of  stress  and  how  far 
to  the  escape  of  part  of  the  carbon  from  the  hardening  to 
the  cement  state. 

Abel's  results  show  that  at  a  straw  heat  the  condition  of 
carbon  changes  quite  rapidly.  But  the  changes  which 
occur  at  100°  C.  we  naturally  ascribe  to  the  relief  of  stress, 
because  it  is  easy  to  understand  how  stress  should  be  re- 
lieved at  this  low  temperature,  especially  since  we  find 


b  Barus  and  Strouhal:  Bulletin  of  the  U.  S.  Geological  Survey,   No.  14,  pp. 
B4-55. 
c  Idem,  pp.  93-4. 


32 


THE    METALLURGY    OF    STEEL. 


similar  changes  occurring  at  100°  in  silver  and  in  German 
silver,  while  a  change  in  the  condition  of  carbcn  at  such 
low  temperatures  would  certainly  be  more  unexpected. 

§  54.  ACTTAL  INFLUENCE  OF  THE  SEVERAL  PROXIMATE 
EFFECTS  OF  HARDENING,  TEMPERING  AND  ANNEALING.— 
Let  us  now  consider  how  far  the  changes  in  each  of  the 
physical  properties  of  steel  are  due  to  each  of  the 
proximate  effects  of  these  operations. 

I.  TENSILE  STRENGTH  AND  DUCTILITY. — I  believe  that 
the  changes  in  these  properties  are  chiefly  due  to  corre- 
sponding changes  in  the  condition  of  carbon,  not  only 
because  of  the  fair  correspondence  between  them  but 
because  the  changes  in  tensile  strength  and  ductility  are 
the  more  marked  the  higher  the  percentage  of  carbon  is. 
But  this  indication  is  slightly  equivocal,  for,  owing  to  the 
high  elastic  limit  of  high-carbon  steel  its  particles  come  to 
rest  under  stress  which  would  be  impossible  in  low-car- 
bon steel,  because  the  particles  of  this  metal  would  flow 
when  exposed  to  it :  it  is  therefore  possible,  though  I  think 
highly  improbable,  that  high-carbon  steel  gains  more 
strength  and  ductility  when  hardened  than  that  which 
contains  less  carbon,  solely  because  it  is  capable  of  retain- 
ing more  intense  residual  stresses.  Be  this  as  it  may, 
several  facts  conspire  to  show  that  change  in  the  chemical 
condition  of  carbon  is  not  the  sole  cause  of  these  change: 
in  tensile  strength  and  ductility. 

A.  The  tensile  strength  of  almost  carbonless  iron  may  be 
much  increased  by  sudden  cooling.     (See  Tables  8,  L>,  and 
10,  §  34.)    The  tensile  strength  of  Cases  2  and  3,  in  Table 
8,  is  increased  41  and  40  %  respectively,  and  their  elonga- 
tion is  lowered  by  79  and  47  %  by  water-quenching,  though 
they  contain  but  '07  and  '03  %  of  carbon  respectively. 

I  heated  to  whiteness  two  pieces  of  wrought-iron  cu1 
from  the  same  bar:  one  was  slowly  cooled,  the  other 
quenched  in  cold  water.  The  slowly  cooled  bar  had  47,- 
GOO  Ibs.  tensile  strength,  25  %  elongation  in  2  inches,  and 
15  %  reduction  of  area,  against  42,700  Ibs.,  G  %  and  J  %  for 
the  quenched  bar.  Now  if  a  change  in  the  condition  oi 
carbon  (from  which  the  bar  was  almost  free)  sufficient  to 
account  for  this  great  change  in  the  properties  of  the  iron 
was  induced  by  sudden  cooling,  that  change  would  have 
simultaneously  greatly  affected  the  hardness,  which  is  so 
closely  dependent  on  the  condition  of  carbon :  but  I  wa 
unable  to  detect,  by  the  method  of  indentation,  any  differ- 
ence in  hardness. 

B.  Though  the  changes  in  the  condition  of  carbon  and 
in  tensile  strength  and  ductility  at  first  appear  to  follow 
similar  laws,  yet  closer  observation  appears  to  reveal 
marked  discrepancies.     Thus  for  given  quenching  tem- 
perature, known  to  be  high  enough  to  transfer  the  carbon 
to  the  hardening  state,  the  more  sudden  and  violent  the 
cooling  the  more  completely  doubtless  is  the  carbon  re- 
tained in  that  state.     But  the  tensile  strength  seems  to 
follow  quite  another  law,   reaching  a  maximum    with 
moderately  sudden  cooling,  and  again  rapidly  declining  ii 

i  he  cooling  becomes  more  sudden.  This  occurs  even  in 
steel  with  comparatively  little  carbon.  (See  cases  12,14, 
and  16,  Table  8.)  Still  again,  since  on  quenching  the  ex- 
terior of  a  bar  cools  more  suddenly  than  the  interior,  the 
carbon  in  it  should  be  the  more  completely  retained  in 
the  hardening  state:  yet,  as  shown  by  t.ie  experimem 
which  I  will  shortly  describe  the  interior  of  a  hardened 
bar  is  sometimes  vastly  stronger  tensilely  than  the  outside. 


My  experiments  indicate,  though  not  conclusively,  that 
quenching  from  temperatures  which  are  not  quite  high 
nough  to  transfer  carbon  to  the  hardening  state,  while  it 
does  not  affect  the  hardness  may  strongly  influence  tensile 
strength  and  ductility.     Should  further  investigation  cor- 
roborate this,  it  would  still  further  illustrate  the  discrepan- 
cies between  the  behavior  of  carbon  and  the  changes  in 
hese  properties. 

I  believe  that  the  tensile  strength  and  ductility  are 
greatly  influenced  by  the  stresses  set  up  by  sudden  cool- 
ing and  relieved  by  subsequent  heating  (as  set  forth  in 
§51,  I,  B  and  C),  for  the  following  reasons.  If  these 
stresses  act  in  the  manner  which  I  have  supposed, 
then,  if  we  cut  a  hardened  steel  bar  into  a  series  of 
concentric  cylinders  and  thereby  partially  relieve  these 
itresses,  the  sum  of  the  tensile  strength  of  the  detached 
cylinders  should  differ  materially  from  that  of  the  undi- 
vided bar. 

Let  P  =  the  tensile  strength  per  square  inch  of  the  undi- 
vided bar. 

A  =  the  area  of  its  cross-section. 
pl  —  the  tensile  strength  per  square  inch  of  the  cen' 

tral  core  after  dividing  the  bar. 
p2  =  that  of  the  cylinder  adjoining  this  core. 
p3,  p*,  etc.  =  those  of  the  other  cylinders. 
a1,  a2,  a3,  etc.  =  the  areas  of  their  cross-sections. 
Then,  if  my  hypothesis  is  true,  P  X  A  would  not 
usually  equal  2  pX  a.  The  same  hypothesis  implies 
that  for  given  conditions  a  stress  of  one  certain  degree  of 
intensity,  S,  should  produce  the  maximum  tensile  strength 
for  the  undivided  bar,  greater  than  that  produced  by 
either  more  or  less  intense  stress :  and  hence  that  if  the 
stress  in  the  undivided  bar  were  greater  than  S,  since  sub- 
dividing it  into  cylinders  would,  by  lessening  tha  stress, 
bring  it  nearer  to  S,  2p  X  a  would  be  greater  than  P  X  A. 
Were  the  stress  in  the  hardened  bar  less  than  $then 
2pXa<PxA.  Furthermore,  if,  even  after  subdi- 
viding the  bar  the  stresses  still  residual  in  thb  detached 
annuli  were  greater  than  /S,  then,  since  tho  stresses  in  the 
comparatively  slowly  cooling  central  core  should  be  less 
intense  than  in  the  exterior  layers,  p1  should  be  greatei 
than  p",  p2  greater  thanjp3,  etc.  If  my  hypothesis  were 
false,  and  if  the  gain  of  strength  by  hardening  were  wholly 
due  to  some  chemical  feature  of  hardening,  as,  for  in- 
stance, to  its  preserving  the  status  quo  or  to  some 
chemical  change  caused  by  the  sudden  change  cf  tem- 
perature or  by  the  accompanying  stress,  then  such  subdi- 
vision of  the  bar  should  not  be  expected  to  alter  the  chem- 
ical condition  of  its  members,  and  in  this  case  v.e  should 
find  that  2pXa  =  PxA.  Moreover,  since  this  chemi- 
cal feature  should  be  more  marked  in  the  rapidly  cooling 
exterior  than  in  the  comparatively  slowly  cooling  core,  we 
should  usually  find  that^?1  <  p~,  p1  <  p3,  etc.  If,  for  in- 
stance, the  increase  of  tensile  strength  were  wholly  due  to 
its  retaining  carbon  in  the  hardening  state,  since  this  re- 
tention would  evidently  be  more  complete  in  the  exterior 
of  the  bar  than  in  the  interior  the  outside  should  be  the 
strongest,  as  it  actually  is  the  hardest. 

To  test  the  matter,  I  cut  a  f-inch  round  steel  bar  (Xo. 
14'5  in  Table  8),  containing  0-39$  carbon,  into  five  equal 
pieces.  All  were  heated  nearly  to  whiteness  in  a  muffle, 
under  identical  conditions.  One  was  slowly  cooled,  the 
others  quenched  very  rapidly  by  agitation  in  cold  water. 


THE    RATIONALE"' 6  F     HARDENING    AND    ANNEALIMi. 


This  quenching  appeared  so  violent  as  to  set  up  stresses 
much  greater  than  tf,  and  the  steel  became  so  hard  that  it 
could  be  machined  only  with  extreme  difficulty.  One 
of  the  hardened  bars  received  no  further  treatment.  A 
second  had  its  exterior  turned  down  in  a  lathe  to  a  diameter 
of  0*505  inches  ;  a  third  was  in  the  same  way  reduced  to 
a  diameter  of  0'2o9  inches  ;  while  a  fourth  had  its  interior 
removed  by  drilling  holes  across  it  radially,  and  then  filing 
their  sides  away  till  only  thin  segments  of  the  exterior 
remained.  This  was  done  at  two  points  in  the  length  of 
the  piece,  enabling  me  to  determine  the  strength  of  the 
exterior  twice.  The  following  results  were  obtained  : a 

Tensile  strength,  Elonga- 

Lbs.  per  s%  in.  tion  %.  In. 

The  annealed  bar,  0-734"  diameter 92,900  31 '2  3" 

The  hardened  bar,  0-74"  diameter 118,000                 0'8  2" 

Core  of  the  hardened  bar,  0-565"  diameter 141,000                 O'O  2" 

Core  of  the  hardened  bar,  0-259"  diameter S48,000                 3'0  0'5" 

Segments  of  the  exterior  shell  I  1st  experiment. ..  165,000  ....  .... 

of  the  hardened  bar "..."(  2d  experiment. . .   167,000  ....  .... 

Thus  the  sum  of  the  tensile  strength  of  the  several 
detached  portions  greatly  exceeds  that  of  the  undivided 
bar,  and  the  strength  rises  as  we  approach  the  center ;  or, 
algebraically,  ~s  p  x  a  >  P  x  A  '•  P1  >  p~ ',  p2  >  p3,  etc. 
These  facts,  taken  in  conjunction  with  Abel's  discovery 
that  pressure  applied  to  cold  steel  does  not  change  the 
condition  of  its  carbon,  almost  amount  to  a  mathematical 
demonstration  that  the  tensile  strength  of  hardened  steel 
is  powerfully  affected  by  factors  other  than  chemical  con- 
dition. And  while  they  do  not  demonstrate  the  truth  of 
my  hypothesis,  since  they  may  be  shown  to  accord  with 
other  suppositions,  yet  as  they  are  in  themselves  surpris- 
ing, hitherto  unsuspected  so  far  as  I  know,  incompatible 
with  the  other  explanations  offered,  but  experimentally 
verified  corollaries  to  it,  they  certainly  support  it  power- 
fully. So  does  the  fact,  predictable  from  it,  that  while 
moderately  sudden  cooling  raises  the  tensile  strength, 
violently  sudden  cooling  lowers  it.  So  does  the  fact  that 
cold  working,  which  may  be  expected  to  set  up  stresses 
like  tliose  ascribed  to  sudden  cooling,  produces  closely 
similar  results,  always  lowering  ductility,  and,  if  moderate 
(as  in  ordinary  cold-rolling),  raising  the  tensile  strength, 
but  if  violent  (as  in  punching  and  shearing)  actually 
lowering  it.  So  does  the  observation,  so  far  as  it  is  com- 
plete, that  sudden  cooling  strengthens  and  renders  brittle 
only  those  metals  in  which  it  is  capable  of  setting  up 
severe  stresses.  These  it  can  only  create  in  metals  which, 
with  at  least  moderately  high  coefficient  of  expansion, 
combine  low  thermal  conductivity  with  high  modulus  of 
elasticity  and  high  elastic  limit.  Metals  with  high  ther- 
mal conductivity  cool  and  hence  contract  at  an  almost 
uniform  rate  throughout  their  cross-section :  this 
removes  the  cause  of  stress.  If  the  modulus  be  low,  given 
distortion  from  dissimilar  rates  of  contraction  produces 


a  The  strength  of  the  inner  core,  248,000  pounds  per  square  inch,  is  indeed  ex- 
traordinary, and  I  should  discredit  it  if  I  saw  any  possibility  of  error.  But  as  I 
tested  the  steel  myself  and  have  carefully  verified  my  calculations,  I  am  forced  to 
believe  that  we  here  have  stress  of  a  degree  of  intensity  especially  favorable  to 
high  tensile  strength,  such  as  exists  in  hard-drawn  wire,  whose  tensile  strength 
rises  to  432,000  pounds  per  square  inch  (Percy:  Journ.  Iron  and  Steel  Inst.,  1886, 
I.,  p.  70).  Wire  with  0'828$carbon  is  reported  with  344,960  pounds  tensile  strength 
(idem),  and  thin  hardened  steel  plates  are  quoted  with  314,800  pounds  tensile 
strength.  (Emery  :  Report  of  U.  S.  Senate  Select  Committee  on  Ordnance  and  War 
Ships,  1886,  p.  468).  The  fact  here  brought  outthat  the  tensile  strength  of  a  steel 
bar  may  be  less  than  half  that  of  a  test  piece  cut  from  its  center,  and  may  be  much 
less  than  the  mean  tensile  strength  of  test  pieces  cut  from  various  portions  of  it, 
maybe  of  practical  importance  in  ascertaining  the  tensile  strength  of  large 
hardened  pieces,  such  as  gun  hoops.  It  may  be  demonstrated,  but  it  should  not  be 
assumed,  that  the  annealing  to  which  such  pieces  are  generally  submitted  after 
hardening  removes  this  source  of  error. 


out  little  stress.  If  the  elastic  limit  be  low  severe  stress 
cannot  exist,  because  the  metal  flows  under  the  growing 
stress  and  relieves  it  before  it  can  become  severe.  Gold, 
j  silver,  copper  and  many  of  its  alloys  have  very  high  tlier- 
jinal  conductivity  with  in  general  low  modulus  and  low 
elastic  limit.  Now,  with  repeated  experiments,  under- 
taken to  elucidate  this  point,  I  find  that  the  rate  of  cool- 
ing from  dull  chsrry -redness  does  not  appreciably  affect 
the  tensile  strength  or  ductility  of  silver,  copper  or  brass, 
nor  the  tensile  strength  of  gold  or  German  silver :  and, 
while  I  found  the  last  two  metals  somewhat  less  ductile 
after  sudden  than  after  slow  cooling,  the  difference  was 
within  the  limits  of  experimental  error. 

I  know  of  no  direct  evidence  that  the  supposed  knead- 
ing effect  of  sudden  cooling  actually  increases  the  tensile 
strength  and  ductility.  The  progressive  strengthening  and 
toughening  caused  by  repeated  quenchings  each  followed 
by  an  annealing  indeed  seem  at  first  to  point  to  such  a 
kneading  effect,  since  most  of  the  other  effects  of  sudden 
cooling  should  be  removed  by  subsequent  annealing,  while 
the  kneading  effect  might  be  expected  to  persist  through 
reheating  to  a  moderate  temperature.  This,  however,  is 
far  from  conclusive.  Reheating  to  W  breaks  up  coarse 
crystallization  ;  but  Coffin  finds  that,  in  case  of  soft  steel, 
repeated  reheatings  to  W  may  be  needed  to  break  it  up 
completely.  Thus  the  beneficial  action  of  our  repeated 
quenchings  and  annealings  may  be  due  to  progressive 
destruction  of  pre-existing  coarse  crystallization  rather 
than  to  our  supposed  kneading  effect.  (§  245,  p. 
175.) 

That  in  so  far  as  sudden  cooling  checks  a  tendency  to 
coarse  crystallization  it  tends  to  increase  ductility  is 
rendered  very  probable  by  the  fact  that  when,  as  in  the 
case  of  phosphoric  iron,  this  tendency  is  very  strong, 
sudden  cooling  gives  greater  ductility  than  slow  cooling. 
It  is  extremely  probable  that  it  in  the  same  way  tends  to 
increase  the  tensile  strength,  though  this  is  not  easily  shown 
except  in  extreme  cases.  Bessemer,1*  by  enabling  a  mass 
of  wholly  decarburized  molten  ingot  metal  to  cool  so  slowly 
that  after  five  or  six  days  it  was  still  very  hot,  found 
when  it  was  cold  that  it  had  resolved  itself  into  cubical 
crystals,  some  of  them  with  edges  over  0'25  inches  long  : 
the  individual  crystals  were  highly  malleable ;  but  the  mass 
as  a  whole  was  so  incoherent  that,  holding  it  in  the  hand, 
showers  of  detached  crystals  were  readily  broken  off  by 
blows  from  a  2-lb.  hammer — the  slow  cooling  had  destroyed 
both  strength  and  ductility. 

Similar  effects  are  probably  producible  in  other  metals. 
Some  inconclusive  trials  seemed  to  show  that  while,  as  al- 
ready stated,  if  copper  has  been  heated  to  a  temperature  not 
above  dull  redness,  its  strength  and  ductility  are  almost  in- 
dependent of  the  rate  at  which  it  has  then  been  cooled,  and 
while  these  properties  are  not  seriously  affected  by  heat- 
ing it  almost  to  its  melting  point  (say  1,000°  C.),  provided 
it  be  then  suddenly  cooled,  yet  that  if  it  be  slowly  cooled 
from  1,000°  it  becomes  very  weak,  brittle  and  coarsely 
crystalline :  its  strength,  ductility  and  silky  fracture  are 
completely  restored  by  quenching  from  redness,  its  coarse 
crystallization  obliterated,  perhaps,  by  interstratal  motion 
too  slight  to  produce  serious  stress.  Were  this  confirmed 
we  would  refer  these  effects  to  coarse  crystallization, 
because  it  occurs,  because  it  is  a  competent  cause,  and 


~b  Jon  rnafon;he  Iron  and  Steel  Institute,  1885,  I.,  p.  200. 


/$& 

I,  .  r      ' 

((UNIVERSITY 
RNIA- 


34 


THE    METALLITRUY    OF     STEEL. 


because  change  of  stress  and  of  chemical  condition  (the 
other  recognized  functions  of  the  rate  of  cooling)  can 
hardly  produce  such  effects  in  this  metal. 

Riche  found  that  bronzes  with  20$  tin  and  80$  copper 
were  tougher  after  sudden  than  after  slow  cooling.8 

II.  The  changes  in  hardness  are  probably  almost  wholly 
due  to  corresponding  changes  in  the  chemical  condition  of 
carbon.  (A.).'  The  degree  of  hardness  imparted  by  sudden 
cooling,  instead  of  rising  gradually  and  uniformly  with 
the  quenching  temperature,  remains  practically  nil  till  a 
temperature  approaching  dull  redness  is  reached,  when, 
with  slight  further  increase  in  quenching  temperature,  it 
leaps  rapidly  to  a  maximum,  thus  apparently  closely  fol- 
lowing the  changes  in  the  chemical  condition  of  carbon. 
(B).  Thin  bars,  cooling  more  suddenly  than  thick  ones, 
also,  I  believe,  are  hardened  more  by  quenching.  (C). 
The  increase  of  hardness  caused  by  quenching  is  roughly 
proportional  to  the  percentage  of  carbon  in  the  metal, 
being  practically  nil  for  practically  carbonless  iron.  The 
supposition  that  the  latter  fact  is  chiefly  due  to  the  more 
intense  stress,  the  more  powerful  kneading  and  the  more 
complete  prevention  of  coarse  crystallization  caused  by 
sudden  cooling  in  high-  than  in  low-carbon  steel  appears 
improbable,  though  these  factors  may  intensify  the  effects 
of  the  changes  in  the  condition  of  carbon. 

That  the  hardness  caused  by  sudden  cooling  is  not  due 
chiefly  to  the  stresses  which  it  sets  up  is  very  probable, 
because  both  exterior  and  interior  are  hardened,  though 
under  opposite  kinds  of  stress  :  because  thin  bars,  though 
their  stresses  should  be  less  severe,  are,  I  believe,  har- 
dened more  than  thick  ones :  and  because,  though  violent 
stresses  probably  arise  when  practically  carbonless  iron  is 
quenched  (as  inferred  from  its  loss  of  ductility)  it  is  not 
rendered  appreciably  harder,  at  least  in  certain  cases." 

The  protection  from  coarse  crystallization  afforded  by 
quenching  hardly  appears  a  competent  cause  of  the  hard- 
ness simultaneously  produced  :  and  the  facts  that  a  cop- 
per rod,  which  (as  described  in  §  54,  I. ),  was  so  slowly 
cooled  as  to  become  coarsely  crystalline,  weak  and  brittle, 
did  not  differ  in  hardness  from  similar  but  quenched  and 
fine-grained  ones,  and  that  the  coarse  crystallization  in- 
duced in  practically  carbonless  iron  by  slow  cooling  is  ac- 
companied by  no  apparent  change  of  hardness,  go  to  show 
that  it  is  not  the  true  cause. 

§54.  A.  APPARENT  ANOMALY. — I  find  manganese  steel 
very  slightly  softer  (as  measured  by  indentation),  and  it  is 
said  to  be  decidedly  tougher,  after  sudden  than  after  slow 
cooling.  We  know  as  yet  too  little  of  its  thermal  con- 
ductivity and  modulus  of  elasticity  to  discern  whether 
this  toughening  is  due  mainly  to  the  prevention  of  coarse 
crystallization,  or  to  the  formation  at  a  high  temperature 
of  some  chemical  compound  which,  preserved  by  sudden 
cooling,  is  tougher  and  softer  than  some  other  compounds 
into  which  it  is  resolved  at  some  lower  temperature  dur- 
ing slow  cooling  :  but  we  may  conjecture  that  the  soften- 
ing due  to  sudden  cooling  arises  in  this  latter  way. 

§  65.  OTHER  EXPLANATIONS  OF  HARDENING.   (Cf.  Pp.  187-9). 

DIAMOND  THEORY. — This  explanation,  hardly  compe- 
tent to  explain  a  single  phenomenon  of  hardening  and 
utterly  incompatable  with  many  of  them,  merits  notice 
solely  because  its  discussion  and  even  commendation  by 

a  Thurston  :  Materials  of  Engineering;,  III. ,  p.  485, 
>>See  my  experiment  described  in  §  54,  I  ,  A, 


those  who  should  have  gauged  it  better  has  given  it  fic- 
titious value.  Briefly,  sudden  cooling  has  been  sup- 
posed to  harden  steel  by  converting  its  carbon  into  dia- 
mond. It  is  certain  that  hardened  steel  does  not  con- 
tain diamond,  because  none  is  found  in  the  residue  from 
dissolving  it  even  in  dilute  acids.  The  readiness  with 
which  hardened  steel  of  0'4  carbon  is  cut  by  steel  of 
higher  carbon,  which  will  not  scratch  stones  which  are 
incomparably  softer  than  diamond,  hardly  points  to  the 
presence  of  the  gem.  Diamond  powder  imbedded  in  a 
soft  matrix  should  destroy  the  edge  of  the  best  steel  tool. 
A  soluble  substance  cut  by  steel  is  not  diamond. 

Now,  sudden  cooling  may  triple  the  tensile  strength  of 
steel  which  contains  but  0'4$  carbon,  while  wholly  de- 
stroying its  great  ductility.  If  it  is  conceivable  that  a 
skeleton  of  diamond  dust  could  produce  these  two 
effects  simultaneously  on  a  matrix  of  soft  ingot-iron,  of 
whose  mass  it  formed  but  0-4$  (raising  the  tensile  strength 
perchance  by  preventing  flow),  can  it,  in  view  of  the  evi- 
dence negativing  the  presence  of  diamond,  be  regarded  as 
a  probable  explanation,  with  such  tierce  causes  at  hand 
as  the  preceding  sections  have  set  forth  \  The  evidence 
supporting  the  diamond  hypothesis  is  too  inconclusive  to 
merit  reproduction. 

OCCLUDED  GASES. — It  has  been  suggested  that  at  a  high 
temperature,  or  during  sudden  cooling,  steel  expels  oc- 
cluded cases,  gradually  reabsorbing  them  as  the  tempera- 
ture descends  in  slow  cooling  :  that  suddenly  cooled  steel 
is  hard  because  it  has  had  no  opportunity  to  reabsorb 
the  gases  expelled  when  it  was  hot  or  during  sudden 
cooling,  that  slowly  cooled  steel  is  soft  because  it  has  had 
this  opportunity. 

Roberts0  has  demolished  this  theory  by  heating  steel  wire 
in  vacuo,  suddenly  cooling  part  of  it  by  immersion  in 
mercury,  but  slowly  cooling  the  remainder.  The  suddenly 
cooled  part  was  glass-hard,  the  slowly  cooled  part  soft. 
No  gases  were  expelled  during  the  sudden  cooling. 
Clearly  suddenness  of  cooling  and  not  absorption  and  ex- 
pulsion of  gases  cause  the  phenomena  observed. 

§  56.  AKERMAN'S  THEORY.4 — Of  a  very  different  order  is 
the  explanation  learnedly  and  ingeniously  expounded  by 
this  illustrious  metallurgist.  Recognizing  that  residual 
stress  may  lower  tensile  strength,  he  appears  to  attribute 
the  changes  in  hardness,  ductility  and  structure  as  well 
as  the  chief  changes  in  tensile  strength  caused  by  sudden 
cooling  not  to  its  maintaining  by  its  suddenness  the 
chemical  status  quo,  not  to  its  giving  no  opportunity  for 
coarse  crystallization,  not  to  its  kneading  action  which  as 
I  believe  increases  intermolecular  cohesion,  prevents  and 
even  breaks  up  coarse  crystallization,  but  directly  and,  as 
I  understand  him,  solely  to  its  compression  as  such,  which, 
in  his  view,  forces  carbon  into  the  hardening  state,  there- 
by increasing  strength  and  hardness,  but  diminishing 
ductility,  and  breaks  up  coarse  structure. 

Compression  would,  I  think,  be  quite  incompetent  to 
explain  the  phenomena,  even  if  it  were  known  to  have  the 
power  of  transferring  carbon  to  the  hardening  state  ;  and 
what  evidence  there  is  indicates  that  it  has  this  power  to 
but  a  slight  extent  if  at  all. 

(1.)  If  compression  causes  the  passage  of  carbon  into 
the  hardening  state  and  thus  hardens  steel,  it  must  be 

c  Trans.  Inst.  Mechanical  Engineers,  1881,  p.  706  ;   Engineering,  1881,  p.  646. 
<J  Journal  of  the  Iron  and  Steel  Institute,  1879,  II.,  pp.  504-521. 


RAPIDITY    OP    COOLING    EFFECTED    BY    DIFFERENT    MEDIA,    §57. 


35 


compression  at  a  rather  high  temperature,  for  no  appreci- 
able hardening  is  produced,  no  matter  how  suddenly  the 
steel  is  cooled,  unless  the  quenching  temperature  be  above :; 
certainlimit,  which  we  may  provisionally  call  500°  C.  Now 
if  the  exterior  were  compressed  at  a  temperature  sensibly 
!ib<  >ve  500°  it  would  be  so  plastic;  as  to  bulge  or  buckle :  no 
trace  of  buckling  has  ever  been  observed,  so  far  as  I  am 
aware,  yet  the  exterior  hardens  more  than  any  other  portion. 
(2.)  Many  cases  suggest  themselves  in  which  no 
compression  can  occur,  yet  in  which  steel  is  hardened.  A 
steel  cylinder,  around  which  a  line  steel  wire  is  so 'tightly 
stretched  as  to  be  in  extreme  tension,  is  heated  and 
quenched.  The  wire,  as  it  cools  so  much  faster  than  the 
cylinder,  must  remain  in  tension  at  least  ay  long  as  it  is 
above  500°.  Doubtless  it  would  still  be  hardened.  Its 
inner  particles  are  doubtless  compressed  by  the  resistance 
of  the  cylinder  to  its  contraction  :  nevertheless  its  net 
condition  is  tension :  the  tension  to  which  it  is  exposed 
vastly  outweighs  the  compression.  (3.)  The  exterior  of  a 
steel  bar  during  sudden  cooling  undergoes  tension  at  a  high 
temperature,  followed  by  compression  at  a  lower  one  :  the 
interior  undergoes  compression  at  a  high  temperature  fol- 
lowed by  tension  at  a  low  one.  Yet  both  interior  and  ex- 
terior are  rendered  harder.  Are  we  asked  to  believe  that 
both  sets  of  conditions  force  carbon  into  the  hardening 
state?  (4.)  If  we  suppose  that  it  is  compression  at  some 
critical  temperature  which  forces  carbon  into  the  harden- 
ing state,  then  it  is  clear  that  in  a  bar  of  certain  propor- 
tions there  must  be  a  region  which  at  the  critical  tempera- 
ture will  be  neither  in  compression  nor  tension :  such  a 
region  would  not  on  this  theory  be  hardened :  actually 
every  portion  is.  (5.)  The  difference  between  the  rates  of 
cooling  and  contraction  of  adjacent  layers  during  sudden 
cooling  would  be  greater,  and  consequently  the  pressure 
would  be  greater,  in  thick  than  in  thin  bars  :  on  Aker- 
man's  theory  the  thick  bar  should  be  rendered  harder 
than  the  thin  one,  while  actually  the  reverse  is  true, 
which  accords  with  the  status  quo  explanation,  since  the 
thin  bar  must  cool  faster  than  the  thick  one,  and  hence 
more  perfectly  preserve  the  chemical  condition  which 
existed  at  redness. 

So  much  for  its  competence  to  explain  the  phenomena. 
Now  for  the  evidence  that  compression  forces  carbon  into 
the  hardening  state. 

1.  Caron  found  that  hot  iron  hammered  on   an   anvil 
covered  with  charcoal  powder  became   far   more  steely 
on  its  face  than  if  simply  heated  in  contact  with  char- 
coal.    Since  (1 ),  the  hammering  may  have  promoted  the 
absorption  of  carbon  by  bringing  the  charcoal  into  more 
intimate  contact  with  the  iron  and  not  by  pressure  as  such, 
and  since  (2)  if  we  admit  that  pressure  does  favor  the  ab- 
sorption of  carbon,  it  does  not  follow  that  it  favors  the 
passage  of  previously  combined  carbon  into  the  hardening 
state,  I  attach  little  weight  to  this. 

2.  CAKON"  found  in  blister  steel  in  the  state  in  which  it 
came  from  the  cementing  furnace  somewhat  less  harden- 
ing carbon  than  when  hammered  ;  when  rolled  it  had  an 
intermediate  amount,  and  when  hardened  very  much  more. 
This  is  inferred  from  the  quantities  of  (cement)  carbon  in- 
soluble in  dilute  acid  which  he  found,  which  were : 

.     In  unforged  blister  steel 1'6S4 

"  the  same  hammered l'S4!J 

"  the  same  hardened 0-240 

a  Comptes  Rendus,  LVL,  p.  45. 


It  is  inferred  that  the  pressure  of  hammering  <ln ri- 
mmed the  passage  of  carbon  into  the  hardening  state.  It 
appears  much  more  probable  that  the  slight  excess 
of  hardening  carbon  in  the  hammered  over  that  in  the 
unhammered  and  probably  pretty  well  annealed  blistrr 
steel  is  due  to  the  comparatively  rapid  cooling  which  t!ir 
hammered  steel  underwent  because  of  its  reduced  cross- 
section,  and  because  of  its  contact  with  the  cold  faces  of 
hammer  and  anvil.1' 

Against  this  inconclusive  evidence  we  have  the  greater 
hardness  of  outside  than  inside,  and  of  small  than  of 
thick  bars  when  quenched — /.  e.,  the  most  thorough  har- 
dening where  we  have  least  compression  :  and  further,  the 
fact  that  cold-forging  does  not  transfer  carbon  to  the  har- 
dening state.  Thus  Abel,1'  examining  discs  of  the  same 
steel,  some  hardened,  some  annealed,  and  some  cold-rolled 
without  subsequent  treatment,  found  the  carbon  un- 
attacked  by  chromic  acid  solution  (cement  carbon)  as 
follows : 

Carbon  unattacked  by  chromic 

solution. 

Per  100  of      Per  100  of  total 
steel.  carbon  present. 

In  the  cold-rolled  steel 1-0392  94      % 

In  the  annealed  steel 0-8302  97      % 

In  the  hardened  steel 0'1782  17±j< 

To  show  that  quenching  works  by  compression,  Akerman 
adduces  the  resemblance  of  the  effects  of  quenching  to 
those  of  hot-forging  in  removing  the  coarseness  of  struct- 
ure of  burnt  iron  and  the  brittleness  consequent  to  it,  and 
to  those  of  cold-forging,  in  raising  tensile  strength  and 
elastic  limit,  in  lowering  ductility  and  in  giving  fine 
structure.  I  find  it  easier  to  ascribe  these  resemblances 
not  to  compression  alone,  nor,  indeed,  chiefly,  but  also  to 
the  other  features  which  these  operations  have  in  common, 
kneading  action,  interstratal  motion  and  residual  stress. 

§  57.  HAPIDITY  OF  COOLING  EFFECTED  BY  DIFFERENT 
MEDIA. — In  general,  the  greater  the  specific  gravity, 
specific  heat,  mobility,  latent  heat  of  gasification,  coefficient 
of  expansion  and  thermal  conductivity,  and  the  lower  the 
boiling  point  and  the  initial  temperature  of  the  cooling 
medium,  the  more  suddenly  will  the  immersed  metal  cool. 
Mercury  cools  steel  extremely  rapidly  because  it  is  ex- 
tremely heavy  (i.  e.,  the  surface  of  the  steel  is  exposed  to 
a  great  mass  of  it)  and  decidedly  mobile  :  water  cools  it 
rapidly  because,  while  very  mobile,  it  has  high  specific  heat 
and  latent  heat,  of  gasification  and  low  boiling  point.  Oil 
cools  steel  slowly  because  it  is  comparatively  light  and 
viscid,  and  has  low  specific  heat  and  high  boiling  point. 
A  low  boiling  point  favors  rapid  cooling,  for,  as  a  liquid 
cannot  rise  above  its  boiling  point,  if  this  be  low  it  always 
remains  cool.  If  water  contains  soap,  or  is  covered  with 
an  oil  film,  it  cools  steel  less  energetically,  the  soap,  we  may 
surmise,  temporarily  forming  a  coating  on  the  steel  as  the 


b  Osmund's  observations,  published  since  Akennan's  paper,  might  at  first  be 
thought  to  accord  with  Akerman's  view  (see  §  14).  He  found  that  iron  and 
steel,  when  cold-forged,  just  as  when  hardened  by  quenching,  evolved  when  dis- 
solved more  heat  than  the  same  steel  after  annealing  :  whence  it  might  be  inferred 
that  cold-forging  produced  the  same  chemical  results  as  quenching.  It  is  however 
on  further  examination  very  improbable,  I  think,  that  the  similar  behavior  of 
cold-forged  and  quenched  steel  is  due  to  similar  condition  of  carbon.  For  we  find 
that  cold-forging  increases  the  evolution  of  heat  from  steel  with  only  0-172  carbon 
as  much  as  it  does  that  of  steel  with  0-542,  and  nearly  as  much  as  when  the  carbon 
is  1-172  ;  and  quenching  too  affects  the  heat  evolution  of  steel  bat  slightly  more 
when  1-17^  carbon  is  present  than  when  there  is  but  0'54;,'.  Now  if  the  increased  evo- 
lution of  heat  on  dissolving  coM-forged  steel  were  due  to  a  change  in  the  condition 
of  carbon  caused  by  cold-forging,  then  the  increase  should  be  thrice  as  great  with 
0-542  carbon  as  when  only  0  •  172  carbon  is  present. 

c  Trans.  Institution  Mechanical  Engineers,  1881,  p.  708, 


36 


THE    METALLURGY    OF     STEEL. 


water  which  had  dissolved  it  is  gasified,  the  oil  perhaps 
adhering  to  the  steel  as  a  thin  film  when  it  is  immersed. 

The  rapidity  with  which  water  cools  steel  is  lessened  by 
the  formation  of  a  layer  of  steam  between  it  and  the  steel, 
which  has  low  conductivity,  specific  heat  and  specific 
gravity.  Hence  J  arolimek  suggested  that  steel  be  dipped 
slowly,  so  that  the  steam,  forming  only  near  the  surface, 
may  escape  readily,  and  so  that  the  steel,  once  it  enters  the 


water,  may  cool  the  quicker.  For  hardening  certain  pieces, 
he  advises  a  spray  of  water,  through  the  interstices  between 
whose  drops  the  steam  may  readily  escape.  These  methods 
appear  to  be  of  limited  application  and  value  ;  they  have 
not  come  into  extended  use,  at  least  in  this  country.  He 
further  advises  hardening  in  a  stream  of  water,  which 
hastens  cooling  not  only  by  exposing  fresh  surfaces  of 
water  to  the  metal  but  also  by  dragging  away  the  steam. d 


CHAPTER    III. 

IKON    AND    SILICON. 


§  60.  SUMMARY. — Silicon  alloys  with  iron  in  all  ratios, 
at  least  up  to  30^,  being  readily  reduced  from  silica  by 
carbon  in  the  presence  of  iron.  It  rarely,  if  ever,  exists 
in  iron  in  the  graphitoidal  state.  It  diminishes  the  power 
of  iron  to  combine  with  carbon,  not  only  when  molten 
(thus  diminishing  the  total  carbon  content),  but  more  espe- 
cially at  a  white  heat,  thus  favoring  the  formation  of 
graphite  during  slow  cooling.  (See  §  18.)  It  increases  the 
fusibility  and  fluidity  of  iron :  it  lessens  the  formation  of 
blowholes  :  by  reducing  iron  oxide  it  apparently  removes 
one  cause  of  redshortness :  it  hinders  at  high  tempera- 
tures the  oxidation  of  iron  and  probably  of  the  elements 
combined  with  it.  Its  effect  on  the  welding  power  of 
steel  is  in  dispute.  If  like  carbon  it  confers  the  power  of 
hardening  on  sudden  cooling  it  is  to  an  unimportant 
extent.  It  is  thought  by  the  majority  to  increase  ten- 
sile strength  slightly,  and  to  render  steel  brittle  and 
redshort :  but  it  very  often  does  not  have  this  effect. 
Silicon  steels  with  1  to  2,  or  even  2 '5  silicon,  sometimes 
excellent  for  cutting  hard  steel,  have  been  made. 

§  61.  ABSORPTION  OF  SILICON. — Iron  absorbs  silicon 
greedily,  uniting  with  it  in  all  proportions  at  least  up  to 
30$,  and  apparently  the  more  readily  the  higher  the  tem- 
perature, absorbing  it  even  at  a  red  heat  when  imbedded 
in  sanda  and  charcoal.  Ferro-silicons  of  the  following 
compositions  have  been  made  : 


No. 

T~ 

2 

3 
4 
6 

%  Silicon. 

Made  by 

Obtained  by  heating  together. 

30-8 
31-71 

20-17 

18-77 
18- 

Halm. 
E.  Riley. 

Hahn. 
Percy. 
E.  Riley. 

Ferrous    chloride,    salt,    sodium    and    silico-fluoride    of 
sodium. 
Iron   oxide,  quartz,  charcoal   in   excess  ;   steel-melting 
heat,  48  hours. 
Ferrous  chloride,  silt,  silicon,  sodium,  and  fluorite. 
Sulphide  of  iron,  silica,  and  charcoal. 
Silicate  of  iron  with  charcoal  :    steel-melting  heat,   48 
hours. 

1.  Ilahn,  Ann.  Chcm.  Phonn.  CXXIX.,  1SW.    Kxposed  2  hours  to  nickel-melting  heat  :  light 
bronze  to  gray  :  extraordinarily  brittle  :  fracture  homogeneous,  non-crvstulline  :  feebly  attracted  by 
magnet:  Sp.  Gr.  6'289.    2.  K.  Eiley,  Journ.  Cliem.  Soc.,  1872,  XXV.,  p.  562.      S.  Halm,  ioc. 
cit.:  completely  fused  after  2'5  hours  exposure  to  the  strongest  heat:  extremely  brittle.     4. 
Percy,  Iron  and  Steel,  p.  88  :  hard  and  brittle.     R.  K.  IJiley,  Ioc.  cit. 

Though  silica  can  neither  be  reduced  by  ironb  alone  nor 
by  carbon  alone,  it  is  readily  reduced  by  carbon  if  iron  be 
present  to  alloy  with  the  resulting  silicon,  which,  under 
these  conditions,  is  readily  reduced  even  from  the  walls  of 
clay  and  graphite  crucibles,  from  acid  slags,  and  even  from 
basic  ones  if  the  temperature  be  excessively  high.  (Carbon 
also  reduces  silica  in  presence  of  copper  or  silver.)  Nor 
is  the  presence  of  free  carbon  necessary,  for  the  carbon 
initially  contained  in  iron  reduces  silicon"  from  the  walls 


a  Karsten,Eisenhiittenkunde,  I.,  p.  477;  Eng.  and  Mining  Jl.,  1875, 1.,  p.  287: 
b  Percy  :  Iron  and  Steel,  p.  91. 

o  Comptes  Rendus,  LXXVL,  p.  483  :    Journ.  Iron  and   St.  Inst.,  1885,  I.,  pp, 
290,  295. 


of  clay  and  still  more  readily  from  those  of  graphite 
crucibles,6  the  graphite  of  the  latter  doubtless  contributing 
towards  the  reducing  action.  The  manganese  of  manga- 
niferous  irons  also  seems  to  reduce  silicon'  from  the  walls 
of  crucibles  and  even  from  those  of  cupola  furnaces/'  with 
oxidation  and  scorification  of  the  manganese.  (Cf.  §  268  D.) 

Caron8  melted  cast-iron  containing  Q-QQfc  silicon  in 
crucibles,  (A)  alone  and  (B)  with  6%  metallic  manganese. 
Melted  alone  its  silicon  fell  to  0-88,  and  on  a  second  fusion 
to  0'80.  Melted  with  Qr/0  manganese  the  silicon  rose  to 
1'3$  and  on  a  second  fusion  without  further  addition  to 
1*66$,  with  heavy  loss  of  manganese.  (See  §  81.) 

So  readily  is  silicon  reduced  in  presence  of  iron,  that 
Troost  and  Hautefeuille,"  melting  cast-steel  containing  -10^' 
silicon  and  1  '54^  carbon  in  a  siliceous  crucible,  found  that, 
after  two  hours  fusion,  it  contained  "80^  silicon  and  only 
•70$  carbon.  They  also  found  that  fused  cast-iron  in  pro- 
longed contact  with  porcelain  lost  carbon  and  gained 
silicon,  till  the  latter  metalloid  in  some  cases  reached  &%, 
Muller,1  melting  white  cast-iron  in  a  graphite  crucible 
raised  its  silicon  from  '07  to  1'07£,  and  its  carbon  from 
3'59  to  3'64$  while  its  manganese  fell  from  2'04  tol-86;/. 

§  G2.  REMOA^AL  OF  SILICON.— Silicon  may  be  oxidized, 
according  to  Caron,  by  both  carbonic  acid  and  carbonic 
oxide:  it  is  removed  from  molten  iron  very  rapidly  by 
atmospheric  air  and  by  simple  contact  with  iron  oxide, 
magnesia,  and  other  bases. . 

The  oxidation  of  silicon  in  presence  of  carbon  and  man- 
ganese will  be  specially  considered  later. 

For  every  temperature  and  set  of  conditions  a  certain 
balance  between  the  oxidized  and  unoxidized  silicon  and 
carbon  corresponds  to  equilibrium  :  if  the  oxygen  be  not 
distributed  according  to  this  balance,  it  will  redistribute 
itself  till  the  balance  is  approached,  provided  the  tempera- 
ture be  high  enough  to  permit  a  transfer.  (1)  The  higher 
the  temperature,  (2)  the  more  oxidized  and  the  less  un- 
oxidized silicon  bo  present,  (3)  the  less  oxidized  and  the 
more  unoxidized  carbon  be  present,  the  more  completely 
will  oxygen  combine  with  carbon  in  preference  to  silicon  : 
the  opposite  conditions  favor  the  union  of  oxygen  with 
silicon  rather  than  with  carbon.  The  presence  of  bases 
strengthens,  that  of  metallic  iron  weakens  the  affinity  of 
silicon  for  oxygen.  At  temperatures  even  as  low  as  the 


d  Metallurgical  Review,  I.,  p.  153. 

e  Eng.  and  Mining  Jl.,  1883,  II.,  p.  367. 

*  Ledebur  :  Handbuch,  p.  241  ;  Percy  :  Iron  and  Steel,  p.  139. 

g  Comptes  Rendus,  56,  p.  328. 

h  Comptes  Rendus,  LXXVL,  1875,  p.  483. 

i  Stahl  uud  Eisen,  1885,  V.,  p.  181:  Journ.  Iron  and  St.  Inst.,  1885,  I.,  p.  294. 


IRON   AND    SILICON,    §65. 


37 


melting  point  of  steel  with  V1%  carbon  (say  1600°  C.), 
carbon  may  deoxidize  silicon  :  at  the  highest  temperature 
of  the  Bessemer  process,  the  affinity  of  carbon  for  oxygen 
greatly  outweighs  that  of  silicon. 

§  63.  THE  CONDITION  OP  SILICON  IN  IRON.— Silicon,  like 
carbon  and  boron,  exists  in  three  states,  viz  ,  amorphous, 
graphitoidal  and  diamond-like.  It  behaves  towards  alu- 
minium and  zinc  as  carbon  does  towards  cast-iron,  dissolv- 
ing in  these  metals  when  melted,  and  separating  out  in  a 
crystalline  form  when  they  solidify.  It  was  formerly 
thought  that  silicon  frequently  occurred  in  the  graphitoidal 
state  in  iron  :  but  recent  investigations  show  that  it  rarely, 
if  ever,  does  so  under  ordinary  conditions.  It  is  true  that 
Percy,  whose  observations  led  him  to  believe  that  silicon 
separates  graphitically  during  the  slow  cooling  of  gray 
iron,  thought  that  he  found  unmistakable  evidence  of  the 
existence  of  separated  silicon"  in  kish,  i.  c. ,  the  graphi- 
tic mass  which  separates  from  cast-iron  supersaturated 
with  carbon.  Sorby,b  with  a  very  high-power  microscope, 
finds  beautiful  triangles,  rhombs  and  crosses  in  cast-iron, 
sometimes  ruby-red,  sometimes  dark,  which  he  believes 
are  separated  silicon  :  but  no  reasons  are  given  to  sup- 
port this  view.  Eichter0  thought  that  he  had  found  sili- 
con in  denned  crystals  in  cast-iron:  Henry0  thought  he 
had  found  it  in  crystals  in  the  graphite  of  cast-iron  :  Blaird 
asserts  that  kish  is  quite  as  frequently  graphitoidal  silicon 
as  graphite,  without,  however,  adducing  evidence.  In 
brief,  I  cannot  find  that  graphitoidal  silicon  has  ever  been 
unmistakably  identified  in  iron. 

Now  Snelus,  Jordan,  Morton,  and  Turner  have  vainly 
sought  it,  nor  did  Abel  find  it  during  a  prolonged  ex- 
amination of  cast-irons.  Were  it  frequently  present  it 
would  hardly  have  been  missed  by  all  these  investigators, 
though  we  cannot  infer  that  it  may  not  form  under  excep- 
tionally favorable  conditions.  But  as  iron  has  the  power 
of  combining  with  much  more  silicon  (30^)  than  cast-iron 
proper  ever  contains,  the  separation  of  graphitoidal 
silicon  would  be  most  surprising.  The  reason  why  graphite 
separates  so  readily  from  cast-iron  is  that  iron,  when  man- 
ganese is  absent,  is  only  able  to  unite  chemically  with  a 
small  quantity  of  carbon.6 

The  occurrence  of  crusts  and  druses  of  silica'  and  of 
silicates  on  the  exterior  and  in  the  vugs  of  cast-iron  and 
in  the  hearths  of  blast-furnaces  is  not,  as  has  frequently 
been  supposed,  prima  facie  evidence  of  the  extrusion  and 
subsequent  oxidation  of  graphitoidal  silicon,  since  the 
silicon  may  have  escaped  from  the  iron  in  combination 
with  some  other  element  and  have  become  subsequently 
oxidized.  Passing  by  siliciuretted  hydrogen  and  chloride 
and  fluoride  of  silicon,  all  volatile  and  possible  though 
improbable  causes  of  the  siliceous  druses,  sulphide  of 


a  Percy  :  Iron  and  Steel,  pp.  181,  511. 

b  Journ.  Iron  and  St.  Inst,  1886,  I.,  p.  144. 

cldem.,  1871,  p.  36. 

dldem,  1886,  I.,  p.  82. 

e  Snelus,  sifting  the  finer  from  the  coarser  portions  of  the  borings  of  graphitic 
cast-iron,  found  a  larger  proportion  of  the  friable  graphite  in  the  fine  than  in  the 
coarse  portions,  but  no  similar  concentration  of  silicon  occurred,  whence  ho 
inferred  that  it  was  all  chemically  combined.  (Journ.  Iron  and  St.  Inst,  1871, 
p.  34.)  Turner  and  Jordan  (Idem,  18S6,  I.,  p.  172)  vainly  sought  silicon  in  the 
residue  from  dissolving  siliceous  cast  iron,  nor  were  they  able  to  separate  it  from 
comminuted  cast  iron  with  the  magnet.  Morton  (Idem,  1874,  I. ,  p.  102)  examined 
No.  1  Bessemer  and  white  iron,  each  with  nearly  5  %  silicon,  by  several  apparently 
decisive  chemical  methods,  but  was  unable  to  detect  free  silicon,  though  he  spe- 
cially sought  it. 

t  Journ.  Iron  and  St.  Inst.,  1886, 1.,  pp.  82,  97,  98:  1871,  I.,  p.  44:  Trans.  Am. 
lust.  Mining  Engineers  XII,,  p.  643:  Percy  op.  eit.  p.  507. 


silicon  (SiSg)  may  be  considered  as  a  not  unlikely  cause. 
According  to  Fremy*  and  Ledebur  it  is  formed  by  the  re- 
action of  sulphur,  carbon  and  silica,  at  a  white  heat,  or  by- 
passing bisulphide  of  carbon  over  a  mixture  of  carbon  anil 
silica.  It  is  volatile  at  a  high  temperature,  and  in  moist 
air  is  rapidly  oxidized  to  silica,  with  formation  of  sulphur- 
retted  hydrogen.  Colson"  finds  two  volatile  compounds  of 
silicon,  SiS  and  SiSO,  formed  by  passing  bisulphide  of 
carbon  over  silicon  at  a  high  temperature.  Sulphide  and 
silicide  of  iron  may  not,  however,  directly  react  upon  each 
other,  since  Percy1  on  melting  them  together  obtained  two 
distinct  and  almost  unaltered  layers.  Crusts  of  silicates 
(not  silica)  are  probably,  in  my  opinion,  often  due  to  the 
liquation  of  silicides  from  the  solidifying  cast-iron  and 
their  subsequent  oxidation. 

Silica  and  silicates  mechanically  intermixed  and  arising 
from  the  oxidation  of  silicon  previously  combined  with 
iron  often  exist  in  ingot  metal :  readily  mistaken  for  sili- 
con, their  effects  have  been  attributed  to  it.  Pourcel,J 
volatilizing  the  iron  in  certain  steel  castings  with  chlorine, 
obtains  "a  network  of  silicate  of  iron  preserving  the  origi- 
nal form  of  the  pieces."  A  cloud  of  siliceous  dust  escaped 
when  steel,  prepared  by  Turner  by  adding  ferro-silicon 
to  unrecarburized  basic  Bessemer  steel,  was  broken  in 
the  testing  machine :  its  fracture  revealed  many  small 
pipes  partly  filled  with  a  whitish  siliceous  powder :  dis- 
solved in  acids  it  yielded  white  flakes  of  silica  unlike  the 
ordinary  gelatinous  variety." 

§  64.  EFFECT  OF  SILICON  ON  TENSILE  STRENGTH  A»D 
DUCTILITY. — It  is  generally  thought  to  increase  tensile 
strength, 'though  slightly  :  the  prevalent  views  as  to  its 
effects  on  ductility,  usually  ill-founded,  differ  widely. 
Probably  a  large  majority  of  metallurgists  think  that  it 
diminishes  ductility,  especially  under  shock,  and  far 
more  for  given  increase  of  tensile  strength  than  carbon 
does,™  and  that  its  effect  is  the  stronger  the  more  carbon 
is  present.  Interested  patentees  have  proclaimed  that 
even  '02^  of  silicon  seriously  affects  ductility,  and  have 
deceived  many  of  narrow  experience.  Others  think  that 
up  to  'o  or  even  'If0  it  increases  tensile  strength  without 
at  all  diminishing  ductility"  and  is  highly  beneficial. 
Many  insist  that  it  makes  steel  very  redshort,  many  that 
it  can  only  be  tolerated  when  accompanied  by  much  man- 
ganese :  both  views  are  contradicted  by  others. 

§  65.  DETAILED  EVIDENCE  AS  TO  THE  EFFECTS  OF  SILI- 
CON ON  DUCTILITY  AND  FOUGEABLENESS. — I  here  offer 
examples  of  siliceous  steels  which  are  ductile  and  non-red- 


eComptes  Rendus,  1853:  Ledebur,  Handbuch,  p.  343. 

h  Comptes  Rendus,  Vol.  94,  p.  1526:  Ledebur  loc.  cit. 

1  Iron  and  Steel,  p.  95. 

i  Journ.  Iron  and  St.  Inst.,  1877,  I.,  p.  44. 

k  Journ.  Chem.  Soc.,  1887,  p.  142. 

1  Deshayes  (Private  communication,  April  13,  1887,  and  Classement  et  emploi 
des  aciers)  considers  that  '01^  silicon  raises  the  tensile  strength  by  143' pounds 
per  square  inch. 

m  Snelus  (Journ.  Iron  and  St.  Inst.,  1871, 1.,  p.  34)  says  that  about  •!£  silicon 
makes  Bessemer  steel  hard  and  brittle  when  cold:  in  "Chemistry  Applied  to  the 
Arts  and  Manufactures,"  he  says  that  it  makes  steel  both  redshort  and  coldshort 
especially  if  carbon  be  present,  so  that  while  '6$  silicon  may  not  make  steel  par- 
ticularly brittle  when  less  than  -\%  carton  is  present,  yet  with  '4  to  '5£  carbon 
even  '2$  silicon  produces  decided  redshortness  and  coldshortness,  and  •?>;<'  wou'd  be 
dangerous.  Hackney  (Inst.  Civ.  Engrs.,  XLII.,  p.  35)  considers  that  forgiven 
increase  of  hardness  silicon  increases  brittleness  so  much  more  than  carbon  that 
more  than  "lor  '2%  is  unsafe  in  rail  steel.  Akermau  (Journ.  Iron  and  St.  Inst.,  1878, 
II.,  p.  379)  considers  the  belief  that  silicon  dimici:;hcs  resistance  to  shock  com- 
pletely confirmed.  Deshayes  believes  that  '01£  silicon  diminishes  the  elongation 
in  3-9  inches  by  -08^. 

iiMiiller  :  Journ.  Iron  mid  St.  lust.,  1S8,!,  I.,  p.  374. 


38 


THE    METALLURGY    OP     STEEL. 


short  (A  to  G) :  results  of  statistical  examinations,  indi- 
cating that  silicon  does  not  affect  ductility  (H  to  J):  facts 
implying  that  it  does  (K  to  M) :  an  attempt  to  reconcile 
them  (N  to  Q):  and  a  resume  (R) 

(A)  SILICON  STEEL. — In  Table  19,  §  66,  good  steels  with 
from  -54  to  2'07  and  even  7'4$  silicon   are   quoted:    at 
many  points  within  these  limits,  then,  silicon  is  not  in- 
compatible with  good  quality. 

(B)  CRUCIBLE  STEEL  will  be  admitted  to  be  excellent 
steel,  certainly  better  than  ordinary  Bessemer  and  open- 
hearth  steel  and  ordinarily  more  ductile   for  given  ten- 
sile strength  :  yet  it  generally  contains  far  more  silicon 
than  they  do.     Taking  35  examples  of  tool  steel,  tested 
by  D.  Smith,8  we  find  the  silicon  between   '07  and  1'28, 
and  in  many  cases  above  '20$.     Arranging  them  in  the 
order  of  merit  for  cutting  tools  the  percentages  of  silicon 
are  as  follows:  Best   '17  and  1 '28:   '14  and  -19  :   '29:   '10 
and  -13  :   "31  :   '21  and  "23  :   '37  :   '20  :    -09  :   '10  :   '19  :  -14  : 
•10  and  -25  :   '27 :  '07  and  -11— worst.     This  should  finally 
dispose  of  the  notion  that  silicon  is  only  tolerable  when 
carbon  is  very  low,  since  none  of  these  steels  have  less 
than  0'7C%  and  most  of  them  have  over  \%  carbon. 

(C)  STEEL  CASTINGS,  when  annealed,  considering  their 
disadvantage  in  not  having  been  forged,  compare  very 
favorably  with  forgings  in  tensile  strength  and  ductility  ; 
yet  their  silicon  is  much  higher  than  that  of  ordinary 
forgings,  running  usually  from  0'20  to  0'55,  or  even  0-6$, 
and  that,  too,  with  carbon  as  high  as  '96$  (see  Table  9). 
It  is  often  said  that  silicon  may  do  for  castings,  but  cer- 
tainly not  for  forgings :    and  that,  moreover,  we  cannot 
usually  anneal  forgings,  while  these  castings  have  to  be 
annealed  to  give  them  toughness.   The  annealing  is  needed 
not  to  counteract  the  effects  of  silicon,  but  those  of  irregu- 
lar contraction  and  coarse  structure :  and  the  proof  of  this 
is  that  if  we  forge  one  of  these  castings  it  remains  tough, 
even  without  annealing.     (See  Table  17  A.) 

(D)  EXAMPLES  OF  GOOD  SILICEOUS  STEELS  are  given 
in  Table  17,  all  sufficiently  forgeable  to  be  rolled  into  rails, 
sufficiently  tough  to  endure  in  the  track  in  some  cases  re- 
markajjly  well,  in  all  at  least  well  enough  to  escape  at- 
tention, and  how  much  better  we  know  not. 

Did  silicon  always  increase  brittleness  and  redshortness 
as  much  as  it  is  thought  to,  neither  12  nor  18  (with  but 
•22.  manganese  to  counteract  redshortness)  could  have 
been  rolled,  and  they  and  others  would  have  broken  under 
the  straightening  press.  You  who  hold  that  high  silicon 
is  only  permissible  with  certain  percentages  of  certain 
other  elements,  mark  well  how  in  Tables  17  and  19  the 
carbon  is  now  high,  now  low,  now  nil ;  and  how,  be 
it  high  or  low,  it  is  now  joined  to  high,  now  to  low  manga- 
nese :  mark  too  No.  12,  with  high  silicon  carbon  and 
phosphorus. 

TABLE  IT. — SILICIFEEOCS  BAILS  OP  AT  LEAST  TOLEEABLI  QPALITT. 


Carbon  
Silicon  
Sulphur  .... 
Phosphorus 
Manganese. 

1 

2 

8 

4 

5 

6 

T 

8 

9 

12 

18 

1C. 

17 

18 

f 

•50 
•62 
•025 
•058 
1-50 

a 
•47 
•84 
•06 
•11 
1-48 

a 

•7« 
•58 
•01 
•056 
1-85 

f 
•24 
•52 
•02 
•09 
•78 

f 
•29 
•51 
•06 
•10 
•76 

f 
•23 
•79 
06 
•18 
•91 

t 

•17 
•84 
•02 
•08 
1-14 

f 
•52 
•87 
•05 
•11 
2'08 

f 

•70 
•59 

•02 
•06 

1-84 

f 
•45 
•76 
•06 
•18 
•75 

f 

'•88" 
•19 
•10 
1-61 

c 
•36 
•47 

d 

•48 

•48 

0 

under  '10 
•88 
•04 
•07 

•22 

•12 
•57 

•08 

•78 

a  =  redshort.    c  =  extraordinarily  good  rail.  E.  W.  Hunt,  Trans.  Am.  Inst.  Mining  Engineers, 
IX.,  p.  536.    d  =  tough  good  rail.  Dudley,  idem,   p.  341.    c  =  very  tough  rail,  Snolus,  Journ- 
Iron  and  St.  Inst.,  1882,  II.,  p.  583.    f  =  private  notes. 

MULLER"  states  that  at  one  German  works  the  com- 

"Thurston  :  Materials  of  Engineering,  II.,  pp.  434-6. 
"  Glaser's  Annalen,  X.  ,  Nos.  9  and  10.    Journ.  Iron  and  St.  Inst.  ,  1883,  1,  p.  374  . 

position  of  steel  rails  lay  for  over  three  years  between  the 
following  limits : 


Carbon. 
O'lO  to  0-15 


Silicon. 
0-3  to  0'6 


Manganese. 
0-6  to  1-0 


Phosphorus. 
0-13  to  0-15 


Sulphur. 
•03 


Copper. 
•05 


He  quotes  the  mechanical  properties  of  64  excellent 
rails,  whose  composition  apparently  lies  between  the 
limits  just  given  as  follows  : 


40  )  Had  tensile  (  71,111  to  78,335  )    Lbs.       3  had  from  34 '4  to  40]  , 
9V    strength   \  78,225  "  85,337  \    per     20    "        "    40'      "50  I' 
15  )        from       (  85,337  "  93,483  )  sq.   in.  37    "        "    50'     "  60  f 

14    "        "    60-     "68J 


contrac- 
tion of 
area. 


He  quotes  steel  with  carbon  0'14,  silicon  0'435, 
manganese  0'828,  and  phosphorus  0'15,  which  combines 
100, 000  pounds  tensile  strength  witli  24$  elongation.  Such 
ductility  in  steel  with  0 "15  phosphorus  is  rather  surpris- 
ing :  hence  if  silicon  has  affected  its  ductility  at  all  it  has 
probably  increased  it. 

Table  18  gives  many  siliceous  steels  which  combine  high 
tensile  strength  and  ductility. 

(E)  SPECIAL     EXPERIENCE. — The    open-hearth   steel, 
justly  famed  for  its  excellence,  made  at  an  eastern  U.  S. 
mill,  is  often  decidedly  siliceous,  the  spring  grade  usually 
containing    from    -10    to    '30$    silicon.     Indeed,    certain 
customers,  on  receiving  steel  with  less  than  the  'usual  per- 
centage of  silicon,  complain  of  brittleness,  though  igno- 
rant of  its  composition. 

(F)  J&UN    STEEL,  surely,    for  given   tensile   strength, 
should  have  the  highest  attainable  resistance  to  shock  :  yet 
it  is  often  purposely  siliceous  (Table  j9).     The  decision 
of  the  Swedish  ordnance  commission,  apparently  reached 
after  thorough  study,  that  gun-barrel  steel  should  have 
•25  to  -40^  silicon  is  of  weight.0 

TABLE  17A.— SILICIFEKOUS  Gnu  STEELS. 


Tensile 

Elastic 

No. 

Carbon. 

Silicon. 

Manga 
nese. 

Phos 
phorus. 

Sulphur 

Copper. 

strength 
Lbs.  per 

limit. 
I.lis.  IIIT 

EIoTi  Ca- 
tion. 

tion  ot 

sq.  in. 

sq.  in. 

1 

•12 

•28 

•58 

•11 

•02 

-S3  000 

4-.'  iii;^ 

18'7 

48-8 

2.   ... 

•47 

•44 

-41 

•08 

•04 

"6,759 

I8'8 

44-7 

8  

•45 

•85 

•54 

•04 

tr 

83,000 

82,713 

21- 

51- 

4. 

•40 

•32 

•61 

•04 

•02 

83,800 

86,000 

22- 

50-2 

5 

•35®  -48 

•25®  -40 

•(16  or 

less 

6  

•60 

•19 

•18 

tr 

•27 

1.  Gun  barrels  for  Russian  army,  forged.  2.  Gun  barrels  for  Swedish  Government,  from 
Witten-upon-Ruhr :  considereJ  admirable.  3  and  ft.  Bofors  open-hearth  steel  for  guns.  5. 
Composition  considered  best  suited  for  gun  barrels  by  Swedish  Ordnance  Commission.  The  pre- 
ceding from  Gautier,  Journal  Iron  and  Steel  last.,  1881,  II.,  p.  452.  6.  Krupp  gun  steel,  Kern, 
Metallurgical  Review,  II.,  p.  519. 


(G)  MRAZEK  concluded  that  the  redshortness  attributed 
to  silicon  was  due  to  silicate  mixed  with  the  iron :  he  found 
that  metallic  silicon  added  in  certain  proportions  to  iron 
did  not  alter  its  properties  (in  any  respect  ?).d 

(H)  RAYMOND,*  analyzing  by  the  method  of  least 
squares  Dudley's  data  of  the  composition  and  wearing 
power  of  64  rails,  finds  that  silicon  increases  the  wearing 
power,  thus  having  an  effect  opposite  to  that  of  carbon 
and  phosphorus. 

(I)  P.  G.  SALOM,  analyzing  Dudley's  data  by  the  same 
method,  finds  that  phosphorus  and  carbon  greatly  di- 
minish elongation  while  increasing  tensile  strength,  but 
that  silicon  increases  both  tensile  strength  and  ductility. 

(J)  STATISTICAL  EXAMINATION. — The  results  of  an 
analysis  of  354  sets  of  observations  of  tensile  strength  and 
ductility,  drawn  from  many  sources  with  no  selection  be- 
yond the  rejection  of  tungsten  and  chrome  steels,  are 

c Journ.  Iron  and  St.  Inst.,  1881,  II.,  p.  459. 

d  Gautier  :  Journ.  Iron  and  St.  Inst.,  1877,  I.,  p.  48. 

'•  Trans,  Am,  Inst,  Mining  Engineers,  IX,,  p,  007. 


INFLUENCE  OF  (SILICON  ON  THE  PHYSICAL  PROPERTIES  OF  STEEL.     §  66.  :!'.) 


.60 

.60 

60 

60 

60 

60 

60 

60 

60 

.50 

50 

i 

50 

50 

I. 
E 

LEG 
mile  Str< 
on^stioD 

sr 

END: 

i?th  

50 

50 

T.ll 

50 

.40 

Carbon, 
0  to  0:10 

7. 

.40     5    ' 

.20  to  i(3 

• 

cm 
.40  0lSO 

bon, 
oO.M 

Car 
40  °'40  ' 

tx>n, 
oOJO 

^ 

bon, 
.60 

C" 

40     -W| 

bon, 
.70 

Co: 

10   -70' 

|K)I1, 

.80 

Ca, 
40     -80' 

bon, 
W 

ICar 

1.90  a 
40  I 

M) 

Cm 
wi.oot- 

bon, 
Jl.10 

..SO 

a! 

E 

.30    Si 

| 

.30 

-       1 

f 

30         / 

I 

.30     t 

X 

30 

.30    r 

f,r 

\° 

t*~ 

.30    ..5 

i 
n 

.30 
.80 

.VO 

4 

B 

j 

,M     E 

f 

I 

m 

.20       1- 

i 
1h 

04 

t- 

!  i 

r 

Jo 

T 

.10    t 

TENSILE  STRENG1 
Scale  | 

•s  |Z^ 

"ElbNGATloH 

1 

1 

/» 

1 

.Sll       > 

j 

1 

r- 

I 

\ 

.-2.10 

i 

ofe 
3/1 

J 

o 

JO  w  _ 
1 

z's* 
v- 

JO_|J_ 

! 

/I 
/ 

||    | 

1 

.10  * 

1 

.10 

5 

I 

g  „ 

i 

Inn.  in 

;i,!..  ;oo 

I/I 

100  lln." 

\ 

Silicon 

/'    | 

Silicon 

1 

Silicon 

' 

-r 

Silicon 

Silicon 

Silicon 

Scile-uf  Te 

sfle  Sir,- 

gib,         6     100,001 

ttoa       o 

1  Hi1).  ifW,<*>0  HID-    *•*        WfQ1^  Ib&i 

••7.    pflt     |       fjs 

100,000  It/s 

100,000  Ibs. 

i«7<, 

100,000  ll)»,      0         JOO.OOO  IU.               100, 
iplk          |               »?7«                          1 

WOIbj. 

100,( 

1 

OOIbs. 

1- 

100,000  Ibe. 

Fig.  6. 

TAliLK  is.— KFKK<T  OF  SILICON  ox  TKNHII.K  STRKXGTII  AND  KLONUATION. 


(  'arlnin. 

Si  0@0-0.-, 

si  n-n.->@o-Ki 

Si  -111©-!.? 

Si  -15®  "20 

Si  -.>i)©-80 

Si  -3n@-40 

Si  -40@-50 

Si  -50@-60 

Si  -60@-70 

Si  -T0@-8fl 

-^ 
g 

1 

•-'•2 
11 
11 
88 

4 
6 
9 
1 
1 

Tensile 
strength 

m 

o 
d 

Tensile 

strength 

i 

M 

0 

d 

ta 

Tensile 
strength 

I 

1 

•s 

1 

Tensile 
strength 

j 
I 

3 
o 

Tensile 
strength 

I 

a 

a 
o 

w 

o 
o 
d 
pq 

Tensile 
strength 

I 

<a 

Tensile 
strength 

1 

S 

I 

o 
6 
'ft 

Tensile 
strength 

1 

S 

1 

O 

d 

Tensile 
strength 

d 

o 

I 

_o 

o 

•L 

Tensile 

strcllL'tll 

T 

i 

0@  -10 

•\<^l     ••_'.! 

.;,„    -,o 
•41  1@  -50 
-.in©  -no 

"0©   -SO 

•Srtffl   'M 
•90®1-00 

M)ll@),l-10 
1-10©  1-20 

I'lino.  i-:in 
(•80®  1-ln 
l.liif,/1-.-iii 

59.1S1 

27- 

i 

51,000 

s 

46,000 

29' 

1 
5 
7 
B 

1 
5 
9 
2 
2 
2 
2 

55,000 
74,000 
67,000 
83,400 
104,300 
130,000 
109,000 
131,300 
Mli.nno 
130,000 
96,500 
127,500 

25- 
24  4 
21- 
19-2 
12-3 
14' 
6' 
3-4 
8- 
5- 

'8:5 

80,686 

Tit.  in  in 
18,000 
81.400 

-s  .-,011 

inn,  inn 

14!)]000 
134,0110 

•2li- 
23- 
16-5 
S  li 
3- 
4- 
4  4 

s- 

4 

83,700 

I--.-, 

5 
14 
1 

'it' 

29 
3 
3 

69.1MX) 
84,600 

117,400' 
124,400 

21- 

l.->  li 
13-3 

e:7 

4") 
4-5 
8 

2 
5 
1 

1 
8 
14 
1 

"j' 

1 

MI.  ni  in 

•III  SI  HI 

Tl.ni.i 
98,  

1-21.  .-.nil 
l:!ll  -21111 

188,000 

9fl,ilOO 

liin.iioo 

IT' 

19-2 
•20- 
•'II- 
C-3 
4-8 
5' 

2 

'  a 

2 
5 
14 
8 
4 
1 
1 

'  »7,500 
114,800 
110,500 
125,000 
125,900 
136,200 
123,000 
106,000 

16" 

15  7 
5'6 
8-9 

5'6 
7-2 
8- 

1 
2 
11 
4 

70,000 
16,000 

102,000 
107,000 

8' 
18-5 
11-3 

82 

1 

87,000 

21- 

1 

110,1100 

19- 

3 

1 

98,700 
104,000 

13- 
10- 

1  8 
8' 

2 

107,500 

7' 

"i 
l 
l 

l 

140.000' 
140,000 
114,000 

10- 

3 
1 

79,000 
147,000 

S 

81,000 

1-1 

1 

95,000 

118,000 

1 

1 

'.i-2.ni  in 
98,000 

1 

135,000 

T 

given  in  Table  18,  and  graphically  in  Fig.  6,a  with 
silicon  as  ordinate,  tensile  strength  and  elongation 
as  abscissae.  I  first  divide  the  cases  into  groups  of 
nearly  constant  carbon,  each  of  which  has  a  separate  dia- 
gram :  and  these  again  into  sub-groups  of  nearly  constant 
silicon.  Each  curve  in  Fig.  6  and  each  horizontal  line  in 
Table  18  represent  one  primary  group  with  (nearly)  con- 
stant carbon  but  varying  silicon  :  each  spot  on  the  curves 
and  each  number  in  the  table  represent  one  sub-group 
with  carbon  and  silicon  both  nearly  constant. 

This  method,  while  not  quantitatively  accurate, 
woTild,  when  applied  to  so  many  cases  whose  silicon  varies 
so  widely,  reveal  the  effects  of  silicon  qualitatively,  were 
they  weighty,  constant  and  cumulative,  just  as  it  unmis- 
takably reveals  those  of  carbon.  Passing  in  any  line 
from  left  to  right  tensile  strength  rises  almost  uninter- 
ruptedly till  carbon  passes  1  "00,  Avhen  it  declines  :  elon- 
gation falls  almost  continuously."  But  no  constant  effect 
can  be  traced  to  silicon  :  passing  down  some  columns  ten- 
sile strength  rises  and  elongation  falls,  both  slightly  :  but 
in  as  many  the  reverse  occurs.  The  curves  too,  gene- 
rally nearly  vertical,  turn  as  often  to  left  as  right. 

This  result  indicates,  not  that  silicon  never  injures  duc- 
tility but  that,  if  it  does,  it  also  promotes  it  as  often  and  as 
much.  An  analysis  of  more  extended  data  is  desirable. 


a  The  curves  are  derived  by  plotting  a  curve  for  each  column  of  Table  18,  at- 
taching to  each  spot  a  weight  proportional  to  the  number  of  cases  it  represents, 
finding  the  center  of  gravity  of  each  group  of  three  consecutive  spots  (1st,  2d,  3d, 
then  3d,  3d,  4th,  etc.),  and  drawing  new  curves  through  these  centers  of 
gravity. 

Slight  discrepancies  exist  between  the  curves  for  carbon  '70  to  -SO  and  "60  to 
•70,  and  the  corresponding  numbers  in  Table  18,  due  to  my  incorporating  ad- 
ditional matter  into  the  table  after  these  curves  had  been  engraved. 

b  This  method  of  analysis  applied  to  steels  with  varying  phosphorus  reveals  the 
effects  of  this  element  on  ductility  very  clearly  (Table  87  and  Fig.  8,  §  1S3) . 


Now  for  the  evidence  that  silicon  makes  iron  brittle  and 
redsliort. 

(K.)  FOR  HOLLEV'S"  conclusion,  that  silicon  injures 
wrought-iron,  I  find  little  warrant  in  his  data,  the  results 
obtained  by  the  U.  S.  Board  for  Testing  Metals.  True,  the 
worst  of  his  irons  has  the  highest  silicon,  but  then  it  also 
has  almost  the  highest  phosphorus  :  he  has  several  excel- 
lent irons  with  high  silicon,  which  is  therefore  compatible 
with  excellence.  Arranged  "in  order  of  elongation  their 
silicon  percentages  are — Greatest  elongation,  O'lO:  '07: 
•14:  -17:  '16:  "16:  '20:  '11:  '16:  '14:  -15:  -16:  "27— 
lowest  elongation. 

(L)  TURNER'S  EXPERIMENTS"  do  not  in  my  opinion 
justify  his  conclusions  that  silicon  increases  redshortness 
and  tensile  strength  but  diminishes  static  ductility. 
Adding  varying  quantities  of  ferro-silicon  to  apparently 
different  lots  of  unrecarburized  basic  Bessemer  steel,  he 
obtained  steels  with  from  '009  to  '4%  silicon,  almost  free  from 
other  elements,  and  in  certain  cases  very  redshort.  In 
view  of  our  almost  complete  ignorance  of  the  composition 
of  the  redshort  ones,  and  of  the  facts  that  some  of  them 
received  less  ferro-silicon  than  some  of  the  non-redshort 
ones,  and  that  much  larger  percentages  of  silicon  do  not, 
in  normal  manufacture,  cause  redshortness,  the  observed 
variations  in  redshortness  are  more  naturally  ascribed  to 
variations  in  the  percentage  of  oxygen  in  the  unrecar- 
burized steel  than  to  variations  in  the  silicon  of  the  recar- 
burized  metal.  Further,  the  non-coalescing,  non-rising 
silicates  which,  thanks  to  the  almost  total  lack  of  mangan- 
ese, should  and  apparently  did  form,  are  more  probable 


c  Trans.  Am.  Inst.  Mining  Engineers,  VI.,  p.  101. 
d  Journ.  Chem.  Soc.,  1887,  p.  139. 


40 


THE    METALLURGY    OF    STEEL. 


causes  of  redshortness  than  is  silicon."  His  testing  machine 
results,  if  more  numerous,  might  indicate  that  silicon 
raises  tensile  strength  :  but  they  are  too  scanty  and  dis- 
cordant" to  even  faintly  suggest  that  it  lowers  static  duc- 
tility. 

(M)  THE  PREVALENT  BELIEF  of  Anglo-Saxon  steel 
makers,  voiced  by  Snelus  who  says  "all  steel  makers  are 
aware  that  if  the  silicon  rises  to  over  '2%  the  carbon  must 
be  kept  down  to  about  -35#,  or  the  rail  will  ordinarily  be 
brittle"0  cannot  be  so  easily  dismissed:  yet,  as  it  is  at 
least  largely  based  not  on  systematic  but  casual  observa- 
tion, it  may  prove  a  superstition. 

Now  to  reconcile  this  belief  with  the  facts  I  have  detailed. 

(N")  SILICON  A  CONCOMITANT,  NOT  A  CAUSE  OF  BRITTLE- 
NESS  AND  RtDSiioRTNESS. — Forsyth  (I  know  no  more 
competent  observer),  informs  me  that  in  the  Bessemer  pro- 
cess a  considerable  percentage  of  silicon  introduced  with 
the  recarburizing  additions  affects  the  ductility  and  forge- 
ableness  of  the  steel  but  slightly,  while  the  same  percent- 
age of  silicon  if  residual,  i.  e.  if  remaining  in  the  blown 
steel  from  that  initially  in  the  cast-iron,  would  be  fatal. 
This  indicates  that  the  residual  silicon  does  not  cause  the 
brittleness,  but  that  both  spring  from  a  common  source  : 
this  may  be  the  high  temperature  which  almost  necessarily 
accompanies  high  residual  silicon.  Many  steel  makers 
report  that  ingots  crack  in  rolling  if  cast  unduly  hot,  but 
that  if  the  steel  be  cooled  before  casting  it  rolls  soundly, 
even  if  unduly  hot  when  blown. 

(O)  DIRECT  AND  INDIRECT  EFFECTS  OF  SILICON. — As 
the  indirect  effect  of  silicon  in  increasing  soundness  and 
continuity  (§  67)  should  increase  tensile  strength  and  duc- 
tility, and  as  our  statistics  indicate  that  its  net  effect  on 
these  properties  is  nil,  it  may  be  that  it  directly  dimin- 
ishes them,  masking  its  indirect  effect.  But  that  if  this 
be  its  direct  effect  it  is  either  not  constant  and  cumulative 
or  slight,  is  shown  by  the  excellence  of  many  of  the  sili- 
ciferous  steels  quoted. 

(P)  SILICA  is  often  mistaken  for  silicon :  who  knows 
how  far  it  is  responsible  for  this  metalloid's  bad  name ! 

(Q)  CHKMICAL  CONDITION. — Finally,  I  suspect  that 
silicon  enters  into  different  combinations  in  steel,  some 
promoting,  some  injuring  ductility  and  forgeableness. 
Its  passage  into  one  or  another  of  these  states  may  follow, 
in  an  obscure  and  complex  way  (to  be  revealed  by  proxi- 
mate rather  than  ultimate  analysis),  even  trivial  changes 
in  ultimate  composition  and  treatment. 

RESUME. — We  have  on  the  one  'hand  the  widespread 
dread  of  silicon  among  the  most  competent  judges :  on 
the  other  the  belief  of  many  high  authorities  in  its  harm- 
lessness,  the  failure  of  statistical  examination  to  show 
that  it  causes  brittleness,  and  the  numberless  instances  of 
good  and  often  admirable  siliceous  steels,  the  percentages 
of  whose  carbon  and  manganese  vary  within  very  wide 
limits,  and  apparently  without  law.  Making  all  reasonable 
allowance  for  the  discrepancies  between  static  ductility 
as  revealed  by  the  testing  machine  and  the  power  to  resist 
shock,  no  doubt  can  remain  that  very  many  highly  sili- 
ceous steels  are  in  every  sense  ductile. 


»  That  at  least  some  of  the  steel  held  silica  or  silicates  is  shown  by  the  escape  of 
a  cloud  of  siliceous  dust  on  breaking  one  piece. 

b  Numbered  in  order  of  silicon  content,  1  having  the  least,  and  arranged  in 
order  of  elongation,  they  stand  1  (highest),  3,  6,  8,  5,  2,  4,  7  (lowest).  Arranged 
in  order  of  reduction  of  area,  they  stand  1  (highest),  3.  6,  8,  S,  5,  4,  7  (lowest). 

c  Jour.  Iron  and  Steel  Inst.,  1883,  II,,  p.  584. 


Let  each  one  reconcile  these  facts  in  his  own  way.  While 
we  can  hardly  with  our  present  light  reach  final  con- 
clusions, yet,  after  making  all  reasonable  allowance  for 
the  belief  that  silicon  is  often  considered  a  cause  when  it 
is  merely  a  concomitant  of  brittleness  and  redshortness 
and  for  its  being  a  scapegoat  for  the  sins  of  silica,  in  view 
of  the  profound  and  widespread  belief  in  its  hurtfulness, 
I  believe  it  on  the  whole  probable  that  it  often  and  under 
certain  conditions  causes  brittleness,  especially  under 
shock,  and  psrliaps  also  redshortness  :  but  that  in  many 
and  probably  in  the  great  majority  of  cases  it  is  harmless, 
and  that  it  may  sometimes  even  increase  ductility,  be  it 
directly,  be  it  indirectly  by  promoting  soundness  and  con- 
tinuity. If  only  occasionally  injurious  it  could  readily 
acquire  a  bad  name.  I  regard  its  influence  as  dependent 
on  its  chemical  condition,  on  which  we  have  no  light :  it 
is  very  probable  that  it  more  often  injures  high-  than  low- 
carbon  steel,  and  that  the  presence  of  an  abundance  of 
manganese  counteracts  its  tendency  to  cause  redshort- 
ness. 

In  brief,  the  presence  of  silicon  does  not  prove  but  sug- 
gests brittleness,  and  calls  for  unusually  rigorous  tests. 

It  probably  slightly  increases  tensile  strength,  chiefly 
by  increasing  the  continuity. 

TABLE  19.— SILICON  STEELS. 


1 

2 

I 

4 
5 
6 

S 
'.i 

In 
11 

Silicon. 

Carbon. 

1 

•o 

g  ;  I  Phosphorus. 

1 
1 

•06 

Ductility. 

Welding 
power. 

Cold. 

Hot. 

7  4 
2-44 

2  07 
20 
1-5 
1'6± 
1-38 

1-34 

1  25 

1-02 
54 

tr 
•4 

Brittle 

Good 

Perfect 

Forges  readily  at  white,  with 
care  at  red  heat. 
Tensile  strength,  107,500  Ibs.; 
elongation,  3^. 
Efficient  for  cutting  tools. 

Very  strong. 

Tensile  strength,  114,240  Ibs.; 
elastic   limit.   C'2,720  Ibs.; 
elongation,  S'5£. 
Good  ;"stands  all  tests  usual 
for  good  tool  steel. 
Best  cutting  steel  tested  by 
U.  S.  B'd  to  test  metals. 

Tough 
Coldshort 

Very  go«l 
llather  poor 
Very  good 

'•'is 

'•84 

1-28 

1  20 

•28 
26 

•it 

... 

Perfect  (?) 

•41 

48 
•91 

•004 
0 

•045 

•07 
tr 

Good 

1'orges  at  red 
(  ;,,„,! 

None 

High 

?oft  and  tough 

I .  Mrazek,  .Tourn.  Iron  and  St.  Inst.,  1877.  I.,  p.  45  :  Proc.  Inst.  Civ.  Eng.,  1676,  XLIV.,  p. 
376.  Made  by  fusing  iron  wire,  sodium,  silica,  and  lluorite  in  Hessian  crucible.  Exceedingly 
brittle  cold,  hardens"  slightly  on  quenching  from  redness:  contains  little  or  no  manganese. 
2.  Snelus,  Journ.  Chem.  Soc.,  1887,  p.  182.  3.  Kiley.  Idem.  1^72.  XXV.,  p.  582:  .Tourn.  Iron 
and  St.  Inst..  1872,  I  ,  pp.  274-7.  4.  Hupfeld,  coldshort,  malleable  with  difficulty  :  Journ.  Iron 
and  St.  Inst.,  1SS2,  I.,  p.  870.  K.  Mrazek,  Idem,  1S77.  I.,  p  44,  M.  Hadflclds:  Weeks,  Trans. 
Am.  Inst.  Mining  Engrs  ,  XIV.,  p.  938.  1.  Hanlisty.  Steel  for  Guns  and  Projectiles,  p.  6. 
«.  Mushet'B  "titanium"  steel,  quite  free  from  titanium.  Kiley,  Journ.  Chem.  Soc.,  1872, 
XXV.,  p.  562.  9.  Thurston,  Mails,  of  Engineering,  II.,  n.  436.  10.  Mrazek,  Proc.  Inst.  Civ. 
Eng.,  1876,  XLIV.,  p.  816.  11.  Idem,  soft  and  tough  cold,  forges  at  both  red  and  white,  welda 
easily,  though  free  from  manganese. 


§  66.  SILICON  STEEL,  in  one  case  with  over  1%  silicon, 
has  been  made  by  several  metallurgists.  It  is  reported 
that  hard  steel  with  1  to  2$  silicon  is  or  has  been  made 
on  a  commercial  scale  in  Sheffield.  Rileyd  reports  steel  with 
2'07$  silicon,  which  endured  well  when  used  for  turning 
the  skin  from  cast-steel  wheels,  a  most  trying  task,  forged 
admirably  with  particularly  sharp  edges,  and  was  decid- 
edly tough,  as  shown  by  the  edge  of  the  tool  turning  up 
slightly.  Other  instances  are  given  in  Table  19,  of  which 
the  most  remarkable  is  Mrazek'  s  with  7'4$  silicon,  which 
forged  readily  and  welded  perfectly  !  Silicon  steel  is  said 
to  have  an  adhesive  scale,  and  a  fine  or  indeed,  if  the  sili- 
con be  very  high,  an  earthy  fracture.6 

While  it  is  too  early  to  speak  positively,  silicon  steel 
does  not  appear  to  promise  as  well  as  tungsten,  chromium 
and  manganese  steels,  though  it  may  prove  advantageous 


a  Journ.  Chem.  Soc.,  1872,  XXV.,  p.  563  :  Journ.  Iron  and  St  Inst,,  1872,  I., 
p.  274-7. 
«  Muller  :  Journ.  Iron  and  St.  Inst,,  1882,  1.,  p.  376. 


INFLUENCE    OF    SILICON.      §  71. 


41 


to  add  silicon  to  them  for  certain  purposes.  For  several 
years  iron  was  puddled  in  this  country  with  so-called 
"codorus"  or  "silicon"  ore,  which  had  no  other  effect 
than  to  afford  a  bulky  slag  in  the  puddling  furnace.  The 
venders  of  the  ore  impudently  called  this  puddled  iron 
"  silicon  steel,"  though  both  free  from  silicon  (the  average 
silicon  in  six  samples  which  I  took  was,  by  Wuth's  deter- 
mination, 0-()7#)  and  clearly  no  more  steel  than  any  other 
puddled  iron  is.  I  had  the  good  fortune  to  investigate 
this  swindling  manufacture  twice  and  to  expose  it  to  two 
prominent  consumers.  Holley  sang  of  it — 

"  There  was  au  old  man  of  Cad&rus,  who  said  he  took  out  the  phosph&rus, 
So  the  iron  he  puddled,  and  with  chemicals  muddled. 
But  the  puddling  took  out  the  phosph&rus." 

§  67.  EFFECT  OF  SILICON  ON  SOUNDNESS. — Silicon  pro- 
motes soundness  in  ingots  and  other  castings  by  restrain- 
ing the  formation  of  blowholes,  and  by  reducing  iron  oxide, 
and  it  thus  indirectly  restrains  redshortness.  Indeed, 
Sandberga  considers  that  0'10$  silicon  is  the  smallest 
amount  permissible  for  rolling  rails,  angles,  etc.,  as  with 
less  the  steel  cracks  in  rolling,  a  striking  example  of  how 
the  most  experienced  may  be  deceived :  for  in  many  Ameri- 
can works  the  silicon  in  rail  steel  habitually  lies  between  '02 
and  'OS;?,  yet  the  proportion  of  second  quality  rails  does 
not  rise  above  3$  and  is  frequently  below  \%  for  months. 

Investigating"  the  question  of  silicon  in  soft  steel  I  find 
that  in  ordinary  American  Bessemer  practice  it  rarely  rises 
over  0'02$,  and  is  occasionally  as  low  as  0'004  (these  ex- 
tremely small  amounts  are  rarely  accurately  determined). 
Yet  this  steel,  practically  free  from  silicon,  with  only  say 
•09  to  ']%%  carbon  and  with  manganese  '30  to  '40$  is  rolled 
into  plates  as  thin  as  No.  12  W.  G.,  in  certain  cases  with- 
out edging  passes,  and  without  serious  cracking.  Silicon 
therefore  is  not  essential  to  sound  rolling.  It  was  for- 
merly thought  that  silicon  prevented  blowholes  in  steel 
by  restraining  the  formation  of  carbonic  oxide,  silicon 
being  oxidized  in  preference  to  carbon.  But  since  Muller 
has  shown  that  blowholes  are  due  to  nitrogen  and  hydro- 
gen, we  must  infer  that  silicon  acts  by  increasing  the  solu- 
bility of  these  gases  in  the  solid  steel,  so  that  it  is  able  to 
retain  in  solution  while  solidifying  the  gas  which  it  had 
dissolved  while  molten.  Silicon  eliminates  iron  oxide 
from  steel  by  reducing  part  of  it  and  itself  forming  silica 
which  combines  with  the  remainder  of  the  oxide,  to  form 
a  silicate  which  escapes  by  rising  to  the  surface  more  or 
less  completely  according  to  its  condition  of  aggregation 
(cf.  effects  of  manganese  on  soundness). 

§  69.  FUSIBILITY.— Silicon  appears  to  increase  the  fusi- 
bility of  iron,  though,  at  least  when  abundantly  present, 
less  than  the  same  percentage  of  carbon  does.  Thus  Mrazek 
found  that  iron  with  7'4$  silicon  was  intermediate  in  fusi- 
bility between  steel  of  0'75^  carbon  and  cast-iron  of  5% 
carbon.  It  is  probable  that  it  lowers  the  melting  point  of 
steel  also,  since  the  experience  of  -the  makers  of  open- 
hearth  steel  (say  with  silicon  ()•].')  to  0'40),  is  that 
siliciferous  steel  cannot  in  forging  be  safely  exposed  to  so 
high  a  temperature  as  that  which  has  but  little  silicon,  all 
other  conditions  being  alike.  Further  investigation  may, 
however,  show  that  this  is  merely  a  superstition. 

FLUIDITY.— Silicon  is  said  to  give  very  great  fluidity: 
hence  the  highly  siliciferous  Scotch  irons  are  greatly 
prized  for  making  fine  sharp  castings,  and  are  used  even 


a  Trans.  Am.  Inst.  Mining  Engineers,  X.,  p.  409. 

b  Trans.  Am,  lust.  Mining  Engineers,  XV.,  to  appear. 


for  the  manufacture  of  elaborate  cast-iron  jewelry,  chains, 
brooches,  etc.0 

OXIDATION.— Silicon  appears  to  indirectly  retard  the 
oxidation  of  iron  at  high  temperatures  and  of  the  other 
elements  combined  with  it.  Thus  Akermand  points  out 
that  in  the  Bessemer  process  the  more  silicon  the  iron  con- 
tains the  less  completely  is  the  oxygen  of  the  air  consumed. 
So  too  siliciferous  cast-irons  do  not  sparkle  while  running, 
while  if,  as  in  Krupp's  process  (pig- washing)  the  cast-iron 
be  almost  completely  deprived  of  its  silicon,  it  effervesces  in 
the  air  as  it  runs  from  the  furnace  with  extreme  brilliancy, 
which  is  perhaps  enhanced  by  the  reaction  of  small  sus- 
pended particles  of  iron-oxide  on  the  carbon  present. 

This  effect  of  silicon  is  probably  an  indirect  one :  when 
present,  by  absorbing  part  of  the  oxygen  to  which  the  iron 
is  exposed,  it  diminishes  pro  tanto  the  oxidation  of  carbon, 
restraining  the  formation  of  carbonic  oxide  and  carbonic 
acid  and  the  ebullition  which  their  escape  causes  and  which 
in  itself  hastens  oxidation  by  increasing  the  surface 
exposure.  Its  influence  on  the  solubility  of  carbonic 
oxide  in  iron  may  contribute  to  these  phenomena. 

§  70.  THE  WELDING  POWER  of  iron  and  steel  does  not 
appear  to  be  lessened  more,  if  indeed  as  much,  by  silicon 
as  by  carbon.  In  addition  to  Mrazek' s  steel  with  7'4$  sili- 
con and  Hadfield'  s  with  over  1  •$%  silicon,  both  said  to 
weld  perfectly,  we  have  the  results  obtained  by  the  U.  S. 
Testing  Board  which,  in  my  opinion,  do  not  indicate  that 
silicon  affects  the  welding  power  of  weld  iron.  Of  13  irons 
examined,  one  with  O'lG  silicon  (the  highest  in  silicon  but 
4)  welded  the  second  best.  On  the  other  hand  three  of 
the  irons  highest  in  silicon  welded  worst.  Placing  them 
in  the  order  of  the  excellence  of  welding  their  silicon  was 
as  follows:  Best  welding,6— 0 '14:  '16:  -07:  '16:  -14:  -17: 
•15  :  -16  :  '10  :  '16  :  -20  :  '17 :  '27— worst  welding. 

§71.  EFFECT  OF  SILICON  ON  CAST-IRON. — -Silicon  affects 
the  properties  of  cast-iron  in  two  ways,  by  forcing  car- 
bon out  of  combination  and  into  the  graphitic  state,  and 
by  its  own  direct  specific  effects.  The  latter  may  be 
traced  ia  the  changes  in  the  properties  of  the  metal  which 
accompany  variations  in  the  percentage  of  silicon  when 
this  element  does  not  reach  au  amount  high  enough  to  af- 
fect the  condition  of  the  carbon  present.  Under  these  con- 
ditions Turner's  results'  indicate  that  silicon  makes 
cast-iron  softer,  and  increases  its  tensile  and  crushing 
strength  while  lowering  its  specific  gravity.  They  are  as 
follows : 


Sp.gr. 

Rela- 
tive 
hard- 
ness. 

Tensile 
strength. 
Lbs.  per 
sq.  inch. 

Modulus 
of 

elasticity. 

Crushing 
strength. 

Total 
carbon. 

Graph- 
ite. 

Com- 
bined 
carbon. 

Silicon. 

7-73 
7-67 
7-63 
7-47 

72- 

52- 
42- 

22,720 
27,580 
28,490 
31,440 

25,790,000 
28,670,000 
31,180,000 
23,500,000 

168,700 
204,800 
207,300 
183,900 

1-98 
2-00 
2-09 
2-21 

0-38 
0-10 
0-24 
0-50 

1-60 
1-90 
1-85 
1-71 

0-19 
0-45 
0-96 
1-37 

As  the  silicon  rises  beyond  1  •  4  the  percentage  of  graphite 
at  first  increases  rapidly,  then  falls  off  slowly  :  while  ten- 
sile and  compressive  strength  both  decline  uninterrupt- 
edly. While  experience  shows  that  no  one  set  of  observa- 
tions on  the  effects  of  foreign  elements  on  iron  is  concln  sive, 
Turner's  results  are  so  harmonious  as  to  inspire  confi- 
dence. 


c  Abel,  Jour.  Iron  and  Steel  Inst.,  1886, 1.,  p.  197. 
d  Engineering  and  Mining  Journa!,  1875,  I.,  p.  311. 
»•  Trans.  Am.  Inst.  Mining  Engineers,  VI.,  p.  116. 
f  Journ,  Iron  and  St.  Inst.,  1886, 1.,  p.  174. 


42 


THE    METALLURGY    OF    STEEL. 


CHAPTER    IV. 
IRON    AND    MANGANESE. 


§  75.  SUMMARY. — Manganese  alloys  with  iron  in  all 
ratios,  being  reduced  from  its  oxides  by  carbon  at  a  white 
heat,  and  the  more  readily  the  more  metallic  iron  is  pres- 
ent to  combine  witli  it.  It  is  easily  removed  from  iron 
by  oxidation,  being  oxidized  even  by  silica,  and 
partly  in  this  way  partly  in  others  it  restrains  the 
oxidation  of  the  iron,  while  sometimes  restraining 
sometimes  permitting  the  oxidation  of  the  other  ele- 
ments combined  with  it.  It  is  also  apparently 
removed  from  iron  by  volatilization.  Its  presence 
increases  the  power  of  carbon  to  combine  with  iron  at 
very  high  temperatures  (say  1400°  C.),  and  restrains  its 
separation  as  graphite  at  lower  ones.  (See  carbon. )  By 
preventing  ebullition  during  solidification  and  the  forma- 
tion of  blowholes,  by  reducing  or  removing  oxide  and 
silicate  of  iron,  by  bodily  removing  sulphur  from  cast-iron 
and  probably  from  steel,  by  counteracting  the  effects  of 
the  sulphur  which  remains  as  well  as  of  iron-oxide,  phos- 
phorus, copper,  silica  and  silicates,  and  perhaps  in  other 
ways,  it  prevents  hot-shortness,  both  red  and  yellow.  (It 
does  not  however  counteract  the  coldshortness  caused  by 
phosphorus.)  These  effects  are  so  valuable  that  it  is  to- 
day well  nigh  indispensable,  though  admirable  steel  was 
made  before  its  use  was  introduced  by  Josiah  Marshall 
Heath." 

It  is  thought  to  increase  tensile  strength  slightly,  hard- 
ness proper,  and  fluidity,  to  raise  the  elastic  limit,  and,  at 
least  when  present  in  considerable  quantity,  to  diminish 
fusibility.  It  is  generally  thought  to  diminish  ductility  : 
evidence  will  be  offered  tending  to  show  that  its  effects  in 
this  respect  have  been  exaggerated.  While  1-5  to  2 •&%  of 
manganese  is  nearly  universally  admitted  to  cause  brittle- 
ness,  steel  with  8%  of  manganese  is  astonishingly  ductile : 
with  further  increase  of  manganese  the  ductility  again  di- 
minishes. Steel  with  8  to  10%  manganese,  though  ex- 
tremely tough,  is  so  hard  as  to  be  employed  without 
quenching  for  cutting-tools.  It  is  denied  and  asserted 
with  equal  positiveness  that  manganese  confers  the  power 
of  becoming  harder  when  suddenly  cooled,  but  it  is  gener- 
ally thought  to  make  steel  crack  when  quenched. 

OXIDE  of  manganese  gives  slags  a  strong  characteristic 
green  color  and  considerable  fluidity,  and  makes  them  so 
strongly  corrosive  that  their  effect  on  the  linings  of  open- 
hearth,  cupola  and  other  melting  furnaces  must  be 
guarded  against. 

§  76.  COMBINING  POWER. — There  appears  to  be  no 
limit  to  the  extent  to  which  manganese  can  combine  with 
iron  :  the  higher  the  percentage  of  manganese  in  the  alloy 
the  higher  is  the  temperature  needed  in  the  blast-furnace 
for  its  production.  These  alloys  contain  considerable 
carbon,  but  are  often  almost  completely  free  from  silicon, 
of  which  they  sometimes  contain  but  0'06$.  Ferro-man- 
ganese  containing  more  than  90$  manganese  often  crum- 
bles to  powder  in  the  air. 

The  analyses  of  several  siliciferous  ferro-manganeses 
are  given  in  Table  1.  Most  of  the  compositions  in  Table 
20  are  normal. 


»  Percy:  Iron  and  Steel,  p.  840. 


§  77.  VOLATILITY. — Manganese  appears  to  volatilize 
with  considerable  rapidity  at  a  white  heat.  Thus  Jordanb 
states  that  at  a  French  blast-furnace  10$  of  the  manga- 
nese charged  could  not  be  accounted  for  by  the  contents 
of  metal,  slag  and  dust.  The  fumes,  white  at  first,  turned 
red  on  burning.  Much  reddish  gas  escaped  from  the  tap 
hole.  Further,  ferromanganese  of  84-9$  manganese  lost 
4$  of  its  manganese  on  being  exposed  to  the  heat  of  a 
wind  furnace  for  2f  hours  in  a  brasqued  crucible,  in  which 
scorification  can  hardly  have  occurred. 

§  78.  EFFECT  ON  FUSIBILITY. — A  large  percentage  of 
manganese,  as  in  ferromanganese,  raises  the  melting 
point  of  iron  :  but  smaller  percentages  may  lower  it,  for 
a  small  addition  of  a  less  to  a  more  fusible  body  (e.  g. ,  of 
lead  to  tin,  or  silver  to  lead,  or  bisilicate  of  magnesia  to 
that  of  lime)  often  produces  one  more  fiisible  than  either. 

§  79.  MANGANESE  AND  BLOWHOLES. — Be  it  by  increas- 
ing the  solubility  of  gases  in  steel,  so  that  it  retains  while 
solidifying  the  gas  which  it  dissolved  when  molten,  be  it 
by  preventing  the  oxidation  of  carbon  and  the  formation 
of  carbonic  oxide,  manganese  like  silicon,  though  proba- 
bly less  thoroughly,  hinders  the  formation  of  blowholes. 
Ingots  containing  but  '005$  of  silicon  and  which  but  for 
manganese  would  be  exceedingly  porous,  are  rendered  by 
it  comparatively  solid. 

§  80.  MANGANESE  AND  OXIDATION. — As  the  oxidation 
and  deoxidation  of  manganese  in  the  presence  of  carbon 
and  silicon  will  be  fully  discussed  in  a  later  chapter,  I  here 
confine  myself  chiefly  "to  a  few  generalizations. 

While  manganese  is  reduced  from  its  oxides  by  carbon 
at  a  white  heat  even  in  the  absence  of  iron,  thus  revealing 
an  affinity  for  oxygen  weaker  than  that  of  silicon :  yet, 
be  it  because  its  affinity  for  iron  is  weaker  than  that  of 
silicon,  be  it  because  acid  slags  seize  and  hold  its  oxide, 
when  both  are  combined  with  iron  manganese  is  often 
more  readily  oxidized  than  silicon,  especially  in  the 
presence  of  acid  slags,  and  often  causes  the  reduction  of 
silicon  from  the  walls  of  cupola  furnaces  and  of  crucibles. 

Manganese  added  to  molten  oxygenated  iron  removes  its 
oxygen  as  oxide  or  silicate  of  manganese.  It  not  only  thus 
cures  but  may  even  prevent  oxygenation  :  in  certain 
cases  when  added  to  molten  iron  it  is  flhought  to  permit 
the  oxidation  of  carbon  and  silicon  while  preventing  that 
of  iron,  or  at  least  preventing  the  redshortness  which  we 
attribute  to  oxygenation.  So  too  the  presence  of  manga- 
nese in  solidified  steel  appears  to  hinder  its  oxygenulioii 
in  heating  and  forging :  hence  an  otherwise  needlessly 
large  amount  of  manganese  (say  '5$)  is  often  purposely 
left  in  soft  steel  which  is  liable  to  fall  into  careless  hands. 

Manganese  appears  to  act  upon  oxygenated  iron  in  two 
distinct  ways,  (1)  by  reducing  iron  oxide,  (2)  by  forming 
a  readily  separating  double  silicate  of  iron  and  manga- 
nese :  it  may  act  in  both  ways  simultaneously. 

(1)  While  iron  oxide  if  present  in  molten  steel  remains 
diffused  or  dissolved  through  the  mass  of  the  metal  and 
renders  it  redshort,  behaving  as  cuprous  oxide  does 
towards  metallic  copper,  silicate  and  probably  oxide  of 


t>  Metallurgical  Review,  II.,  p.  455.    Rev.  ludust.,  July  3,  1878. 


MANGANESE    VERSUS    SULPHUR.       §  81. 


•1.1 


TAISI.K  '-'"       Si'ii:i:Ki.Kl>K\    .\M>  Fn:>:oM AM. AM  -I  . 


1. 

2. 

3. 

6. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

IS. 

14. 

IS. 

16. 

17. 

18. 

n. 

20. 

21. 

18. 

li 

4-28 

li 
I  88 

B 

I  89 

A 

•riii 

A 
t-OI 

J 

3  9 

P 

•1  .V! 

Dl 
4-M 

A 
440 

E5 

•_'  .;:, 

El 

4  111 

K2 
5  68 

E3 

:,  :;i 

D2 

i  M; 

El 

i;  "i 

(' 
6-61 

E4 

i;  'u 

G 

6'50 

C 

II 

6'87 

C 

C 

,-;i 

•88 

88 

0-88 

il  -J7 

•8 

•M 

•16 

0  80 

in  "ii 

•M 

M 

•1  '  .V-' 

n  28 

'il 

'02 

•80 

'51 

*61a 

•54 

•  :,r, 

.V.I 

•ea 

•M 

•08 

•09 

•ill 

•08 

•08 

•18 

-'4 

•88 

•  17 

IH; 

'17 

"t 

•08 

08 

traoo 

•00 

•01 

•001 

•06 

0 

6-87 

j:oi 

6-12 

11  -1'2 

I'.'-IKI 

18-8 

j:|  -J4 

18'g6 

14-11 

20  -MI 

28-35 

05  •  'J2 

;•»  r.i 

7  1  r, 

76-95 

80*00 

35.3 

S6-95 

S7'2 

^7  -, 

••-'.•> 

•21 

•no 

•17 

R-feri'llcrx.—A.  Sii-jri-n  :  Jour.  Iron  mill  St.  Inst.,  1*SO,  II..  p.  7li.">.      ]',.  unknown,  Irlc-ni.  ]v,ii.  I.,  p.  ;;cn.     ('.  unknown,  private  mil..-.     In.  Trrn-Xoire.  privatf  DOta. 
T.csrlnl/:i.     I-'.'-',  Obcrhnusen.      K:i,  Ilm-nli-.      K4.  Kurlmrt.       E.">.  'lYnv-Nuin-.  :M  II-CMII  Ledebnr,  llaiidtjnch,  ji.  317.     K,  Fninklinilc.  Xc  w  .Icrsi-v.  private  noti-n.     (I. 
II.  *  'iviiirr,  priv;u<>  i-niiiiniinicatiun.     II,  tin-  >anif.  .1.  (iiiyli.y,  private  i-immiuiiH-alinn.      ,1,  I  lowlais,  .Journ.  Iron  and  Steel  Inst.,  1874,  I.,  p.  78.    a  In  100  consecutive  casts 
Uiinin^  over  NI;  manganese,  tin:  silir.on  averages  iV131;S. 


C,  unknown,  privalr  IM.I.  -.     I  >i.  Tern -Noire,  private  notes.  1)2,  U.  S.,   Idem.     Kl, 

A-     f  ferromangane8e  con. 


manganese  escape  from  the  iron  by  rising  to  the  surface 
of  the  molten  mass.  Hence,  as  in  the  Bessemer  and  open- 
hearth  processes  of  making  steel  the  metal  under  ordinary 
conditions  becomes  slightly  oxygenated,  manganese  is 
usually  added  at  the  completion  of  these  processes,  in  the 
form  of  a  manganiferous  cast-iron  (spiegeleisen,  ferrc- 
manganese) ;  it  reduces  the  iron  oxide  and  is  itself  oxi- 
dized and  scorified.  It  has  been  assumed  that  this  reaction 
between  the  manganese  and  iron  oxide  is  expressed 
accurately  by  the  formula— 

Fe3O4  +  Mn  =  MnO  +  3FeO. 

and  "Ford  supports  this  view  by  showing  that,  assum- 
ing the  unrecarburized  steel  to  contain  0'24^  oxygen  as 
magnetic  oxide,  in  the  practice  at  the  Edgar  Thomson 
Steel  Works  the  amount  of  manganese,  0'18$,  removed 
from  the  metal  corresponds  closely  to  this  formula.  But 
this  coincidence  is  purely  accidental.  Indeed,  from  his 
statement  it  is  not  clear  that  his  assumption  that  the  steel 
contained  '24^  oxygen,  on  which  the  whole  rests,  is  any 
thing  more  than  guess.  It  is  highly  probable  that  in  the 
presence  of  so  vast  an  excess  of  metallic  iron  the  oxygen 
exists  as  ferrous  rather  than  as  magnetic  oxide  :  more- 
over the  quantity  of  manganese  which  is  removed  by  the 
reaction  varies  very  greatly,  as  will  be  shown  by  examples 
in  due  time.  Further  still,  its  removal  is  largely  and 
probably  chiefly  due  to  the  action,  not  of  iron  oxide  con- 
tained in  the  metal,  but  of  the  supernatant  slag.  This  is 
shown  by  an  experiment  at  an  American  Bessemer  mill, 
in  which  simply  preventing  the  metal  from  coming  into 
contact  with  the  slag  after  the  addition  of  the  ferro-man- 
ganese  greatly  diminished  the  loss  of  manganese.  In  their 
ordinary  practice  on  adding  \%  of  80%  ferromanganese 
to  the  blown  steel  in  the  ladle,  58$  of  the  manganese 
thus  added  was  removed :  but  in  a  special  charge  made 
under  otherwise  like  conditions  the  steel  was  separated 
from  the  slag  before  adding  the  ferromanganese,  by 
pouring  it  from  the  ladle  through  the  nozzle  in  its  bot- 
tom into  a  second  ladle,  in  which  \%  of  ferromanganese 
was  added,  and  from  which  the  steel  was  subsequently 
teemed  into  molds  in  the  ordinary  way.  In  this  case 
only  21$  of  the  manganese  added  was  removed  from  the 
steel.  I  here  summarize  these  results  : 


Ferro  m  an  gan  ose 
of  80^  Mn  added 
to  blown  steel. 

Manganese 
removed. 

Composition  of  steel. 

|4 

°  h-S 

».  0 

i^i 

o 

§h 

g 

I 

- 

S3 

B 

III 

r 

«p 

i 

O 

1 

J5" 
Cfi 

r 
i- 

0-80 
0-80 

0-33 
0-12 

58- 
21- 

•075 
•069 

•386 
•638 

•on 

•016 

•062 
062 

Miiller  found  that  0'354$  manganese  was  removed  in  a 
spiegel  reaction  of  the  acid  Bessemer  process  in  which  slag 


a  Trans.  Am.  lust  Mining  Engineers,  IX. ,  p.  396. 


was  present :  that  in  the  basic  Bessemer  process  0-389$ 
manganese  was  eliminated  when  slag  was  present,  but  that, 
when  the  slag  was  wholly  removed  before  recarburizing, 
only  from  0  to  0'064$  of  manganese  was  expelled.b 

(2)  Manganese  appears  to  free  molten  steel  from  minute 
mechanically  suspended  particles  of  slag  which  cause  red- 
shortness,  by  forming  a  double  silicate  of  manganese  and 
iron,  which,  by  coalescing  more  readily  than  the  simple  sili- 
cate of  iron,  rises  more  completely  to  the  surface.  Thus 
Pourcel,0  volatilizing  by  chlorine  the  iron  of  two  pieces  of 
steel,  to  the  first  of  which  when  molten  he  had  added  silicon 
alone,  to  the  second  both  silicon  and  manganese,  obtains 
from  the  first  a  residual  network  of  silicate  of  iron,  while 
the  second  volatilizes  completely,  leaving  no  residuum. 

This  is  usually  confusedly  explained  by  saying  that 
the  double  silicate  is  more  fusible  than  the  simple  one. 
But  the  simple  silicates  of  iron,  such  as  would  form  under 
these  conditions,  fuse  at  temperatures  vastly  below  that  of 
the  molten  steel,  and  if  they  were  not  melted  they  would 
still  rise  to  the  surface  just  as  quickly  as  if  they  were. 
Does  cork  rise  less  rapidly  through  water  because  it  is  a 
solid  ?  What  the  manganese  does  is  either  to  make  a  sil- 
icate which  is  specifically  lighter  than  the  simple  silicate 
of  iron,  or  more  probably  one  which  more  readily  coalesces 
into  globules  so  large  that  their  upward  motion  is  but 
little  impeded  by  the  friction  of  the  surrounding  steel. 

§  81.  MANGANESE  vs.  SCLPHCK.—  Manganese  not  only 
counteracts  the  redshortness  caused  by  sulphur  but  in 
some  cases  actually  removes  this  metalloid  from  iron, 
sometimes  (probably  because  sulphide  of  manganese  like 
sulphide  of  calcium  is  less  soluble  in  metallic  iron  than 
sulphide  of  iron  is)  by  forming  some  compound  rich  in 
sulphur  and  manganese  which  liquates  or  separates  by 
gravity,  and  perhaps  sometimes  by  carrying  oxygen  to  the 
sulphur.  Thus  Akermand  quotes  a  manganiferous  slag 
from  a  Sfwedish  blast-furnace  with  1 '4$  sulphur,  while  the 
accompanying  cast-iron  had  but  some  hundredths  of  one 
per  cent  of  sulphur.  Parry0  found  2$  sulphur  in  manga- 
niferous blast-furnace  slags:  when  the  slags  were  less 
manganiferous  they  contained  less  sulphur,  while  the  cast- 
iron  contained  more. 

Here  sulphide  of  manganese  appears  to  enter  the  slag 
like  sulphide  of  lime,  and  like  sulphide  of  iron,  which  Le 
Play'  found  in  considerable  quantities  in  ferruginous  cop- 
per-smelting slags.  Other  sulphides,  especially  that  of  zinc, 
dissolve  in  slags.  Akerman  considers  that  manganese 
drags  sulphur  into  the  blast-furnace  slag  even  more  power- 
fully than  calcium  does. 


b  Stahl  und  Eisen,  1883,  pp.  446-453  :  idem,  1884,  p.  71.   Zeit.  Vereins  Deutsc. 
Ing.,  XXII.,  p.  385. 

c  Journ.  Iron  and  St.  Inst.,  1877, 1.,  p.  44. 
d  Eng.  and  Mining  Jl.,  1875,  2,  p.  214. 
e  Percy,  Iron  and  Steel,  p.  39. 
t  Description  des  Proc<Mes  Metallurgiques  employees  dans  le  Pays  de  Galles,  p. 

SIS. 


44 


THE    METALLURGY    OF    STEEL. 


In  three  sets  of  experiments  (1)  on  phosphoric,  (2)  on 
sulphurous  and  (3)  on  siliceous  cast-iron  respectively, 
each  melted  (A)  alone  and  (B)  with  metallic  manganese, 
Caron  found  that  the  addition  of  manganese  energetically 
expelled  sulphur,  increased  the  percentage  of  silicon  (by 
reducing  it  from  the  walls  of  the  crucible)  but  had  little 
effect  on.  phosphorus.  His  results  follow:* 


Phosphoric 
cast-iron. 

Sulphurous 
cast-iron. 

Siliceous 
cast-iron. 

%  phosphorus. 

%  manganese. 

£ 

I 
"3 
• 

•« 

%  manganese. 

t  silicon. 

%  manganese. 

1.. 

2.. 
3.. 
4. 
5.. 
6.. 

7.. 
8.. 

9.. 
10.. 

The  initial  cast-irons  

0-83 

1-15 
1-14 

0-99 

0-88 

1  30 
0-80 
1-66 

The  initial  Iron  remeltcd  without  addition  

0-82 

The  initial  iron  remelted  with  6%  metallic  man- 
ganese ....            

0-80 
0-79 
0-78 

0  78 

4-58 

a 
0-34- 

1  05 

o-io 

0-96 

0-08 
1-08 

007 

3-92 

4-77 

No.  1  remelted  a  second  time  without  further 
addition...                         

No.  2  remeltcd  a  second  time  without  further 
addition  ....              ... 

8-74 

2-81 

2-98 

No.  8  remeltcd  for  the  third  time  without  further 
addition  

No.  4  remelted  for  the  third  time  without  further 
addition 

0  76 

o-rti 

0  74 

1-62 
1-57 

1-73 
1-22 

The  initial  iron  melted  with  lot  ferric  oxide      .  . 
The  initial  iron  melted  with  10J<  ferric  oxide  and 

0-61 
0-37 
0-52 
0-18 

2-52 

1-10 

No.  7  remelted  a  second  time  with  10#   ferric 
oxide  

No.  8  remelted  a  second  time  with  10^   ferric 
oxide  (no  further  addition  of  manganese).  ...... 

a  This  figure  is  given  in  the  original  as  T15:  but  this  is  evidently  ft  misprint,  as  Caron  remarks  : 
*' We  see  from  these  results  that  by  a  sim  pie  fusion  in  a  crucible  with  access  of  air  manganese 
removes  more  than  7-10ths  of  the  sulphur  which  the  cast-iron  contains  (on  voit,  d'apres  ces 
rcsultats  que,  par  une  simple  fu&ion  dans  un  creuset  ou  1'air  a  acces,  le  manganese  enleve  a  la 
fonte  plus  des  7-10  du  soufre  q'elle  contient)."  Nevertheless  the  original  figure  is  copied, 
blindly  it  seems,  in  most  text-books.  The  iron  after  fusion  with  manganese  must  have  had  less 
than  U'84  of  sulphur,  which  is  3-10ths  of  that  initially  present. 


E.  Riley,b  on  melting  a  cast-iron  which  contained  '207$ 
sulphur  with  10%  of  ferromanganese  found,  that  the  sul- 
phur fell  to  0'035$.  Percy0  considers  that  the  manganese, 
in  Caron' s  experiments,  expelled  sulphur  by  carrying  oxy- 
gen to  it;:  while  I  venerate  his  opinions,  the  facts  that 
just  about  enough  manganese  was  lost  to  form  the  sul- 
phide, MnS,  with  the  expelled  sulphur,  that  manganese  has 
the  power  of  dragging  sulphur  into  blast-furnace  slags, 
apparently  as  sulphide  of  manganese,  very  much  as  iron 
and  calcium  do,  and  that  manganese  and  sulphur  so  often 
appear  to  segregate  together  in  iron,  coupled  with  Wai- 
rand's  results  incline  me  to  believe  that  in  Caron' s  case 
also  much  at  least  of  the  sulphur  escaped  in  combination 
with  manganese. 

Walrand,  after  melting  300  parts  of  sulphurous  cast- 
iron  in  one  crucible  and  24  parts  of  spiegeleisen  of  IQ% 
manganese  under  lime  in  another,  poured  the  cast-iron 
into  the  spiegel,  and  stirred  the  mixture  for  a  minute, 
when  an  insupportable  odor  of  sulphurous  acid  arose  from 
the  supernatant  slag:  the  sulphur  of  the  cast-iron  fell 
from  0  50  to  0-06.d  The  manganese  could  not  have  carried 
oxygen  to  the  sulphur  so  rapidly  as  to  have  caused  the 
almost  instantaneous  expulsion  of  the  latter  which  appears 
to  have  occurred :  sulphur  and  manganese  probably  com- 
bined and  rose  to  the  surface  together,  when,  exposed  to 
the  air,  the  sulphur  became  rapidly  oxidized. 

Under  favorable  conditions  drop-like  masses  separate 
from  liquid  cast-iron  and  float  on  its  surface :  in  these 
Ledebur"  finds  much  more  sulphur  and  manganese  than  in 
the  mass  of  the  iron. 


Carbon. 

Segregation 3'Sl  8 

Mother  metal 3'4G8 


Silicon.  Phosphorus.  Sulphur.  Manganese. 
I"-!','.)            04T5  0223  B'188 

2-196  0-056  2-C20 


Oxygen. 

Iron.       (Diflerence ) 
87099  1-328 

0-000 


When  steels  which  contain  any  considerable  quantity 


a  Comptes  Rendus,  LV1. ,  p.  828,  1863. 

b  Journal  of  the  Iron  and  Steel  Institute,  1877,  I . ,  105. 

c  Iron  and  Steel,  p.  137. 

<l  Revuo  Universelle,  X.,  1881,  2,  p.  407. 

<•  Handbuch  der  Eisenhiittenkunde,  p.  357. 


of  sulphur  also  contain  so  much  manganese-  that  this 
metal  segregates  to  an  extent  which  can  be  detected,  the 
segregated  portion  is  in  general,  in  the  many  cases  which 
I  have  examined,  richer  also  in  sulphur  than  the  mother 
metal,  indicating  that  a  compound  containing  both 
sulphur  and  manganese  has  segregated. 

Besides  bodily  removing  sulphur  from  iron,  manganese 
counteracts  the  effects  of  that  which  remains.  This  it  may 
do  by  giving  the  particles 'of  the  metal  greater  mobility 
and  plasticity  at  forging  heats  :  or  by  combining  directly 
with  the  sulphur  to  form  a  sulphide  of  manganese,  which 
woiild  only  affect  the  iron  as  an  intermixed  foreign  sub- 
stance. The  fact  that  sulphurous  irons  are  ordinarily 
far  more  malleable  at  a  yellow  than  at  a  red  heat  favors 
the  former  view :  but  both  explanations  may  be  true,  and 
the  readiness  with  which  sulphide  of  manganese  segre- 
gates from  iron  under  favorable  circumstances  lends 
probability  to  the  second  explanation.  We  may  suppose 
that  sulphide  of  manganese  (with  perhaps  also  other 
metals)  forms,  which,  owing  to  its  small  quantity  and 
to  the  viscosity  of  the  inclosing  steel  does  not  aggregate 
into  masses  sufficiently  large  to  be  readily  recognized 
except  under  the  most  favorable  conditions. 

§  82.  INFLUENCB  OF  MANGANESE  ox  THE  EFFECTS  OF 
PHOSPHORUS,  COPPER  AND  SILICON. — The  special  variety 
of  hot-shortness  thought  to  be  due  to  phosphorus,  like 
that  caused  by  sulphur,  is  counteracted  by  manganese, 
but  probably  rather  by  its  making  the  steel  plastic  and 
thus  counteracting  the  tendency  to  crystallize  which  phos- 
phorus causes,  than  by  its  forming  phosphide  of  mangan- 
ese and  thus  preventing  the  direct  action  of  phosphorus 
on  the  matrix  of  iron  :  for,  were  the  latter  the  case,  then, 
since  phosphorus  tends  strongly  to  segregate  in  steel,  we 
should  find  manganese  accompanying  it  in  its  segregations, 
just  as  it  accompanies  sulphur :  but,  examining  many 
cases  of  segregation  in  cast-iron  and  in  steel  which  is  both 
phosphoric  and  manganiferous,  I  find  little  to  suggest 
cosegregation  of  phosphorus  and  manganese.  In  Caron's 
experiment  just  cited  manganese  expelled  sulphur  but 
not  phosphorus. 

The  redshortness  due  to  copper  and  the  hot-shortness 
thought  to  be  due  to  silicon  are  also  remedied  by  the  pres- 
ence of  manganese.  As  the  tendency  of  iron  to  crystallize 
becomes  very  strong  as  it  approaches  the  melting  point, 
as  it  is  at  this  temperature  that  phosphorus  seems  to  render 
steel  non -malleable,  and  as  phosphorus  lowers  the  melting 
point  and  increases  the  tendency  to  crystallize  at  all  tem- 
peratures, .it  has  been  thought  that  its  hot-shortening  effect 
was  due  to  its  lowering  the  melting  point,  and  that  man- 
ganese counteracted  its  effects  by  raising  the  melting  point. 
As  sulphurous  irons  are  malleable  at  a  high  but  brittle 
at  a  low  (red)  heat  while  phosphoric  irons  are  malleable  at 
a  red  but  brittle  at  a  high  heat,  and  as  manganese  counter- 
acts the  effects  of  both,  and  as  it  moreover  counteracts 
hot-shortness  no  matter  at  what  temperature  and  from 
what  cause  it  may  arise,  whether  from  phosphorus,  sul- 
phur, copper,  silicon,  iron  oxide,  suspended  silicate  of 
iron  or  blowholes,  we  may  ascribe  its  effects  to  its  directly 
increasing  the  plasticity  of  the  steel  at  all  temperatures  at 
and  above  redness,  to  its  even  increasing  the  range  of  tem- 
perature through  which  plasticity  prevails,  on  the  one 
hand  raising  the  melting  point,  on  the  other  lowering  the 
point  at  which  plasticity  gives  way  to  rigidity. 


MANGANESE    AND    HOT-SHORTNESS.       §83. 


,^  f-3.  QUANTITATIVE  EFFECTS  OF  MANGANESE  ON  HOT- 
SHORTNESS. — Most  of  the  manganese  that  is  added  to 
steel  passes  immediately  into  the  slag.  If  the  metal  con- 
tains sulphur  or  phosphorus  in  important  amount  it  is 
desirable  that  a  considerable  quantity  of  metallic  manga- 
nese should  remain  unscorilied  to  counteract  their  effects  : 
and  even  in  metal  practically  free  from  sulphur  and  phos- 
phorus the  presence  of  a  little  residual  manganese  is  im- 
portant, but  whether  through  any  direct  action  or  merely 
because  it  is  a  guarantee  that  all  oxide  of  iron  has  been 
reduced  is  not  clear :  I  incline  to  the  latter  view,  because 
admirable  non-redshort  iron  was  made  before  the  employ- 
ment of  manganese. 

It  is  at  present  impossible  to  state  the  quantities  of  man- 
ganese required  to  counteract  the  effects  of  given  quanti- 
ties of  sulphur  and  phosphorus.  In  order  to  completely 
reduce  iron  oxide  once  formed  in  steel  it  is  probably 
necessary  to  add  so  much  manganese  that  the  quantity 
which  remains  after  the  reduction  of  the  iron  oxide  is  in 
many  cases  far  more  than  is  needed  to  counteract  the  sul- 
phur and  phosphorus  present.  Thus  at  an  American  Bes- 
semer works  steel  with  carbon  "07,  sulphur  '05,  phosphorus 
•05  and  manganese  about  '35^,  was  regularly  made.  One 
charge  was  allowed  to  remain  in  the  converter  long  after 
being  blown  and  after  the  addition  of  ferromanganese, 
till  ebullition  had  nearly  ceased.  It  was  then  poured 
and  formed  sound  non-redshort  ingots,  which  had  only 
0'18$  manganese.  It  is  so  extremely  difficult  to  decide 
how  far  the  quantity  of  manganese  which  we  find  it  neces- 
sary to  leave  in  the  steel  in  any  particular  case  is  merely 
residual  from  the  excess  which  we  have  to  add  to  com- 
pletely reduce  iron  oxide  or  remove  iron  silicate  as  in  the 
case  just  described,  how  far  it  is  simply  a  guarantee  that  re- 
oxidation  has  not  occurred,  how  far  it  is  needed  to  counter- 
act sulphur,  phosphorus,  silicon  and  copper  and  to  prevent 
blowholes,  nay  even  how  faritis  simply  suspended  oxide  or 
silicate  of  manganese  (of  which  the  last  portions  may  re- 
move themselves  by  gravity  but  slowly),  than  an  attempt  to 
quantify  its  effects  in  any  of  these  respects  must  with  our 
present  data  be  fruitless,  except  perhaps  in  the  case  of 
steel  containing  so  much  sulphur  or  phosphorus  that  the 
quantity  of  residual  manganese  needed  to  counteract  them 
is  clearly  more  than  is  needed  for  other  purposes. 
The  difficulty  of  such  an  attempt  is  shown  by  a  study 
of  Table  21.  Not  to  needlessly  multiply  cases,  how  can 
we  reconcile  the  fact  that  steel  of  composition  48 
in  repeated  trials  rolled  badly,  at  least  at  one  time, 
unless  its  manganese  was  above  0'80#,  with  the  fact 


that  No.  7,  with  less  than  ith  as  much  manganese  but 
with  more  than  twice  as  much  phosphorus  can  be  rolled 
at  all  ?  If  you  answer  that  No.  7  has  not  enough  carbon 
to  vitalize  its  phosphorus,  how  can  we  meet  the  fact  that 
No.  12  with  only  l-3rd  as  much  manganese  but  with  more 
phosphorus  and  thrice  as  much  carbon,  and  No.  22  with 
about  half  as  much  manganese  but  with  more  phosphorus 
and  twice  as  much  carbon  as  No.  48  can  be  rolled  at  all  ? 
If  it  be  answered  that  silicon  is  so  extremely  hurtful  an 
impurity  that  Nos.  7,  12  and  22  are  enabled  to  roll  by 
having  slightly  less  of  it  than  No.  48,  how  is  it  that  No. 
28  (Table  21)  with  four  times  as  much  of  this  terrible 
silicon,  with  twice  as  much  phosphorus  and  30$  more  car- 
bon can  be  rolled  with  only  80$  of  the  manganese  which 
No,  43  is  known  to  require  ?  How  can  No.  12  (in  Table 
17)  with  more  carbon,  with  9  times  as  much  silicon,  with 
twice  as  much  phosphorus,  and  with  more  sulphur  be 
rolled  with  less  manganese  than  No.  48  (Table  21)  re- 
quires ?  How  can  No.  16  (Table  21),  an  extraordinarily 
good  rail,  with  the  same  carbon,  with  6  times  as  much 
silicon,  with  50$  more  phosphorus  be  rolled  with  only 
70$  as  much  manganese  as  No.  48  demands  ?  The  problem 
is  at  present  insoluble. 

Wendel*  proposed  the  formula — 

Mn  =  -8(0  +  0-5S1)  +  4P. 

(in  which  the  figures  refer  to  percentages)  as  giving  the 
quantity  of  residual  manganese  needed  to  insure  sound 
rolling.  This  formula,  doubtless  useful  for  Wendel's 
special  conditions,  is  not  of  general  application.  Here 
steel  with  but  a  fraction  of  the  manganese  which  it  calls 
for  rolls  admirably  :  there  steel  with  twice  as  much  man- 
ganese as  it  prescribes  rolls  badly. 

Thus  in  Table  21  we  find  many  cases  of  apparently  well- 
rolling  steel  with  less  than  half,  and  others  with  but  l-4th 
(2  cases),  l-7th  (4  cases),  l-9th,  and  even  l-20th,  and  in 
Table  29  (No.  48)  l-17th  of  the  manganese  which  this 
formula  demands,  while  among  the  badly-rolling  ones  are 
several  with  much  more  and  three  with  actually  twice  as 
much  manganese  as  it  requires.  Nor  does  the  formula  fit 
the  facts  much  better  if  we  apply  it  only  to  steels  com- 
paratively free  from  sulphur  and  phosphorus,  for  which 
it  was  particularly  designed.  Indeed  it  is  the  practice 
at  some  admirable  works  to  diminish  the  manganese  as 
the  carbon  increases  instead  of  increasing  it  as  Wendel's 
formula  demands.  A.S  we  hare  neither  a  scientific  basis 
for  calculating  the  quantity  of  residual  manganese  needed 
to  prevent  hot-shortness  under  given  conditions,  nor  even 


a  Trans.  Am.  Inst.  Mining  Engineers,  IV.,  p.  3(54. 


TABLE  21.—  MAXUANKSK  AM>  FORGEABLENESS. 


Si—  1  known  or  supposed  to  forge  tolerably  well. 

No  

1. 

3. 

8. 

5. 

6. 

J 
•10 

•003 
•2S 

8.          9. 

10. 

11. 

12. 

B 

1-03 
02 
•09 

'  '  '••»' 

13. 

15. 

a. 

17 

18 

19. 

21.        22. 

25. 

26. 

2i. 

2S. 

G  t 
•IS 
•14 
•16 
•00 
•00 

F. 

1-30 
•01 
•02 
traeo 
•05 

E 
•96 
•02 
08 
trace 
•08 

Of 
•17 
tracc 
1      -22 
trace 
•15 

J 
•15         -14 
•006       -003 
•34         -26 

E 
2-37 
•20 
•03 
•09 
•is 

•20 
•IS 
•03 
•03 
•21 

j 

•19 
•006 
•26 

'•25 

F 
•10 
•005 

'  '  ;2S' 

j 

•20 

•009 
•IS 

":>!> 

F 
•10 
•015 
•10 

•*i 

F 

i-oo 

•u:! 
•04 

"'•So' 

•12 
"•24 
'•89 

•47 
•44 
•OS 
•04 
•41 

F 

•so 

•04 
•10 
•04 
•50 

•23 
'•88 
"•60' 

a  A 

'   J6 
63 

•45 
':29 

"•n 

J 

•4S 
•32 
•17 

'•'«7 

Manganese  

•18 

•19         -19 

Steel  known  or  supposed  to  forge  tolerably  well. 

Steel  known  to  forge,  badly. 

No  

30. 

83. 

S4. 

85. 

36. 

3S. 

39. 

41. 

42. 

43.      1       45. 

i 

46 

47. 

49. 

49 

50. 

.->! 

52. 

83. 

54. 

55. 

eF 

•:',-. 
•it; 
•24 
•117 
1-37 

56. 

5T. 

F 

•89 
•28 

F 
•40 
•10 
•07 
•OT 
•85 

0-4 

F 
•87 
•67 
•12 
•05 
•90 

'i'6" 

F 
•40 
•04 
•09 
•05 
•95 

2'i" 

F. 

•35 

•07 
•07 
•06 
•96 

066 

J 
•28 
•08 
•67 

"99" 

c  D 
•85 
•08 
•08 
•05 
•9@MO 

F 
•33 
•03 
•M 

•08 
1  05 

o-65 

5 

F 
•87 
•05 

'  '  :io 

1-10 

o-c-,c, 
5 

F 
•84 
•07 

•14 
•10 
I'll 

io'@  is 

F 
•34 
•04 
•15 
•07 
1-68 

Yo@i 

A 

'  ;2oi 
•H 

Dd 
85 
•08 
•OS 

•I!.') 
<-60 

D 

•35 
•03 
•OS 

•05 

•6®  -8 

,ir, 
•a 

:.v 
•<« 

•34 

dD 

•23 

'•52 
•09 

•n 

dl? 

•SO 

•51 
•OS 
•H 

F 
•47 
•84 
•11 
•06 
1  48 

F 
•70 
•60 
06 
•01S 
1  84 

r 

•76 
•58 
•06 
»    -01 
1-85 

F 
•52 
•87 
11 

•li.-, 

_'•"•• 

e 
•41 
•04 

•15 

•ol 

.'  119 

Mlinon                         

•71 

<  'n|i[nT    

M««V%S« 
CheinUtry  of  Iron.    J     lieck-Ouerhard,  Jour.  Iron  and  Steel  Inst.,  1SS6,  1  ,  p.  204.      His  statements  an,  so  extraordmary  as  iliat  1  «Mrtt«l  in-.,. 

46 


THE    METALLURGY    OF    STEEL. 


TABLE  22. — MANGANESE  AND  SULPHUR  IN  STEEL  KNOWN  OR  BELIEVED  TO  HATE  FORGED  AT  LEAST  TOLERABLY  WELL. 


No  

IJ 
I. 

,TM 
2. 

,TM 
3. 

JM 
4. 

BC 
7. 

I  J 

10. 

BD 

12. 

BEG 
15. 

K 

17. 

BHL 
18. 

BEG 

19. 

BE 

20. 

B  C 

21. 

BD 

22. 

I  C 
24. 

BD 

25. 

BEF 

28. 

BD 

30. 

BD 

82. 

A 
33. 

BD 

86. 

BD 

37. 

A 
88. 

H 

44. 

1  30 

1'OS 

1-11 

1  32 

•22 

2-89 

•47 

•07 

•fvt 

•15 

•06 

•27 

•36 

•06 

2  37 

•08 

•07 

•07 

•45 

•69 

•OS 

•52 

•41 

Silicon         

•01 

•21 

•23 

•117 

•00 

14 

•4T 

•38 

•01 

•04 

•oo 

13 

•20 

•03 

•08 

•02 

•02 

06 

•04 

•01 

•OS 

•OS 

•<K 

•05 

•05 

•36 

•20 

•41 

•18 

2-06 

•28 

•30 

1-03 

1  35 

•.-,:, 

•18 

•67 

•36 

•66 

•59 

•92 

•91 

•69 

1T4 

•97 

•02 

•<M 

•02 

•01 

•09 

02 

•oo 

•05 

•09 

•04 

•10 

•09 

•09 

•08 

•03 

•08 

•05 

•08 

•08 

•05 

•09 

•OS 

•05 

•09 

0 

0 

0 

0 

•02 

•03 

•04 

•05 

•06 

•06 

•07 

•07 

•08 

•08 

•09 

•10 

•11 

•12 

•13 

•14 

•15 

•16 

•17 

•28 

A.  Bell,  Manufacture  of  Iron  and  Steel,  pp.  414-115  :  Bessemer  rails.  B.  Private  notes.  C.  British  J).  Bessemer,  Western  IT.  S.  E.  Bessemer.  Eastern  U.S.  F.  Somewhat  redshort. 
G.  Rolled  admirably.  II.  U.  8.  open-hearth.  I.  Metcalf,  Trans.  Am.  Inst.  Mining  Engineers,  IX.,  p.  549.  J.  Crucible  steel.  K.  Cammel's  armor  plate.  L.  Boiler  plate.  M.  Thurston,  Mails, 
of  Engineering,  p.  434.  N.  Morrell,  Metallurgical  Review,  II.,  p.  193. 


trustworthy  empirical  formulae,  the  steel  maker  has  to 
proceed  tentatively  when  under  unusual  conditions. 
The  examples  of  well  and  ill-rolling  steels  in  Table  21,  ar- 
ranged in  the  order  of  their  manganese  contents,  may 
serve  as  rough  guides  :  other  examples  occur  in  Tables 
17,  22,  28,  29  and  30. 

Table  22  gives  the  compositions  of  many  steels  with  sul- 
phur from  0  to  0  22^.  They  are  selected  from  a  vast 
number  at  hand,  primarily  to  show  how  small  a  quantity 
of  manganese  may  suffice  to  restrain  the  redshortness  con- 
ferred by  sulphur,  at  least  so  fully  as  under  favorable 
conditions  to  permit  the  rolling  of  T  rails  with  thin  flanges. 
We  may  infer*from  this  table  that  for  this  purpose  it  is 
only  necessary  that  the  manganese  should  equal  say  4-5 
times  the  sulphur  present,  even  when  the  latter  rises  to 
0'16^.  But  the  percentage  of  manganese  required  for 
other  reasons  may  greatly  exceed  that  which  the  sulphur 
present  calls  for.  Moreover  as  the  sulphur  rises,  even  if 
the  manganese  rises  proportionally,  the  redshortness  and 
the  difficulty  of  forging  increase.  But,  after  seeing  so 
many  apparently  trustworthy  empirical  formulae  prove 
worthless  under  altered  conditions,  it  would  be  rash  to 
conclude  that  4'5  parts  of  manganese  are  always  needed 
or  always  suffice  to  counteract  one  part  of  sulphur. 

§  84.  INFLUENCE  OF  MANGANESE  ON  TENSILE  STRENGTH 
AND  DUCTILITY. — Manganese  may  affect  these  properties 
in  iron  both  indirectly,  by  restraining  the  formation  of 
blowholes,  and  directly  by  entering  into  chemical  union 
with  the  metal.  Moreover,  the  manganese  present  may 
not  all  be  directly  alloyed  with  iron  but  may  exist  in  vari- 
able proportions  as  oxide,  silicate,  or  sulphide,  of  un- 
known and  inconstant  composition,  and  the  effect  of  each 
of  these  substances  on  iron  doubtless  not  only  differs  from 
those  of  the  others  but  also  itself  varies  with  varying  con- 
ditions. We  should  therefore  hardly  expect  careful 
scrutiny  to  support  the  popular  belief  that  the  effects  of 
manganese  are  constant  and  cumulative,  and  I  for  one 
should  expect  its  influence  to  vary  greatly  under  varying, 
and  perhaps  but  slightly  varying,  conditions  :  and  the  evi- 
dence at  hand  indicates,  I  think,  that  it  does  thus  vary. 

In  so  far  as  it  prevents  blowholes  it  doubtless  increases 
both  tensile  strength  and  ductility.  But  few  discriminate 
between  its  direct  and  indirect  effects :  still  less  have  its 
different  direct  effects  been  distinguished  from  each  other : 
the  opinions  held  chiefly  regard  its  net  effect.  Some  day 
we  may  make  these  discriminations  clearly :  to-day  it  is 
impossible.  But  it  is  of  practical  moment  to  learn  whether 
its  net  effect  is  on  the  average  good  or  bad :  or,  failing 
this,  whether  it  is  usually  or  often  so  strongly  marked 
that  it  should  be  taken  into  account. 

Formerly  regarded  by  nearly  all  as  merely  a  necessary 
evil,  it  has  largely  lived  down  its  bad  repute.  In  1872  four 
distinguished  steel  metallurgists  gave  me  the  figures  '5, 
•5,  '75  and  \%  respectively  as  the  highest  amount  of  man- 


ganese which  should  be  tolerated  in  Bessemer  rail  steel 
under  any  conditions  whatsoever.  To-day  rail  steel  oc- 
casionally contains  as  much  as  2-l$  manganese  and  fre- 
quently as  much  as  1  '55$.  In  1872  Holley  thought  manga- 
nese could  not  safely  rise  above  '5%  :  in  1878  he  reported 
the  admirable  qualities  of  steel  castings  with  '94$  manga- 
nese. Not  a  few  now  regard  manganese  in  moderation  as 
harmless  or  even  beneficial :  very  many  have  been  pre- 
judiced against  it,  often  unconsciously,  by  their  personal 
interest  in  the  standing  of  open-hearth  steel,  which  is 
ordinarily  less  manganiferous  than  Bessemer  steel.  But, 
making  all  allowances  for  prejudice,  many  intelligent  and 
unbiassed  metallurgists  dread  it  and  echo  Siemens' s  illog- 
ical complaint  that  it  is  but  a  cloak  for  impurities. 

I  now  present  evidence  as  to  its  effects  on  tensile 
strength  and  ductility. 

A.  SALOM,"  analyzing  by  the  method  of  least  squares 
Dudley's  data  as  to  the  composition,  tensile  strength  and 
ductility  of  64  rails,  finds  that  manganese  increases  both 
tensile  strength  and  ductility,   but  by  an  insignificant 
amount. 

B.  RAYMOND,1"  similarly  analyzing  Dudley's  data  as  to 
wear,  finds  that  manganese  has  no  effect. 

C.  THE  AUTHOR'S  ANALYSIS. — It  may  justly  be  objected 
to  these  deductions  that  they  are  based  on  utterly  in- 
sufficient data,  the  number  of  cases  being  very  small,  and 
that  the  other  variables  vary  so  greatly  as  to  mask  the 
effects  of  variations  of  manganese.     Gatewood0  has  pre- 
sented incomparably  more  valuable  data,  both  numerous 
and  with  but  trifling  variations  in  the  variables  other  than 
carbon  and  manganese.     They  indicate  that  manganese 
has  no  important  constant  effect  on  either  tensile  strength 
or  ductility,  at  least  within  the  limits  manganese  0'20  to 
0-60  and  carbon  '12  to  '22$.    Of  these  I  have  analyzed  two 
sets,  the  Chester  steel,  with  130  cases,  with  carbon  be- 
tween O'lO  and  0'22  (in  110  of  these  the  carbon  is  between 
•12  and  '17),  the  manganese  varying  from  '20  to  -73 :  and 
the  Norway,  with  no  less  than  369  heats,  whose  carbon 
varies  from  '11  to  "31  (in  355  of  them  it  lies  between  012 
and  0-22)  and  whose  manganese  varies  from  -17  to  '64. 

An  analysis  of  the  first  set  indicated  that  between  these 
limits  manganese  raised  the  tensile  strength  at  the  rate  of 
16,430  pounds  per  square  inch  per  \%  (or  164  Ibs.  per 
•01$  manganese),  or  about  one  fourth  as  much  as  the  same 
percentage  of  carbon  does.  The  second  set  yields  far  more 
valuable  results,  because  its  cases  are  far  more  numerous, 
and  because  certain  tedious  precautions  were  employed  in 
its  analysis  which  were  omitted  in  the  study  of  the  first  set. 

I  divide  the  369  cases  into  primary  groups,  each  with 
constant  carbon,  and  determine  the  average  manganese 
for  each  group.  These  are  subdivided  into  secondary  groups 


a  Trans.  Am.  Inst.  Mining  Engineers,  XIII.,  p.  157. 

>J  Idem,  IX.,  p.  60 r. 

c  Kept.  Nav.  Advisory  Bd.  on  Mild  Steel,  1886. 


INFLUENCE    OF    MANGANESE    ON    TENSILE    STRENGTH    AND    DUCTILITY. 


84. 


47 


each  with  constant  manganese  as  well  as  carbon.  Not- 
ing the  amounts  by  which  the  manganese  and  the  tensile 
strength  of  each  group  differ  from  those  of  the  primary 
group  in  which  it  lies,  we  assume  that  the  deviations 
of  tensile  strength  are  so  far  due  to  those  of  manganese 
that,  if  we  eliminate  the  effects  of  other  variables  by  taking 
the  mean  of  a  large  number  of  cases,  we  shall  discover  the 
relation  between  manganese  and  tensile  strength.  To  this 
end  I  combine  into  tertiary  groups  all  those  secondary 
groups  whose  manganese  differs  by  like  algebraic  amount 
from  the  average  manganese  of  their  primary  groups,  and 
I  find  the  average  deviation  of  the  tensile  strength,  etc.,  of 
the  members  of  each  tertiary  group  from  the  average  ten- 
sile strength,  etc.,  of  their  primary  groups.  If  now  within 
the  limits  of  manganese  0'!7  and  '64,  and  carbon  '12  and 
'22,  manganese  has,  as  is  generally  believed,  an  effect  which 
is  largely  independent  of  other  variables,  and  which  is 
constant  and  cumulative,  taking  such  a  large  number  of 
cases  of  steel  produced  and  tested  under  like  conditions, 
with  all  other  variables  reduced  to  their  narrowest  limits, 
then  the  average  deviations  of  the  tensile  strength,  etc.,  of 
these  tertiary  groups  should  bear  a  traceable  relation  to 
the  corresponding  deviations  of  manganese,  and  plotting 
them  as  I  have  done  with  deviations  of  tensile  strength, 
etc.,  asordinates.  deviations  of  manganese  as  abscissse,  we 
should  obtain  a  curve  of  some  degree  of  regularity.  Actu- 
ally the  resulting  zigzag  for  tensile  strength  is  perfectly 
hopeless :  it  does  not  even  suggest  that  the  effect  of 
manganese  is  on  the  whole  either  to  increase  or  to  dimin- 
ish tensile  strength. 

Here  and  there  a  group  shows  much  higher  tensile 
strength  than  its  neighbors,  but  these  excesses  are  not 
referable  to  any  simple  principle,  and  they  are  probably 
due  to  other  causes  than  variation  in  manganese.  Fig.  7, 


Increase  (+}  or  decrease  (— )  of 
tensile  strength  (Ibs.  per  sq.  in.) 
corresponding  to  excess  (  +  )  or  de- 
ficit ( —  t  of  Manganese  above  and 
below  the  average  percentage. 


+  SOOH* 


+  400  11)S. 


/Ibs. 


-  800  Ibs. 


0%         +0.30% 


Fig.  7. 

which  shows  a  curve  derived  from  the  tertiary  groups  by 
combining  them  by  fives  into  quaternary  groups  and  plot- 
ting the  centers  of  gravity  of  the  latter,  indicates  either 
that  the  effects  of  manganese  on  tensile  strength  are  not 
constant,  but  sometimes  positive  sometimes  negative,  or 
that  they  are  so  insignificant  as  to  be  completely  masked 
by  trifling  variations  of  other  variables. 

The  indications  as  to  the  effects  of  manganese  on  duc- 
tility (as  measured  by  elongation)  are  more  conclusive : 


the  elongation  of  each  tertiary  group  so  closely  approxi- 
mates the  average  of  its  primary  group  that,  combining 
the  tertiary  groups  by  fives,  the  elongation  of  the 
quaternary  groups  thus  produced  in  no  case  differs  by 
as  much  as  0'5%  from  the  elongation  of  their  primary 
groups,  suggesting  that,  if  manganese  does  directly  cause 
brittleness,  it  is  balanced  by  its  indirect  effect  of  increasing 
ductility  by  promoting  continuity. 

D.  DESK  AYES  from  examination  of  the  Terre-Noire  steels 
concludes  that,  when  the  manganese  is  in  the  neighborhood 
of  0*5$,  an  increase  of  O'l^of  manganese  raises  the  tensile 
strength  about  l-3rd  as  much  as  0'1#  of  carbon  does,  or  say 
from  2560  to  2845  Ibs.  per  sq.  in. :  that  it  raises  the  elas- 
tic limit  slightly  more  than  the  tensile  strength  ;    that 
it  diminishes  the  permanent  elongation  on  rupture,  but 
by  only  about  l-6th  or  l-7th  as  much  as  carbon  does,  an 
increment  of  0'\%  manganese  diminishing  the  elongation 
by  hardly  0'5^.a 

The  effects  which  he  attributes  to  manganese  are  so 
slight  that  they  may  easily  be  due  to  variations  of  other 
variables  :  and  as  I  have  neither  his  data  nor  hio  method 
of  analyzing  them  I  know  not  how  much  weight  to  attach 
to  his  conclusions^  They  on  the  whole  harmonize  with  the 
results  of  our  other  evidence,  in  indicating  that  the  net  ef- 
fects of  manganese  within  moderate  limits  are  compara- 
tively unimportant  as  regards  tensile  strength,  and  insig- 
nificant as  regards  elongation. 

E.  I  have  known  the  rails  of  a  western  Bessemer  mill  to 
contains  2-1%  manganese  when  the  carbon  was  below  -30^: 
at  another  it  frequently   reaches  1  -55%  with  '35$  carbon. 
Table  17  gives  three  cases  in  which  the  manganese  varies 
from  1-85^  with  -76^  carbon  to  2-08^  with  -52^  carbon,  in 
rails. 

F.  An  eminent  but  dogmatic  authority    states    that 
manganese  in   tool  steel  must  not  exceed  0-2$:  yet  very 
good  tool  steel  with    '5  b  and  even  "78^  °  manganese  is 
recorded.     I  have  a  trustworthy  analysis  of  Jessop's  best 
saw  steel  with  manganese  0-45,  carbon  1'06,  silicon  -19  and 
phosphorus  '024. 

G.  Steel  castings  of  admirable  quality  are  often  highly 
manganif erous :  e.  ff.,  No.  40,  table  9,  with  rio  manganese, 
•45    carbon,   and  '35    silicon,    with    105,080  Ibs.    tensile 
strength  and  Yt'5%  elongation  :  the  same  table  gives  many 
other  tough  and  strong  castings  with  from  '94  to  1'OS^ 
manganese. 

H.  Excellent  boiler  plate  steel  which  passes  the  rigorous 
government  tests  often  has  more  than  '55,  and  occasionally 
as  much  as  "64$  manganese. 

T.  Experienced  makers  of  soft  open-hearth  steel  report 
that  the  addition  of  a  moderate  amount  of  manganese, 
with  simultaneous  diminution  of  carbon,  greatly  increases 
the  ductility  of  steel  containing  '24$  carbon,  and  nearly 
free  from  manganese. 

RESUME. — Let  each  reader  reconcile  these  facts  with  the 
prevalent  dread  of  manganese  as  best  he  may  :  his  conclu- 
sions will  not  injure  the  facts  :  neither  will  mine,  which 
are  as  follows.  The  statistical  examinations  A  to  D  indi- 
cate that,  on  the  average,  the  net  effects  of  manganese  on 
tensile  strength  and  ductility  are  slight.  G  shows  that  if 
•9  to  \'\%  manganese  ever  seriously  injures  static  ductility, 


»  Aunales  des  Mines,  1879,  p.  549. 

bThurston,  Materials  of  Engineering,  II.,  p.  435. 

=  Engineering  and  Mining  Journal,  1875,  II.,  p.  383, 


48 


THE    METALLURGY    OF    STEEL. 


there  are  many  cases  in  which  it  does  not.  The  fact  that  rails 
(E)  with  1  '55$  manganese  and  "35  carbon  very  often  suc- 
cessfully pass  the  straightening  press  and  that  those  with 
over  2%  manganese  and  -§1%  carbon  occasionally  do,  indi- 
cates that,  if  manganese  renders  steel  brittle  under  shock, 
this  effect  is  either  slight  or  exceptional  or  non-cumula- 
tive, while  H  indicates  that  it  is  slight.  F  indicates  that,  if 
say  -45%  or  less  of  manganese  lessens  the  power  of  steel  to 
hold  a  cutting  edge,  this  effect  is  not  constant:  and  the 
presence  of  '45$  manganese  in  the  crucible  saw  steel  of  a 
maker  whose  product  has  and  apparently  deserves  the 
very  highest  reputation,  indicates  that  if  it  tends  to  pro- 
duce this  effect  this  tendency  can  be  safely  combated. 

While  the  evidence  is  too  fragmentary  to  warrant  final 
conclusions,  it  certainly  strongly  suggests  that  the  present 
dread  of  manganese  is  largely  a  superstition :  that  while 
1  or  2$  of  manganese  is  probably  liable  to  cause  decided 
brittleness,  its  effects  have  been  grossly  exaggerated,  and 
that  Dudley's"  conjecture  that  5  parts  of  manganese  cause 
as  much  brittleness  as  one  part  of  -phosphorus  is  very  wide 
of  the  mark. 

§  86.  MANGANESE  STEEL. — While  the  small  amounts  of 
manganese  in  ordinary  commercial  steel  increase  its  forge- 
ableness  and  within  certain  limits  its  brittleness,  yet  when 
so  much  manganese  is  present  that  its  effects  outweigh 
those  of  carbon  and  that  it  forms  a  true  manganese  steel, 
the  alloy  becomes  extraordinarily  tough  and  difficultly 
forgeable :  it  possesses  a  combination  of  hardness  and 
toughness  which  should  be  of  value  for  tools  which  cut  by 
impact,  and  which  is  not  otherwise  attainable  so  far  as  I 
know,  at  least  in  any  material  available  for  the  arts.  Sev- 
eral attempts  to  utilize  its  remarkable  properties  have 
been  made  of  late,  and  others  are  to  be  expected. 

The  extreme  brittleness  of  tungsten  steel  often  prevents 
us  from  availing  ourselves  of  its  intense  hardness,  which 
equals  that  of  any  steel  within  my  knowledge :  manganese, 
which  gives  such  toughness  and  hardness,  holds  out  prom- 
ise as  a  means  of  remedying  this  defect,  and  indeed  tung- 
sten steel  often  contains  from  1  to  2 -5%  of  manganese.  But 
as  both  tungsten  and  manganese  steel  are  difficultly 
forgeable,  this  defect  would  probably  still  restrict  its  use. 

The  open-hearth  cutlery  steel  of  a  western  United 
States  mill  in  two  cases  contained 


Manganese. 
1-25 
1-00 


Carbon. 
•35 
•45 


Silicon. 
•09 
•09 


But  this  can  hardly  be  classed  as  a  true  manganese  steel. 
N.  Washburn,  at  Allston,  Mass.,  is  reported  to  have  made 


railway  car  wheels  of  steel  containing  1%  manganese  and 
0'6$  carbon,  and  to  have  suspended  his  manufacture  solely 
for  legal  considerations. 

Far  better  known  is  Hadfield's  b  manganese  steel,  which 
contains  from  7  to  30$  manganese.  The  following  speci- 
mens of  his  steel  have  been  described  : 

I.b  Manganese,  9.8 ;  carbon,  0  72  ;  silicon,  (V37;  sulphur, 
0  06  ;  phosphorus,  0-08.  Elongation  in  8  inches,  (1)  22$,  (2) 
28-9$:  tensile  strength,  (1)106,490,  (2)  119,054  Ibs.  per 
sq.  in. 

II. b  9  to  10$  manganese :  can  be  machined,  but  with 
difficulty.  With  more  manganese  the  steel  can  hardly 
be  cut  by  carbon  steel. 

III.C  12'5$  manganese.  Hard-drawn  wire,  tensile 
strength  246,480  Ibs.  per  sq.  in.  The  same  annealed  107,- 
520  Ibs.,  with  20$ ±  elongation.  Modulus  of  elasticity 
23,890,000  Ibs.  per  sq.  in.,  or  about  85$  of  that  of  carbon 
steel. 

IV.d  17'5$  manganese,  0'8$  carbon.  Hardly  cut  in  a 
lathe  by  carbon  steel.  When  quenched  in  water  it  could 
be  bent  double  without  cracking. 

V.b  18$  manganese.  Could  be  forged,  but  with  diffi- 
culty. 

I  found  a  specimen  of  manganese  steel  readily  forge- 
able  between  dull  and  light  redness :  at  a  yellow 
or  very  dull  red  heat  it  was  tender,  and  below  the  latter 
temperature  extremely  so.  Cold-forging  raises  its  ten- 
sile strength  but  makes  it  brittle.  Its  toughness  is  re- 
stored by  heating  it.  I  find  it  slightly  softer  and  it  is  said 
to  be  much  tougher  after  sudden  than  after  slow  cooling. 

Its  electric  conductivity  is  very  low,  12$  of  that  of  iron 
(1'8$  of  that  of  copper?)  according  to  Barrett.0  It  is  but 
very  slightly  magnetic :  Bottomley e  found  that,  after 
being  submitted  to  the  most  powerful  magnetizing  force, 
its  permanent  magnetism  was  but  0-02$  of  that  of  ordi- 
nary steel,  while  Barrett  found  that  its  induced  magneti- 
zation in  a  uniform  field  was  but  0'3$  of  that  of  iron : 
but  for  the  high  cost  of  manganese  this  property  would 
commend  this  steel  for  the  plating  of  iron  vessels,  which, 
if  built  of  this  wonderful  material,  would  have  little  devi- 
ation of  the  compass. 

It  is  stated  by  interested  persons  to  be  exceedingly 
fluid,  to  solidify  with  but  little  contraction,  and  without 
blowholes,  and  to  be,  even  without  forging,  "harder, 
stronger,  denser  and  tougher"  than  most  forged  steel. 

Brustlein'  states  that  it  welds  with  great  facility. 

Concerning  manganese  steel  see  further  Appendix  I. 


CHAPTER   V. 
IRON    AND    SULPHUR. 


§  90.  SUMMARY. — Sulphur  unites  with  iron  probably  in 
all  proportions  up  to  53 -3$,  being  readily  absorbed  from 
many  sources.  It  may  however  be  prevented  from  com- 
bining with  iron  and  even  expelled  from  it  by  many 
agents  (e.  g.,  basic  slags,  carbon,  silicon,  manganese,  oxy- 
gen, water,  ferric  oxide).  Certain  of  these  in  the  blast  fur- 
nace prevent  the  sulphur  present  from  combining  with  the 
cast-iron,  and  in  the  conversion  of  cast-iron  into  malleable 

uTraus.  Am.  lust.  Mining  Engineers,  1879,  VII.,  p.  197, 


iron,  whether  by  puddling,  by  pig- washing  or  by  the  basic 
process  much  of  the  sulphur  of  the  cast-iron  is  expelled. 
It  causes  cast-iron  to  retain  its  carbon  in  the  combined  state. 
Carbon  and  sulphur  and  perhaps  also  silicon  and  sulphur 
are  mu  tually  exclusive  within  limits.  Sulphur  makes  mal- 


b  Weeks.,  Trans.  Am.  Inst.  Mining  Engineers,  XIII.,  p.  333  ;  also  XV, 

c  The  Electrician,  Jan.  7,  1887. 

<J  S.  Wellman,  private  communication. 

e  The  Electrician,  loc.  cit. 

t  Journal  Iron  and  St.  Inst.,  1886,  II.,  p.  775. 


DESULPHURIZATION.      §  93. 


48 


leable  iron  redshort  and  interferes  with  its  welding,  but 
these  effects  are  largely  effaced  by  the  presence  of  manga- 
nese. It  is  thought  to  make  malleable  iron  slightly 
tougher  and  softer  when  cold,  but  to  make  cast-iron  hard- 
er, though  this  latter  effect  is  at  least  in  part  due  to  its 
musing  it  to  retain  the  carbon  in  the  combined  state.  It 
increases  the  fusibility  of  cast-iron  but  makes  it  thick  and 
sluggish  when  molten  and  gives  rise  to  blowholes  during 
its  solidification. 

§  91.  COMBINATION.— Sulphur  unites  readily  with  iron 
in  many  proportions  (the  sulphides  Fe8S,  FeaS,  FeS,  Fe2S3, 
FerS8  and  FeS3  =  Fe  40'7£,  S53'3#  are  recognized),  being 
greedily  absorbed  by  it,  as  the  following  paragraphs  show, 
from  sulphurous  fuel  and  even  from  sulphurous  gases, 
from  the  sulphates  of  baryta  and  lime,  and  probably  from 
other  sulphates.  Ferrous  sulphide  (FeS  with  36*36^  sul- 
phur) appears  to  dissolve  in  non-carburetted  iron  or  to 
unite  with  it  in  the  igneous  way  in  all  proportions : 
Percy,8  melting  ferrous  sulphide  and  iron  together  in 
various  proportions,  obtained  completely  fused  and 
apparently  homogeneous  products. 

Willis  states  that  in  the  open-hearth  process  30^  of  the 
sulphur  contained  as  sulphate  of  baryta  in  some  ore  that 
was  added  was  absorbed  by  the  steel."  Finkener  found 
that  when  metallic  iron  and  lime  sulphate  were  exposed 
to  a  white  heat  in  -cacuo  the  mass  was  fused,  an  oxide  and 
sulphide  formed  (whether  any  iron  sulphide  formed  is  not 
stated).0  This  indicates  that,  in  the  presence  of  an  acid 
slag,  e.  g.,  in  the  open-hearth  process,  metallic  iron  would 
take  up  sulphur  from  lime  sulphate. 

Odelstjerna  and  Forsbergd  found  that  steel  in  the  open- 
hearth  furnace  absorbed  from  0*015  (015?)  to  0'3^  sul- 
phur from  the  producer  gas,  as  proved  by  repeated  experi- 
ments, and  crucially  by  desulphurizing  this  gas  by  adding 
in  the  gas-producers  7  parts  of  crushed  lime  to  100  of  coal, 
when  the  absorption  of  sulphur  by  the  steel  ceased. 
Hardisty"  states  that  he  has  often  found  '01  to  '02$  more 
sulphur  in  open-hearth  steel  than  could  be  accounted  for 
by  the  iron  charged. 

Finkener,*  heating  iron  in  an  atmosphere  of  sulphurous 
acid  found  that  the  iron  absorbed  sulphur,  and  was  in  part 
simultaneously  oxidized. 

M.  White  informs  me  that  repeated  investigations  at  the 
Bethlehem  Iron  Works  have  shown  more  sulphur  in  the 
Bessemer  ingots  than  is  contained'in  the  cast-iron  when  it 
runs  into  the  converter ;  this  excess,  amounting  to  say 
0'008$,  is  probably  absorbed  by  the  steel  from  the  sides 
of  the  ladles,  which  in  turn  probably  absorb  bisulphide  of 
carbon  from  the  producer  gas  with  which  they  are  heated. 

§92.  THE  CONDITION  OF  SULPHUR  IN  IRON. — Several 
facts  suggest  that  in  solid  iron  sulphur,  at  least  in  part 
and  under  favorable  conditions,  exists  not  in  simple  uni- 
form combination  with  the  matrix  of  metal,  but  as  a  sul- 
phide, probably  of  indefinite  composition,  dissolved  or 
suspended  in  particles  usually  so  minute  as  to  escape 
detection.  It  tends  strongly  to  segregate  or  even  to  liquate 
from  cast-iron :  it  is  often  very  irregularly  distributed 


a  Percy,  Iron  and  Steel,  p.  33. 
«>  Journal  Iron  and  St.  Inst.,  1880, 1.,  p.  91. 
c  Wedding,  Basische  Bessemer  oder  Thomas  Process,  p.  155. 
d  Journal  Iron  and  St.   Inst.,  1886,  I.,  pp.  125,  337  ;  Iron  Age,  April  8,  1886 
p.  11. 

c  Journ.  Iron  and  St.  Inst.,  1886,  I.,  p.  128. 
f  Wedding,  Der  basische  Bessemer-  oder  Thomas-process,  p.  155. 


through  sulphurous  steel.  £nelus,  sifting  the  borings  of 
cast-iron,  found  the  finer  and  more  graphitic  portions 
unduly  sulphurous.8  When  cast-iron  is  dissolved  in  hydro- 
chloric acid  "even  after  all  the  iron  is  dissolved  and  the 
solution  boiled  for  some  time,  sulphuretted  hydrogen  is 
still  given  off" — especially  in  case  of  siliceous  cast-iron." 

§  93.  REMOVAL  OF  SULPHUR. — Fortunately  sulphur  is 
readily  removed  from  iron  by  many  reagents,  lime,  mag- 
ncsi-.i,  the  alkalies  (and  their  basic  silicates),  carbon,  sili- 
con and  manganese,  which  all  probably  remove  it  as  sul- 
phide, since  their  sulphides,  unlike  that  of  iron,  are  but 
slightly  soluble  in  the  metal:  ferric  oxide,  atmospheric 
oxygen,  steam  and  alkaline  nitrates,  which  oxidize  and 
expel  it  as  sulphurous  and  sulphuric  acids:  and  heat 
alone,  which  decomposes  sulphates  ol  iron  (e.  gr.,  in  roast- 
ing iron  ores)  volatilizing  the  sulphur  as  sulphuric  acid. 
Further,  manganese  counteracts  the  effects  of  moderate 
amounts  of  sulphur  retained  by  the  iron. 

A.  CARBON  removes  sulphur  from  ferrous  sulphide  and 
apparently  from  cast-iron  and  Steel,  probably  in  both 
cases  as  bisulphide  of  carbon,  CS.,,  which  forms  when  sul- 
phur and  carbon  meet  at  a  red  heat.  Very  inflammable, 
it  burns  in  the  air  to  carbonic  and  sulphurous  acids. 
Hochstiitter1  in  Percy's  laboratory,  exposing  sulphide  of 
iron  (which  had  about  29$  sulphur  and  was  therefore 
nearly  ferrous  sulphide)  with  charcoal  in  covered  brasqued 
crucibles  to  a  white  heat,  expelled  2 1*13^  of  the  sulphur 
initially  present,  obtaining  a  sulphide  with  about  33  34$  of 
sulphur  and  a  small  quantity  of  highly  siliciferous  metal- 
lic iron  (iron  89-53,  silicon  9 -41).  The  expulsion  of  sulphur 
is  attributable  to  the  carbon  present. 

That  sulphur  is  expelled  from  cast-iron  by  carbon  is 
indicated  by  Smith's  experiment  in  Percy's  laboratory. 
Exposing  white  cast-iron  to  a  steel- melting  heat  in  a 
graphite  crucible  with  an  excess  of  charcoal,  collecting 
and  remelting  the  resulting  buttons  under  charcoal,  he 
found  that  the  sulphur  which  was  initially  0'78$  had 
fallen  to  0  -34^,  and  the  iron  had  become  mottled.  Similarly 
both  Smith  and  Weston  in  Percy's  laboratory  melted  gray 
cast-iron  with  ferrous  sulphide  in  such  small  proportion 
that  it  was  wholly  either  decomposed  or  absorbed  by  the 
cast-iron.  A  very  considerable  proportion  of  sulphur  was 
in  general  expelled.3  Their  results  are  here  summarized. 

TABLE  22  A.— FUSION  OP  CAST-IKON  WITH  FEKKOCB  SULPIIIDB. 


No. 

Observer. 

[n  the    mixture  of 
cast-iron  and  FeS 
before  fusion. 

In  the  fused  product. 

Loss  on 
fusion. 

Grade  of  the  product. 

Carbon. 

§ 
I 

CO 

Carbon. 

•a 

•3 

en 

Carbon. 

1 

Combin'd 

1 

5 

& 

3 

S 

1 
2 
3 
4 
5 
6 
T 
8 

Smith.  Weston. 

8-84 
4-16 
4-31 
4  39 

4-38 
2-23 
I'M 

0  70 

2-68 
•78 
•90 

2:46 

i'u 

3-17 
3'9 

2-12 
1-68 

0-72  ' 

•67 
•26 
•71 

2  26 
0-55 

White,  no  graphit   separated. 
'*      graphite  separated. 

Mottled      "             " 
White        "             " 
Mottled. 
Graphite  separated. 
White        "            " 

•73 
•34 
•09 

1-90 

•81 
•52 

1-65 

1  13 

1  to  4  inclusive.  Non-sulphurous  graphitic  east  -iron,  prepared  by  heating  sheet  iron  in  chemically 
pure  charcoal,  was  melted  with  sulphide  of  iron  containing29'9^  sulphur.  6.  Gray  jaet-lron  melted 

tiner  pae  gass      cy  cr  .  , 

that  nothing  can  have  fallen  in  :  yet  a  considerable  quantity  of  pulverulent  graphitic  matter  was 
found  between  metal  and  slag.  6.  The  white  cast-iron  produced  in  5  remelted  in  a  graphite 
crucible  with  a  great  excess  of  charcoal.  7.  Another  variety  of  gray  cast-iron  was  melted  under 
plate  glass  in  a  clay  crucible  with  the  same  sulphide.  A  considerable  quantity  of  graphitic  matter 
was  found  between  metal  and  slag.  8.  Gray  iron,  about  No.  2  in  grade,  was  melted  in  a  clay 
cruciblo  under  a.  plug  of  charcoal  with  the  same  sulphide :  graphitic  matter  was  found  on  the 
surface  of  the  button. 


g Journ.  Iron  and  St.  Inst.,  1871, 1.,  p.  40. 

h  E.  Riley,  Journ.  Chem.  Soc.,  1872,  XXV.,  p.  540. 

I  Percy,  Iron  and  Steel,  p.  34. 

3  Percy,  Op.  Cit.,  pp.  133  to  136. 


THE    METALLURGY    OF     STEEL. 


So  too  Biley  obtained  graphitic  cast-iron  free  from  sul- 
phur by  fusion  in  a  highly  sulphurous  gas-carbon  cruci- 
ble, the  excess  of  carbon  present  apparently  either  pre- 
venting the  absorption  of  sulphur  from  the  crucible  walls 
or  actually  expelling  it  when  absorbed.* 

In  cementation  (carburization  of  malleable  iron  by  pro- 
longed heating  in  contact  with  charcoal)  the  sulphur 
has  been  observed  to  fall  from  '577  (?)  to  'Ol7b  :  from  '055 
to  '019C :  from  '04  to  '02,  and,  in  case  of  white  cast-iron 
heated  for  35  days  in  charcoal  from  '101  to  -036.  Ledeburd 
thinks  that  bisulphide  of  carbon  is  probably  evolved 
from  solidifying  sulphurous  cast-iron. 

In  view  of  these  facts  KarstenV  statement  that  sulphide 
of  iron  with  the  minimum  of  sulphur  remains  unchanged 
when  exposed  to  carbon  for  an  hour  at  the  strongest 
white  heat,  but  takes  np  some  carbon,  is  hard  to  explain. 
The  experiments  of  Percy' s  laboratory  are  so  conclusive 
that  we  must  conclude  either  that  Karsten  was  mistaken 
or  that  the  special  conditions  of  his  experiments  prevented 
the  expulsion  of  sulphur. 

B.  MUTUAL  EXCLUSIVENESS  OF  SULPHUR  AND  CAR- 
BON.— The  experiments  of  Table  22  A  not  only  show  that 
carbon  when  present  in  excess,  as  in  cementation  and  in 
fusion  in  carbonaceous  crucibles,  expels  sulphur,  and  that, 
under  favorable  but  little  known  conditions  even  the  com- 
paratively moderate  quantity  of  carbon  in  gray  cast-iron 
may  so  completely  expel  sulphur  that,  as  in  case  7,  it  falls 
•from  '90  to  •().")$,  but  also  that,  as  noticed  in  §  20,  sulphur 
in  turn  expels  carbon,  probably  in  part  by  dragging  it  off 
as  bisulphide  of  carbon,  partly  by  lowering  the  saturation 
point  of  the  iron  for  carbon.  Indeed,  No.  7  indicates  that 
even  when  so  little  as  '09  per  cent  of  sulphur  remains 
it  may  cause  the  graphitic  separation  from  molten 
gray  iron  of  part  of  the  carbon  which  it  had  previously 
retained,  or  that  it  may  at  least  prevent  the  reabsorption 
of  the  graphite  expelled  before  the  sulphur  had  fallen  to 
so  low  a  proportion.  While  part  of  the  carbon  thus 
expelled  probably  escapes  as  bisulphide,  it  is  clear  that  the 
expulsion  of  a  part  is  due  to  the  effect  of  sulphur  in  low- 
ering the  saturation  point  of  the  iron  for  carbon :  for  not 
only  is  much  more  carbon  expelled  in  every  case  than  is 
needed  to  form  bisulphide  with  the  sulphur  simultaneously 
eliminated,  but  in  many  cases  a  layer  of  graphite  occurs  on 
the  surface  of  the  resulting  button  of  iron,  which  itself  is 
perfectly  white ;  and  moreover,  as  in  No.  4  (and  also  No.  3  ?) 
a  heavy  loss  of  carbon  may  occur  even  when  no  sulphur  is 
removed.  The  expelled  carbon  which  in  these  experi- 
ments remains  as  graphite,  because  protected  by  a  layer 
of  glass,  would  doubtless  be  oxidized  under  ordinary  con- 
ditions. 

We  safely  attribute  these  effects  to  the  presence  of  sul- 
phur, for  when,  in  an  experiment  parallel  with  No.  8, 
gray  cast-iron  was  melted  under  glass  in  a  clay  crucible  at 
an  excessively  high  temperature  and  under  the  same  con- 
ditions as  prevailed  in  these  experiments  except  that  no 
sulphide  was  added,  the  fracture  of  the  iron  remained 
dark  gray,  and  no  indication  of  white  iron  arose. 

In  the  experiments  which  we  have  been  considering  a 
little  sulphur  is  added  to  an  excess  of  iron  :  both  sulphur 


a  Journ.  Iron  and  St.  Inst.,  1877,  I,  p.  162. 

b  Percy,  Iron  and  Steel,  p.  773. 

c  Ledebui ,  Handbuch  der  Eisenhiittenkunde,  p.  954. 

d  Idenvp.  251. 

c  Percy,  Op.  Cit.,  p.  136  ;  Karsten,  Eisenhiittenkunde,  I.,  p.  429. 


and  carbon  are  partly  expelled,  but  (if  we  exclude  the 
trifling  quantity  of  graphite  formed)  a  single  product 
with  a  moderate  amount  of  carbon  and  sulphur  arises. 
Under  other  and  imperfectly  defined  conditions,  e.  g. 
when  a  large  quantity  of  sulphide  comes  into  contact  with 
cast-iron  at  a  high  temperature,  two  products  arise,  sul- 
phide of  iron  and  metallic  iron,  which  do  not  mix. 

Thus,  in  Hochstatter' s  experiment  above,  siliciferous  iron 
did  not  mix  with  iron  sulphide  from  which  it  had  been 
reduced  by  an  excess  of  carbon :  so  too  Karsten,'  bringing 
sulphur  and  cast-iron  together,  obtained  two  products, 
sulphide  of  iron  and  a,  cast-iron  containing  but  0'44G^.of 
sulphur.  In  Karsten's  experiment  by  successive  additions 
of  sulphur  more  and  more  of  the  iron  was  removed  from 
the  cast-iron  and  converted  into  sulphide,  and  as  the  car- 
bon was  not  proportionally  removed  the  metal  grew  richer 
in  carbon  till  it  became  saturated  (which  appears  to  have 
occurred  when  the  carbon  rose  above  5'f>$).  After  this  the 
excess  of  carbon  separated  as  graphite,  which  collected 
between  the  layers  of  metal  and  sulphide.  Karsten's 
statement  that  the  cast-iron  thus  obtained  in  presence  of 
5  '5%  carbon  held  -45$  of  sulphur  harmonizes  poorly  with 
the  other  results  which  I  give  above,  and,  so  far  as  I  know, 
with  common  observation.  As  we  know  that  very  many 
of  the  older  determinations  of  sulphur,  even  by  most 
careful  chemists,  were  excessively  high,  we  may  reason- 
ably doubt  whether  this  iron  actually  contained  any- 
thing like  this  quantity  of  sulphur. 

From  what  has  been  said  it  appears  (1)  that  iron  which 
is  not  highly  carburetted  unites  with  sulphuretted  irons 
and  even  with  iron  sulphides,  and  (2)  that  highly  car- 
buretted irons  unite  with  sulphuretted  irons  when  the 
latter  are  distinctly  metallic  (a  partial  expulsion  of  sul- 
phur or  carbon  or  both  usually  occurring  when  the  per- 
centage of  these  elements  exceeds  a  now  unknown  limit): 
yet  (3)  highly  carburetted  irons  do  not,  at  least  under  cer- 
tain conditions,  unite  with  any  large  quantity  iron  sul- 
phides so  rich  in  sulphur  as  to  be  no  longer  metallic  but 
matte-like  ;  and  cast-iron  may  even  remain  in  contact 
with  such  an  iron  matte  without  becoming  exceedingly 
rich  in  sulplmr.  The  behavior  of  metallic  iron  toward  its 
sulphide  here  resemble  that  of  metallic  lead  and  copper 
toward  theirs. 

C.  SILICON. — Silicon  like  carbon  appears  to  expel  sul- 
phur from  iron  to  a  certain  limited  extent,  though  prob- 
ably not  enough  to  be  of  importance  commercially,  as  a 
high  proportion  of  silicon  may  coexist  with  sufficient  sul- 
phur to  ruin  iron  for  most  purposes. 

Thus  Hochstatter*  found,  in  Percy's  laboratory,  that 
though  silica  at  a  white  heat  had  no  effect  on  ferrous  sul- 
phide, yet  if  carbon  were  present  to  reduce  the  silica  to 
silicon  (e.  g.  as  when  silica,  ferrous  sulphide  and  carbon 
were  raised  to  a  white  heat  in  a  graphite  crucible)  the 
ferrous  sulphide  was  decomposed,  its  sulphur  largely  ex- 
pelled (as  sulphurous  acid  ?)  and  a  ferro-silicon  resulted, 
whose  composition  in  three  cases  was  as  follows  : 

Iron  by  loss...                                               80-23  83'28  81-53 

Silicon 18-77  15-33  16-76 

Sulphur I'OO  1-40  1-71 

Sulphur  expelled  per  100  of  that  initially  present.  . .  97-46  96-28  92'83 

According  to  Turner  sulphur  and  silicon  appear  to 
mutually  exclude  each  other  much  as  sulphur  and  carbon 


f  Percy,  Iron  and  Steel,  p.  131. 
K  Percy,  Iron  and  Steel,  p.  38. 


DESULPHURIZATION.       §  93. 


51 


do  :  lie  finds  that  the  addition  of  sulphur  to  siliceous  iron 
causes  the  separation  of  graphitic  matter  containing  sili- 
con :  the  addition  of  silicon  to  an  iron  containing  sulphur 
causes  the  separation  of  graphitic  matter  rich  in  sulphur." 
D.  THE  ALKALIES  AND  ALKALINE  EARTHS,  potash,  soda, 
lime,  magnesia  baryta  (and  alumina?),  rapidly  and  almost 
completely  remove  sulphur  from  ferrous  sulphide  and 
from  cast-iron  as  alkaline  or  earthy  sulphide :  as  these 
sulphides  are  readily  soluble  in  many  silicates,  while  ap- 
parently almost  insoluble  in  metallic  iron,  the  employment 
in  the  blast-furnace  cf  basic  slags  (a  portion  of  whose  base 
is  readily  taken  up  by  the  sulphur)  almost  completely 
prevents  sulphur  f  r  5m  entering  the  cast-iron.  This  action, 
for  which  Ledebur  suggests  the  general  formula  FeS  -{- 
CaO  -j-  C  =  Fe  -f  CaS  -f-  CO  is  so  complete  that  at  the 
Clarence  blast-furnaces  only  from  2 '5  to  5$  of  the  sulphur 
in  the  materials  charged  enters  the  cast-iron.b  The  pres- 
ence of  free  lime,  etc.,  is  not  necessary  to  the  removal  of 
sulphur,  since  basic  silicates  of  linle,  magnesia,  etc.,  also 
remove  it :  the  more  basic  the  slag  and  the  more  there  is 
of  it  the  more  thoroughly  is  the  sulphur  removed ;  lime 
appears  to  remove  it  far  more  energetically  than  magnesia. 
These  facts  are  illustrated  by  experiments  of  Akerman  and 
Ledebur.0  Akerman  with  otherwise  identical  conditions 
obtained  from  the  same  ore  iron  with  '09,  '0  i  and  '01$  sul- 
phur by  reducing  it  with  addition  of  15$  silica,  5%  carbonate 
of  lime  and  20$  carbonate  of  lime  respectively.  The  readi- 
ness with,  which  sulphur  is  removed  from  cast-iron  by  basic 


%  sulphur  in  result- 
ing iron 

%  sulphur  in  result- 
ing slag  


Akerman,  ore  smelted  with, 


Ledebur;  iron  witu2'33*  sulphur  smelted  with 


quartz. 


•09 


limestone . 


•04 


20* 


•01 


200*  of 
calcareous 


silicato 


•079 
1-445 


200*  of 

calcareous 

bisilicate 

slag. 


•357 
•681 


200*o 
magnesian 
suigulo- 
silicato 
slaff . 


1-069 


200*  of 

magnesian 

bisilicato 

slag. 


•39 
•29 


slags  is  shown  by  Ledebur' s  results  obtained  on  melting 
cast-iron  containing  2 '33$  sulphur  with  different  slags. 
The  singulosilicates  (the  more  basic)  took  up  far  more  sul- 
phur than  the  bisilicate  slags,  and  the  calcareous  far  more 
than  the  magnesian,  the  iron  retaining  '079$  sulphur  when 
melted  with  the  calcareous  singulo-  and  '357  with  the  cal- 
careous bi-silicate :  '26$  with  the  magnesian  singulo-  and 
•39$  with  the  magnesian  bi-silicate.  The  greater  desul- 
phurizing power  of  lime  than  of  magnesia  is  illustrated 
by  the  Illinois  blast-furnace  practice,  in  which  the  substi- 
tution of  calcite  for  dolomite  materially  diminished  the 
percentage  of  sulphur  contained  in  the  cast-iron. 

That  the  power  of  basic  silicates  to  remove  sulphur  in- 
creases with  the  temperature  is  suggested  not  alone  by 
the  fact  that,  cateris  paribus,  the  hotter  the  blast-furnace 
the  freer  the  cast-iron  from  sulphur  (here  the  larger  pro- 
portion of  fuel  and  the  more  basic  slags  which  ordinarily 
accompany  high,  temperature  might  be  regarded  as  the 
cause  of  the  accompanying  freedom  from  sulphur),  but 
by  large  scale  experiments  of  Bell.d  Fusing  iron  oxide 
with  soda  waste  (which  contains  17$  ±  sulphur  with  cal- 
cium and  lime)  at  a  low  temperature,  his  product  had  as 
much  as  32$  sulphur  with  4$  oxygen :  at  a  higher  tem- 
perature nearly  all  the  iron  was  recovered  as  cast-iron, 


a  Journ.  Iron  and  St.  In=t.,  1886,  I.,  p.  184. 

b  Bell,  Principles  of  the  Manufacture  of  Iron  and  Steel,  p.  164. 

<•  Ledebur,  Handbueh  der  Eiseubiittenkunde,  p.  249. 

d  Bell,  loc.  cit. 


containing  only  1  to  2$  of  sulphur.  Unfortunately  Bell 
does  not  recite  his  conditions  so  fully  as  to  make  it  clear 
that  the  more  complete  expulsion  of  sulphur  was  due 
directly  to  the  higher  temperature  rather  than  to  some 
accompanying  condition. 

The  presence  of  basic  slags  in  cupola-furnace  fusion 
may  in  this  way  not  only  restrain  the  absorption  of  sul- 
phur from  the  fuel,  but  even  largely  eliminate  sulphur 
from  cast-iron."  Walrand,'  melting  sulphurous  cast-iron 
both  in  basic  and  in  siliceous  cupolas  with  from  10 
to  20$  of  lime,  found  that  in  both  the  greater  portion  of 
the  sulphur  was  removed  during  the  fusion.  Rol- 
let8 reports  that  a  simple  fu&ion  in  a  cupola- furnace  with 
basic  slag  removes  b5  to  90$  of  the  sulphur  of  but  moder- 
ately sulphurous  cast-irons,  and  90  to  95  and  occasionally 
98$  of  that  of  highly  sulphurous  ones,  containing  0'5$  of 
sulphur  or  more.  If  the  cupola  be  water-jacketed  the 
lining  may,  according  to  Rollet  be  either  acid  or  basic : 
but  if  unjacketed  its  lining  must  be  basic.  The  slag 
may  contain  as  much  as  2  $  of  silica. 

Both  Rollet  and  Walrand  employ  fluor-spar  :  it  prob- 
ably assists  desulphurization  by  liquefying  the  slag :  but 
that  it  is  not  essential  is  shown  by  the  fact  that  its  almost 
complete  omission  (line  3)  did  not  interfere  with  desul- 
phnrization.  Table  23  summarizes  their  results. 

TABLE  23. — I)EStri.rinTRizATioN  IN  CUPOLA  MELTING. 


No. 

Number  of  heats. 

tt 

0 

•^ 

1 

p 

u 

Additions  per  100  »f  cast-iron 
average. 

£Sul 
avei 

si 

I1 

>hur 
•age. 

%  Manga- 
nese 
average. 

t  Phos- 
phorus. 

*Carhon. 

*  Silicon. 

i 
•5. 

• 

•j 

! 
I 

K 

B 
I 

J 
!<3 
•< 

»l 

«2  3 

| 

II 

•< 

t 

a 

3 

1 

t 

£ 

S 

1 

1 

1 

1.     . 
8.   . 
3.   .. 
4.  .. 
5.   .. 
6.  .. 
7 

12 
1 
1 
1 
4 
4 

Basic 

Acid 
Acid 

B± 
0 

f 
f 

8 
8 

15± 
15 
10 

IS 
17-5 

6'9± 
8 
0  8 
1-3 
4'5 
62 

ni-8 
12 
18 
13 

19 
14 
( 

•62 
•58 
'71 
•71 
76 
•49 
•22 
•37 
•52 

•10 
•17 
•10 
17 
•OS 
•07 
•01 
•01 
•04 

•30 

•28 

1-40 
1-40 
1-80 
tr. 
tr. 

1-82 
1-26 
•81 
tr. 
tr. 

:3S 
•06 
•12 

•07 

•35 
1'95 

•06 
•07 
•41 

3  50 
2  90 

•-'••>:> 

8  50 
3  09 
2'SO 

•90 
•65 
•45 

8.... 

T'2®33 

2-4@4'8 

,3     j 

9.... 

Nos.  1  to  6,  Walrand ;  7  to  9,  Eollct. 


E.  MANGANESE  like  the  metals  of  the  alkaline  earths  ap- 
pears to  have  the  power  of  removing  sulphur  as  sulphide, 
since  manganiferous  blast-furnace  slags  often  contain  a  large 
amount  of  sulphur.     Thus  Parry  reports  finding  not  less 
than  2$  sulphur  in  these  slags  when  manganiferous,  while 
when  less  manganiferous  they  contained  less  sulphur  and 
the  accompanying  cast-iron  had  so  much  the  more.    Aker- 
man11 indeed  considers  that  manganese  removes  sulphur 
in  this  way  even  more    powerfully  than  calcium   does, 
so  that  under  like  conditions  the  richer  the  slags  are  in 
manganese  the  richer  are  they  also  in  sulphur. 

In  other  cases  manganese  causes  the  segregation  and 
liquation  of  compounds  rich  in  manganese  and  sulphur 
from  cast-iron  and  steel.  The  addition  of  spiegeleisen  to 
molten  sulphurous  cast-iron  causes  an  immediate  removal 
of  sulphur.  (See  §  81.) 

F.  HiDROGENdoes  not,  according  to  Percy,1  decompose 
ferrous  sulphide  :  yet  BoussingaultJ  states  that  Bouis  ob- 
served a  continuous  evolution  of  sulphuretted  hydrogen, 
which  persistently  blackened  acetate  of  lead  paper,  on 


<•  Jour.  Iron  and  St.  Inst.,  1880, 1.,  p.  213. 
f  Revue  UniverseUe,  X.,  p.  408,  1881. 

g  Stahl  und  Eisen,  III. ,  p.  305,  1883.     From  Bulletin  de  la  Socie'te'  de  1'Industrie 
Min<§rale. 

h  Ledebur,  Handbueh  de  Eisenhiittenkunde,  p.  258. 
I  Iron  and  Steel,  p.  33. 
i  Comptes  Rendus,  52,  p.  1,009. 


52 


THE    METALLURGY    OF     STEEL. 


passing  hydrogen  over  different  steels  at  a  red  heat,  which 
indicates  that  hydrogen  gradually  removes  sulphur  from 
steel.  Either  this  action  is  very  slight,  or  it  is  confined  to 
certain  conditions  of  exposure,  since  not  only  does  the  at- 
mospheric hydrogen  ordinarily  fail  to  remove  any  notable 
quantity  of  sulphur  in  the  Bessemer  process,  but  Forsyth,a 
blowing  simply  enormous  volumes  of  steam  along 
with  air  in  Bessemerizing  cast-iron,  found  that  no  re- 
moval of  sulphur  occurred :  yet  here  hydrogen  must  have 
been  abundantly  present,  since  the  steam  must  have  been 
decomposed  by  the  molten  iron. 

G.  STEAM  energetically  decomposes  ferrous  sulphide 
with  the  formation  of  sulphuretted  hydrogen  and  sul- 
phurous acid  as  well  as  hydrogen,  the  latter  being  formed 
perhaps  directly,  perhaps  by  the  action  of  water  on  the 
iron  oxide  previously  formed  (say  2FeS  -f-  4H2O  =  2  FeO 
-f  SO2  +  H2S  +  6H). 

It  is  stated  that  sulphur  may  be  expelled  from  cast-iron  by 
steam,  e.g.  that  when  cast-iron  which,  when  cast  in  pigs 
has  0'05$  sulphur,  is  granulated  in  water  it  is  freed  from 
this  element,0  and  that  the  steam  from  damp  sand-molds 
expels  sulphur  from  cast-iron  as  sulphuretted  hydrogen."1 
It  is  further  stated  that  prolonged  immersion  in  water  even 
at  the  ordinary  temperature,  and  even  simple  exposure  to 
moist  air  for  years  par! ially  removes  sulphur  from  iron 
Boussingault6  found  that  steam  gradually  removed  sul- 
phur from  steel  at  a  red  heat.  Exposing  cast-steel  (acier 
fondu,  not  molten  steel  as  Lenox  Smith'  translates  it)  in 
a  porcelain  tube  at  a  red  heat  to  steam,  a  persistent  odor  of 
sulphuretted  hydrogen  arose,  which  continued  during 
the  whole  course  of  the  experiment  (8  h.  SOmin.)  and 
acetate  of  lead  paper  was  persistently  blackened  by  it. 
So  too  Parryg  stated  that  jets  of  steam  blown  upon  the 
cinder  in  the  puddling  furnace  caused  the  removal  of  some 
sulphur  from  the  metal  and  of  a  great  deal  of  sulphur 
from  the  cinder.  Evidently  in  case  of  cast-irons  with  but 
little  sulphur  this  action  does  not  occur  to  an  important 
extent  at  high  temperatures  unless  under  special  condi- 
tions, since  the  employment  of  steam  in  the  Bessemer  pro- 
cess does  not  remove  sulphur. 

In  Parry's  case  the  steam  may  have  caused  the  removal 
of  sulphur  from  the  iron  indirectly,  by  decomposing  the 
ferrous  sulphide  of  the  slag,  and  thus  increasing  the 
power  of  that  slag  to  take  up  fresh  portions  of  sulphur 
from  the  metal.  This  accords  well  with  his  statement  that 
much  more  sulphur  was  removed  from  slag  than  metal, 
and  with  the  familiar  removal  of  sulphur  from  blast  fur- 
nace slags  with  the  accompanying  odor  of  sulphuretted 
hydrogen  by  steam  evolved  from  the  moist  ground  over 
which  they  flow.  This  suggests  the  possibility  of  increas- 
ing the  expulsion  of  sulphur  in  the  basic  Bessemer  pro- 
cess by  the  injection  of  steam  along  with  the  blast :  by 
desulphurizing  the  slag  it  might  increase  its  desulphur- 
izing power. 

H.  FERRIC  OXIDE,  FERROUS  SULPHATE  AND  ATMOS- 
PHERIC OXYGEN. — In  the  roasting  of  pyritous  ores  part  of 
their  sulphur  is  volatilized  without  oxidation :  part  is 


directly  oxidized  to  sulphurous  acid  and  thus  volatilized, 
be  it  by  the  atmospheric  oxygen  or  by  the  ferric  oxide  of 
the  ore  itself  (FeS  +  3,O  =  FeO  +  S0a,h  and  FeS  + 
10Fe3O3  =  7Fe3O4  +  SOa') :  part,  especially  at  low  tem- 
peratures, is  converted  into  ferrous  sulphate,  which  at 
higher  ones  in  part  reacts  on  still  undecomposed  ferrous 
sulphide  with  expulsion  of  sulphur  as  sulphurous  acid 
(say  FeS  +  3FeSO4  =  4FeO  +  4SO2,  in  this  way  sul- 
phur may  be  completely  expelled  according  to  Berthier), 
and  is  in  part  decomposed  with  complete  expulsion  of  its 
sulphur  as  sulphurous  and  sulphuric  acids  (2FeSO4  = 
Fe3S06  +  S03  and  FeS06  =  Fe2O3  +  S(V). 

The  sulphur  of  cast-iron  may  also  be  oxidized  and  ex- 
pelled by  ferric  oxide,  as  is  shown  by  its  rapid  expulsion 
in  pig-washing  (the  Bell-Krupp  process),  in  the  basic 
open-hearth  process  and  in  puddling,  in  which  say  60  to 
90,  40  to  90  and  50  to  60$  respectively  of  the  sulphur  may 
be  removed,  partly  at  least  as  ferrous  sulphide,  since  as 
much  as  1%  of  this  substance  occurs  in  puddling  slags. 

I.  ALKALINE  NITRATES  as  in  the  Heatou  process  (in 
which  molten  cast-iron  is  brought  into  contact  with  nitrate 
of  soda)  rapidly  remove  sulphur  from  cast-iron.  Thus 
Prof.  Miller  reports  that  by  this  process  the  sulphur  was 
reduced  from  0-113  to  -018$.  Snelus*  reports  1  "225$  "sul- 
phuric acid"  in  the  slag  of  the  Heaton  process.  Gruner1 
found  that  from  85  to  94$  of  the  sulphur  of  cast-iron 
containing  0-34$  sulphur,  and  from  67  to  100$  of  that 
contained  in  a  cast-iron  with  -09$  sulphur  was  expelled 
by  this  process  ;  the  slag  had  in  one  case  0'6()$  sulphur 
and  070$  sulphuric  acid. 

§  94.  EEDSHORTNESS.— Sulphur  has  the  specific  effect  of 
making  iron  exceedingly  brittle  at  a  red  heat  and  of  destroy- 
ing its  welding  power.  Its  effects  are  in  general  most 
marked  at  a  dull-red  heat,  and  irons  which  crack  at  this 
temperature  owing  to  the  presence  of  a  small  percent- 
age of  sulphur  may  often  be  readily  forged  at  higher  tem- 
peratures, while  when  cold  they  are  as  malleable  and  in- 
deed often  more  malleable  than  non-sulphurous  irons.  If 
however  the  percentage  of  sulphur  is  considerable,  the  iron 
is  no  longer  malleable  even  at  temperatures  above  redness. 
Manganese  counteracts  these  effects  of  sulphur.  (See 
§81.)  The  redshortness  imparted  by  a  given  percentage 
of  sulphur  is  probably  independent  of  the  percentage  of 
carbon  which  accompanies  it:  but  more  sulphur  can 
usually  be  tolerated  in  steel  rich  in  carbon  than  in  others 
because  such  steel  usually  contains  much  manganese 
also. 

Eggertz™  found  that  at  a  red  heat  weld  iron  with  0-02$ 
sulphur  cracked  when  punched  through,  and  with  0'03$ 
sulphur  cracked  at  the  corners  when  being  drawn  out. 
But  I  doubt  if  the  effects  of  '03  per  cent  of  sulphur 
would  ordinarily  be  serious :  Bell"  quotes  iron  rails, 
whose  manufacture  calls  for  great  malleableness,  with 
0-124  sulphur  though  without  manganese.  Their  com  posi- 
tion was,  carbon  -10,  silicon  trace,  sulphur  '124,  phosphorus 
•363,  manganese  trace.  Another  had  '08  sulphur  with  "11 
manganese. 


a  Trans.  Am.  Inst.  Mining  Engineers,  XII.,  p.  36rf. 

b  Balling,  Compendium  der  Metallurgischen  Chemie,  p.   52.    Percy,  Iron  and 
Steel,  p.  33  ;  Watts,  Dictionary  of  Chemistry,  III. ,  p.  400. 
c  Akerman,  Eng.  and  Mining  Jl.,  1875, 1.,  p.  353. 
d  Ledebur,  Op.  Cit.,  p.  251. 
e  Comptes  Rendus,  52,  p.  1,008. 
t  Manufacture  of  Steel,  Gruner,  Smith,  p.  76. 
8 Percy,  Op.  Cit.,  p.  667 


h  Balling,  Op.  Cit.,  p.  46. 
I  Percy,  Op.  Cit.,  p.  35. 
1  Balling,  Op.  Cit.,  pp.  36-40. 
k  Journ.  Iron  and  St.  Inst.,  1871,  II.,  p.  186. 
i  Annales  des  Mines,  1869,  XVI. 

mEng.  and  Mining  JL,  1875,  I.,  p.  458  :  Jerukontorets  Annalen,  1860,  p.  15. 
n  Manufacture  of  Iron  and  Steel,  p.  428.    Journal  Iron  and  St.  Ins':.,  1877,  II., 
p.  325. 


THE     EFFECTS     OF     SULPHUR.       §  96. 


The  older  determinations  of  sulphur  are  not  to  be 
trusted,  since  precautions  to  prevent  its  absorption  from 
the  coal  gas  were  too  often  omitted :  they  gave  the  sul- 
phur in  weld  iron,  even  when  apparently  of  good  quality, 
as  high  as  ()-60  and  even  '757$.  Rejecting  these  old 
analyses  and  all  other  doubtful  ones,  I  find  that  among  86 
cases  of  weld  iron,  drawn  from  many  sources,  the  maxi- 
mum sulphur  is  0'124$  ;  many  are  reported  as  quite  free 
from  sulphur,  while  the  average  is  only  '017$ :  but  as  a 
majority  of  the  cases  represent  unusually  good  irons  the 
average  here  given  is  somewhat  below  that  of  com- 
mercial irons.  Eleven  iron  rails*  given  by  Bell  average 
•045  sulphur. 

Ingot  metal  it  is  thought  may  contain  a  much  larger  per- 
centage of  sulphur  than  can  be  tolerated  in  weld  metal, 
be  it  because  the  sulphur  in  the  former  is  less  liable  to 
be  locally  concentrated,  be  it  because  it  contains  far  more 
manganese,  whose  presence  counteracts  sulphur.  The 
highest  percentages  of  sulphur  which  I  have  met  in  rail 
steel  are  given  in  Table  24. 


TAIILE  24.— SULPHUROUS  KAIL  STEEL. 


Carbon  . 

Silicon. 

Phosphorus. 

Sulphur. 

Slag. 

Copper, 

1. 

2.. 
8. 
4.. 

5 
6. 
7. 

•787 
•072 
•865 
•686 
•803 
•252 
•41 
•45 

•0-1:5 
•041 
•041 
•041 
•009 
•008 

•10  ' 

•099 

•Ils:i 

•988 

•240 
•194 

•nil 
•06 

•173 
•18S 

"J17 

•143 
•107 
•22 

•15 

•S31 
•816 
•'.115 
•'.110 

•604 
•97 
1-81 

•1124 
•1122 
•040 
•022 

il-.'ll 
•020 

•073 
•074 
•077 
•1175 
•018 

•on 

French  rail. 

9 
10. 
11 

•41 
•52 
•52 

•14 

•OS 
•12 

•O.r) 

•08 

•05 

•15 
•17 
•15 

1-46 
1-04 
1  01 

r.ritish  rails. 

12. 
13. 
14. 
15. 
16. 
17. 
18. 
19. 

•89 

.•-'ll 
•31 
•22 
48 
•54 
•43 
•29 

•14 

•14 
•07 
•09 
•07 

•07  ' 

•06 
•04 
•04 
•03 
•12 
•12 
•13 

•20 
•21 
•23 
•62 
•54 
•30 
•46 

•69 
•50 
•49 
•48 
1-88 
1-56 
181 

b" 

c 

•04 
•08 
•06 
•07 

Slightly  redshort. 
I  Very  redshort. 
f  Total  wreck. 
Fell  in  pieces. 

Nos.  1  to  6j  Forsyth  Western  U.  9.  rails,  private  communication.  7.  Morrell,  Metallurgical 
Review-,  II..  p.  193.  8  to  11,  Bell,  Manufacture  of  Iron  and  Steel,  p.  414.  12  to  J  5, 
Wasum,Stalil  unil  Kisen,  lsS2,  p.  192.  16  to  •  9,K.  VV.  Lodge,  private  communication,  Feb.,  1SS7; 
rails  made  at  an  Illinois  mill,  a.  These  analyses  are  Iroiu  the  opposite  end  of  the  rail  from  which 
analyses  1  and  2  come.  b.  This  heat  of  steel  yielded  60#  of  "  lost"  (i.  e.,  worthless)  rails  and  36;? 
of  second  quality  rails  :  it  was  so  redshort  that  some  of  the  ingots  fell  to  pieces  in  the  blooming 
roll-train,  c,  This  heat  yielded  73$  of  first  quality  rails,  1S#  of  second  quality  and  9$  of  '•  lost  " 


Some  European  rails  appear  to  be  much  richer  in  sul- 
phur than  those  made  in  this  country:  thus  while  W. 
Richardsb  admits  that  0*20$  sulphur  makes  steel  very  red- 
short,  Thomas"  states  that  this  amount  can  be  tolerated, 
and  E.  Rileyd  has  known  rails  with  0'27  sulphur  to  pass 
the  mechanical  tests  required.  But  with  these  high  per- 
centages of  sulphur  the  steel  is  so  redshort  that  it  must 
be  rolled  at  a  very  high  temperature.  Instances  in  which 
the  sulphur  in  rails  exceeds  '18%  are  so  rare  that  they 
might  be  thought  to  represent,  not  the  average  composi- 
tion of  the  whole  rail,  but  merely  that  of  some  segre- 
gated spot.  I  am,  however,  convinced  that  analyses  7, 
16,  17,  18  and  19,  with  from  -22  to  -62$  of  sulphur,  rep- 
resent the  mother  metal,  since  the  observers  privately  in- 
form me  that  the  borings  were  taken  from  the  upper  por- 
tion of  the  head  of  the  rail,  while  segregations,  if  present, 
occur  at  the  junction  of  head  and  web,  i.e.,  near  what 
has  been  the  center  of  cross-section  of  the  ingot.  (These 
analyses  are  from  thin-flanged  T  rails.) 

Sandberg,"  whose  opportunities  for  observation  are  ex- 
cellent, states  that,  in  about  800  instances,  rail  steel  (pre- 
sumably largely  British)  contained  usually  from  -03  to  ' 


a  Manufacture  of  Iron  and  Steel,  p.  428. 
b  Journ.  Iron  and  St.  Inst,  1880,  I.,  p.  100. 
c  Idem,  p.  1 10. 
d  Idem.,  p.  197. 

e  Trans.  Am.  Inst.  Min.  Eng.,  X.,  p.  410,   1882  :    Journ.   Iron  and  St.    Inst., 
1883,  I.,  p.  258. 


sulphur  :  20$  of  the  cases  had  less  than  -03$  sulphur  and 
24$  of  them  had  more  than  '06$.  The  rail  steel  of  our 
Eastern  mills  has  usually  from  -03  to  '06$  sulphur:  that  of 
our  Western  mills  has  usually  somewhat  more,  occasion- 
ally as  much  as  '10,  -12  and  even  exceptionally  '14$.  When 
sulphur  is  under  '08  its  effects  are  probably  almost  com- 
pletely effaced  by  the  presence  of  '8')$  manganese,  since 
with  this  composition  the  redshortness  is  so  slight  that  T 
rails,  the  formation  of  whose  thin  flanges  necessitates 
great  malleableness,  can  be  rolled  with  so  little  cracking 
that  at  some  mills  only  0'4$  of  the  rails  made  are  of  sec- 
ond quality  (i.  e.  have  cracked  flanges). 

In  some  of  the  western  mills  however,  especially  when 
high  phosphorus  accompanies  high  sulphur,  as  much  as 
10$,  and  at  one  mill  occasionally  even  15$  of  the  rails  have 
been  of  second  quality.  From  the  evidence  I  judge  that 
if  the  sulphur  often  rises  above  0-08  a  considerable  per- 
centage (say  2  to  4$)  of  second  quality  rails  is  liable  to 
be  made,  if  above  0-11$  the  number  of  second  quality 
rails  is  liable  to  be  excessive,  and  if  it  be  as  high  as  0'18$ 
the  number  is  likely  to  be  ruinous. 

Pieces  of  a  shape  which  can  be  produced  without  ne- 
cessitating such  extreme  malleableness  as  the  formation 
of  the  thin  flanges  of  T  rails  requires  may  contain  more 
sulphur :  and  we  may  suspect  that  the  rails  quoted  by 
Riley  as  containing  0'27$  of  sulphur  were  not  of  the 
thin  flanged  T,  but  of  the  comparatively  easily  rolled 
double-headed  pattern.  But  it  is  rare  to  find  more  than 
0'12  sulphur  in  any  steel.  Crucible  tool  steel  has  ordi- 
narily less  than  0'01$  (though  Metcalf  quotes  wire  dies 
with  0'09$).f  Nail  plate  has  usually  from  0'05  to  0-10, 
boiler  plate  from  0-02  to  0'08$. 

Manganese  counteracts  the  effects  of  sulphur,  as  de- 
scribed in  §  81,  where  it  is  stated  that  in  many  cases  4'5 
parts  by  weight  of  manganese  so  far  counteract  the  effects 
of  1  part  of  sulphur  as  to  permit  the  rolling  of  flanged  T 
rails. 

§  95.  WELDING. — Sulphur  also  interferes  with  the  welding 
power  of  iron,  but  we  have  little  quantitative  information 
as  to  its  effect  in  this  respect.  The  U.  S.  testing  board  found 
that  -046$  sulphur  in  wrought-iron  (the  highest  percentage 
which  they  encountered)  did  not  affect  its  welding.g  Hr.r- 
bord  reports  basic  open-hearth  steel  with  carbon  '13,  sul- 
phur -125  and  manganese  '51$  and  another  lot  with  car- 
bon. "16,  sulphur  -20  and  manganese  "78$  which  welded 
perfectly  ;  this  is  most  surprising,  even  if  we  make  great 
allowance  for  the  elastic  sense  in  which  "  perfect  welding" 
is  often  used.h 

§  96.  TENSILE  STRENGTH  AND  DUCTILITY. — The  red- 
shortness  caused  by  sulphur  may  diminish  tensile  strength 
and  ductility  by  breaking  up  the  continuity  through 
cracks,  perhaps  internal  and  beyond  detection.  But 
apart  from  this  let  us  consider  its  direct  effects.  In 
moderate  quantity  sulphur  makes  weld-iron  tougher,  and 
it  is  generally  thought  to  have  the  same  effect  on  ingot 
metal :  though  the  evidence  is  neither  decisive  in  kind 
nor  in  amount,  it  favors  this  view.  Many  American  ex- 
perts with  preconceived  and  tenaciously  held  belief  that 
manganese  like  phosphorus  makes  steel  brittle,  yet  find- 
ing in  western  rails  percentages  of  manganese  with 


*  Trans.  Am.  Inst.  Mining  Engineers,  IX. ,  p.  549. 
BHolley,  Trans.  Am.  Inst.  Mining  Engineers,  VI.,  p.  111. 
h  Journ.  Iron  and  St.  Inst.,  1886,  II.,  pp.  701-703  and  735. 


THE    METALLURGY    OF     STEEL. 


phosphorus  which,  in  their  view,  should  make  them  so 
brittle  that  they  should  break  under  the  straightening 
press,  explain  their  ductility  by  supposing  that  the  sul- 
phur, which  is  often  high  in  western  rails,  makes  steel 
tough,  counteracting  the  manganese  and  phosphorus.  But 
unfortunately  this,  like  other  explanations  based  on 
limited  knowledge,  will  not  stand  the  least  scrutiny :  for 
we  find  many  western  rails  with  abnormally  high  man- 
ganese and  phosphorus,  with  high  carbon  yet  with  very 
little  sulphur,  which  are  still  tough.  So  here  the  ex- 
plainers must  fall  back  on  hydrogen  or  ozone  or  what- 
ever they  can  think  of  which  is  undeterminable.  In 
Table  25  are  collected  a  few  cases  of  rails  whose  com- 
position should,  if  the  ordinary  views  be  correct,  be  ex- 
tremely brittle,  whose  sulphur  is  low,  in  many  cases  ex- 
tremely low,  yet  which  at  least  are  not  extremely  brittle : 
indeed,  some  of  them  are  extremely  tough. 

TABU;  25. — GOOD  EAII.S  WITH  HIGH  PIIOSPHOKUS  AND  MANGANESE  BUT  LOW  SULPUUB. 


• 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

•34 
•M 

res 

•15 
•07 

•37 
•05 
1  50 
•14 
•07 

.45 
•06 
1-23 
•14 
•04 

•88 
•01 
1-45 
•15 
•05 

•35 
•05 
1-58 
•14 
•06 

•40 
•06 

1-58 
•12 
•06 

•42 
•04 
1-3S 
•13 
•08 

•38 
•06 
1  57 
•12 
•023 

•42 
•05 
1-39 
•18 

•02S 

•76 
•58 
1-85 
•06 
•013 

•52 
•87 
2-03 
•11 

•05 

•70 
•60 
1-84 
•06 
•018 

•38 
•08 

1-87 
•24 
•07 

? 
•49 
•74 
•144 
•055 

Silicon 

Nos.  1  to  9  Inclusive,  rails  from  U.  S.  ores  rolled  at  a  western  U.  S.  mill.    Nos.  10  to  13  rails 
rolled  fro:n  imported  blooms  at  another  western  mill.    Private  communications.    14.   Mailer, 
Journ.  Iron  and  St.  Inst.,  1882,  1.,  p.  375. 

Important  light  might  have  been  thrown  on  the  effect 
of  sulphur  on  strength,  ductility  and  wearing  power  had 
Dudley  and  Beck-Guerhard,  in  their  investigations  into 
the  relations  between  composition  and  the  physical 
properties  of  rail  steel,  determined  the  sulphur  in  the 
rails  observed :  this  they  unfortunately  neglected  to  do, 
pleading  that  sulphur  is  so  very  objectionable  to  the  rail- 
maker  that  the  consummer  need  not  trouble  himself 


about  it,  as  if  it  were  not  extremely  possible  that  varia- 
tions of  sulphur  below  the  maximum  which  the  rail- 
maker  can  permit  might  not  affect  the  wearing  power, 
both  directly  and  indirectly,  and  help  to  explain  the 
inconsistencies  in  their  results.  A  high  percentage  of 
sulphur  may  indirectly  have  a  most  potent  effect  on  wear," 
by  necessitating  finishing  the  rail  at  an  excessively  high 
temperature. 

Morrell,"  when  comparing  by  his  wearing-test  appa- 
ratus steel  No.  7  of  Table  24  with  Cambria  steel  with  much 
less  sulphur  but  of  otherwise  closely  similar  composition 
(viz  ,  carbon  '44,  manganese  '53,  phosphorus  "079,  sul- 
phur '02),  found  that  the  rail  rich  in  sulphur  lost  weight 
much  more  rapidly  than  the  other,  in  one  case  80$  faster. 
As  far  as  this  goes  it  indicates  that  sulphur  makes  steel 
softer,  but  it  throws  no  strong  light  on  toughness  and 
tensile  strength,  because  one  swallow  makes  no  summer, 
and  because,  though  toughness  usually  accompanies  soft- 
ness and  low  tensile  strength,  there  is  no  necessary  relation 
between  them.  Kerpely  b  from  prolonged  examination 
considers  that  sulphur  softens  steel :  E.  Williams c  con- 
siders that  it  toughens  it :  Parry d  is  unequivocally  of 
the  opinion  that  it  strengthens  it :  Adamson e  thinks 
that  it  renders  it  brittle,  but  he  appears  to  have  some- 
thing like  a  monopoly  of  this  opinion. 

§  97.  SULPHUR  IN  CAST-IRON. — Sulphur  is  generally 
thought  to  make  cast-iron  hard  and  brittle.  The  Fin- 
spong  (Swedish)  gun  cast-iron  has  from  O'lO  to  0-15$  of 
sulphur  intentionally  imparted  to  it  by  the  addition  of 
pyrites.  But  whether  the  hardness  is  directly  caused  by 
the  presence  of  the  sulphur  is  doubtful,  for  it  is  well 
known  that  sulphur  has  the  specific  effect  of  causing  car- 
bon to  be  retained  in  the  combined  state,  which  in  itself 
of  course  greatly  increases  the  hardness  of  the  iron.' 


CHAPTER   VI. 
IRON    AND    PHOSPHORUS. 


§100.  SUMMARY. — PHOSPHORUS,  the  steelmaker's  bane, 
unites  with  iron  probably  in  all  proportions  at  least  up  to 
26$,  being  readily  absorbed  by  it,  especially  at  high  temper- 
atures and  when  under  deoxidizing  conditions,  from  acid 
phosphates  and  silico-phosphates.  Fortunately  itjis  readily 
removed  from  iron,  especially  under  strongly  oxidizing 
conditions,  by  contact  with  strong  bases  (oxides  of  iron 
and  manganese,  the  alkalies  and  alkaline  earths)  and  by 
basic  silicates  and  even  silico-phosphates,  by  alkaline  car- 
bonates and  nitrates  and  by  fluor  spar.  It  is  volatilized 
under  many  conditions,  e.  g.,  when  phosphates  are  heated 
with  carbon  (the  presence  of  metallic  iron  more  or  less 
completely  prevents  this  volatilization) :  and  when  molten 
phosphoric  cast-iron  is  brought  in  contact  with  alkaline 
nitrates  or  (probably)  with  fluor  spar.  In  the  blast- 
furnace, however,  phosphorus  is  not  effectively  volatilized, 
for  any  which  volatilizes  immediately  recondenses.  Hence 
in  the  blast-furnace  nearly  all  the  phosphorus  passes  into 
the  metal,  though  a  little  is  found  in  the  slag  if  the  deox- 
idizing conditions  be  weak.  In  puddling  90$,  and  in  the 
basic  Bessemer  process  96  to  99$  or  even  more  of  the  phos- 
phorus initially  present  may  be  removed  under  favorable 
conditions. 


Phosphorus  probably  has  little  effect  on  tensile  strength 
under  gently  applied  load  :  but  phosphoric  iron  is  readily 
broken  by  jerky,  shock-like  or  vibratory  stresses,  some- 
times when  quite  trifling : — it  is  treacherous.  It  some- 
times affects  iron  but  slightly,  sometimes  under  apparently 
like  conditions  profoundly : — it  is  capricious.  It  usually 
increases  the  elastic  limit,  thus  raising  the  elastic  ratio, 
an  index  of  brittleness.  It  diminishes  also  the  elongation 
and  contraction  on  rupture,  two  other  measures  of 
ductility,  affecting  this  property  like  tensile  strength 
much  more  under  shock  than  under  quiescent  stress.  Car- 
bon greatly  intensifies  these  effects  of  phosphorus,  and 
silicon  may  intensify  them,  but  certainly  to  a  very  much 
smaller  degree  if  at  all.  Low  temperature  is  thought  to 
intensify  them,  but  I  find  no  evidence  to  support  this 
opinion,  i.  e.  to  show  that  there  is  more  difference  between 
the  ductility  of  phosphoric  and  that  of  non-phosphoric 


a  Metallurgical  Review,  II.,  p.  193. 
b  Idem,  II.,  p.  531. 

c  Journ.  Iron  and  Steel  Inst.,  1880,  I.,  p.  199. 
d  Idem,  p.  198. 
« Idem,  p.  197. 

'  Akerman,  Eng.  and  Mining  Jl.,  1875, 1.,  p.  458  :   Turner,  Jour.  Iron  and  St. 
Inst.,  1886, 1.,  p.  184  :  Ledebur,  Handbuch,  p.  251. 


THE    CONDITION    OF    PHOSPHORUS    IN    IRON. 


101. 


65 


steel  at  very  low  temperatures  than  at  70°  F.  Rapid  cool- 
ing and  forging  during  cooling,  by  preventing  the  coarse 
crystallization  to  which  phosphoric  iron  strongly  inclines, 
oppose  the  effects  of  phosphorus  on  ductility.  It  is  cer- 
.tain  that  phosphorus  does  not  always  diminish  the  hot- 
malleableness  of  iron,  at  least  at  moderate  temperatures  ; 
but,  by  increasing  the  tendency  to  coarse  crystallization, 
it  probably  diminishes  malleableness  at  very  high  tem- 
peratures, and  especially  when  the  iron  has  slowly  cooled 
without  forging  from  a  very  high  temperature  to  a  some- 
what lower  though  still  high  one,  as  this  seems  to  be  the 
condition  most  favorable  to  coarse  crystallization.  It  is 
thought  to  increase  the  welding  power  and  to  slightly  lower 
the  modulus  of  elasticity :  what  evidence  I  find  opposes 
the  latter  view. 

§  101.  THE  CONDITION  OF  PHOSPHORUS  iff  IRON. — In 
ingot  metal  phosphorus  exists  chiefly  if  not  exclusively 
as  phosphide  :  but  in  weld  metal  it  probably  exists  both 
us  phosphide  and  as  phosphate,  i.  e.  as  part  of  the  me- 
chanically intermixed  slag,  in  which  condition  it  is  reason- 
able to  suppose  that  its  effect  on  the  mechanical  properties 
of  the  metal  should  be  comparatively  slight.  Many,  and 
perhaps  an  indefinite  number  of  phosphides  of  indefinite 
composition  may  exist  in  iron,  for  we  find  wide  differences 
between  the  chemical  behavior  of  different  portions  of 
phosphorus  even  in  one  and  the  same  piece  of  iron,  and 
apparently  equally  wide  discrepancies  between  the  effect 
of  a  given  quantity  of  phosphorus  on  the  physical 
properties  of  different  irons.  The  differences  in  the  chem- 
ical behavior  of  phosphorus  are  exemplified  by  the  fact 
that,  on  dissolving  some  steels  in  chlorhydric  acid,  part  of 
(he  phosphorus  escapes  as  phosphoretted  hydrogen,  part 
is  found  as  phosphoric  acid,  part  apparently  as  some 
lower  oxygen  acid,  while  still  another  part  is  insoluble. 

The  existence  in  solid  iron  of  a  definite  phosphide  of 
iron,  Fe3P,  and  probably  that  of  a  definite  phosphide  of 
manganese,  MnaP3,  is  well  established.  Hvoslef,a  on  melt- 
ing the  non-magnetic  phosphide  Fe3P  under  borax,  ob- 
tained the  magnetic  phosphide  Fe3P,  while  Percy,  by  di- 
gesting in  cupric  chloride  a  phosphide  prepared  by  the 
action  of  lumps  of  phosphorus  on  red-hot  iron,  obtained  a 
crystalline  phosphide  with  85$  iron,  corresponding  closely 
to  Fe3P,  which  should  contain  84 '4$  phosphorus.  These 
facts  suggest  that  iron  and  phosphorus  preferentially  com- 
bine in  this  particular  ratio.  Shimer'sb  investigations  in- 
dicated the  presence  of  such  a  phosphide  in  cast-iron, 
though,  as  he  had  been  unable  to  completely  free  it  from 
titanium  carbide,  he  had  not  definitely  determined  its  com- 
position. 

Less  than  a  month  later  L.  Schneider0  described  the 
phosphide  Fe3P,  which  he  isolated  from  eight  different 
samples  of  cast-iron  by  digestion  in  cupric  chloride,  as  a 
crystalline,  dark  gray,  strongly  magnetic,  friable  sub- 
stance, with  metallic  lustre,  almost  insoluble  in  dilute 
acids,  rapidly  dissolved  by  nitric  acid  and  by  aqua  regia, 
and  dissolved  by  hot  concentrated  chlorhydric  acid  with 
evolution  of  phosphoretted  hydrogen.  Three  of  the 
cast-irons  examined  contained  a  considerable  amount  of 
manganese :  one  of  these  yielded  a  slightly  manganifer- 
ous  magnetic  phosphide,  the  others  yielded  highly  manga- 

a  Journ.  Prakt.  Chemie,  LXX.,  p.  149. 

b  "  Titanium  Carbide  in  Pig-iron,"  read  in  October,  18S61  before  the  Am.  Inst. 
Mining  Engineers, 
c  Oesterreicb.  Zeitschrift,  1886,  p.  735,  No.  45. 


1. 

2. 

8. 

4. 

5. 

6. 

7. 

8- 

0-2 
2-5 

"i:J.r) 

H  47 
0-58 

0 
1-48 

•07 
0-94 

4-88 
2-01 
5-7 
20  5 

0  00 

IS-  15 
3'4 
5-2  '8 
87-7 

0-60 

•28.7 
IP-:;S 
54  4 
88  8 

o-io 

In  the  <™'-i™n]  Phosphorus           .  ... 

intn  in  it.                             /  Phosphorus. 

IlisiTi'iKLiiry   l>"U\v-'M     phosphorus   found 

18-6 

o-ir, 

is'i 

0  15 

18-2 
0-25 

18-8 

0-25 

is  :> 
0-05 

niferous  and  non-magnetic  phosphides.     These  three  man 
ganiferous  phosphides  corresponded  very  closely  to  the 
formula  xFe3P,yMn3P2. 

The  composition  of  these  eight  phosphides  is  surpris- 
ingly close  to  the  calculated  composition,  especially  as 
other  substances  insoluble  in  cupric  chloride  would  be  ex- 
pected to  accompany  the  phosphide.  I  here  summarize 
Schneider's  results. 

PHOSPHIDES  OBTAINED  BY  SCHNEIDER  ON  DIGESTING  CAST-IRON  IN  CUPRIC  CHLORIDE. 


The  presence  of  phosphates  in  weld  iron,  long  reason- 
ably suspected  because  the  metal  contains  a  consider- 
able quantity  of  the  slag  which  accompanies  its  produc- 
tion and  which  ordinarily  contains  phosphates,  and 
because  the  properties  of  weld  metal  are  often  but  slightly 
affected  by  the  presence  of  a  considerable  quantity  of 
phosphorus,  is  shown  to  be  exceedingly  probable  by  the 
fact  that  when  weld  metal  is  volatilized  with  chlorine  a 
large  proportion  of  its  phosphorus  remains  in  the  non- 
volatile residue. 

There  is  however  little  reason  to  expect  the  presence 
of  an  important  quantity  of  phosphate  in  ingot  metal,  ex- 
cepting perhaps  that  made  by  the  basic  process,  (A)  be- 
cause the  slag  which  accompanies  its  production  is  ordi- 
narily nearly  or  quite  free  from  both  phosphates  and 
phosphides  ;  (B)  because  the  metal  itself  ordinarily  con- 
tains but  a  trifling  quantity  of  such  slag,  often  less  than 
0-02$ ;  (C)  because  the  slag  which  accompanies  the  pro- 
duction of  the  metal  is  ordinarily  acid,  and  we  find  that 
metallic  iron  greedily  reduces  and  absorbs  the  phosphorus 
from  acid  slags ;  and  (D)  because  if  phosphorus  were 
present  as  phosphate,  i.  e.  as  a  simply  mechanically  inter- 
mixed foreign  substance,  we  should  reasonably  expect 
that  it  would  gradually  separate  from  the  molten  ingot 
metal  by  gravity :  while  in  fact  phosphoric  steel  may  lie 
for  hours  in  tranquil  fusion  in  the  open-hearth  furnace  ap- 
parently without  the  loss  of  the  smallest  trace  of  phospho- 
rus. But  in  spite  of  these  obstacles  Dudley  would  explain 
the  difference  (of  whose  existence  I  endeavor  to  show 
in  §  129  there  is  no  evidence)  between  the  forging  proper- 
ties of  Bessemer  steel  made  (A)  in  the  Clapp-Griffiths  and 
(B)  in  the  common  converter  by  the  existence  of  phos- 
phorus as  phosphate  in  the  former."1  But  as  he  offers  no 
evidence  we  may  dismiss  his  plea.  Cheever  would  ex- 
plain the  different  chemical  behavior  of  different  portions 
of  phosphorus  in  the  same  piece  of  steel,  and  the  differ- 
ent effects  of  phosphorus  on  the  physical  properties  of 
different  steels,  by  the  existence  of  both  phosphates  and 
phosphides,  though  these  differences  are  as  fully  and 
more  simply  explained  by  the  existence  of  different  phos- 
phides. He  argues  that,"  because  certain  definite  phos- 
phides of  iron  are  difficultly  soluble  while  certain 
phosphates  dissolve  readily,  and  because  part  of  the  phos- 
phorus found  in  ingot  iron  and  steel  is  readily  soluble, 
therefore  this  portion  exists  as  phosphate,  a  conclusion 
certainly  not  warranted  by  the  premises.  The  fact  that 
certain  phosphides  dissolve  with  difficulty  does  not  prove 

a  Trans.  Am.  Inst.  Mining  Engineers,  XIV.,  1886,  p.  938. 
eQp.  Cit.,  XV.,  1887,  to  appear. 


THE    METALLURGY    OF     STEEL. 


that  none  dissolve  readily.  Indeed,  a  phosphide  of  manga- 
nese, MnaP2,  whose  presence  is  far  more  probable  than  that 
of  a  phosphate,  is  thought  to  be  readily  soluble.  To  clear 
the  matter  up  he  volatilizes  several  irons  with  chlorine, 
and  examines  the  non-volatile  residiie  for  phosphorus, 
at  the  same  time  treating  other  portions  of  the  same 
irons  with  several  weak  solvents,  cupric  sulphate,  ferric 
chloride,  cold  dilute  chlorhydric  acid,  etc.  I  here  sum- 
marize the  more  important  features  of  his  results  :a 


When  the  many  necessary  precautions  are  observed  and 
when  we  know  that  oxygen  is  wholly  absent,  phosphorus 
found  in  the  residue  from  ignition  in  chlorine  may  be  held 
to  have  existed  in  the  metal  as  phosphate.  The  liability 
to  err  in  this  method  is,  however,  very  great,  and  hero  sev- 
eral facts  raise  suspicion  of  error.  (1)  The  proportion  of 
the  total  phosphorus  apparently  existing  as  phosphate  is 
often  very  much  lower  in  unrecarburized  than  in  recarbur- 
ized  metal :  (2)  all  or  nearly  all  the  phosphorus  of  weld 
metal  appears  as  phosphate  :  and  (3)  the  indications  af- 
forded by  the  weak  solvents  are  largely  directly  opposed 
to  those  of  the  chlorine  treatment.  The  solvents  indicate 
that  much  or  most  of  the  phosphorus  of  the  cast-iron  is 
phosphate,  chlorine  shows  that  none  of  it  is :  the  solvents 
indicate  that  nearly  all  the  phosphor  us  of  the  decarburized 
metals,  of  the  steels  and  of  the  weld  irons  is  phosphate, 
chlorine  indicates  that  little  of  it  is.  To  abandon  the  orig- 
inal ground  and  assume  that  it  is  the  phosphides  that  dis- 
solve readily  and  the  phosphates  that  resist,  helps  little : 
for  then  the  solvents  would  show  that  say  half  the  phos- 
phorus of  the  cast-iron  is  phosphate,  while  chlorine  shows 
that  none  is.  Cheever's  results  diminish  the  improbabil- 
ity of  the  existence  of  important  quantities  of  phosphate 
in  ingot  metal :  in  my  opinion  evidence  less  tainted  with 
suspicion  is  needed  to  convert  it  into  a  probability.  Note 
that  a  smaller  proportion  of  the  phosphorus  of  Clapp- 
Criffiths  than  of  other  Bessemer  steel  appears  as  phos- 
phate. 

SEGREGATION. — Phosphorus  has  a  strong  tendency  to 
segregate  in  phosphoric  steel ;  this  may  give  rise  to  errone- 
ous determinations  unless  special  precautions  are  taken. 
I  append  a  few  cases  observed  by  Porsyth. 

SEGREGATION  OF  PHOSPHORUS. 


Metal. 

Phosphorus  existing  as  phosphate  per  100  of  total 
phosphorus. 

As  indicated  by  ignition 
in  chlorine. 

As    indicated    by 
solvents. 

weak 

0 
90  ±  to  100 

2  ± 
26  ± 

14®20  ± 

50  ± 
73 

63  ± 

S7@91  ± 

75  ± 

Weld  iron                                 

Blown  and    unrecarburized    Bessemer     Btccl 

Ilosscmer  steel  (Clapp-Griftiths  converters)... 

A 

B 

A 

B 

A 

B 

A 

B 

•60 
•09 
•29 
•79 

•31 
•09 
•11 
•68 

•70 

'  :85 

1-'f> 

•25 

•07 
•97 

•39 
•08 
•23 

•85 

•30 
•03 
•14 
•71 

•30 
•01 
•24 
•59 

•25 
•01 
•19 

00 

Silicon                

MaliLMin  -••  

A  =  Segregation.    B  =  Mother  metal  . 
Private  communication  Jan.  27.  1S86. 

§  102.  UNION  OF  PHOSPHORUS  AND  IKON — DIRECT 
COMBINATION. — Phosphorus,  when  dropped  on  red-hot 
iron,  is  greedily  absorbed  :  but  Percyb  was  unable  in  this 
way  to  make  iron  take  up  more  than  8  '4$  phosphorus, 
forming  a  beautifully  crystalline  substance,  approaching 
the  composition  Fe6P. 


COMBINATION  UNDEU  DEOXIDIZING  CONDITIONS. — Under 
strongly  deoxidizing  conditions  iron  can  take  up  a  large 
percentage  of  phosphorus,  certainly  26$.  Thus  Brackels- 
berg,  melting  lime  phosphate  with  ferric  oxide  and  coal 
in  a  carbonaceous  crucible,  obtained  iron  phosphide  with 
26'36$  phosphorus.  This  was  the  highest  percentage 
which  he  succeeded  in  obtaining,  even  though  a  great 
excess  of  phosphate  was  present  and  though  the  con- 
ditions were  strongly  deoxidizing. 

In  the  blast-furnace  iron  readily  absorbs  a  large  per- 
centage of  phosphorus.  Lord0  quotes  cast-iron  made  in 
Ohio  with  4-9$  phosphorus,  though  a  high  percentage  of 
phosphorus  does  not  appear  to  have  been  aimed  at. 

At  Hoerde  in  AVestphalia  ferro-phosphorus  with  20$ 
phosphorus  is  made  in  the  blast-furnace  from  apatite 
and  slag  of  the  basic  Bessemer  process.4 

§  103.  ACTION  OP  SLAGS  (Phosphates  and  Silicates).— 
Under  certain  conditions  metallic  iron  takes  up  phosphorus 
from  the  phosphates  of  lime,  iron,  etc.,  and  from  their  silico- 
phosphates,  especially  in  presence  of  carbon,  silicon  and 
manganese  :  under  other  conditions  these  compounds  re- 
move phosphorus  from  metallic  iron. 

Which  of  these  actions  will  occur  and  the  extent  to 
which  it  will  occur  depends  primarily  on  the  basicity  of 
these  phosphates  and  silicates  and  on  the  strength  of  the 
ixisting  oxidizing  or  deoxidizing  conditions,  (I  include 
the  presence  of  carbon,  silicon  and  manganese  in  the  iron 
itself  as  a  deoxidizing  condition),  and  secondarily  on  the 
temperature,  on  the  percentage  of  phosphorus  which  the 
iron  contains,  and  on  the  proportion  of  iron  oxide  to 
lime,  etc.,  among  the  bases,  ferruginous  slags  probably 
removing  phosphorus  more  energetically  than  calcareous 
ones  of  like  basicity.  In  general,  intimate  mixture  with  a 
highly  basic  and  preferably  ferruginous  slag  under  strong 
oxidizing  conditions  and  at  a  relatively  low  temperature 
favors  the  removal  of  phosphorus  from  iron:  the  opposite 
conditions  oppose  it.  These  factors  must  all  be  taken  into 
account  to  fully  comprehend  the  phenomena  of  the  absorp- 
tion of  phosphorus  by  iron  and  its  removal.  Carbon, 
manganese  and  silicon  in  iron  oppose  the  removal  of  phos- 
phorus by  being  preferentially  oxidized,  and  by  reducing 
the  phosphoric  acid  formed  by  its  oxidation.  Yet  in  pud- 
dling, in  pig-washing  and  in  the  basic  Bessemer  process 
we  see  that  dephosphorization  sometimes  progresses  to  a 
considerable  extent  while  the  iron  still  contains  much 
manganese,  silicon  and  carbon :  indeed  in  pig  washing 
93$  of  the  initial  phosphorus  may  be  removed  while  the 
iron  yet  retains  90$  of  its  initial  carbon. 

§101.  BASICITY  OF  SLAG. — The  influence  of  this  factor 
is  most  clearly  seen  by  comparing  cases  in  which  all  other 
conditions  are  nearly  alike,  of  which  the  most  striking 
are  found  in  the  Bessemer  process.  In  the  acid  lined 
converter  the  necessarily  siliceous  slags  almost  complete- 
ly prevent  the  removal  of  phosphorus.  Bell,e  overblow- 
ing a  charge  of  phosphoric  cast-iron  in  an  acid  converter 
converted  about  25$  of  its  iron  into  oxide,  yet  the  phos- 
phorus in  the  metal  increased  (owing  to  the  elimination 
of  part  of  the  iron  and  the  concentration  of  the  whole  of 
the  phosphorus  in  the  remainder)  from  T33  to  1'66$,  sim- 
ply because,  even  after  scorifying  so  much  iron,  his  slag 


a  Private  communication,  Feb.  22,  June  27,  1887, 
b  Percy,  Iron  and  Steel,  p.  60, 


'•Trans.  Am.  Inst.  Mining  Euginwrs,  XII..  p.  506. 
d Journal  Iron  and  St.  lust.,  1880,  II.,  p.  754. 
e  Jour.  Iron  and  St.  last.,  1877, 1.,  p.  117, 


DEPHOSPHOKIZATION.      §  105. 


remained  acid,  having  45'38  silica  (the  oxygen  ratio  of  base 
<o  acid  being  1 :  T94,  a  bisilicate).  In  the  basic  Bessemer 
process,  however,  all  other  conditions  remain  almost  pre- 
cisely the  same,  except  that  a  basic  slag  is  substituted  for 
an  acid  one,  which  permits  us  to  dephosphorize  the  metal 
practically  completely.  Berthier  a  taught  that  by  the  use 
of  lime  in  the  blast-furnace  phosphorus  may  be  prevented 
from  uniting  with  the  cast-iron — "because  this  earth  tends 
to  remove  phosphorus  from  the  iron; — to  form  phosphate 
of  lime." 

The  perspicacious  Gruner  is  credited  with  being  the 
first  to  point  out  that,  since  phosphorus  can  in  general 
only  be  eliminated  from  iron  in  contact  with  a  basic  slag, 
the  necessarily  acid  slag  of  the  ordinary  Bessemer  con- 
verter bars  its  removal :  this  he  stated  in  1857, b  re- 
peating in  1869°  that  'Ewhen  the  slags  contain  40$ 
silica  the  bases  no  longer  retain  phosphoric  acid :  phos- 
phide of  iron  is  continuously  regenerated"  and  in  1879d 
' '  the  proportion  of  silica  should  not  exceed  30$,  for  be- 
yond this  the  iron  phosphate  is  decomposed  anew  by  the 
carbon."0 

While  slag  with  over  60$  of  silica  may  retain  small 
quantities  of  phosphoric  acid  though  in  contact  with 
metallic  iron,  and  while  a  considerable  proportion  of  phos- 
phorus may  be  removed  from  iron  which  is  in  contact  with 
slags  holding  over  30$  of  silica  together  with  even  as  much 
as  C$  of  phosphoric  acid  (e.  g.  slag  47  in  Tab"le  26),  yet  it 
is  probably  true  that  nothing  approaching  complete  de- 
phosphorization  can  be  accomplished  in  presence  of  slags 
containing  as  much  as  30$  silica.  W.  Richards'  states 
that  phosphorus  will  not  leave  iron  rapidly  in  the  basic 
Bessemer  process  unless  the  silica  in  the  slag  be  below 
20$,  and  that  the  most  complete  dephosphorization  is  ob- 
tained when  it  is  below  15$ :  Gilchrist  corroborates  this, 


Process. 

Bute. 

Puddling. 

Basic. 

Puddling. 

Basic. 

Basic. 

Percentage  of  silica  in  slag   ... 
Percentage  of  phosphoric  acid 

31-7 
5-93 

27-77 
2-19 

24-' 
S'56 

20-27 
5  ± 

16-60 
13-94 

10-5 
2'05 

Percentage  of  phosphorus  in- 

1-43 

1-27 

•47 

Pcrcentage  of  phos'phorus    in 
metal     accompanying      this 

0'64 

•23 

0-15 

•07 

•02 

•008 

Oxygen  ratio  of  base  :  ncitl   .  . 
Oxygen  ratio  of  total   bases  : 

1  :  1-19 
1  :  0-25 

1  :  0-88 
1  :  0-78 

1  :  0-88 
1  :  0-13 

1  :  0-75 
1  :0'83 

1  :  0-8S 
1  :  0-14 

1  :  0-81 
1  :  0-70 

Number  in  Table  26  ... 

47 

32 

80 

21 

81 

2 

a'f  rait'j  de  la  Voie  Seche,  II.,  p.  376. 

b  Bulletin  de  L'lndustrie  Minerale,  II.,  p.  199  :  Journ.  Iron  and  St.  Inst.,  1883, 
II.,  p.  661. 

c  Annales  des  Mines,  1869,  XVI.,  p.  300. 

dldem,  1879. 

o  It  has  been  stated  that  he  considered  temperature  as  serious  an  obstacle  to  de- 
phosphorization as  acidity  of  slag  :  but  a  perusal  of  his  writings  leaves  no  doubt 
in  my  mind  that  he  regarded  a  basic  slag  as  the  first  requisite,  and  considered  tem- 
perature as  an  important  element  chiefly  because  of  the  difficulty  of  maintaining 
basic  linings  at  high  temperatures.  (Idem,  1869,  p.  373). 

t  Journal  Iron  and  St.  Inst,  1879, 1.,  pp.  159-201. 


as  do  the  many  published  analyses  of  metal  and  slag  of 
this  process. 

As  the  silica  of  the  slag  falls  below  30$  the  complete- 
ness with  which  phosphorus  can  be  removed  from  the  iron 
rapidly  increases.  Among  a  host  of  recorded  cases  of  the 
treatment  of  iron  containing  a  considerable  portion  of 
phosphorus,  the  following  are  the  most  complete  instances 
which  I  have  met  of  dephosphorization  for  given  silica  in 
the  accompanying  slag  : 


DOS.  39,  44,  45,  46,  48,  50,  52,  53  and  54  Table  26  further  illustrate  the  fact  that  slags  containing 
from  30  to  44$  of  silica  may  yet  hold  phosphoric  acid  in  the  presence  of  metallic  iron,  which  in  certain 
cases  contains  considerable  carbon  ;  e.  g..  No.  52  (basic  Kessemer  slag),  in  which  the  slag  has  44-SjC 
silica  with  2~3^  phosphoric  acid,  though  in  contact  with  metal  holding  8#  of  carbon.  Further,  cer- 
tain of  them  illustrate  the  removal  of  phosphorus  from  iron  when  in  contact  with  slags  holding 
more  than  30$  of  silica 


§  105.  BASICITY  OP  SILICATES  COMPARED  WITH  THAT  OF 
PHOSPHATES. — In  comparing  the  influence  of  the  basicity 
of  phosphates  on  their  dephosphorizing  power  with  that 
of  silicates,  we  may  either  select  phosphates  and  silicates 
of  like  percentage  of  acid,  e.  g.,  comparing  phosphates  of 
30$  phosphoric  acid  with  silicates  of  30$  silica  :  or  those 
of  like  atomic  ratio  of  base  to  acid,  e.  ff.,  comparing  trical- 
cic  phosphate  with  tricalcic  silicate :  or  finally  those  with 
like  oxygen  ratio  of  base  to  acid,  e.  g.,  comparing  the 
metallurgical  bi-silicate  of  lime  with  what  may  by  analogy 
be  called  the  bi-phosphate,  2'5-CaO,  P205. 

Our  scanty  data  do  not  permit  accurate  comparisons  : 
yet,  whatever  standard  we  employ,  phosphates  appear 
to  have  much  greater  dephosphorizing  power  than  sili- 
cates of  like  basicity. 

Hilgenstock  found  that  apparently  practically  carbon- 
less iron  absorbed  phosphorus  abundantly  from  tricalcic 
phosphate,  and  that  it  even  took  up  a  little  from  tetracal- 
cic  phosphate:  Finkener  observed  that  it  took  up  none  from 
triferrous  phosphate,  but  that  it  absorbed  a  little  from 
phosphates  which  were  but  slightly  more  acid,  even  from 
one  with  2'9  equivalents  of  base  to  one  of  acid.  But  a 


TABLE  25  A.— COMPOSITION,  ETC.,  OF  PUKE  PHOSPHATES  AND  SILICATES. 


NAMES. 


Chemical, 

Metallurgical. 

Formulae. 

Percentage  composition. 

Oxygen 

ratio. 
Baso  -t-  Acid. 

P80B. 

8iO2. 

CaO. 

FeO. 

PHOSPHATES  : 
Mono-(nu'ta)-calcic  phosphate  

Quinqniphosphate  of  limo  

CaO,  P206  =  CaP.,0  
2CaO,  P8OS  =Caal'sO7  

71-70 
55-91 
5035 
45-81 
48-18 
88-81 
83-64 
66-34 
49-65 
44-09 
39-44 
87-15 
83-03 
28-28 

28-29 
44-08 
49-64 
54.19 
56-81 
61-18 
66-35 

1  :5 
1  :2-5 
1  :2 
:l-7 
:l-5 
:l-25 
:1 
:5 
:2-5 
:» 
:l-7 
:l-5 
:125 
:  1- 

TrKortho)-        "            "          (nearly  apatite)  

3CaO,  P2OS  =  Ca3P8O8  

4CaO,  PjjOs  =  Ca4P8O»  
5CaO,  P2Os  =  Ca6P2O10.... 
FcO,  P206  =  FePsO6  
2FeO,  P205  =  Fc8P8O7.... 

33-65 
50-36 
5590 
60-56 
62-84 
66-96 
71-71 

Mono-(meta)-fcrrous     4l          
Di-(pyro)-                                     

Ferrous  quinquiphosphatG  

Tri-(ortho)-ferrous         "         (vivianitc  less  water)  

SFeO,  PjjOs  =  FesP208  

Tetra-ferrous                    ll           
Penta-  "                         "          

'  '        singulophospbate  

4FeO,  P-jOs  =  Fe4PsO9  
5FeO,P2O6  =  Fe5P8Oio.... 

SlLIC-ATEB  I 

Trisilicate  of  lime 

2CaO  3Si02  —  CaoSi3O«  

61-64 
51-72 

38-36 

48-27 

:8 

:2 
:l-5 
:1 
:0'67 
:05 
:8-0 
:2-0 
1  :1-S 
1  :1 
1  :0-6T 
1  :0-5 

Bisilicate          " 

CaO  8iO2  —  CaSfOs 

Sesquisilioate  "     
Singulosilicatc  oflime  

4CaO,  3SiO2  =  Ca4SisOio  ... 
2Ca<>,  SiO.i  =  C;uSi<>4  
30aO   8i03  —  CasSiO5  

44-53 
34-xi 
26-31 
21-11 
55-53 
4545 
88-44 
29-35 
21-73 
17-28 

55-46 
65-17 
73-68 

78-88 

Dicalcic                          "                                                                           

41-41! 
54-54 
61-55 
7064 
78-26 
82-76 

4CnO,  SiOa  —  Ca4SiO6  

2FeO  3Si02  —  Fe2Si3O6  

"        bisilicate  

FeO,SiO2  =  FoSi03  
4FeO  8SiO2  —  Fe4Si3Oio... 

"        singulosilicate  

2FeO,  SiO8  =  Fe88iO4  
3FeO,  8iO2  —  Fo^iOs  

Te'raferrous                    "           

"        subsilicate  

4Fe(),  8iO2  =•  Fe4SiO6  

Composition. 


«8 


THE    METALLURGY    OF     STEEL. 


TAIU.K  2G. — DEIMIOSPUORIZATION  vs.  SLAG  BASICITY. 


No            .                 .  .. 

2. 
B.B. 

8. 

S. 
B.B. 
E. 

4. 
Puil. 

Q. 

6. 
B.B. 
F. 

9-50 
9  76 
7-24 
1-66 
59-85 
5-01 
6-16 
tr. 

V:6:47 

1:0-09 
1-04 

•06 

7. 
B.B. 

c. 

8. 
Pud. 

E, 

9. 
BB. 

F. 

10. 
S.d. 
I. 

11. 
P.w. 

N. 

1-2. 
BB. 
F. 

13. 
B.B. 
K. 

14. 
Kif. 
P. 

16. 

B.B. 

II. 

16. 
B.B. 
K. 

17. 
B.B. 

C. 

IS. 
B.B. 

0. 

19. 
B.B. 
G. 

20. 
IJ.B. 
E. 

21. 
Pud. 
K. 

23. 
B.o. 
H. 

24. 
B.B. 
D. 

25. 
B.B. 
E. 

26. 
Pod 

L. 

27. 
Pud. 
L. 

Iteference  

Silica 

10  5 
2-05 
49-00 
11  42 
25-0 

S-60 
5  79 
84-87 
22-59 
27-48 

12-75 
3-12 
67  09 
14  39 
0  18 
0'18 
•65 
2-85 
S. 
•05 
1:0-41 

1:0-91 
•49 

•06 

9-72 
10  -6* 
8'58 
3  81 
49  75 
6-42 
5  93 
2-21 
CaS. 
2  26 
1:0-50 

1:0-14 
1-28 

•02 

15-79 
1-66 
69-52 

!l  -21 

13-81 
7  38 
6  70 
1-30 
57-85 
6-98 
6-20 
tr. 

18'SO 
8-46 
49-24 
7  05 
tr. 

'20-4' 

8. 
0  41 

1:  -58 

1:0-57 
•07 

95 
11-5 

70-3  -] 

1-9 
0-3 
2-1 
4-1 

11-10 

12-43 
8-90 
1-75 
50-21 
!l  -84 
4-40 
tr. 

10-47 
10-83 
40  11 
6-88 
26-74 

15-47 
4-11 

76  81 

11  38 
12- 
8  24 
8-16 
51- 
4.74 
3-50 
2  85 
CaS. 
3-15 
1:0-61 

1:0-13 
1-40 

•07 

9- 
14-5 
15  -43 
3  18 
8S  C 
9-5 
4-98 
1-85 

i':6:62 

1:0-21 
1  45? 

•04 

11-32 
1-2  41 
4  45 

0  57 
it;  3-2 
4  87 
1-96 
•39 

1:0-62 

1:0-06 
1-28 

•48 

1-2  -2.-, 
1-2  IN 
9-4-2 
1  61 
48  3S 
5-60 
5-82 
2  81 
I'aS. 
2-34 
1:0  63 

1:0-12 

m 

•03 

2  45 
22  23 
15-10 
5  74 
46-82 
1-14 
2-75 
2-85 

15- 
12  2 
12-21 
1-17 
40  -OS 
10  67 
4  76 
2-5 

20-27 
5  ± 
61  '20 
5-20 
2  12 
2  04 

'  '2:91 

1:0-75 

1:0-83 
•47 

•07 

10  00 
•23-05 
3  -87 
2-29 
45'37 
9-12 
4-20 
1  05 

1:0  70 

1:0-07 
3-32 

•04 

12-78 
16-0* 
4  t-7 
4  06 
47-87 
7  79 
8-85 
1-12 

1:0-79 

1:0-11 
»-18 

•15 

13 
12-5 
17-5 
29 
33  48 
11-7 
8-79 
1-11 

1:0:S2 

1:0-19 
1-45? 

•OS 

8-T8 

•2-77 
56  57 
(i-Sli 

15  75 
•M 
C3  9 
8  55 

Phosphoric  acid  
Ferrous  oxide  

Lime  

1  95 
:33 

"s." 

•68 
1:0-60 

1:0-96 

"2'  81 

Oxide  of  manganese...  . 

1  40 

Ti'62' 
18-5 
1:0-84 

1:1- 
1-49 

•45 

TiO,' 
10  89 
1:0-86 

1:1 
•63 

•29 

1-88 

8. 
•26 

ogriaasEr 

rat>0     |    iron  oxides., 
f  In  Initial  metal. 
1'hos-    1  In  metal  accom- 
phorus  |     panyiug     this 
L     slag  

1:0-31? 
1O-70? 

•(KB 

1:0-37 

1.0-69 
1-46 

b.   -04 

1:0-5 
1:0"  S 

•25 

1:0  51 

1:0-08 
0-96 

•05 

1:0  -r>6 

1:0-85 
2-23 

•08 

1:0-59 

1:0  11 
1-04 

•(1C 

1:6-60 

1:0-57 
1-19 

•13 

1:0-67 

1:0-24 
2-6@S-2 

02®  06 

1:0-74 

1:0-15 
1-45? 

•04 

•82 

No 

28. 
B.B. 
B. 

29. 
B.B. 
B. 

SO. 
B.li. 
E. 

31. 
B.B. 
E. 

32. 
Pud. 
K. 

33. 
B.B. 
E. 

34. 
P.w. 

N. 

37. 
B.li. 
E. 

39. 
B.B. 

E 

40. 
B.B. 
E. 

41. 
Kef. 
P. 

43. 
Pud. 
L. 

44. 
Eef. 
O. 

45. 
Kef. 
P. 

46. 
BB. 
B. 

47. 
1S.B. 

E. 

48. 
B.B. 
T. 

4(1. 
Kef 
O. 

50. 
B.li. 
E. 

50a. 
Sd. 
J. 

51. 
A.B. 
A. 

52. 
BB 

8. 

53 
B.B. 

E. 

54. 
B.B. 
E. 

fill. 
B.f. 
X. 

63-2 
2-21 
5-12 

Process  
Reference  

Silica        

17-8 
13-83 
13-59 
2-00 
34-73 
9-56 
6-24 
2-26 

21-1 
10-86 
13-89 
1-71 
29-44 
7-88 
12-49 
3-63 

24-00 
8-56 
14  6± 
3-24 
37-00 
0-30 
8-22 
8-57 

16-6 
13-94 
12'2i 

27-77 
2-19 
59-95 
4-81 

19-50 
11-11 
24-22 
4-88 
36-12 

10-40 
20-00 

Ui-o 

7-3 
0-7 
19-3 
2-00 

22-20 
7-46 
51-95 
4-08 
10-52 

36-8 
1  04 
8'09± 

14-4 

17-86 
IS-  16 
5-28 
87-49 

26-41 
4-14 
57-85 
2-57 
2-20 
0-24 
3-90 
2-47 
S. 
•05 

Id- 

1:0-85 
1.47 

•84 

11-87 
•2-111 
5-2-05 
8-86 

31-05 
2-79 
43-90 
10-08 
1-56 
85 
5  90 
4-37 
8. 
•03 

1:1-06 
1:0-04 

30-31 
2-56 
51-83 
8-60 
1-55 
•73 
4-96 
5*  73 

86-08 
2-11 
5-58 
0  49 
88-42 
0-88 
9-30 
4-69 
S. 
•09 

1:1-19 

1:0-OS 
1-21 

I'll 

31-7 
5-93 
15-04 
3-35 
32-9 
0-26 
4-59 
4-06 
8. 
•05 

1:1-19 

1:0-25 
1  42 

0-64 

36-80 
8-12 
3-97 

•41; 
89-5 
::•::'.' 
11-02 
1-30 

83-33 
2-26 
55-11 

38-8 
1-13 
6'4 
0-71 
37-36 
0-26 
7-  -21 
6-43 

29-00 
4-94 
46-20 

'2-6S 

45-38 

'47-19 
•2-SC. 
1-40 
tr. 

44-8 
23 

30  7 
2-26 

31-0 
4-14 

Phosphoric  acid.  .  . 
Ferrous  oxide  .  .  . 
Ferric  oxide  

1  19 
0-50 
2-71 
5-75 

S. 
•17 
a. 
1:1-4.-. 

0:0-91 

14-8 

IS'S 

25-1 

19-13 
4-67 

Oxide  of  Mn  

5-29 

1-40 
1-19 

3-07 

8-71 
1  30 

50 
15-56 

2-92 
•51 

3-60 

TIOj 

14-80 

1:1-04 

1:1- 
1-04 

•23 

8. 
•80 

c  0  1  Base:  ncid  .  . 
-*3  1  Total  bases 
O  2  |  H-iron  oxides 
{In  initial  metal 
In    metal    ac- 
companying 
this  slag.... 

1:0-86 

1:0-18 
1'5± 

•06 

1:0-87 

1:0-18 
l-5± 

•15 

1:0-88 

1:0-13 
1-27 

•15 

1:0-88 
l:ii-14 

4:0-88 
1:0-7S 

1:0-92 

1:0-88 
1-39 

•20 

1:0-93 

1:0-55 
2-92 

"77 

1:0-98 

1:0-80 
1-19 

•13 

1:1-    ± 
1:0-04  ± 

1-25 

1:1- 

1:0-32 
1-19 

•29 

1:1-1 
1:0-8 

1:1-26 

a. 
1:1-52 

1:0-116 

a. 
1:1-64 

a. 
1:194 

1  :0-95 

1-21 

1-11 

3-0 
•86 

1-44 
1-23 

1-44 
1  07 

•02 

•23 



1-C6 

A.  Bell,  Journ  .  Iron  and  St.  Inst.,  1S77,  I.,  p.  117.     Acid  Bessemer  process.     B.  Ditto,  Principles  of  the  Manufacture  of  Iron  and  Steel,  p.  409.     Basic  Bessemer.      C.  Massencz,  Jour.  Iron 
and  St.  Inst..  1880,  II.,  p.  475.     Basic  Bessemer.     D.  Wedding,  idem,  p.  552.    Basic  Bessemer.    E.  Thomas  and  Gilchrist,  idem,  1S79,  I.,  p.  123.    Basic  Bessemer.     F.   Pink,   Idem,   1880,   I.,   p. 
O.  Engineering  and  Mining  .11.,  1888,   II.,  p.  17.     Basic  Bessemer.      H.  Iron  Age,  Aug.  6th,  1885,  p.  37.     111.  Tunner,  Metallurg.  Review,  I.,  p.  57S.      Siemens  direct 


61.    Basic  Bessemer.         .  . 

process,  1st  tapping.      I.  Bell,  Jonrn.  Iron  and  St.  Inst.,  1877.  1.,  p.  112.     Siemens  direct  process. 

bnch  der  Eisenhiittenkumle,  pp.  798,  800.       L.  Snclus,  Jour.  Iron  and  St.    Inst.,  1872,  I., 

Eng.    Krupp's  pig  washing.      O.  Bel!,  Principles  Manuf.  Iron  and  Steel,  p.  394.    Keflne 

Inst.,  1879,  I.,  p.  222.     Puddling.      M.  Snelus,  idem,  1S79,  I.,  p.  244,  140.      Basic  Besseme 

Stahl  und  Eiscn.  1SSO,  10,  p.  637.     Basic  Bessemer.      V.  Harbord,  Journ.  Iron  and  St.  Inst,  1SS6,  II.,  p.  700. 

Gmndriss  der  Eisenhiittenkunde,  p.  167.    Blast  furnace.       Y.  Harbord,  Loc.  cit. 

a.  Excluding  alumina,    ft.  Metal  accompanying  similar  slag.     A.B.  Acid  Bessemer.     B.B.  Basic  Bessemer.     B.o.  Basic  open-hearth.    Pud.  Puddling.     Kef.  Kefinery.     S.d.  Siemens  direct 
process.     B.f.  Blast  furnace.    P.w.  Pig  washing. 


.        ,         ,     .      .  .  ,  ,    .,     .        . 

J.  Siemens,  idem,  p.857.  Siemens  direct  process.  K.  Schilling,  puddling,  Ledebur,  Hand- 
I.,  p.  259.  Puddling.  OT.  Percy,  Iron  and  Steel,  p.  66'.  Puddling.  N.  Holley,  Trans.  Am.  Inst.  Min. 
nery.  P.  Ditto,  pp,  854,  359.  Refinery.  Q.  Ditto,  p.  360.  Puddling.  R.  Lewis,  Jour.  Iron  and  St. 
er.  T.  Finkener.  Ledebur,  Handbuch  d'er  Elscnhiittenkunde,  p.  924.  Basic  Bessemer.  U.  Elirrnworth, 
Basic  open-hearth.  W.  Ledebur,  Handbuch,  pp.  797,  SOO.  Pudding.  X.  Kcrl, 


slag  which  is  to  actively  absorb  phosphorus  must  be  con- 
siderably more  basic  than  one  which  is  barely  able  to  hold 
in  the  presence  of  non-carburetted  iron  the  phosphorus 
which  it  already  has.  Hence  we  may  infer  that  about  3'5 
atomic  equivalents  of  ferrous  oxide  or  4 '5  of  lime  to  one 
of  phosphoric  acid  are  needed  to  permit  complete  dephos- 
phorization,  and,  at  a  rough  guess,  we  may  say  that  2 '75 
equivalents  of  ferrous  oxide  or  3 '5  of  lime  to  one  of  phos- 
phoric acid  should  permit  dephosphorization  to  proceed 
till  the  metal  retains  but  0'6  of  phosphorus. 

It  is  true  that  Stead  found  that  almost  pure  carburetted 
iron  absorbed  biit  0'1$  of  phosphorus  when  melted  between 
layers  of  (tribasic  ?)  lime  phosphate  in  a  lime-lined  cru- 
cible, which  at  first  seems  discordant  with  Hilgenstock' s 
statements  concerning  the  absorption  of  phosphorus.  But 
we  do  not  know  how  much  lime  was  absorbed  by  Stead's 
initial  lime  phosphate  from  the  lime  lining.  In  this  way 
his  slag  may  easily  have  become  even  more  basic  than 
tetracalcic  phosphate.  In  this  view  there  seems  to  be  little 
justification  for  Mathesius'  statement11  that  Hilgenstock' s 
results  are  directly  contradicted  by  Stead's,  and  by  his 
own,  in  which  an  extremely  basic  lime-phosphate  ex- 
tracted phosphorus  from  ferro-phosphorus,  and  that  they 
are  therefore  attribiitable  to  experimental  error. 

In  Hilgenstock' s  experiments  metallic  iron  was  melted 
in  contact  with  tricalcic  phosphate  and  an  excess  of 
earthy  base  :  it  invariably  took  up  phosphorus,  and  con- 
siderably more  when  this  excess  consisted  of  the  com- 
paratively inert  magnesia  than  when  an  excess  of  lime 
was  employed. 


»  Stahl  und  Eisen,  VI.,  p.  643.  1886,  No.  10. 


As,  by  the  absorption  of  part  of  the  basic  excess 
present,  and  by  the  reduction  of  part  of  their  acid  by  the 
metallic  iron,  the  final  composition  of  his  phosphates  was 
doubtless  more  basic  than  their  initial  composition,  his 
results  leave  little  doubt  that,  even  in  the  absence  of  car- 
bon, metallic  iron  may  absorb  phosphorus  from  phos- 
phate which  is  at  least  as  basic  as  tricalcic  phosphate  and 
probably  more  basic  yet,  and  to  a  moderate  degree  from 
slags  at  least  as  basic  as  tetra-phosphate.  As  Finkener' s 
experiments  were  performed  in  an  iron  boat  in  an  atmos- 
phere of  nitrogen  it  is  probable  that  his  ferrous-phos- 
phates remained  approximately  of  their  initial  basicity 
in  those  cases  in  which  the  iron  absorbed  no  phosphorus 
from  them,  and  at  most  became  but  slightly  more  basic, 
by  the  substitution  of  iron  oxide  for  phosphoric  acid,  in 
those  in  which  the  metal  absorbed  phosphorus.  Their  re- 
sults are  summarized  in  Table  26  A  :  they  will  be  again 
referred  to. 

Turning  now  to  the  silicates,  I  have  already  stated  that 
slags  with  over  30$  of  silica  do  not  in  general  permit  us 
to  reduce  the  phosphorus  in  iron  below  '60%  ±  :  such  sili- 
cates may  then  be  roughly  likened  to  a  3'5-basic  lime  phos- 
phate or  a  2'7fi-basic  ferrous  phosphate  in  dephosphorizing 
power.  Slag  21  Table  26,  already  referred  to,  with  25  -±  % 
acid,  of  which  4-5ths  are  silica,  and  whose  bases  are  chiefly 
iron  oxides,  permits  almost  complete  dephosphorization  : 
we  may  then  roughly  liken  it  to  calcic  phosphate  with 
4-.')  equivalents  of  base  to  one  of  acid,  or  to  ferrous  phos- 
phate with  3-5  equivalents  of  base  to  one  of  acid.  This 
is  summarized  in  Table  26  B. 

These  figures  suggest  that,  as  regards  influence  on  de- 


DEPHOSPHORIZATION.      §  106. 


TABLE  21!  A.— AIMOKPTIOX  OK  I'll  OBPIIOKVS  FKOM  PHOSPHATES  BY  MBTALLIC  IRON,  ETC. 


Number. 

Observer. 

Conditions  of  experiment. 

Resulting  metal. 

Kind  of  vessel,  ete. 

Time. 

Hours 

Temperature 

Mi'tul,  etc.,  cm  ployed. 

Phosphate  employed. 

Composition. 

Description. 

P.* 

Mn. 

Fe 

1.    .. 

S... 
4  
6.    .. 

7!!" 

8.... 
9 

Ilil'-elistock... 

0-37 
0-72 
1*06 

0-66 

0-27 
0-37 
0-27 
100 

I'OO 

0'1(?) 

0-08S 
0*80 

1-10 
(V 

C7'6 
68-6 

'  The  button  showed  an  ab- 
sorption of  only  O'l^uf  phos- 
phorus. n 

Jo    iron    phosphide    formed. 
Sintered. 

ron  phosphide  formed.   Com- 
pletely fused. 
'  Dilute  sulphuric  acid  evolved 
but    little    phosphoretted 
hydrogen,    ».    e.,    a  littlo 
phosphorus    was   reduced 
by  the  iron,  Sintered. 

10  important  action. 

Completely   reduced    to   iron 

phosphide. 

^/ompletely   reduced    to    iron 
phosphide, 

ompletely    reduced    to    iron 
phosphide,  phosphorus  part- 
ly volatilized.     No  slag. 
'he  phosphide  contained  about 
S5£  of  the  phosphorus    in- 
itially present. 
he   reduction   of  the    phos- 
phorus    must     have     been 
effected  chleHv  by  the  iron 

Stead  

14 

14 

With  neutral  lining  

"        with  great  ex 

Tricalcic,    with    a  smal 

excess  of  lime. 

Lined  with    tricalcic    phos 
pliate  melted  with  lime.  . 

Lime-lined  

Tricalcic,  previously 
melted  with  lime.. 

1 
1 

White 

l'5g.  of  manganese-  phos 

1  part  f<'rro-imng-mi"*e 

1  part  trioalcic,    the  mix 
ture  covered  with  ex- 
cess    of    tricalcic    (?) 

111 

•'        

5  g.  of  nearly  pure  carburettod  iron  

Apparently  n  on  -car  bu  retted  iron,  contain 
i  ni,'  ()-(U%  of  phosphorus     

2  layers  of  triealcic  phos- 
fihate,     enclosing    the 
ron  

11 

Tetracalcic  

.   . 

12  
13... 

.,        ,, 

(4 

14.    ... 

15  

1C.    .   . 
17.... 

IS.... 
19  

2(1  
21  

22  
23  

Kinkener  

.Jrackelsber;,' 

Iron  lioat  in  atmosphere  of 

Apparently  imn-carburetted  iron,  1  part... 
"                      "                     "      2  parts. 

"                      "                     "      4      " 

Triferrous,    1    part. 
3FeO,  P8O5....       .. 
Triferrous,  1  part.  ( 
Dilemma,    1    "     f 
-2-5FeO,  P8O  .  ... 

[ron  bout  in  atmosphere  ol 

Iron  boat  in  atmosphere  ol 

Trfferrous  3  parts  1 
Diferrous    1      "     f 
=  2-75FeO,  PaOB..1 
Triferrous  9  parts  1 
Dilcrrous    1       "       f 
=2*9  FeO,  1*2  O$  ...  j 

Iron  Itoat  in  atmosphere  ol 

\tniosphere     of      carbonic 

White. 

Umosphere    of     nitrogen, 

Cast-iron  with  3  -8^  carbon  ;  just  enough  to 
unite   with  the  oxygen  present  as  car- 
bonic oxide  

Triferrous  phosphate..  .  . 
in 
proportion  to  yield  iron 
with  2%  phosphorus  if 
wholly  reduced  

UinospHere  of  carbonic  ox- 
ide.    tallic  boat  

irasqued  crucible  

1 

55  parts  diferrous  phos- 
phate, 35-5  part*  difer- 
ric     phosphate,      MM 
parts  ferric  oxide.  .  ... 

5  g.  tricalcic  (  ?}  phosphate 
3'85g.  ferric  oxide.... 

24-55 
24-50 

0-82 

5'45 
5'32 

S9.I2 

Carbonless  crucible  (?)  

»      

phate  

HIUIKXSTOI-K.  stahl  and  Eisen,  VI.,  p.  525,  1SS6  ;  Kev.  Univ.,  XX.,  3,  p.  661,  1SS6;  Iron  Age,  Sept.  2,  1SS6,  p.  15.    STEAD,  Ehrenwerth,  Oest.  Zcit.  fur  Berg-  und  Huttenwesen,  XXIX.,  p  1114, 
1881.    Fix-KF.NKR,  Wedding,  Der  Basische  Bessemer-oiler  Thomas-Process,  pp.  153-1.    BucKnoBBBO,  Stahl  unrt  Elsen,  V.,  pp.  545-548,  1885,  10. 

TABLE  26  B. 


Basicity  ratios, 

Silicates. 

Phosphates. 

Phosphate  -f-  Silicate,  for 

like  dephosphorizing  power. 

Base. 

f 
Silica. 

Atomic 
ratio, 
base  to 
acid. 

Oxygen 

ratio, 
b  ise  to 
acid. 

% 

Phosphoric 
acid. 

Atomic 
ratio, 
base  to 
acid. 

Oxygen 
ratio,  base 
to  acid. 

Percentage 
ratio. 

Atomic 
ratio. 

Oxygen 
ratio. 

Most  acid  slag  in  whose  presence   phosphorus  1 

Lime 

80 

2-5 

1  :0'S 

42 

3-5 

1  :l-48 

1-40 

1-40 

1-79 

can  be  reduced  to  0  '60&                                     I 

Iron 

80 

1-944 

1  :  1-029 

41  -S 

2-75 

1  :  1-82 

1-39 

1-42 

1-77 

Most  acid  slag  in  whose  presence  phosphorus  i 

Lime 

36 

4-5 

1  :1-H 

can  be  almost  completely  removed.                  ) 

Iron 

25 

2-49 

1  :  0-88 

86-6 

8-5 

1  :l-48 

1-44 

1-41 

1-60 

phosphorizing  power  of  slags,  \%  of  silica  should  be 
counted  as  equal  to  1'4±  of  phosphoric  acid  :  one  atomic 
equivalent  of  silica  as  1  '4  ±  of  phosphoric  acid  :  and  that,  if 
we  employ  the  oxygen  ratio  of  base  to  acid,  1  of  oxygen 
in  silica  should  count  as  T7±  in  phosphoric  acid.  These 
numbers,  however,  rest  on  a  very  doubtful  basis,  and  can 
at  best  serve  as  very  rough  and  makeshift  guides. 

Ehrenwerth  a  considers  that  to  prevent  absorption  of 
phosphorus  by  metal  from  slag  ("rephosphorization") 
on  recarburizing  in  the  basic  Bessemer  process,  it  is  only 
necessary  that  the  slag  should  contain  enough  earthy  base 
to  form  subsilicate  with  the  silica  present  and  tribasic 
phosphate  with  the  phosphoric  acid,  but  that  rephosphor- 
ization will  occur  unless  this  condition  is  satisfied  :  but 
he  seems  to  lose  sight  of  the  oxides  of  iron  and  manganese, 
which,  if  we  look  beyond  this  single  process  to  puddling 
and  the  basic  open-hearth,  we  find  are  at  least  as  effi- 


aOest.  Zeitschrift,  fur  Berg-  und  Hiittenw&sen,  1881,  p.  130. 


cient  in  retaining  phosphorus  in  the  slag  as  are  the 
earthy  bases.  In  the  basic  open-hearth  process  permanent 
dephosphorization  may  be  effected  with  slags  which  have 
far  from  enough  earthy  base  to  satisfy  Ehrenwerth' s  for- 
mula, e.  g.  a  slag  mentioned  by  Harboard  which  contains 
12%  of  silica  and!3'3of  phosphoric  acid,  yet  only  15 '2$ 
of  lime  with  5 '75$  of  other  earthy  bases  :  but  its  43 -1$ 
of  ferrous  oxide  permits  it  to  almost  completely  dephos- 
phorize the  metal,  the  phosphorus  having  fallen  from  3 '56 
to  Q-01%.  Here  the  conditions  on  recarburizing  appear 
to  be  identical  with  those  of  the  basic  Bessemer  process. 
§106.  FERRUGINOUS  vs.  CALCAREOUS  PHOSPHATES  AND 
SILICO-PHOSPHATES. — As  the  removal  of  phosphorus  from 
metal  to  slag  requires  its  oxidation  and  conversion  into 
phosphoric  acid,  ferruginous  slags,  themselves  sources 
and  carriers  of  oxygen,  dephosphorize  iron  much  more 
energetically  than  calcareous  ones  when,  as  in  the  pud- 
dling, pig- wash  ing  and  basic  open-hearth  processes,  the 


60. 


THE    METALLURGY    OF     STEEL. 


oxidation  of  the  phosphorus  has  to  be  effected  by  the  slag 
itself,  and  when  there  is  but  little  contact  between  metal 
and  air.  But  how  does  their  dephosphorizing  power  com- 
pare when,  as  in  the  basic  Bessemer  process,  intimate  ad- 
mixture of  air  permits  rapid  oxidation  of  phosphorus,  so 
that  we  do  not  have  to  rely  on  the  slag  for  our  oxygen 
supply  ?  Let  us  compare  first  slags  of  like  basicity,  then 
those  of  similar  percentage  composition. 

The  evidence  which  I  have  met  indicates  that  pure  phos- 
phates of  iron  yield  up  their  phosphorus  to  metallic  iron 
less  readily,  whence  we  infer  that  they  absorb  it  from  iron 
more  greedily,  than  pure  lime  phosphates  of  like  basicity : 
that  is,  that  under  like  conditions  an  equilibrium  between 
the  tendency  of  phosphorus  to  pass  into  slag  and  its  oppo- 
site tendency  to  pass  into  the  metal  is  reached  with  iron 
slags  when  they  are  more  phosphoric  and  in  general  more 
acid  than  is  the  case  with  lime  slags.  Hilgenstock's  ex- 
periments just  referred  to  indicate  that  the  latter,  when 
tetrabasic  with  oxygen  ratio  of  base  to  acid  1  :  1'25,  and 
perhaps  even  when  more  basic  than  this,  still  yield  up  a 
little  phosphorus  to  metallic  iron :  while  Finkener's  re- 
sults indicate  that  with  iron  phosphates  an  oxygen  ratio 
of  1  :  1'67,  as  in  triferrous  phosphate,  barely  suffices  to 
prevent  the  absorption  of  phosphorus  by  metal  from  slag. 
(These  statements  may  only  hold  true  of  the  particular 
conditions  of  the  experiments  on  which  they  are  based.) 

For  similar  percentage  composition  lime  slags  are 
more  basic  than  iron  slags,  measuring  basicity  atomically 
or  by  the  oxygen  ratio  of  base  to  acid.  Thus  ferrous -sili- 
cate with  30$  silica  is  a  singulo-silicate,  lime  silicate 
with  the  same  percentage  of  silica  is  between  a  singulo  and  a 
subsiiicate,  their  oxygen  ratios  being  1 :1  and  1:0.8  respect- 
ively. It  might  be  inferred  that  lime  slags  would  have 
greater  power  of  removing  phosphorus  from  iron  than 
ferruginous  slags  of  corresponding  percentage  composition, 
and  that  a  given  degree  of  dephosphorization  could  be 
attained  with  a  higher  percentage  of  silica  in  the  accom- 
panying slags  when  calcareous  than  when  ferruginous. 
But,  as  suggested  by  Table  26  B,  the  greater  basicity  of 
lime  slags  appears  to  be  approximately  balanced  by  the 
greater  readiness  with  which  phosphorus  is  removed  by 
metallic  iron  from  lime  than  from  iron  phosphates  of 
like  basicity.  A.t  least,  in  the  study  of  a  great  number  of 
cases  I  have  neither  been  able  to  convince  myself  that  cal- 
careous slags  remove  phosphorus  from  iron  more  fully 
than  ferruginous  ones  of  like  percentage  composition  or 
the  reverse.  The  slags  of  the  basic  Bessemer  process, 
sometimes  almost  free  from  iron  oxide,  and  essentially 
silico-phosphates  of  lime,  permit  extremely  thorough  de- 
phosphorization :  witness  No.  23  of  Table  26,  which  holds 
23-05$  of  phosphoric  acid  though  but  6'16$  of  iron  oxide, 
while  the  accompanying  metal  has  but  0'04$  of  phos- 
phorus. Among  the  six  cases  of  maximum  dephosphori- 
zation for  given  silica  lately  quoted  we  find  that  three  are 
of  ferruginous  and  three  of  calcareous  slags.  ' '  Honors 
are  easy." 

The  preceding  statement  is  not  designed  to  apply  to  con- 
ditions which  are  so  strongly  deoxidizing  as  to  tend  to 
nearly  completely  reduce  the  phosphates — unless  indeed 
silica  be  present  to  relieve  the  phosphoric  acid  from  duty. 
When  ferrous  phosphates  are  heated  with  a  deoxidizing 
agent,  as  in  experiments  19  to  20,  Table  26  A,  both  iron 
and  phosphorus  are  completely  reduced.  But,  though 


lime  phosphates,  even  in  the  absence  of  silica  readily 
yield  a  portion  of  their  phosphorus  to  metallic  iron,  and 
a  very  large  portion  to  the  joint  influence  of  iron  and  car- 
bon, their  complete  dephosphorization  is  doubtless  far 
more  difficult  than  that  of  iron  phosphates,  iinless  indeed 
an  abundance  of  silica  be  present  to  displace  phosphoric 
acid  from  the  lime  phosphate  :  for  the  irreducible  lime  re- 
tains its  diminishing  stock  of  acid  with  ever  increasing 
stubbornness,  while  the  base  of  the  iron  phosphate  is  de- 
oxized  part  passu  with  its  acid.  But  that  a  very  large 
proportion  of  the  phosphorus  of  pure  lime  phosphates 
may  be  reduced  by  iron  and  carbon  jointly  is  shown  by 
experiment  22,  Table  26  A,  in  which  on  heating  (tri  ?)  cal- 
cic phosphate  in  a  graphite  crucible  with  ferric  oxide  and 
carbon,  about  &••%  of  its  phosphorus  appears  to  have  been 
reduced  and  to  have  entered  the  metallic  iron  formed. 

§  107.  STRENGTH  OF  OXIDIZING  CONDITIONS. — That  the 
intensity  of  the  existing  oxidizing  or  deoxidizing  tendencies 
plays  as  important  a  part  as  the  basicity  of  the  slag,  is 
shown  by  several  independent  considerations. 

(A).  BLAST-FURNACE.  While  under  the  strongly  oxidiz- 
ing conditions  of  the  refinery,  the  puddling  furnace  and  the 
basic  Bessemer  converter  part  of  the  phosphorus  may  re- 
main in  the  slags  even  if  they  be  comparatively  acid  (ses- 
qui-silicates),  under  the  strongly  deoxidizing  conditions 
of  the  blast-furnace  the  whole  of  the  phosphorus  may  re- 
main combined  with  the  metallic  iron  even  if  the  slags  be 
extremely  basic  (sub-silicates). 

Thus  in  Table  26  the  comparatively  acid  slags  44,  45  and 

49  (refinery),  32  (puddling),  50  A  (Siemens  direct)  and  ^<5, 
47,  48,  50  and  52  (basic  Bessemer)  all  hold  phosphoric 
acid  (e.  g.,  5  '93  phosphoric  acid  with  31 '7  silica)  though 
most  of  them  are  approximately  sesqui-silicates.     Yet  in 
the  manufacture  of  ferro-manganese  in  the  blast-furnace 
the  slags,  though  extremely  basic,  are  reported  as  often 
absolutely  free  from  phosphorus,  even  in  the  extreme  case 
quoted  by  Pourcela  of  a  slag  with  only  18$  silica;  though 
this  slag  is  more  basic  even  than  a  sub-silicate,  (oxygen 
ratio  =  1 :0'37±),   the  whole  of  the  phosphorus  unites 
with  the  cast-iron.      If  it  be  objected  that  the  compara- 
tively low  temperature  of  the  refinery  furnace  favors  the 
scorification  of  phosphorus,  we  have  in  Table  26  the  com- 
paratively acid  slags  of  the  basic  Bessemer  process  Nos. 

50  and  47  with  38 -8  silica  (oxygen  ratio  of  base  to  acid 
1  :  1-52  =  a  sesqui-silicate)  yet  holding  1-13  phosphoric 
acid,  and  with  31 '7  silica  (oxygen  ratio  =  1 : 1'19)  holding 
5  '93  phosphoric  acid. 

It  appears,  moreover,  that  as  long  as  the  strength  of  the 
reducing  action  of  the  blast-furnace  is  approximately  con- 
stant, (as  inferred  from  constancy  of  the  composition  of  the 
charge  and  of  the  percentage  of  ferrous  oxide  in  the  slag), 
practically  constant  amounts  of  phosphorus  pass  into 
metal  and  slag  respectively,  even  though  the  temperature 
may  alter  considerably,  as  inferred  from  alteration  in  the 
grade  of  the  cast-iron  produced,  which,  as  Bell  has  shown, 
appears  to  be  primarily  a  function  of  the  temperature  and 
only  secondarily  a  function  of  the  reducing  action.  If, 
however,  the  reducing  action  be  weakened,  as  inferred 
from  the  production  of  ferruginous  (scouring)  slag,  the 
percentage  of  phosphorus  in  the  slag  rapidly  increases,  re- 
maining roughly  proportional  to  the  percentage  of  ferrous 


Journ.  Iron  and  St.  Inst.,  1879,  It,  p.  378. 


DEPHOSPHORIZATION    INFLUENCED    BY    DEODORIZING    TENDENCIES.     §  108. 


61 


oxide  which  it  contains."  This  is  illustrated  by  slag  60 
with  63  '2%  silica,  5  12#  ferrous  oxide  and  2  '21  phosphoric 
acid. 

(B).  POUECEL'S  EXPERIMENT.*1 — On  melting  cast-iron  in 
contact  with  basic  phosphoric  slags,  A  in.  a  dolomite-lined 
and  B  in  a  carbon-lined  crucible,  Pourcel  found  that  when 
melted  with  carbon,  but  under  conditions  otherwise  less 
favorable  to  the  absorption  of  phosphorus,  the  cast-iron 
took  up  over  six  times  as  much  phosphorus  as  when 
melted  without  carbon.  White  cast-iron  was  melted 


with  phosphate  of  lime)  each  in  a  lime-lined  crucible,  and 
inclosed  all  three  in  a  large  graphite  crucible,  surrounded 
them  with  powdered  lime,  and  heated  them  to  whiteness 
for  an  hour.  'After  fusion  the  ferromanganeso  held  in  both 
instances  \%  of  phosphorus,  the  initially  nearly  pure  cast- 
iron  held  but  01$. 

Certain  European  writers  go  so  far  as  to  state  dogmat- 
ically, but  without  the  least  foundation  in  fact,  that  phos- 
phorus cannot  be  removed  from  iron  in  the  basic  Bessemer 
process  until  the  whole  of  the  silicon  and  carbon  have 


FXMMI. 

Phosphorus 
in  initial 
metal. 

Composition  of  resulting 
metal. 

rnMipo.sition  of 
accompanying  slag. 

Carbon. 

Silicon. 

Man- 
ganese. 

Phos- 
phorus. 

Sul- 
phur. 

Phosphoric 
acid. 

Silica. 

2-18 
1-2S 
1-36 

8-12 
•70 
1-W 
1-25 
•ll'.l 
2-21 
2-83 
8-25 
8-32 

•15 
tr 
tr 
•11 
•lit 
tr 
•82 
•(12 
•02 

•50 
•80 
•28 

'":86" 
•25 

2-22 
1  22 
1  10 
•81 
•12 
1  17 
•91 
•089 
•11 

•05 
•29 
•85 
•27 
•15 
•84 
•10 

•01 

•03 

8-12 
3  46 
7-74 
7  25 

86-30 
21-25 
28-25 
25' 

Wedding,  Basiseho  Bessemer,  pp.  189,141. 
j.  Massenez,  Journ.  Iron  and  St.  Inst.,  1SSO,  II.,  pp.  47S-JS 

Snelus,  Idem,  1879,  I.,  p.  244. 
Locality  withheld.     Private  Notes. 
Stahl  und  Elsen,  VI.,  p.  637,  1886. 
Snelus,  Op.  Cit,  1872,  I  ,  p.  259. 
Bell,  idem,  1S77,  II  ,  p  &37. 
Holley,  Trans.  Am.  Inst.  Min.  Eng.,  VIII.,  p.  158. 

M 

2-60  db 
1-48  -f 
1-49 
1.35 

0-74 

u 

2-22 

22-69 

Puddling 

••         ••       

•o« 

during  2  hours  with  additions  which  yielded  the  following 
substances : 


Fusion  in  carbon  crucible 
dolomite 


Phosphorus 

in  metal. 

Initial.      Final. 

'06  -64 

'06  '10 


FeO. 
17- 
? 


-Slag. 


CaO.      MgO.     A18O3 
48-          7-S  4  0 

58-  ±     10-6  ±      »  5  ± 


SiOo.      PS05. 

10-9  17-3 

14-80         10-44 

NOTE.—  With  the  fusion  in  the  carbon  crucible  tho  composition  which  the  slag  had  before  fusion 
ia  given  :  with  the  fusion  in  the  dolomite  crucible  I  give  tho  final  composition  of  the  slag,  which 
is  far  more  instructive.  The  latter  slag  held  initially  15£  of  silica  and  9'40£  of  phosphoric  acid. 

The  slag  accompanying  the  fusion  with  carbon  was  one 
which  under  otherwise  like  conditions  would  yield  up  its 
phosphorus  to  iron  much  less  readily  than  the  other, 
since,  though  initially  slightly  more  acid,  reckoning  its 
basicity  from  phosphoric  acid  and  silica  together,  yet  (A) 
it  contained  so  little  silica  as  to  be  practically  a  strongly 
dephosphorizing  slag  (see  §  lOo)  and  (B)  its  final  composi- 
tion must  have  been  far  more  basic  than  the  slag  in  the 
fusion  without  carbon,  since  its  phosphoric  acid  was  al- 
most completely  reduced  by  the  iron. 

§  108.  REDUCING  ACTION  OF  THE  CARBON,  ETC.,  or 
THE  IRON.  —  The  carbon  and  still  more  powerfully  the 
manganese  present  in  metallic  iron  increase  its  tendency 
to  absorb  phosphorus  from  slag,  and  its  power  to  resist 
dephosphorizing  influences.  Thus  Finkener  found  that 
while  apparently  non-carburetted  iron  did  not  take  up 
phosphorus  from  triferrous  phosphate  when  heated  alone 
with  it  in  a  stream  of  nitrogen,  yet,  when  cast-iron  with 
3  '8$  carbon  was  heated  with  this  phosphate  under  appar- 
ently like  conditions,  in  such  proportions  that  the  carbon 
of  the  cast-iron  just  sufficed  to  form  carbonic  oxide  with 
the  whole  of  the  oxygen  of  the  phosphate,  complete  de- 
oxidation  occurred,  and  the  iron  took  up  the  phosphorus 
of  the  phosphate."  (Experiments  14  and  19,  Table  26  A.) 

Hilgenstock,  too,  found  that,  after  fusion  with  pow- 
dered tetracalcic  phosphate,  non-carburetted  iron  held  but 
•088  to  '084$  of  phosphorus,  while  ferromanganese  and  pure 
carburetted  iron  absorbed  I'lO  and  0-80$  of  this  element 
respectively.  (Experiments  11,  12  and  13,  Table  26  A.) 

Experiments  of  Stead's  illustrate  the  greater  power  of 
ferromanganese  than  of  ordinary  cast-iron  to  reduce  phos 
phorus  from  slags.  He  placed  the  mixtures  indicated  in 
experiments  8,  9  and  10  in  Table  26  A  (1,  ferromanganese 
with  phosphate  of  manganese,  2,  ferromanganese  with 
phosphate  of  lime,  and,  3,  nearly  pure  carburetted  iron 


a  Percy,  Iron  and  Steel,  p.  512. 

b  Journ.  Iron  and  St.  Inst.,  1881, 1.,  p.  324. 

o  Wedding,  der  Basische  Bessemer  oder  Thomas  process,  pp.  153-4. 


been  oxidized,  /.  e.  not  until  the  "after-blow."  They 
here  overstate  the  influence  of  an  undoubted  principle.  I 
append  a  few  instances,  which  could  be  multiplied,  in 
which  a  very  considerable  quantity  of  phosphorus  has 
been  scorified,  though  the  metal  from  which  it  has  been 
removed  and  with  which  the  slag  is  in  contact  contains 
much  carbon,  and  in  certain  cases  much  silicon  as  well. 

In  the  basic  Bessemer  process  the  retention  of  the  phos- 
phorus till  after  nearly  all  the  carbon  has  been  removed, 
has  been  explained  by  the  supposition  that  the  slag, 
though  apparently  strongly  basic  from  the  start,  is  not 
effectively  so :  that  is  to  say  that  much  of  the  lime  re- 
mains in  lumps  uncombined  with  silica  and  inert  till  near 
the  end  of  the  operation,  when,  with  rise  of  temperature 
and  protracted  violent  stirring,  it  gradually  combines :  and 
many  observations  accord  with  this  view. 

The  experience  at  Creusot  and  Athus  shows  that,  in 
the  basic  process  as  in  pig-washing,  nearly  all  the  phos- 
phorus may  be  removed  before  any  considerable  percent- 
age of  carbon  has  been  oxidized,  by  simply  making  the 
slag  effectively  basic,  e.  g.  by  liquefying  it  through  the 
addition  of  fluor  spar.  By  this  means  the  phosphorus  in 
the  metal  was  in  one  case  reduced  from  2 -3  to  0-22%  dur- 
ing the  first  period,  and  before  the  carbon  began  to  burn 
rapidly,  the  slag  then  carrying  18^  of  phosphoric  acid. 
As  explained  in  §112,  this  was  not  due  to  volatilization 
of  phosphorus  or  silicon.4 

Stead  found  that  when  powdered  lime  was  blown  through 
the  metal  in  the  basic  Bessemer  converter,  and  therefore, 
owing  to  its  fine  state  of  division  and  intimate  exposure  to 
freshly  formed  phosphoric  acid,  at  once  became  an  active 
component  of  the  slag,  the  phosphorus  was  removed  before 
the  carbon,  of  which  a  large  quantity  remained  after  com- 
plete dephosphorization.6 

In  the  basic  open-hearth  process,  all  the  bases  of  whose 
more  ferruginous  and  fusible  slags  rapidly  become  effec- 
tive, dephosphorizalion  may  progress  far  while  the  metal 
still  holds  a  great  deal  of  carbon.  Thus  Harbord  quotes 
a  case  in  which  phosphorus  fell  from  2 '3^  to  '99^,  while 
the  metal  retained  '84$  of  carbon  and  '08  of  silicon.' 

Finally,  in  pig-washing  under  favorable  conditions 


d  Iron  Age,  February  25,  1886,  p.  7. 

e  Journ.  Iron  and  St.  Inst.,  1886,  II.,  p.  717. 

t  Idem,  pp.  701-3. 


62 


THE    METALLURGY    OP    STEEL. 


of  the  phosphorus  present  may  be  removed  while'95^  of 
the  carbon  remains" ;  and  in  other  cases  we  find  that  cast- 
iron  containing  initially  8 "637$  carbon  and  1'351$  phos- 
phorus holds,  after  washing,  3  -25$  carbon  with  -089£ 
phosphorus,  8-209#  carbon  with  •085^  of  phosphorus, 
etc.b 

§  109.  EFFECT  OF  TEMPERATURE. — Of  all  the  evidence 
adduced  to  show  that  high  temperature  favors  the  reten- 
tion of  phosphorus  by  metallic  iron,  that  of  the  puddling 
furnace  and  of  Bell's  experiments  alone  appear  to  me  con- 
clusive, the  retention  of  phosphorus  in  the  other  cases 
which  I  have  met  appearing  explicable  on  other  grounds. 

In  puddling  by  far  the  highest  temperature  is  reached 
at  the  very  end  of  the  operation.  This  high  temperature 
appears  to  cause  the  iron  to  reabsorb  from  the  slag  part 
of  the  phosphorus  which  it  has  previously  given  up  to  it. 
Thus  Bell  found  that  while  the  iron  granules  just  before 
balling  contained  in  two  cases  0'09  and  0'10$  phosphorus 
respectively,  the  bar  iron  made  from  them  had  0'15  and 
0'145$  phosphorus.0  To  clinch  the  matter  he  exposed  to 
an  intensely  high  temperature  and  in  contact  with  the 
slag  with  which  they  had  been  puddled,  two  lots  of  gran- 
ules which  had  purposely  been  puddled  at  an  unusually 
low  temperature.  In  one  case  the  percentage  of  phos- 
phorus in  the  metal  rose  from  "068  to  0 '145  when  thus 
superheated  ;  in  the  other  it  rose  in  30  minutes  from  '086 
to  '122$,  and  in  160  minutes  to  0'255$.  In  each  case  the 
samples  analyzed  were  first  freed  from  adhering  slag  by 
fusion  with  alkaline  carbonates. 

It  has  long  been  surmised  that  high  temperature  favors 
the  retention  of  phosphorus  by  iron.  Its  retention  in  the 
Bessemer  process  was  in  1865  chiefly  ascribed  by  Wedding 
to  the  high  temperature  of  that  operation.  But,  since  the 
development  of  the  basic  Bessemer  process,  in  which 
phosphorus  may  be  practically  completely  eliminated  at 
an  exalted  temperature  and  with  extreme  rapidity,  it  is 
absolutely  certain  that  the  influence  of  temperature  is 
wholly  subordinate  to  the  united  influence  of  the  com- 
position of  the  slag  and  the  intensity  of  the  oxidizing  con- 
ditions. Pourcel  in  1879,  even  after  the  success  of  the 
basic  process,  eloquently  but  vainly  insisted  that  temper" 
ature  was  more  potent  than  slag -composition.3 

In  his  blast-furnace  experience  he  finds  that  gray  iron 
always  contains  under  like  conditions  more  phosphorus 
than  white,  0*6  vs.  0'%%.  As  gray  iron  is  made  at  a  higher 
temperature  and  with  more  basic  slags  than  white,  he  in- 
fers that  the  effect  of  temperature  in  favoring  the  reten- 
tion of  phosphorus  by  iron  here  outweighs  that  of  slag- 
basicity  in  eliminating  it. 

As  this  experience  is  not  general  (Bell6  does  not  find 
that  iron  made  at  a  low  temperature  has  less  phosphorus 
than  that  made  at  a  higher,  under  otherwise  like  condi- 
tions) the  higher  phosphorus  in  gray  than  in  white  iron 
is  to  be  attributed  to  some  special  accompanying  condition 
rather  than  to  temperature.  High  fuel  ratio  (i.  e.  large  pro- 
portion of  the  reducing  agent)  rather  than  high  temperature 
as  such  is  probably  the  tiera  causa :  for  it  is,  I  believe,  the 
general  experience  that  the  amount  of  phosphorus  in  cast- 


a  Bell,  Principles  of  the  Manufacture  of  Iron  and  Steel,  p.  401. 

b  Bell,  Journal  Iron  and  St.  Inst.,  1877,  II.,  p.  337. 

c  Journ.  Iron  and  Steel  Inst.,  1877,  II.,  p.  339  :   Manuf.  Iron  and  Steel,  p.  403. 

dldem,  pp.  342-4. 

<•  Manufacture  of  Iron  and  Steel,  p.  416. 


iron  is  more  closely  proportional  to  the  strength  of  the 
reducing  conditions  (as  inferred  from  the  percentage  of 
ferrous  oxide  in  the  slag)  than  to  the  blast-furnace  tempera- 
ture (which  is  inferable  from  the  grade  of  the  iron) : 
though  of  course  high  temperature  and  strong  reducing 
conditions  usually,  though  not  always,  accompany  each 
other.  With  such  a  vera  causa  at  hand,  it  seems  super- 
fluous to  call  in  temperature  here  as  a  dominant  factor. 

§  110.  EFFECT  OF  THE  INITIAL  PERCENTAGE  OF  PHOS- 
PHORUS IN  THE  IRON. — It  is  altogether  probable  that,  when 
iron  already  contains  much  phosphorus,  it  absorbs  this 
element  less  readily  from  slags  with  which  it  is  in  contact, 
and  yields  it  up  to  them  more  readily  than  when  it  has 
but  little.  This  is  shown  by  the  familiar  fact  that  while 
comparatively  acid  slags  remove  the  first  portions  of  phos- 
phorus from  phosphoric  cast-iron,  yet  the  last  traces  of 
phosphorus  can  only  be  removed  in  contact  with  extremely 
basic  ones.  Thus  basic-Bessemer  slags  47  and  54  in  Table 
26  with  31-7  and  31-0$  of  silica  have  5-93  and  4-14$  of 
phosphoric  acid,  while  the  accompanying  metal  has  '61 
and  1* 07$  of  phosphorus:  yet,  so  far  as  my  observation 
goes,  such  acid  slags  can  only  remove  phosphorus  from  iron 
which  has  a  comparatively  large  percentage  of  this  ele- 
ment. At  least  among  the  many  recorded  cases  of  basic 
Bessemer,  puddling,  refinery,  pig-washing  and  Siemens- 
direct-process  slags  I  find  none  containing  more  than  3<)$ 
silica  which  accompanies  iron  whose  phosphorus,  if 
initially  much  above  0'50$,  has  fallen  below  this  point. 

So  too,  while  blast-furnace  slags  rarely  contain  an  im- 
portant quantity  of  phosphoric  acid,  yet  if  the  cast-iron  be 
extremely  phosphoric  the  slag  is  habitually  rich  in  phos- 
phoric acid.  The  following  instances  illustrate  this  :f 

Silica  in  slag 34-58 

Phosphoric  acid  in  slag 6  '00 

Phosphorus  in  cast-iron 16-20 

Silicon  in  cast-iron 0'19 

Even  extremely  acid  slags  (e.  g.  with  64$  silica  and 
midway  between  bi- and  trisilicate,  oxygen  ratio  =  1  :  2-57) 
may  retain  a  small  quantity  of  phosphoric  acid  when  in 
contact  with  highly  phosphoriferous  iron.  Thus  Brackels- 
berg,g  melting  phosphate  of  iron  in  a  carbon  lined  crucible 
with  a  small  quantity  of  acid  slag,  obtained  iron  with  22  '27$ 
phosphorus  and  a  slag  which,  in  spite  of  holding  64'31$ 
silica,  contained  0'59$  phosphoric  acid.  Yet  this  was  not 
because  the  iron  was  saturated  with  phosphorus,  for  in 
other  experiments  iron  was  obtained  with  26 '36$  of  this 
metalloid. 

§  111.  EFFECT  OF  CARBONIC  OXIDE. — While  this  gas 
unaided  cannot  reduce  phosphorus  from  triferrous  phos- 
phate, yet  in  the  presence  of  metallic  iron  it  does  reduce 
this  salt,  and  it  probably  reduces  phosphorus  from  phos- 
phoriferous slags  in  general,  even  when  strongly  basic. 

Thus  Finkener  found  that,  while  no  important  action 
occurred  when  triferrous  phosphate  alone  was  exposed  to 
carbonic  oxide  at  a  white  heat ;  yet  when  it  was  mixed 
with  ferric  oxide  in  such  proportion  that  if  the  whole 
were  reduced  an  iron  with  8$  phosphorus  should  result, 
they  were  wholly  deoxidized  when  exposed  to  a  white 
heat  in  an  atmosphere  of  carbonic  oxide.  (Experiments 
18  and  20,  Table  26  A.)h 


36-42 
4-45 

14-36 
0-98 


36-94  3739 

3-65  3-34 

17-59  14-68 

0-30  0-19 


t  Stahl  und  Eisen,  VI.,  10,  p.  642,  1886. 

g  Idem,  1885,  p.  546. 

11  Wedding,  Der  Basisclie  Bessemer  oder  Thomas  Process,  pp.  155-4. 


DEPHOSPHORIZATION,— FAVORED     BY    FLUOR    SPAR.     §  112. 


63 


That  carbonic  oxide  reduces  phosphorus  from  even  ap- 
parently strongly  basic  ferruginous  slags  is  indicated  by 
experiments  by  Pourcel."  After  melting  cast-iron  con- 
taining 2 '5$  carbon  and  0'."$  phosphorus  in  an  ordinary 
apparently  acid-lined  open-hearth  furnace,  he  skimmed 
the  slag,  laying  bare  the  surface  of  the  metal,  which  he 
next  exposed  to  the  action  of  hot  air,  by  cutting  off  the 
gas  supply,  thus  giving  it  a  roasting  comparable  to  the 
roasting  of  blister  copper. 

(A).  Carbonic  oxide  was  evolved  ;  at  the  end  of  15  min- 
utes, during  which  a  layer  of  slag  formed,  no  phosphorus 
had  been  removed  from  the  iron. 

(B).  The  conditions  were  the  same  as  in  (A)  except  that 
the  evolution  of  carbonic  oxide  as  prevented  by  adding 
ferro-silicon  (with  silicon  10$,  manganese  20$).  After  15 
minutes,  during  which  a  slag  formed  as  before,  the  metal 
had  lost  0'15$  phosphorus,  containing  only  0'35  instead  of 
0'50$.  The  slag  contained  phosphoric  acid. 

(C).  In  another  case  the  conditions  of  (B)  were  repro- 
duced :  after  a  while  evolution  of  carbonic  oxide 
recommenced :  the  phosphoric  slag  was  left  on  the 
metal.  After  15  minutes  more,  during  which  both  gas  and 
air  entered  the  furnace,  it  was  found  that  the  metal  had 
reabsorbed  all  the  phosphorus  removed  during  experiment 
(B),  having  now  0'5$  phosphorus. 

(D).  By  thrice  repeating  experiment  (B)  the  phosphorus 
in  the  metal  fell  from  0-5  to  0-24. 

Now  we  infer  that  the  slag  was  basic;  for,  if  acid  de- 
phosphorization  would  not  have  occurred  in  (B) :  it  could 
readily  be  basic  even  in  an  acid  lined  furnace  if  the 
initial  slag  were  first  skimmed,  since  such  quiet  may 
prevail  that  the  silica  which  the  slag  at  its  periphery 
takes  up  from  the  walls  would  only  slowly  diffuse  toward 
the  centre  of  the  slag  layer.  All  conditions  appear  to 
have  been  closely  alike  except  that  in  (A)  and  (C)  car- 
bonic oxide  was  evolved,  but  not  in  (B)  and  (D).  The 
rephosphorization  in  (C)  can  hardly  have  been  due  sim- 
ply to  the  agitation  caused  by  the  escape  of  carbonic 
oxide  :  for,  though  this  would  indeed  increase  the  con- 
tact between  slag  and  carburetted  metal,  thus  strengthen- 
ing the  tendency  to  reduce  phosphorus,  it  would  simul- 
taneously and  probably  to  the  same  extent  increase  the 
exposure  of  slag  to  atmospheric  oxygen,  the  source  of 
the  oxidizing  tendencies.  And  as  the  resultant  of  the 
reducing  action  of  the  metal  and  the  oxidizing  action 
of  the  atmosphere  is  shown  by  (B)  to  oxidize  phos- 
phorus, mere  agitation,  while  it  would  hasten  the  chem- 
ical action,  should  not  reverse  the  direction  of  the  re- 
sultant of  two  chemical  forces  which  it  stimulates  ap- 
parently in  an  equal  degree. 

The  reducing  effectof  carbonic  oxide  in  C  appears  to  have 
been  more  energetic  than  that  of  the  carbon,  silicon  and 
manganese  added  in  B :  the  reducing  action  during  B 
was  strengthened  by  the  presence  of  more  carbon,  silicon 
and  manganese  than  were  present  in  A  and  G,  yet  it  was 
not  strong  enough  to  prevent  oxidation  of  phosphorus  : 
but  when,  as  in  A  and  C  it  was  strengthened  by  the  escape 
of  carbonic  oxide,  it  sufficed  not  only  to  prevent  oxida- 
tion of  phosphorus  but  to  reduce  this  metalloid  back  from 
the  slag.  While  under  favorable  conditions  of  contact 
carbon,  silicon  and  manganese  would  probably  reduce 
phosphorus  far  more  energetically  than  carbonic  oxide,  the 

»  Journ.  Iron  and  St.  lust.,  1879,  II.,  pp.  370-383. 


latter  is  more  effective  in  this  case  because  of  its  exter- 
sive  contact  as  it  bubbles  through  the  slag.  Tliis  explana- 
tion accords  with  experiments  18  and  19,  Table  26  A,  in 
which  the  carbon  of  cast-iron  completely  reduced  the  phos- 
phorus from  triferrous  phosphate,  on  which  exposure  to 
an  atmosphere  of  carbonic  oxide  had  no  important  effect. 
In  pig- washing  it  has  been  observed  that  the  conditions 
which  permit  abundant  evolution  of  carbonic  oxide  cause 
reduction  of  phosphorus  from  the  slag,  which,  as  in  the 
case  just  explained,  can  hardly  be  due  agitation  as  such. 

In  the  basic  Bessemer  process  the  tendency  of  the  car- 
bonic oxide  to  reduce  phosphorus  from  the  slag  as  it 
rushes  through  it  may  be  largely  masked  during  the  blow 
by  the  simultaneous  rapid  oxidation  of  phosphorus  occur- 
ring at  the  bottom  of  the  bath  of  metal,  where  atmos- 
pheric oxygen  is  in  great  excess.  But  it  is  observed  that 
in  recarburizing  the  blown  metal,  the  oxidizing  action  of 
the  blast  having  ceased,  conditions  which  permit  copious 
evolution  of  carbonic  oxide  (e.  g.  the  employment  of  a 
recarburizer  with  much  carbon,  spiegeleisen  instead  of 
ferro-manganese)  cause  reabsorption  of  phosphorus  by  the 
metal.  But  this  may  be  in  part  due  to  the  agitation 
caused  by  the  escape  of  carbonic  oxide,  which  brings  the 
slag  into  more  extended  contact  with  the  metal  which  is 
now  (owing  to  the  addition  of  the  spiegeleisen)  richer  in 
carbon,  manganese  and  silicon  than  during  the  im- 
mediately preceding  period,  when  its  phosphorus  was  be- 
ing oxidized  and  scorified. 

§  112.  FLUOR  SPAR  is  said  to  expel  phosphorus 
together  with  silicon  and  carbon  from  iron,  the  phos- 
phorus partly  as  fluoride  of  phosphorus  PF3  (a  colorless, 
inflammable,  fuming  liquid,  readily  volatilized),  partly  as 
phosphate  of  lime.  Its  employment  in  the  basic  Besse- 
mer process  causes  the  phosphorus  to  leave  the  iron 
rapidly  during  the  early  part  of  the  operation,  but  this  is 
ascribed  to  its  effect  in  fluxing  the  lime  and  rendering  the 
slag  effectively  basic.  Without  fluor  spar  the  lime  is 
thought  to  melt  and  combine  with  the  slag  but  slowly.b 

Henderson0  states  that,  in  1869,  heating  and  melting 
white  cast-iron  during  an  hour  in  a  clay  crucible  lined 
with  magnesia  with  an  inner  lining  of  fluor  spar,  its  phos- 
phorus was  reduced  from  0'75$  to  0-02$,  the  carbon  being 
simultaneously  wholly  eliminated.  Employing  fluor  spar 
in  puddling  in  common  ore-lined  puddling  furnaces,  he 
found  that  much  of  the  silicon  was  volatilized  (as  fluoride, 
SiF4  ?),  and  that  the  slags  were  abnormally  free  from  silica 
and  phosphoric  acid.  Readily  condensed  fumes  were 
given  off  by  the  puddled  balls.  So  too  on  running  cast- 
iron  upon  fluor  spar  dense  fumes  arose  ;  most  of  the  sili- 
con and  part  of  the  phosphorus  were  eliminated,  yet  no 
slag  formed ;  hence  it  is  inferred  that  silicon  and  phos- 
phorus volatilized  as  fluorides.  The  resulting  iron  was 
porous  and  filled  with  a  white  substance. 

In  another  experiment  also  phosphorus  appears  to  have 
been  volatilized  by  fluor  spar.  2,287  pounds  of  cast-iron, 
containing  initially  1'14$  of  phosphorus,  held  but 
0'17$  after  fusion  with  83  pounds  of  fluor  spar  in  an  ore- 
lined  open-hearth  furnace,  the  accompanying  slag  contain- 
ing 2  '84$.  Of  the  25  '7  pounds  of  phosphorus  in  the  initial 
metal,  but  11'49  remained,  4 '39  in  metal  and  7-1  in  slag  : 
to  volatilize  the  missing  14-2l  pounds  as  the  fluoride  PF8 


b  Revue  TJniverselle,  X.,  1881,  p.  418  ;  Iron  Age,  February  25,  1886,  p.  7. 
'•  James  Henderson,  private  communication. 


64 


THE    METALLURGY    OF    STEEL. 


25  '5  pounds  of  fluorine  are  needed,  while  39 '9  pounds  of 
this  element,  or  a  great  excess,  are  supplied  by  the  28 
pounds  of  fluor  spar  present. a  If  these  experiments  are  to 
be  trusted  they  appear  to  show  that  fluor  spar  under  certain 
conditions  volatilizes  phosphorus  as  fluoride. 

It  is  not  easy  to  harmonize  these  results  with  those  ob- 
tained in  Percy's  laboratory,  except  on  the  rather  violent 
assumption  that  cast-iron  retains  its  phosphorus  much 
less  tenaciously  than  the  phosphide  of  iron  Fe2P.  This 
substance,  which  contains  23 ±%  phosphorus,  was  melted 
in  a  brasqued  crucible  with  fluor  spar :  from  the  fact  that 
the  weight  of  the  metal  changed  less  than  0'5  grain  it  is  in- 
ferred that  little  or  no  phosphorus  was  volatilized.b  So 
too  in  the  basic  Bessemer  process,  though  the  employ- 
ment of  fluor  spar  hastens  dephosphorization,  it  appears 
to  be  by  assisting  the  scorification  of  phosphorus  rather 
than  by  volatilizing  it :  at  least  the  slags  contain  a  large 
percentage  of  phosphorus :  one  is  reported  with  18%  phos- 
phoric acid.  Further,  the  quantity  of  air  required  for 
oxidizing  the  phosphorus  and  other  elements,  as  inferred 
from  the  length  of  the  blow  and  revolutions  of  the  engine, 
does  not  appear  to  have  been  lessened  by  the  addition  of 
fluor  spar,  which  would  certainly  indicate  that  the  phos- 
phorus, taking  up  the  oxygen  of  the  blast,  was  removed 
as  phosphate.0 

Henderson's  statements  can  be  reconciled  with  these  by 
supposing  that  under  strongly  oxidizing  conditions,  like 
those  of  the  basic  Bessemer  process,  phosphorus  tends 
rather  to  form  phosphate  than  fluoride ;  but  that  iinder 
the  gently  oxidizing  conditions  of  the  basic  open-hearth 
it  more  readily  forms  fluoride.  But  how  they  can  be 
reconciled  with  Percy's  results  I  know  not. 

To  sum  up,  fluor  spar  appears  to  favor  dephosphor- 
iaation, 

1.  By  liquefying  the  slag,  thus  enabling  it  to  assimilate 
the  lime  present,  part  of  which  might  otherwise  remain 
unmolten  and  inert,  and  thus  rendering  the  slag  effectively 
basic. 

2.  Probably  by  volatilizing  silicon  from  the  metal,  thus 
diminishing  the  formation  of  silica  and  thereby  increas- 
ing the  basicity  of  the  slag. 

3.  In  certain  cases,  e.  g.  when  the  conditions  are  not 
strongly  oxidizing,  By  volatilizing  phosphorus  as  fluoride. 

§  113.  RATIONALE  OF  THE  ACTIOX  OF  SLAGS. — In  the 
puddling  and  other  processes  in  which  the  metal,  whose 
phosphorus  and  other  elements  are  removed  by  oxidation, 
is  protected  from  the  air  by  a  layer  of  slag,  the  iron  oxides 
of  the  slag  carry  oxygen  from  the  air  to  the  metalloids : 
their  remarkable  power  of  carrying  oxygen,  of  determin- 
ing the  oxidation  of  elements  with  which  they  are  in  con- 
tact, is  shown  in  many  metallurgical  operations.  In  roast- 
ing sulphide  ores  with  salt  the  mere  addition  of  ferric 
oxide  prevents  the  sulphur  present  from  escaping  as  sul- 
phurous anhydride,  and  determines  its  complete  oxida- 
tion to  sulphuric  acid  and  thus  the  formation  of  sulphate 
of  soda. 

Doubtless  in  the  basic  Bessemer  process  also,  part  of 
the  oxidation  of  phosphorus  is  due  to  the  action  of  iron 
oxide :  but  it  is  by  no  means  certain  that  phosphorus  may 
not  be  directly  oxidized  by  the  atmospheric  oxygen  as 


a  Henderson,  Iron  Age,  June  11,  1885,  p.  35. 

b  Percy,  Iron  and  Steel,  p.  67. 

c  Iron  Age,  February  25,  1886,  p.  7. 


well.  This  however  is  of  little  practical  moment:  but 
what  is  of  moment  is  that  a  large  quantity  of  phosphorus 
may  in  this  process  be  eliminated  without  the  permanent 
oxidation  and  loss  of  much  iron.  If  the  phosphorus  is 
oxidized  only  through  iron  .oxide,  then  clearly  this  oxide 
plays  a  part  like  that  of  the  oxides  of  nitrogen  in  the 
manufacture  of  sulphuric  acid,  carrying  oxygen  from  the 
air  to  the  phosphorus,  the  presence  of  a  small  quantity  of 
iron  oxide  sufficing  to  oxidize  a  large  quantity  of  phos- 
phorus. 

If  I  understand  Ehrenwerth  aright,  he  considers  it  ridic- 
ulous11 to  suppose  that  phosphorus  can  pass  directly  to 
phosphate  of  lime  in  this  process  without  the  intervention 
of  iron  oxide :  but  I  think  this  belief  deserves  more  tol- 
eration. Thus,  basic  Bessemer  slag  No.  17,  Table  26,  con- 
tains 12-41$  of  phosphoric  acid  and  63-33$  of  lime,  with 
only  5-02$  of  iron  oxide.  Now  it  may  be  that  the  whole 
of  the  phosphoric  acid  which  forms  unites  at  first  with 
iron  oxide,  and  that  this  iron  oxide  is  displaced  so  rap- 
idly by  lime  and  picks  up  a  new  lot  of  phosphoric  acid 
so  suddenly  that  for  a  considerable  length  of  time  it  does 
not  rise  above  5 -02$:  but  this  implies  so  rapid  a  decom- 
position of  iron  phosphate  and  so  instantaneous  a  trans- 
fer of  its  iron  oxide  to  fresh  portions  of  phosphoric  acid 
throughout  such  enormous  masses  of  material,  that  those 
who  find  it  easier  to  believe  that  some,  at  least,  of  the 
phosphoric  acid  unites  directly  with  the  great  excess  of 
lime  present,  do  not  deserve  ridicule.  Indeed,  Mathesius' 
observation6  that,  when  phosphoric  iron  was  melted  with 
lime  and  charcoal  in  a  graphite  crucible  with  careful 
exclusion  of  oxiding  influences,  nearly  half  of  its  phos- 
phorus was  slagged,  apparently  without  the  intervention 
of  iron  oxide,  would  seem  to  rob  this  idea  of  the  humor 
which  Ehrenwerth  found  in  it ;  the  removal  of  phos- 
phorus from  the  interior  of  solid  cast-iron  bars  by  mere 
immersion  in  fused  alkaline  carbonates  (§  114)  may  not 
intensify  his  mirth. 

How  large  a  quantity  of  phosphorus  may  be  oxidized  by 
a  small  quantity  of  iron  oxide  is  shown  by  slags  23  (basic 
open-hearth)  and  17  (basic  Bessemer),  Table  26.  The  latter, 
with  12'41  phosphoric  acid  has  but  6'02$  iron  oxide  :  the 
former  has  23'05  phosphoric  acid  with  but  6'16$  iron 
oxide.  The  oxygen  ratio  of  iron  oxide  to  phosphoric 
acid  in  these  two  cases  is  1 :  6 '25  and  1 :  9'95  respectively. 
Gilchrist'  mentions  basic  Bessemer  slag  with  5  to  6$  iron 
and  13  to  15%  phosphoric  acid.  It  is  clear  that  the  phos- 
phoric acid  is  at  least  in  part  combined  with  lime  in 
these  slags.  The  oxygen  ratio  of  base  to  acid  is  1 : 1  -67  in 
tribasic  (ortho)  phosphate  (e.  g.  apatite,  pyromorphite, 
vivianite,  annabergite,  etc.,  the  most  acid  natural 
phosphates  mentioned  by  Dana),  and  1 : 5'0  in  monobasic 
(meta)  phosphate  (ultra  acid  phosphate).  Now  if  the 
whole  of  the  phosphoric  acid  in  slag  23  is  combined  with 
iron  oxide  and  none  of  it  with  lime,  we  have  an 
astonishingly  acid  iron  phosphate  in  contact  while  molten 
with  an  as  astonishingly  basic  lime  silicate,  the  oxygen 
ratio  of  base  to  acid  in  these  two  compounds  being 
1 : 9-95  and  1 :  0'29  repectively.  It  is  hard  to  believe  that 
two  such  substances  can  coexist  in  the  fused  mass  as  in- 
dependent entities.  


d  "Etwaa  drolligeu  Idee."    Oesterreich.  Zeit.  fur  Berg-  und  Hiittenweeen,  1881, 
p.  102. 

o  Stahl  und  Eisen,  VI.,  10,  pp.  641-3,  1886. 
t  Journ.  Iron  and  St.  Inst.,  1879, 1.,  p.  200. 


RATIONALE     OP    THE    DEPHOSPHORIZING     ACTION    OF    SLAGS.     §  113. 


65 


From  similar  reasoning  I  unhesitatingly  conclude  that 
some  of  the  phosphoric  acid  of  certain  molten  basic 
Bessemer  slags  is  in  part  combined  with  iron  oxide :  this 
granted,  we  distrust  arguments  intended  to  prove  that 
the  phosphoric  acid  of  these  slags  is  in  general  exclusively 
combined  with  earthy  bases,  and  completely  divorced 
from  the  oxides  of  iron.  In  puddling  thorough  dephos- 
phorization  may  occur  with  slags  free  from  lime,  e.  g.  slag 
4,  Table  26,  p.  58,  which  has  3  -12%  phosphoric  acid  with 
but  0'18$  lime  and  0'18^  magnesia,  the  accompanying 
metal  having  but  '06$  phosphorus.  In  the  basic  Bessemer 
process  also  dephosphorization  may  occur  when  the  slag 
contains  so  little  lime  that  it  is  very  probable  that  the 
phosphoric  acid  must  be  largely  combined  with  iron  oxide, 
e.  g.  slag  87,  which  with  7'46  phosphoric  acid  has  but  1O52 
lime.  To  assume  that  all  the  phosphoric  acid  in  this 
slag  is  combined  with  lime  and  that  its  iron  oxides  exist 
wholly  as  silicates,  would  imply  the  coexistence  in  the 
fused  mass  of  an  acid  lime  phosphate  in  contact  with  a 
basic  iron  silicate,  the  oxygen  ratio  of  base  to  acid  in 
these  two  compounds  being  respectively  1  :  1*4  and 
1  :  0-88  respectively.  It  is  far  more  reasonable  to  suppose 
that  the  phosphoric  acid  is  here  combined  with  both  lime 
and  iron  oxide. 

Pourcel  endeavors  to  show  that  phosphorus  exists  in 
the  slag  of  the  basic  process  as  iron  phosphate  by  stating 
that,  when  certain  of  these  slags  are  heated  in  an  atmos- 
phere of  hydrogen,  they  lose  a  quantity  of  oxygen  equal 
to  that  contained  in  the  phosphoric  acid  and  iron  oxide 
present,  while  hydrogen  is  inert  on  pure  phosphate  of 
lime.a  This  is  far  from  cogent,  for  no  evidence  is  offered 
to  show  that  the  loss  of  oxygen  was  not  from  silicates  of 
iron,  manganese,  etc. 

Stead  endeavors  to  prove  that  phosphorus  exists  as 
phosphate  of  lime  and  not  of  iron  in  these  slags  by  show- 
ing that,  when  they  are  fused  after  heating  in  an  atmos- 
phere of  hydrogen,  malleable  (i.  e.  non-phosphoric)  but- 
tons of  iron  are  obtained,  which  indicates  that  the  hydro- 
gen reduced  iron  but  not  phosphorus.b  This  tends  to 
show  that  the  phosphorus  does  not  in  this  particular 
instance  exist  as  iron  phosphate  :  but  it  is  by  no  means 
conclusive. 

Gilchrist"  mentions  a  fact  which  strongly  indicates  the 
existence  of  lime  phosphates  in  the  solidified  basic  Besse- 
mer slag.  Lime  phosphate  is  soluble  in  sul  phurous  acid,  but 
not  when  digested  with  ammonium  sulphide  or  fused  with 
sodium  chloride.  Iron  phosphate  is  insoluble  in  sulphur- 
ous acid  but  soluble  when  digested  in  ammonium  sulphide 
or  fused  with  sodium  chloride.  Now  the  phosphoric  acid  of 
certain  basic  Bessemer  slags  is  completely  soluble  in  sul- 
phurous acid,  but  almost  insoluble  when  digested  in  am- 
monium sulphide  or  fused  with  sodium  chloride.  Yet  the 
phosphorus  of  certain  double  phosphates  of  iron  and  lime 
or  in  certain  silico-phosphates  of  iron  may  possess  the 
specific  properties  shown  by  the  phosphoric  acid  of  these 
slags.  Hilgenstock4  finds  distinct  crystals  of  tetracalcic 


a  Journ.  Iron  and  St.  Inst,  1879,  2,  p.  384.  b  Idem,  p.  1880, 1.,  p.  112. 

c  Journ.  Iron  and  St.  Inst,  1879,  I.,  p.  200. 

a  Stahl  und  Eisen,  VI.,  p.  525,  1886,  No.  8.  Revue  Universelle,  XX.,  p.  457, 
No.  2,  and  p.  655,  No.  3,  1886.  Groddeck  and  Brockmann  find  in  basic  Bessemer 
slag  two  varieties  of  crystals  of  tetracalcic  phosphate,  one  in  brown,  rectangular, 
very  thin,  friable,  transparent  tables  with  vitreous  luster  :  the  other  blue,  minute, 
tabular  or  prismatic  crystals,  apparently  of  the  rhombic  system.  (Revue  Univer- 
selle, XX.,  2,  p.  458,  1886.)  Stead  and  Ridsdale  find  these  in  this  slag,  but  they 
always  find  10  to  \\%  of  silica  in  the  blue  ones.  They  also  find  crystals  of  four 


phosphate  in  the  vugs,  and  bunches  of  it  in  the  solid  por- 
tion of  basic  Bessemer  slags,  which  is  conclusive. 

It  appears  most  philosophic  to  regard  a  fused  slag  as  a 
single  complex  chemical  compound,  a  polybasic  silico- 
phosphate,  in  which  each  element  is  chemically  united 
with  every  other  element  present,  and  in  which  there  are 
no  separate  entities  such  as  phosphates  of  lime  and  sili- 
cates of  iron.  In  this  view  the  evidence  of  Pourcel,  Stead 
and  Gilchrist  is  beside  the  mark,  and  merely  throws  light 
on  the  compounds  which  form  and  perhaps  segregate  and 
crystallize  out  when  the  mass  solidifies  and  passes  from 
the  condition  of  homogeneous  magma  to  that  of  a  hetero- 
geneous mechanical  mixture  of  salts,  sulphides  and 
oxides,  each  crystallizing  and  assuming  an  individual 
existence  as  the  falling  temperature  reaches  its  particular 
freezing  point. 

This  view  is  powerfully  supported  by  the  phenomena  of 
the  devitrification  of  glass,  and  by  that  of  obsidian  in 
nature.6  In  certain  cases  different  portions  of  what  was 
originally  an  apparently  homogeneous  magma  has  in 
solidifying  cooled  at  a  rate  which,  comparatively  rapid 
in  one  portion,  diminishes  by  most  minute  gradations, 
little  by  little,  trace  by  trace,  till  in  another  and  distant 
portion  it  has  been  so  unutterably  slow  that  complete 
refrigeration  may  have  occupied  centuries.  Here  we  can 
follow  every  gradation  from  the  transparent  homogeneous 
glass,  whose  rapid  cooling  has  preserved  the  status  quo 
and  prevented  every  trace  of  differentiation  and  crystalli- 
zation, through  the  first  hardly  perceptible  incipiency  of 
widely  scattered  microscopic  hair  crystals  of  some  mineral 
which  has  barely  had  time  to  isolate  itself  at  its  exalted 
freezing  point  from  the  enclosing  magma.  Thence  through 
stages  in  which  the  crystalline  enclosures  encroach  on  the 
vitreous  mother  mass  more  and  more,  ever  increasing  in 
size  and  number  as  we  reach  portions  which  have  cooled 
more  and  more  slowly,  till  now  the  crystals  predominate, 
now  the  amorphous  glassy  patches  are  seen  among  them 
only  here  and  there,  and  at  last  we  reach  the  completely  de- 
vitrified  crystalline  mass,  composed  of  many  differentiated, 
dissimilar  interlaced  minerals.  Is  it  not  most  philosophic 
to  hold  that  these  independent  entities  were  wholly  inte- 
grated in  the  initial  magma ;  that  their  presence  in  it  was 
wholly  potential ;  that,  unborn  and  even  unconceived, 
their  existence  was  hardly  more  actual  than  that  of  the 
grandson  of  the  boy  who  wall  be  born  a  month  hence  is 
to-day  ? 

§113  A.  DEPHOSPHORIZATION  IN  Co  POL  A  FURNACES.— 
According  to  Rollet*  a  simple  fusion  in  a  cupola  furnace 
with  a  slag  which  after  dephosphorization  should  not  hold 


other  species,  some  of  which  have  been  referred  to  by  Hilgenstoek  and  by  Grod- 
deck and  Brockmann,  three  of  them  consisting  almost  wholly  of  bases  nearly  free 
from  acid,  the  fourth  chiefly  of  t  tetracalcic  phosphate  with  some  10#  of  silicates. 
(Journ.  Iron  and  St.  Inst.,  1887, 1.,  to  appear  :  also  1886,  II.,  p.  715.)  The  dis- 
covery of  so  basic  a  phosphate  has  elicited  a  degree  of  surprise  surprising  in  view 
of  the  existence  of  a  crystallized  native  phosphate  which  may  be  considered  as 
tetrabasic  (wagnerite,  4(%MgO  +  %MgF),  P2O5)  and  of  many  in  which  the  oxy- 
gen ratio  of  base  to  acid  is  far  greater  than  in  tetracalcic  phosphate,  if,  as  is  usual, 
ferric  oxide  be  regarded  as  a  base,  e,  g.  dufrenite  and  cacoxenite,  2Fe2O3P2O5  + 
3-5H2O  and  2Fe2O3,P2O5  +  12H2O,  and  borickite,  5(Fe203,3CaO),  2P2O5  + 
15H2O.  Among  our  slags  we  find  many  which  have  more  than  four  equivalents 
of  base  to  one  of  acid,  e.  g.  final  basic  Bessemer  slag  No.  6,  Table  26,  essentially  a 
silico-phosphate  of  lime,  which  has  over  7  equivalents  of  base  to  one  of  acid.  Those 
who  regard  such  substances  as  chemically  integral  when  molten  will  not  wonder 
at  the  isolation  of  tetrabasic  phosphates,  but  rather  regard  it  as  supporting  their 
views. 

<•  Hague  and  Iddings,  Bulletin  U.  S,  Geol.   Survey,   No.  17,  p.  10  ;  Am.  Journ. 
Sc:ei)ce,  XXVI.,  1883.  '  Stahl  und  Eisen,  III.,  5,  p.  305,  1883. 


66 


THE    METALLURGY    OF     STEEL. 


more  than  18$  of  phosphoric  acid  plus  silica,  removes 
much  or  most  of  the  phosphorus  of  cast-iron.  When  cast- 
iron  was  thus  fused  its  phosphorus  in  three  instances  fell 
from  -07  to  "058$,  from  -35  to  -068$,  and  from  1-95  to  -415$. 
Other  details  of  these  cases  are  given  in  lines  7,  8  and  9, 
Table  23,  p.  61. 

§114.  FUSED  ALKALINE  CARBONATES  (Eaton  process) 
gradually  and  sometimes  almost  completely  remove  phos- 
phorus together  with  carbon  and  silicon  from  the  interior 
of  planed  bars  of  cast-iron  immersed  in  them. 

Of  several  cases  reported  by  T.  'M.  Drown*  the  follow- 
ing shows  the  most  complete  dephosphorization.  The  iron 
itself  showed  no  trace  of  oxidation ;  in  other  cases  how- 
ever oxidation  occurred. 


Outer    layer 
1-16"  thick.? 

Second     layer 
1-16"  thick.? 

Third    layer 
1-16"  thick.? 

Interior. 

Original. 

0-057 

0-166 

0-942 

3-293 

3-56 

Silicon  
Phosphorus       

0-574 
0-015 

0-60T 
0-201 

1-281 
0  776 

1-362 
0  911 

1-38 
0-87 

The  removal  of  phosphorus  and  silicon  from  the  interior 
of  solid  bars  by  the  action  of  alkaline  carbonates  on  their 
exterior  is  interesting  and  surprising. 

§  115.  ALKALINE  NITRATES  (Heaton  process)  expel 
phosphorus  from  molten  iron  very  rapidly.  As  this  process 
was  actiially  carried  out  the  dephosphorization  was  far 
from  complete,  as  it  was  restrained  by  the  senseless  addi- 
tion of  sand,  and  by  insufficiency  of  niter;  but  the  use  of 
a  larger  and  under  most  conditions  prohibitory  proportion 
of  nitrate  would  probably  have  rendered  it  thorough.  The 
nitric  acid,  expelled  from  the  nitrate  by  the  heat  of  the 
molten  iron,  oxidizes  its  phosphorus  energetically  ;  while 
the  soda,  passing  into  the  slag,  renders  it  more  basic  and 
thus  increases  its  power  of  retaining  phosphoric  acid.  In 
two  cases  Grunerb  found  that  58  and  33$  of  the  phosphoric 
acid  contained  in  cast-iron,  which  contained  initially  1'57 
and  1  '2$  phosphorus  respectively,  was  removed  by  this  pro 
cess,  including  16  and  27$  respectively  which  was  volatil- 
ized. In  six  other  cases  he  found  it  reduced  from  1'06  to 
from  0  23  to  0'30$c ;  Miller  found  it  reduced  from  T45  to 
0-30$ ;  but  Snelusd  found  that  hardly  any  phosphorus  was 
removed  from  cast-iron  holding  about  0-5$  of  this  element. 

§  116.  MANGANESE,  whether  (1)  in  metal  or  (2)  in  slag, 
is  thought  to  favor  dephosphorization,  because  its  oxides 
attack  phosphorus  more  energetically  than  those  of  iron, 
and  because  its  phosphates  yield  up  their  phosphorus  to 
metallic  iron  and  the  carbon,  manganese,  etc.,  which  it 
holds  less  readily  than  iron  phosphates  do.  (1).  Manganese 
remaining  in  the  metal  as  it  often  does  at  the  end  of  the 
basic  Bessemer  and  open-hearth  processes,  prevents  the 
metal  from  absorbing  oxygen;  hence  its  presence  in  the  cast- 
iron  employed  for  these  processes  is  doubtless  an  advantage. 

(2).  Oxide  of  manganese  in  the  slag,  like  other  bases, 
assists  dephosphorization:  but  it  appears  probable  that 


a  Trans.  Am.  Inst.  Mining  Engineers,  1879,  VII.,  p.  147.  The  thickness  of 
these  layers  is  not  positively  stated,  but  is  inferred  from  the  context  to  have  been 
about  1-16". 

b  Gruner,  Annales  des  Mines,  1869,  XVI.,  p.  260. 

c  Idem,  1870,  XVII.,  p.  350. 


dephosphorizing  power  can  be  obtained  as  fully  and,  with 
the  usual  relations  of  prices,  far  more  cheaply  by  lime  or 
iron  oxide.  It  was  formerly  thought  that,  in  pig-washing, 
the  costly  oxides  of  manganese  would  effect  more  thorough 
dephosphorization  than  iron  oxides  alone :  experience 
indicates  that,  if  they  here  offer  any  advantage  over  iron 
oxide,  it  is  very  slight  and  not  commensurate  with  their 
higher  cost.  In  this  process  Bell  employs  iron  oxide 
alone,  Krupp  the  mixed  oxides  of  iron  and  manganese. 
I  find  that  in  six  cases  Bell  removes  77,  93,  93,  88,  92 
and  96$  of  the  initial  phosphorus,  while  Krupp  removes 
74,  63,  81,  72,  48  and  72$  in  six  cases :  but  this  is  rather 
misleading,  as  Krupp  may  have  stopped  his  operation 
unnecessarily  early.  A  comparison  of  the  ratio  of 
$  of  initial  phosphorus  removed 

$  of  initial  carbon  removed 

is  more  instructive.  I  find  that  for  6  cases  of  washing 
without  oxide  of  manganese  (Bell)  this  ratio  was  3'5 : 
9-3:  85:  7'3:  9 '2:  and  TO,  or  on  the  average  6 -6:  while 
when  oxide  of  manganese  is  employed  (Krupp)  it  was 
18-4 :  5-9 :  6'5 :  6-8 :  and  6-5,  the  mean  being  8-8.  While 

,.      „  dephosphorization  . 

the  mean  ratio  of  — £-  -  is  thus  slightly  high- 

decarburization 

er  when  oxide  of  manganese  is  employed,  too  few  results 
have  been  published  to  permit  trustworthy  conclusions. 
Thus,  dropping  one  case  from  each  we  find  that  the  mean 
ratio  becomes  7'6  without  and  6'4  with  oxide  of  manga- 
nese, which  would  suggest  that  oxide  of  manganese  op- 
posed dephosphorization.  Actually  at  American  pig-wash- 
ing works  85  to  90$  of  the  initial  phosphorus  is  ordinarily 
removed  with  the  use  of  iron  oxide  only,  leaving  say  '01  to 
•03  phosphorus  in  the  washed  metal.  (See  pig- washing. ) 

§  117.  INTEKKEACTION  OF  SULPHIDE  AND  PHOSPIIIDI: 
OF  IRON. — These  substances  when  melted  do  not  unite 
They  appear  to  react  on  each  other  but  slightly,  the  phos- 
phide taking  up  a  very  little  sulphur,  the  sulphide  a  little 
iron  and  sometimes  a  little  phosphorus.  When,  however, 
lime  phosphate  is  melted  with  pyrites  and  silica  in  thy 
presence  of  carbon,  much  of  the  phosphorus  and  most  of 
the  sulphur  may  be  volatilized,  and  a  phosphide  of  iron 
with  a  little  sulphur  results. 

Thus  Hochstatter,6  in  Percy's  laboratory,  melted  in  clay 
crucibles  the  two  phosphides  Fe6P,  containing  8$  of 
phosphorous,  and  Fe8P,  containing  23-3±$,  separately, 
both  with  ferrous  sulphide  containing  39 '4$  of  sulphur, 
and  with  an  excess  of  sulphur.  Each  phosphide  when 
melted  with,  sulphur  took  up  a  little  of  this  element, 
while  a  thin  layer  of  iron  sulphide  was  formed :  when 
fused  with  ferrous  sulphide,  one  phosphide  became  richer, 
the  other  poorer  in  phosphorus:  they  both  took  up  a  little 
sulphur,  and  were  overlain  by  iron  sulphide.  The  iron 
sulphide  resulting  from  the  fusion  of  the  phosphide  Fe0P 
with  ferrous  sulphide  contained  no  trace  of  phosphorus : 
that  resulting  from  the  fusion  of  the  phosphide  Fe8P  with 
ferrous  sulphide  contained  a  considerable  amount  of  phos- 
phorus in  its  lower  part.  I  here  summarize  these  results. 


d  Journ.  of  the  Iron  and  St.  Inst.,  1871,  II.,  p.  185. 

e  Percy,  Iron  and  Steel,  p.  66. 

Composition  of 
initial  phosphide. 

Fused  with 

Composition  of  Products. 

Character  of  Resulting  Sulphide. 

Iron  Sulphide. 

Iron  Phosphide. 

Phosphorus. 

Iron. 

Formula. 

Phosphorus. 

Phosphorus. 

Sulphur. 

Iron. 

8± 
23'2  ± 

8  ± 
23  2  ± 

92  ± 
76-67 
92  ± 
76  07  ± 

Fe6P 
Fe2P 
Fe6P 
Fe,P 

Sulphur 
FoS 

r«d 

8-45 

2-19 
4  52 
1-25 
4  93 

89-54 

A  thin  layer  of  iron  sulphide,  not  analyzed. 

Sulphide,  free  from  phosphorus. 
Much  sulphide  ,    the  lower  part  had    a  considerable 
amount  of  phosphorus. 

0.00 
A  considerable 
amount. 

10 

19 

75 
19 

87-83 
75.75 

PHOSPHORUS    AND    TENSILE    STRENGTH.      §  122. 


07 


Brackelsberg*  melted  8  parts  of  lime  phosphate,  4'6  of 
pyiite,  4'9  of  silica  and  2 '8  of  alumina  in  a  carbonaceous 
crucible.  Had  the  phosphorus  been  completely  reduced 
the  iron  resulting  would  have  had  45'41$  phosphorus: 
actually  it  hud  21'9,-^  phosphorus  with  2'31$  sulphur. 
The  accompanying  slag  had  48'?n^  silica,  5'48  phosphoric 
acid  and  1  '98;^  sulphur.  A  very  large  proportion  of  the 
phosphorus  was  here  volatilized,  together  with  a  still 
larger  part  of  the  sulphur. 

§  118.  VOLATILIZATION. — Besides  phosphorus  itself,  its 
chlorides,  fluoride,  phosphoretted  hydrogen,  PH3,  phos- 
phorous oxide,  Pa03,  and  phosphoric  acid  readily  vola- 
tilize, the  latter  subliming  below  a  red  heat.  Hence  phos- 
phorus is  volatilized  as  such  by  heating  acid  phosphate 
of  lime,  e.  g.,  mono-phosphate,  in  contact  with  charcoal : 
if  sand  be  added  the  whole  of  the  phosphorus  may  be  ex- 
pelled :  2CaP3Oa  +  2SiO2  +  IOC  =  2CaSiO3+  10CO  +  4P. 

Phosphorus  may  be  partially  volatilized  from  tricalcic 
phosphate  by  heating  it  in  contact  with  iron  oxide  and 
carbon :  and  from  iron  phosphates  by  heating  them  (A)  in 
contact  with  carbon,  either  alone  or  in  presence  of  sili- 
cates :  and  (B)  in  contact  with  silica.  In  the  latter  case  it  is 
probably  expelled  as  phosphoric  acid.  Thus  Bellb  decom- 
posed mono-ferrous  phosphate,  whose  oxygen  ratio  of 
base :  acid  is  1  :  5,  by  heating  it  contact  with  half  its 
weight  of  silica  at  a  bright  red  heat  for  five  hours, 
whereby  4'2^  of  its  initial  phosphorus  was  expelled  (say 
FeP2O6  +  SiO2  =  FeSiO3  +  P2O5).  He  then  cooled  and 
pulverized  it,  next  exposing  it  for  two  hours  to  a  steel 
melting  heat,  whereby  13'4^  more,  or  altogether  Yl'§%  of 
the  initial  phosphorus  was  volatilized. 

It  is  stated  that  if  diferrous  phosphate  is  heated 
in  a  crucible  with  25^  of  powdered  charcoal,  half  its 
phosphorus  is  volatilized,  and  iron  phosphide,  Fe2P, 
containing  2L'7±$  of  phosphorus,  is  formed:0  say 
140  +  2Fe  8P2O7  =  Fe2P  +  14CO  +  2P. 

So  too  Brackelsberg  volatilized  phosphorus  from  much 
less  acid  iron  phosphates  by  the  action  of  carbon  alone. 
He  melted  a  mixture  of  ferrous  and  ferric  phosphates 
(oxygen  ratio  base  :  acid  =  1  : 11 38)  in  carbon  crucibles,  A 
alone,  B  with  a  little  acid  slag.  The  iron  was  almost,  and 
in  one  case  quite,  fully  deoxidized,  and  contained  from 
21 '99  to  24 '56^  phosphorus.  The  accompanying  acid  slag 
contained  a  little  phosphoric  acid,  but  most  of  the  excess 
of  phosphorus  above  that  which  the  iron  was  capable  of 
absorbing,  or  from  14'3  to  18 "73^  of  the  total  phosphorus 
present,  was  volatilized,  or  at  least  was  not  accounted  for. 
I  here  summarize  his  results. 

PHOSPHORUS  VOLATILIZED  ON  MELTING  IRON  PHOSPHATE  (OXTGEN  EATIO  BASE  :  ACID  =  1  : 1-88) 
IN  BKASQUF.D  CRUcntLE.a 


We 
of  I 
uc 

ti 

1 
a 

ght 
rod- 
ts. 

Composition  of  products. 

-« 

"H  3 

*l 

f.  3 

J£ 

tii 

to 

a 
rn 

Metal. 

«m. 

Iron. 

1'lios- 
phoruf. 

Sili- 
con. 

Silica. 

AlsO,. 

FeO. 

CaO. 

MgO 

rso5. 

(1)  Iron  phosphate 

75.45 

24  -55 

14-3 
18-73 
1(5-98 

I.v:t9 

(2)  Iron  phosphate 
melted  with  acid 

2-00 
2-16 
2-OS 

2-19 
4-59 
2.9 

7i;-r, 

ra-w 

7.-,  -114 

21-99 
22-27 
28-00 

1-71 
0-87 
0  94 

54-88 
64-81 

45-79 

b 
9.12 

20-12 

4-98 

3-06 
0-02 

88-79 
11-".-) 
47.23 

1-40 
0-21 

0-70 

•GS 

0  59 
0-23 

(3)  Iron  phosphate 
melted  with  acid 

(4)  Iron  phosphate 
melted  with  acid 
sla*  

>  Brackelsberg,  Stahl  und  Eisen,  V.,  1SS5,  p.  545.    b  Alumina  and  ferric  oxide 


aStahl  und  Eisen,  V.,  1885,  p.  548. 

>>  Manufacture  of  Iron  and  Steel,  p.  397. 

c  Percy,  Irou  and  Steel,  p.  62. 


In  two  fusions  at  the  Stockholm  School  of  Mines, d  in 
which  iron  ore  was  melted  with  carbonaceous  matter  in 
crucibles,  (A)  apparently  with  acid  slag  and  (B)  appar- 
ently with  basic  slag,  a  considerable  quantity  of  phos- 
phorus was  volaiilized,  viz.:  at>out  l-3d  and  l-10th  re- 
spectively of  that  initially  present  in  the  ore.  I  here 
summarize  the  results. 


VOLATILIZATION  OF  PHOSPHORUS. — AHKKMAV. 


Charge. 

Products. 

Ore 

yiux. 

Btafr 

Metal. 

Total 

Loss  of 

*r 

Kind 

Wt.   per 
1(10 

Wt.  per 
100 

Phosphorus 
ill  shig  per 
100  of 

Wt.  per 
100 

Phosphorus  In 
metal  per  100  of. 

Phosphorus 
In  (lag  -f 

phosphorus 
PIT  100  of 
ore. 

ore 

of  ore. 

of  ore. 

Slajf.  I  Ore. 

of  ore. 

Metal. 

Orr>. 

100  of  ore. 

1  '  tV_' 

SiOs 

7* 

1«K 

0-0(8    O'Ol 

66-2 

1-57 

1  (14 

1  115 

0  57 

0-S9 

lime 

25* 

88  75 

•026      -009 

56- 

1  41 

O'TUO 

0  70S 

0-092 

Gruner"  found  that  in  the  Heaton  process,  (treatment  of 
molten  cast-iron  with  nitrate  of  soda)  phosphorus  was 
copiously  volatilized,  especially  if  the  accompanying  slags 
were  acid. 

But  no  important  effective  volatilization  of  phosphorus 
is  to  be  looked  for  in  the  blast-furnace,  for  any  phosphorus 
which  volatilized  would  be  immediately  recondensed  by 
the  cooler  ore  above.  Bell,'  accurately  controlling  his 
materials,  found  that  of  1'578  parts  of  phosphorus  per 
100  of  cast-iron  entering  his  blast-furnaces  from  all 
sources,  1  '441  parts  were  accounted  for  by  the  cast-iron 
and  0'147  by  the  slag,  or  together  1'588,  i.  e.,  the  two 
sides  balance  to  within  0'6$£  of  the  total  phosphorus. 

The  volatilizing  effect  of  fluor  spar  is  discussed  on  p.  63. 

§  122.  EFFECT  OF  PHOSPHORUS  ON  TENSILE 
STRENGTH  AND  ELASTIC  LIMIT. — Disastrous  as  are  the 
effects  of  phosphorus  on  ductiMty,  it  affects  tensile 
strength  under  quiescent  load  comparatively  slightly: 
indeed  it  is  uncertain  whether  moderate  amounts  of  phos 
phorus,  say  0  -25$  or  less,  sensibly  affect  this  property.  Cer- 
tain facts  indeed  suggest  that,  as  phosphorus  rises  from  0 
to  about  0-12^,  it  raises  the  tensile  strength  of  low-carbon 
steel :  but  our  evidence  as  to  the  influence  of  larger  pro- 
portions of  phosphorus,  say  from  0'12  to  0'25$,  is  con- 
tradictory. Table  37  and  Figure  8  give  the  results  of  an 
analysis'5  of  435  cases  of  more  or  less  phosphoric  steel 
selected  at  random :  they  accord  closely  with  the  data 
furnished  by  Gatewoodh  as  to  the  properties  of  619  speci- 
mens of  steel,  so  that  they  are  in  a  sense  based  on  over 
1,000  cases.  The  tensile  strength  curves  in  the  seven 
right-hand  diagrams  are  nearly  vertical,  indicating  that 
phosphorus  does  not  affect  this  property :  but  in  the 
three  left-hand  diagrams,  and  to  a  slighter  extent  in  those 
including  carbon  '2  to  '3^,  these  curves  as  they  rise  at 
first  incline  to  the  right,  but  reverse  at  about  phos- 
phorus 0'12$  and  then  incline  to  the  left.  This  maybe 
accidental,  or  it  may  truly  indicate  that,  in  low-carbon 
steels,  rising  phosphorus  at  first  raises  but  later  dimin- 
ishes tensile  strength  and  that  this  effect  becomes  weaker 
as  carbon  increases.  This  accords  fairly  with  the  state- 
ments of  Ledebur,  Kent  and  Salbm,  and  possibly  with 
Akerman's  experience,  but  not  with  that  of  Deshayes 
except  as  regards  low-carbon  steel. 


d  Akerman,  Eng.  and  Mining  Jl.,  1875, 1.,  p.  475. 

e  Annales  des  Mines,  1869,  XVI.,  p.  260. 

1  Journ.  Iron  and  St.  Inst.,  1871,  II.,  p.  283. 

g  This  analysis  was  made  as  described  in  §  65  J. 

b  Report  of.  U.  S.  Naval  Advisory  Bd.  on  Mild  Steel,  1885,  pp.  188  to  19O. 


68 


THE    METALLURGY    OF    STEEL. 


TABLE  27. — EFFECT  OF  PHOSPHORUS  ON  TENSILE  STRENGTH  AND  ELONGATION. 


•6  Carbon. 

P.  o@-;i3 

P.  '03@-06 

P.  '00®  09             P.  -09@-12 

P.  '12@-15 

P.  -15®  -20 

r.  -20@'25 

P.  '25®  '30 

P.  -30@-40 

o 
/, 

Tensile 
strength 

s 
_c 

1 
a 

0 

W 

S 

O 

i 

Tensile 
strength 

I 

G 
O 

K 

i 

o 
o 

ts 

Tensile 
strength 

I 

0 

o 

fc 

Tensile 
strength 

§ 

1 

O 

iS 

•3 

1 

Tensile 
strength 

a 

_o 

1 

o 

s 

*o 
o 

K 

Tensile 
strength 

| 
tV 

1 
W 

I 

o 

o 
y< 

Tensile 
strength 

| 

1 

§ 
W 

S 

"o 

o 

y, 

Tensile 
strength 

c 
.2 

1 
o 

W 

o 
d 
\f. 

Tensile 
strength 

a 
o 

| 

0@  -05  

3 

r, 

4 

:; 

4 

1 
2 
3 

54,400 
4ll.3«0 
55,000 
55,066 
58,250 

I>'.P,.->00 

69,850 

88233 

80  5 

20  :  9 
27'4 
25  6 
•_':!  s 
21  7 
23' 
15  9 
8'4 

5- 
4-2 
2-1 
8  5 

S 
4 

10 
7 
11 
16 
48 
10 
4 
2 

54,000 
59,750 
61.890 
64,221 
71,709 
76,981 
87,794 
86,940 
95,250 
104,000 

26  5 
20-3 
27-0 
24  5 
21' 
19  5 
19' 
15  6 
14-9 
7'8 

1 

2 
8 
S 
4 
8 
22 
9 
3 
1 

70,000 
56,150 
84,706 
82,200 
M.OOO 
79,937 
82,440 
89,666 
IW,TOO 
119,000 

25' 

27' 
19-5 

is- 

211  1 
15-0 
16- 
14' 
11  5 
6-0 

:«  :; 
29  6 
32  2 
:lll  « 
27  5 
IS  8 
18  0 

'4-8 

8'9 
111  0 
5  3 
7-1 

7 
55 
87 
6 
8 
11 
11 
2 

i 

2 

1 
1 

65,514 
.V.l.  Mil 
62.7SO 
f4,216 
68,260 
75,1100 
88,536 
115,500 

127,  GOO' 
124,300 
170,400 
96,300 

"2' 
4 
5 
1 
13 
7 
2 

79,0(10 
80,575 
79,160 
66,000 
81,907 
75,428 
76,000 

22" 

28 

._,._,. 

14' 
16  2 

111 
1  5 

1 
1 

2 
1 
3 
5 
6 

"l 

5.-1.IKHI 
77,000 
77,500 
77,000 
76,333 
82,380 
90,333 

'  68,000 

25  5 
16  0 
17' 
19' 
17' 
11-6 
11-0 

Y-6 

11;1 
16' 
19' 
19' 
16  8 
8  5 
48 

2 
2 
3 
1 
2 
1 
2 
1 

52,000 
81,000 
09,800 
72.000 
80,550 
72,800 
81,500 
98,500 

9-0 
21-0 
12-5 
4  1 
21- 
20-4 
1-9 
8'2 

"2' 
2 
4 
1 
4 

74,500 
74,500 
70,875 
90,000 
83,750 

13  :3 
6  1 
94 
25' 
19-7 

•10©  -15  
'15@  '20 

3 
1 
8 
2 
3 
2 
3 

09,000 
72.600 
70,3:33 

7S.OOO 

79,866 
100,750 
103,333 

*2'j(fft  'SO 

•soJrh  '4f 

*50@  '60       

'60©  .70 

3 

2 
2 
2 
3 

87,466 

112',750' 
1211,550 
125.250 
131,0110 

2 
2 

HB,5llO 
130,900 

6-8 
6-1 

1 

104,000 

9'4 

'90(51  1  '00 

i'0o@rio 

1'10@1'20  

1'20@1'80 

1-30@1'40  

1 

135,300 

7-3 

1 

123.266 

25 

TENSILE  STRENGTH- 


S.     S 

ELONGATION,, 


"pifbon  0.10  to  O.Mja         Carbon  0.15  to  t.XI%  Carton  0.90  to  0.55%  Carbon  0.85  to  0.30%          Carbon  0.3-S  Q.17S 


Jn.» 
£ 

Ul 

<0.10 


Carlx>n  0.05  lo  0.10% 

\ 

^ 

\ 

/•' 

&/' 

<13 
X 
16 

s 

a 

•f 

,7' 

\ 

\ 

0.20 

| 

P. 

0.20  $ 

^ 

P. 

0.80  S 

\ 

'X 

7 

V 

8 

9 

^ 

M 

0.10     , 

e 

P 

0.10  9 

10 

P. 

0.10" 

jio 

t 

n 

\67 
68 

? 

47 

p4 

"!--49 

20 

ff 

k^ 

100,000     800,000 


100,000     900,000 


KALETOR  ELONGATION  1 


8 

t 

/s 

8 

"•Carbon  0.-4  to  0.5^5  Carbon  0.5  to  O-C^o 

I 

\ 

p. 

0.40  ' 

rj 

p. 

0.20     9 

,/TJ 

0.20  «  J« 

P. 

0.90 

V. 

I 

I 

y 

21 

1J 

16 

8\  8 

10 

!">   p. 

0.10" 

"( 

p. 

0.10  40 

A?. 

12 

0.10 

\23 

0.10 

p. 

?" 

27V 

a: 

a 

;; 

'•!, 

9 

§c 

25 

81 

61 

30 

H 

\:» 

100,000     900,000                      100,000     MO.OOO                      100,000                     100,000                      100,000 

T^ 

Carlion  O.GO 
"5  0.70 


LEDEBPK"  states  tliat  a  small  proportion  of  phosphorus 
has  slight  effect  on  tensile  strength,  but  that  a  large  pro- 
portion lowers  it :  the  second  of  these  statements  agrees 
roughly  with  my  left-hand  diagrams.  Kent  plotted  the 
tensile  strength  (ordinate)  and  carbon  (abscissa)  of  42  steels 
with  from  '06  to  "18%  of  carbon ;  26  had  '03^,  16  had  -10% 
of  phosphorus.  The  latter  formed  a  group  above  the  low- 
phosphorus  group,  and  nowhere  overlapped  it;b  this 
agrees  fully  with  the  easterly  inclination  of  my  low-carbon 
tensile  strength  lines.  Salom,0  analyzing  by  the  method 
of  least  squares  Dudley's  6 1  rail  steels,  with  carbon  from 
•19  to  '62^  and  phosphorus  from  -026  to  -158$,  found  that 
phosphorus  did  not  affect  tensile  strength  appreciably.  My 
curves,  teaching  that  when  carbon  is  above  0-20^  phosphor- 
us affects  tensile  strength  slightly,  agree  with  this.  Aker- 
mand  thinks  that  phosphorus  rather  raises  tensile  strength. 
Studying  more  than  1,000  phosphoric  steels  (Nos.  1  to  3, 
Table  28),  whose  carbon  averages  '325$  and  whose  phos- 
phorus averages  from  -26  to  '348$,  Deshayes6  concludes 
that  -1^'of  phosphorus  raises  the  tensile  strength  by  2,129 
pounds  per  square  inch,  or  about  one-fourth  as  much  as 
the  same  proportion  of  carbon.  This  disagrees  with  Lede- 
bur's  view,  with  Salom' s  results  and  with  my  curves,  which 
suggest  that  when  carbon  is  as  high  as  in  Deshayes'  steels 
phosphorus  should  not  affect  tensile  strength.  We  may 
infer  that,  when  above  say  0-12^,  phosphorus  probably  has 
no  important  constant  effect,  for  if  it  had  the  analyses  of 
statistics  should  yield  concordant  results. 

Phosphorus  however  usually  raises  the  elastic  limit  and 
thus  the  elastic  ratio,  an  index  of  brittleness:  indeed  the 
elastic  limit  and  breaking  strength  of  phosphoric  steels 
occasionally  coincide  (see  cases  14,  17,  Heaton,  and  22-23, 
Clapp-Grifflths,  table  28). 

The  effect  of  phosphorus  on  the  elastic  ratio,  as  on  elon- 


a  Handbuch  der  EisTihuttenkunde,  p.  245. 

b  Private  communication,   Aug.   22,    1887.     With  another  form  of  test  pieces 
these  groups  overlapped  at  one  point. 

c  Trans.  Am.  Inst.  Miu.  Eng.,  XIII.,  p.  157,  1885. 

d  Eng.  and  Min.  Jl.,  1875,  I.,  p.  475. 

e  Aunales  des  Mines,  7  Ser.,  XV.,  pp.  351-3,  1879. 


100,000 
lO'/o 

gation  and  contraction,  is  very  caprici OTIS.  We  occasionally 
find  highly  phosphoric  steels  with  very  low  elastic  ratio, 
e.  g.  steels  10,  12,  Terre  Noire,  and  40,  47,  49,  50  and  51, 
tested  in  Russia,  in  Table  28,  whose  elastic  ratio  lies 
between  037  and  0-63. 

Phosphoric  steels  are,  however,  liable  to  break  under 
very  slight  tensile  stress  if  suddenly  or  vibratorily  ap- 
plied or  shock-like. 

§  123.  EFFECT  OF  PHOSPHORUS  ON  DUCTILITY. — Phos- 
phorus diminishes  the  ductility  of  steel  under  a  gradually 
applied  load,  as  measured  by  its  elongation,  contraction 
and  elastic  ratio  when  ruptured  in  the  ordinary  testing 
machine :  but  it  diminishes  its  toughness  under  shock  to 
a  still  greater  degree,  and  this  it  is  that  unfits  phosphoric 
steels  for  most  purposes.  The  influence  of  "01$  of  phos- 
phorus is  perceptible,  that  of  '20^  is  generally  fatal  in 
ingot  metal :  (see  §  130). 

A.  Static  Ductility. — The  effect  of  phosphorus  on  static 
ductility  appears  to  be  very  capricious,  for  we  find  many 
cases  of  highly  phosphoric  steel  which  show  excellent 
elongation,  contraction  and  even  fair  elastic  ratio,  while 
side  by  side  with  them  are  others  produced  under  appar- 
ently identical  conditions  but  statically  brittle. 

Thus  two  Heaton  bars  (15  and  18,  table  28)  have  high 
contraction  and  good  elongation ;  four,  apparently  made 
under  like  conditions,  have  no  contraction,  and  three  of 
these  but  slight  elongation.  No.  22  (Clapp-GritRths),  with 
carbon  '31,  phosphorus  '40^,  is  almost  as  brittle  as  glass ; 
3  and  12  (Terre-Noire),  with  as  high  or  higher  carbon,  and 
nearly  or  quite  as  high  phosphorus  (carbon,  32  with  phos- 
phorus '35$,  and  carbon  '31,  with  phosphorus  -40$)  are 
admirably  ductile  statically.  28  and  29  (Clapp-Griffiths) 
are  statically  rather  brittle  and  not  tensilely  strong  ;  the 
preceding  and  following  cases  are  fairly  ductile  with  the 
same  tensile  strength.  34  (Heaton)  is  both  strong  and 
ductile ;  35  to  39  are  brittle,  though  made  under  appa- 
rently like  conditions,  and  with  no  corresponding  differ- 
ence in  their  composition. 

But  while  we  find  small  groups  of  cases  of  statically 


INFLUENCE    OF    CARBON    ON    THE    EFFECTS     OF    PHOSPHORUS.      §  124. 


(59 


ductile  phosphoric  steel,  yet  if  we  examine  sufficiently 
large  groups  the  static  brittleness  caused  by  this  element 
is  plainly  seen.  To  illustrate  this  I  present  in  Table  27 
and  graphically  in  Fig.  8  the  results  of  an  analysis  of  485 
cases  of  more  or  less  phosphoric  steel.  The  direction  of 
the  broken  lines  in  Fig.  8  reveals  the  effect  of  phosphorus. 
In  8  out  of  10  large  groups,  each  with  approximately  con- 
stant carbon  but  varying  phosphorus,  the  ductility  lines 
point  west  of  north,  showing  that  with  rising  phosphorus 
the  elongation  declines.  In  two  of  these  (carbon  '60  to 
•70  and  "80  to  '90)  the  westward  obliquity  of  the  elonga- 
tion curve  is  but  slight :  little  weight  attaches  however 
to  these  two  curves,  since  they  represent  but  7  cases  each. 
Furthermore,  the  two  curves  (carbon  '25  to  '30  and  car- 
bon '30  to  '40)  which  at  first  do  not  appear  to  show  the 
influence  of  phosphorus,  since,  though  in  their  lower  por- 
tion pointing  nearly  northwest,  their  upper  portions  point 
N.  N.  E.,  on  further  examination  corroborate  the  teach- 
ing of  the  other  curves.  For  their  westerly -pointing  parts 
are  really  the  ones  which  deserve  weight,  since  they  repre- 
sent many  cases,  while  their  easterly-pointing  portions 
represent  comparatively  few,  the  orientation  of  the  upper 
part  of  the  carbon  -30  to  "40  curve  being  wholly  due  to  5 
cases,  while  its  westerly  pointing  portion  represents  104 
cases.  These  curves  are  obtained  as  described  in  §  65,  J. 

Abnormally  low  contraction  and  high  elastic  ratio  as 
compared  with  the  elongation  are  said  to  characterize 
phosphoric  steels:  and  from  a  careful  examination  of  a 
large  number  of  cases  I  believe  that  this  combination  of 
properties  is  much  commoner  in  phosphoric  than  in  other 
steels.  Thus,  in  Table  28  the  contraction  of  Heaton  steels 
Nos.  13,  14,  16  and  17,  and  of  Clapp-Griffiths  steels 
Nos.  23,  24,  26,  28  and  29  is  abnormally  low  for  their 
elongation:  while  in  Heaton  steels  13  to  18  and  Clapp- 
Griffiths  steels  22,  23,  31,  32  and  33  we  find  abnormally 
high  elastic  ratio  for  the  elongation.  But  these  cannot  be 
set  down  as  constant  characteristics,  for  in  Terre-Noire 
open-hearth  steels  1,  2,  3,  10,  11  and  12,  in  Heaton  steels 
15  and  18,  and  in  Clapp-Griffiths  Bessemer  steels  25  and  34 
the  relation  between  contraction  and  elongation  is  fairly 
normal. 

B.  Ductility  Under  Shock. — If  any  relation  between 
composition  and  physical  properties  is  established  by  ex- 
perience, it  is  that  of  phosphorus  in  making  steel  brittle 
under  shock.  And  it  appears  reasonably  certain,  though 
exact  data  sufficing  to  demonstrate  it  r.re  not  at  hand, 
that  phosphoric  steels  are  liable  to  be  very  brittle  under 
shock  even  though  they  may  be  tolerably  ductile  static- 
ally. The  effects  of  phosphorus  on  shock-resisting  power, 
though  probably  more  constant  than  its  effects  on  static 
ductility,  are  still  decidedly  capricious. 

This  and  the  capricious  behavior  of  phosphorus  under 
the  action  of  solvents,  harmonize  with  the  belief  that  the 
state  of  chemical  combination  in  which  it  exists  in  steel, 
the  mineral  species  which  it  helps  to  compose,  depends 
upon  imperfectly  understood  conditions,  such  as  those  of 
cooling.  It  may  exist  now  as  part  of  the  matrix,  whose 
properties  it  thus  profoundly  affects,  now  as  a  distinct 
phosphide,  whose  composition  and  properties,  and  through 
these  its  effects  on  the  physical  properties  of  the  compo- 
site mass  as  a  whole,  may  differ  greatly. 

§  124.  INFLUENCE  OF  CARBON  ON  THE  EFFECTS  OF 
PHOSPHORUS. — General  experience,  and  especially  the 


TAHI.B  28— PHOSPHORIC  STEIIA 


J;5 

.2  *J 

c 
_o 

| 

10. 

C. 

Si. 

Mn. 

P. 

S. 

H 

11 

1 

In. 

2 

a 

ra 

W 

o 

g 

W 

0 

1 
2 
3 

•32 
-34 

•32 

1-7 
•58 
•67 

•31 
•26 
•35 

78.300 
72,600 

hll.llKl 

51.1100 
47,600 
68,000 

14-63 

i»  45 
19-95 

8" 
S" 
8" 

:!*ft! 
45  05 
41-58 

I  Terrc  Noire.  1s74.      Mean 
J     of  over  1,000  COMB, 

10 

•31 

tr. 

•75 

•25 

tr. 

80,500 

4*.,0oo  22  7 

4" 

47  6 

S 

11 
12 

•27 
•81 

tr. 
tr. 

•80 
•69 

•2t 
•40 

tr. 
tr. 

80,500 
88,200 

50,1100  21  5 
55,61X1  22  2 

4" 
4" 

44  9 
46  7 

1-Terre  Noire,  1S7S. 

13 

-49 

-10 

•30 

•0 

93,600 

01  wo 

8  9 

8" 

o- 

14 
15 

•57 
•52 

•12 
•16 

•23 
•24 

•01 
•01 

93,600 
113,100 

505,600 
107,600 

8  1 
9'4 

8" 
8" 

o- 

80' 

Heaton  process, 

16 

17 

•54 
•54 

•10 

•12 

•24 
•28 

•01 

0 

104,800 
98,000 

96,600 

S  6 
9-4 

8" 
8" 

o- 
o- 

Gruner. 

IS 

-47 

09 

•23 

0 

104,5110 

k'l'.ioo 

10-4 

8" 

48- 

Ifl 

•10 

tr. 

:6S'" 

•32 

•08 

79,440 

5S.500 

24' 

47  0 

20 
21 

•12 
•12 

tr. 
tr. 

•81 
•77 

•43 
•55 

03 
•05 

86,230 
79,780 

07,150 
59,650 

18-75 
23  -M 

31'8 
85  5 

Clapp-GriCiths     Bessemei 

22 

•81 

tr. 

•40 

77,460 

0 

0'62 

o- 

* 

23 

•08 

tr. 

•'50  " 

•72 

'•'03 

75,290 

69,150 

2  25 

2-6 

24 

•13 

tr. 

•78 

•85 

101,540 

74,080 

9-50 

9  44 

25 

f 

74,790 

55,070 

25  25 

8" 

48  8 

27 
2S 

Phosphorus  nut  given,  but! 
supposed  to  bo  high. 

80,030 
80,270 
80.420 

55,060 
56.290 
56,290 

23-0 
22-75 
17  5 

8" 
8" 
8" 

20  II 
80-6 
14-3 

Clapp-Griffiths     Besseme 

211 

I 

78^730 

56.410 

14  25 

8" 

15  3 

f     steel. 

80 

f 

80,940 

58,570 

21  0 

8" 

36  4 

81 

I 

79,870 

58,570 

23  25 

8" 

36  4 

32 

•08 

•01 

•48 

•50 

80,670 

60,240 

23  0 

8" 

82  5 

83 

79,700 

59,550 

23-25 

8" 

37-6 

J 

34 

33 

•14 

•38 

'03 

110,600 

12'5 

29' 

85 

•55 

•18 

•25 

'05 

116,400 

4*0 

6' 

36 

•35 

110,000 

6-0 

9' 

Heaton  steel.    Gruner. 

87 

•37 

113,900 

8-1 

5- 

38 

•32 

"21 

•84 

tr. 

84600 

1*8 

8' 

89 

•48 

•17 

•50 

•08 

112,500 

8'2 

6' 

40 

19 

'•is'cr! 

•51 

90,700 

4'6 

41 

18 

20  Cr. 

•56 

89.600 

24- 

42 

23 

•21  Cr. 

•76 

112,700 

5  7 

Chrome  (?)  steel. 

43 

20 

•32  Cr. 

•76 

105,300 

4-7 

44 

30 

•14  Cr 

•90 

97,700 

19  3 

45 

•30 

•16  Cr. 

•95 

99,500 

8'2 

411 

•28 

'01 

•93 

•33 

? 

90.700 

'62,600 

24-6 

44:i 

47 
4!) 

•24 
•23 
•23 

•02 
•03 
•01 

•49 

99 
•62 

•82 
•67 
•24 

f 
f 

77,800 
'73,900 

29,900 
82,700 

21  1 
22  2 
18-5 

54  8 
59-9 
19-1 

Steel  rails  examined  by 
f     Russian  Commission, 
i 

50 

•19 

01 

•25 

•26 

? 

60,900 

28.000 

10  5 

16-5 

1 

51 

•15 

•01 

•19 

•84 

y 

79.800 

82,700 

15  7 

47-5 

52 
53 
64 

•24 
•28 
•30 

tr. 
•02 

•01 

"29 

82,700 

20-2 

80  1 
23-6 
16-9 

Steel  rails  examined  by 
Russian  Commission. 

•29 
•85 

T8.100 
104,000 

12-8 
11  6 

55 

•25 

tr. 

•82 

14,700 

22-5 

50- 

1,2  and  3  .'   Terrc  Noire.  1874,  Annales  des  Mines,  1879,  p.  351,  mean  of  over  1,000  cases. 

1O,    1  1  and  1  2      Terrc  Noire,  1878.     Idem,  p.  372. 

13  to  18.    Made  by  the  Heaton  process  at  Langley  Mills,  tested  by  Fairbairn.    Annales 


des  Mines,  1870,  XVII.,  pp.  851  to  361. 

I  9  to  24.     Clapp-Gri- ' 
XIV.,  pp.  140-141,  1886. 


I  9  to  24.     Clapp-Griffiths  Bessemer  steel.    E.  W.  Hunt,  Trans.  Am.  Inst.  Mining  Engrs., 

".,  pp.  140-141,  1886. 

*5  to  33.  Clapp-Griffiths  Bessemer  steel.  E.  W.  Hunt,  Trans.  Am.  Inst.  Mining  Engrs., 
XIII.,  pp.  756-7, 1885. 

34  to  39.     Heaton  steel.  Gruner.    Annales  des  Mines,  1869,  XVI. 

4Oto45.  Chrome  steel.  Brown.  Joilrn.  Iron  and  St.  Inst,  1S79,  II.,  p.  358.  Trust- 
worthiness doubtful. 

46  to  51.  Kails  employed  in  Russia.  Bock-Guerhard.  Idem,  1886,  I.,  p.  204.  Trust- 
worthiness doubtful. 

52  to  56.  Bails  tested  in  Eussia.  Jouraffsky.  Idem,  1880,  I.,  p.  192,  Appendix  B. 
Trustworthiness  doubtful. 


results  obtained  by  Slade  in  1869  and  subsequently  by 
Tessie  du  Motay,  at  Terre-Noire,  and  by  R.  W.  Hunt, 
have  abundantly  shown  that  the  influence  of  phosphorus 
is  the  more  severe  the  more  carbon  is  simultaneously 
present,  so  that  while  the  effects  of  0'10$  of  phosphorus 
on  the  ductility  of  steel  which  contains  less  than  0'10$ 
carbon  may  escape  notice  in  rough  testing,  yet  if  the  steel 
contain  \%  carbon  the  effects  of  0'01$  and  perhaps  even  of 
0  '005^  phosphorus  may  be  detected.  This  influence  of  carbon 
on  the  effects  of  phosphorus  is  illustrated  by  Fig.  8.  We 
note  that  the  degree  of  obliquity  of  the  elongation  lines  is 
on  the  whole  only  slightly  greater  for  the  low  than  for  the 
high  carbon  steels,  and  roughly  speaking  indicates  that 
an  increment  of  0-10$  of  phosphorus  diminishes  the 
elongation  by  about  6%  of  the  initial  length  of  the  test 
piece.  This  loss  would  cut  down  the  elongation  of  a  low- 
carbon  steel  (initially  free  from  phosphorus)  from  say  31 
to  25%  of  the  length  of  the  test  piece,  or  by  about  20%  of 
the  original  elongation,  a  loss  which  might  easily  be 
masked  by  the  effects  of  other  variables  :  but  it  would 
lower  the  elongation  of  a  high-carbon  steel  from  say  8  to 
2%,  or  by  15%  of  its  original  value,  enough  to  change  a 
valuable  to  an  utterly  worthless  material. 

Tables  28  and  29  give  many  instances  of  tough  phos- 
phoric steels  low  in  carbon. 


70 


THE    METALLURGY    OP    STEEL. 


§  125.  INFLUENCE  OF  SILICON  ON  THE  EFFECT  OF  PHOS- 
PHORUS.— It  is  often  stated  that  silicon  like  carbon 
greatly  exaggerates  the  effects  of  phosphorus  ;  but  what 
evidence  I  find  very  strongly  opposes  this  view,  and  sup- 
ports Ledebur'sa  statement  that  it  does  not.  Thus  the 
iirst  of  the  Trenton  phosphoric  steels  in  table  29  has 
o -17^' silicon,  0'15  phosphorus  and  0.16  carbon,  yet  is  "ex- 
cellent soft  boiler  plate :  "  No.  50  has  -05  silicon,  -27  phos- 
phorus and  '12  carbon  and  is  "remarkably  tough  boiler 
plate."  These  data  are  from  a  most  conscientious  obser- 
ver, Mr.  F.  J.  Slade. 

So  among  the  Heaton  steels  one  with  nearly  the  highest 
silicon  (0'16$  in  No.  15)  is  more  ductile  than  those  of 
otherwise  similar  composition  but  with  much  less  silicon. 

§  126.  STRUCTURE,  CONDITIONS  OF  COOLING  AND  DUC- 
TILITY.— Phosphorus  tends  to  induce  a  coarsely  crystalline 
structure,  which  is  plausibly  regarded  as  a  proximate  cause 
the  brittleness  of  phosphoric  metal.  As  slow,  undisturbed 
cooling  favors  coarse  crystallization,  while  sudden  cooling 
and  agitation  impede  it,  whether  in  solidification  from 
aqueous  solution,  from  magma  of  molten  rock,  or  from 
fused  or  pasty  metal  or  glass,  it  is  not  surprising  that 
these  same  conditions  respectively  favor  and  oppose  both 
coarse  crystallization  and  brittleness  in  phosphoric  steel. 
We  have  seen  that  sudden  cooling  tends  to  induce  brittle- 
ness  in  ordinary  steel  by  preserving  a  brittle  compound 
of  iron  and  carbon  which  is  broken  up  by  slow  cooling, 
and  by  inducing  severe  internal  stresses  (see  §§  51  C, 
34  B).  But  in  phosphoric  iron  the  net  effect  of  sudden 
cooling  is  sometimes  at  least  to  increase  ductility,  since 
its  toughening  effect  in  preventing  coarse  crystallization 
outweighs  its  opposite  effect  of  internal  stress  and  of  pre- 
serving a  brittle  iron-carbon  compound.  Thus,  while  in 
tables  8,  9,  10,  11,  non-phosphoric  steels  are  tougher 
af'er  slow  than  after  sudden  cooling,  in  the  following 
instance  b  phosphoric  weld  iron  became  much  tougher  on 
sudden  cooling.  It  is  probable  that  this  applies  to  other 
irons  with  much  phosphorus  but  comparatively  little 
carbon. 


Tensile 
strength. 

Elonga- 
tion. 

Contrac- 
tion. 

Carbon. 

Phos- 
phorus. 

61  758 

6'5 

I 

•07 

'26± 

Swedish  charcoal- 
iK-nrth  wvltl  iron. 

Quenched  in  water 
from  redness,  .  .  . 

68,700 

25* 

84* 

•01 

•26± 

So  too,  when  phosphoric  iron  is  heated,  it  appears 
especially  desirable  to  continue  forging  it  until  its  tem- 
perature has  fallen  so  low  that  the  tendency  to  coarse  crys- 
tallization is  no  longer  to  be  feared. 

§  127.  INFLUENCE  OF  COLD  ON  THE  EFFECTS  OF  PHOS- 
PHORUS.— Steel  is  far  more  brittle  under  shock  when  very 
cold  (say  0°  F.)  than  at  the  ordinary  temperature,  and  it  is 
generally  believed  that  cold  increases  the  brittleness  of 
phosphoric  more  than  that  of  non-phosphoric  steel.  The 
most  direct  evidence  on  this  point  that  I  have  met  is  that 
of  a  Russian  commission  ; c  it  strongly  opposes  this  be- 
lief, though  the  commission  does  not  state  so. 

In  their  tests  two  pieces  from  each  of  33  steel  rails  were 
submitted,  one  at  16°  to  20°  C.  (61°  to  68°  F.)  the  other  arti- 
ficially cooled  to  from  —16°  to  —21°  C.  (-f  5°  to  —  6°  F.),  to 
the  drop  test  under  identical  conditions.  Twenty-four  of 


a  Handbuch  der  Eisenhiittenkunde,  1883,  p.  247. 

b  Styffe,  Iron  and  Steel,  pp.  132,  136. 

c  JouraSsky,  Journ.  Iron  and  St.  Inst.,  1880,  3.,  p.  192. 


those  tested  cold  broke :  only  three  of  those  tested  when 
warm  broke.  All  the  rails  with  over  014  phosphorus 
broke  when  cold :  but  as  the  three  fractures  which  oc- 
curred during  the  warm  tests  were  also  of  phosphoric 
rails,  this  merely  shows  that,  warm  or  cold,  phosphorus 
causes  brittleness.  The  difference  between  the  cold-resist- 
ance to  shock  of  the  phosphoric  and  of  the  non-phosphoric 
rails  was  certainly  not  greater,  and  perhaps  even  less  than 
that  which  would  be  expected  at  70°  F  Thus  three  non- 
phosphoric  rails  broke  more  readily  and  three  moderately 
phosphoric  rails  broke  at  least  as  readily  when  cold  as 
five  of  the  phosphoric  ones :  these  non-phosphoric  ones 
with  -07,  '08  and  '10$  phosphorus  and  '40,  -5,  and  -38$ 
carbon  respectively  broke  at  the  first  blow  under  a  drop  of 
8'5  feet :  the  three  moderately  phosphoric  ones,  with  '13$ 
phosphorus  or  less  and  '33$  carbon  or  less,  broke  at  the 
second  blow  under  the  same  fall :  while  of  the  five  phos- 
phoric ones  with  -15,  -15,  -18,  '20  and  -27^  phosphorus  and 
•50,  -31,  -41,  '41  and  '21$  of  carbon  respectively,  the  first 
resisted  two  blows  of  8 -5  feet  and  one  of  9 '5  feet,  and 
the  others  each  resisted  one  blow.  Further,  many  of  the 
rails  which  did  not  break  had  more  phosphorus  than  some 
of  those  which  did.  Thus,  eight  which  did  not  break  had 
from  '1  to  '14^  of  phosphorus  :  while  four  of  those  which 
broke  had  '\%  or  less. 

Unfortunately  grave  doubts  exist  as  to  the  trustworthi- 
ness of  these  results  :  e.  g.  they  credit  the  Seraing  rails 
with  containing  '18  to  -20^  of  phosphorus,  though  cast-iron 
which  could  yield  such  phosphoric  steel  had  never  been 
employed  at  these  works.*1 

The  fact  that,  of  100  steel  rails  with  '25^  phosphorus 
laid  by  Sandberg  in  Sweden,  not  one  broke  during  the 
first  six  years,  though  the  temperature  occasionally  fell 
to — 30°  F.,  weighs  against  the  belief  that  cold  increases  the 
brittleness  of  phosphoric  more  than  that  of  other  steel.* 

§  128.  ILLUSIONS  CONCERNING  THE  NEUTRALIZATION 
OF  PHOSPHORUS. — The  capriciousness  of  the  effects  of 
phosphorus  and  the  fact  that  its  effect  on  the  ductility  of 
low-carbon  steel  is  so  slight  as  to  be  easily  masked, 
coupled  with  the  fact,  if  fact  it  be,  that  statically  ductile 
phosphoric  steel  may  be  brittle  under  shock,  has  led  to 
the  discovery  every  few  years,  and  probably  to  the  sub- 
sequent extreme  annoyance  of  the  discoverers,  of  meth- 
ods of  neutralizing  phosphorus,  or  of  special  conditions  or 
processes  by  which  it  is  rendered  harmless.  If  the  inves- 
tigator of  a  new  process  for  making  excellent  though 
phosphoric  steel  confines  his  attention  to  low-carbon  steel, 
or  to  this  with  a  small  number  of  static  (not  dynamic) 
tests  of  high-carbon  steel,  and  especially  if  he  is  ignorant 
of  the  fate  of  his  predecessors,  he  readily  falls  into  the 
trap,  and  pronounces  absolutely  worthless  processes  to  be 
of  enormous  value.  And  here  I  think  it  wise  to  deviate 
from  the  plan  of  this  work  and  to  introduce  a  little 
ancient  history,  because  it  clarifies  our  atmosphere, 
enables  us  to  view  more  clearly  an  apparatus  to-day  much 
noised  about,  and  justifies  the  extreme  skepticism  as  to 
its  reputed  merits  which  I  have  shown,  precipitating  on 
my  head  the  wrath  of  the  true  believers,  those  men  of 
childlike  and  religious  faith. 

(A).  In  1869  the  HEATON  PROCESS,  which  partially  de- 
phosphorized cast-iron,  yielding  steel  with  from  say  0'23 


<1  Greiner,  Journ.  Iron  and  St.  Inst.,  1880,  I.,  p.  198. 
e  Trans.  Am.  Inst.  Mining  Engrs.,  IX.,  p.  598,  1881. 


ILLUSIONS    CONCERNING    PHOSPHORUS.      §128. 


71 


to  0'50  phosphorus,  was  vigorously  promoted.  Actually 
the  percentage  of  phosphorus  which  it  left  in  the  steel 
was  simply  fatal :  yet  no  less  distinguished  and  compe- 
tent authorities  than  Sir  Wm.  Fairbairn,  Robert  Mallet 
and  Pro.f.  Miller  after  personal  investigation  highly  com- 
mended process  and  product. 

FAIRBAIHN,  examining  six  bars  of  Heaton  steel  with 
from  0-23  to  0-30^  phosphorus,  and  comparing  them  with 
the  best  Sheffield  crucible  steel,  reported  that  under  trans- 
verse flexure  the  Ileaton  steel  showed  a  very  marked 
superiority  over  the  others :  that  it  was  evidently  spe- 
cially adapted  to  resisting  force  of  impact !  That  its 
elongation  was  notably  above  the  mean  of  the  other  bars  : 
that  in  short  it  compared  advantageously  with  the  steel  of 
the  other  makers  (the  best  Sheffield  makers).  This  was 
not  a  joke,  but  a  serious  professional  opinion  by  an  illus- 
trious engineer.  How  Fairbairn  deduced  such  views  from 
his  tests,  whose  results  were  published,  must  remain  a 
mystery.  Gruner  showed  their  true  meaning. 

(B).  PKOFESSOR  MILLIE,  examining  Heaton  steel,  re- 
ported that  the  quantity  of  phosphorus  which  it  retained 
(0-29^)  was  obviously  not  such  as  to  injure  its  quality  ! 
That  it  resisted  many  severe  tests,  being  bent  and  ham- 
mered sharply  around  both  cold  and  at  red  and  yellow 
heats  without  cracking,  and  that  it  welded  satisfactorily. 
This  steel  contained  0'29$  phosphorus,  0'99  carbon,  0*15 
silicon,  0'09^  manganese. 

(C).  MALLET  reported  that  this  process  yielded  excellent 
steel  from  highly  phosphoric  cast-iron,  from  which  no 
"process,  not  even  Bessemer' s  ! "  (which,  with  the  intui- 
tion of  true  genius,  he  saw  was  better  adapted  to  phos- 
phoric iron  than  puddling,  conversion,  and  crucible 
melting)  "  enables  steel  of  commercial  value  to  be  pro- 
duced at  all." 

(U).  TESSIE  DU  MOTAV,*  about  four  years  later,  appears 
to  have  rediscovered  the  already  pretty  well  known  fact 
that  a  large  amount  of  phosphorus  can  be  tolerated  in 
steel,  provided  the  carbon  be  low,  which  was  rather  amus- 
ing to  American  as  well  as  to  well  informed  European 
metallurgists,  as  F.  J.  Slade  b  had  in  1869  made  a  consid- 
erable quantity  of  good  phosphoric  steel,  low  in  carbon. 
I  append  a  few  analyses  of  it. 

TABLE  29.— TBKNTOX  Fiiospiiomc  STEEL,  1869. 


Carbon. 

Silicon. 

Manga- 
nese. 

Phos- 
phorus. 

Sul- 
phur. 

Date. 

Quality,  etc. 

46. 

4T. 

•16 
•12 

•IT 
•015 

•14 
•06 

•153 
•113 

•OT3 
•008 

Dec.  29,  186(1 
Oct.  20,  1869 

Excellent  soft  boiler  plate. 

48. 

•12 

•025 

•07 

•275 

•007 

Oct.  19,  1869 

U                  t«              It              i( 

49. 
50. 
51. 

•125 
•12 
•21 

:052 

•814 

•272 
•345 

Nov.  26,1869 

Remarkably  tough. 
"      boiler  pl«te. 
"      bar. 

Great  excitement  was  manifested  generally  on  the  con- 
tinent when  it  was  announced  in  1874  that  Terre  Noire 
had  solved  the  phosphoric  steel  problem,  where,  Euverte 
stated,  it  had  been  proved  that  a  steel  with  0-30  phosphorus 
and  0-15  carbon  was  very  malleable  and  tit  for  making  rails 
of  good  quality.6 

(E).  The  SHERMAN  process,  which  would  neutralize  but 
not  remove  phosphorus  from  steel,  was  thoroughly  exposed 
by  Menelaus,d  Snelus  and  others  in  1871,  and  by  Enverte 
in  1876,  and  shown  to  have  no  effect  whatsoever.  Yet 
many  eminent  and  experienced  manufacturers,  including 


a  Journ.  Iron  and  St.  Inst.,  1874, 1.,  p.  232. 

b  Raymond,  Trans.  Am.  Inst.  Mining  Engineers,  1875,  III.,  p.  132. 
<•  Jour.  Iron  and  St.  Inst.,  Loc.  Cit. 
,  1871,1.,  p.  452. 


Crawshay  of  Cyfarthfa  and  I  believe  the  Firminy  Iron 
Works,  in  spite  of  these  exposures  are  said  to  have  had 
complete  faith  in  this  ridiculous  operation,  and  actually 
adopted  it :  and  in  1877  it  still  had  such  vitality  that 
large  scale  experiments  with  it  were  carried  out  in  Boston 
under  Holley's  inspection,  who  of  course  again  exposed 
its  worthlessness. 

(F).  RICHARD  BROWN  was  permitted  in  1879  to  read 
before  the  Iron  and  Steel  Institute8  a  paper  in  which  he 
claimed  that,  if  bichromate  of  potash  were  blown  through 
the  steel  in  the  Bessemer  converter,  the  metal  would  be  soft 
and  malleable  even  if  it  contained  1'5$  phosphorus,  and 
among  other  evidence  produced  cases  40  to  45  in  table  28 
to  support  his  statements.  I  mention  this  process  for  no 
merit  of  its  own,  but  to  show  what  rubbish,  provided  it 
;  claim  to  neutralize  phosphorus,  may  be  accepted  by  a 
[  board  so  really  wise  as  that  of  this  institute,  and,  as  I  am 
credibly  informed,  so  conservative  as  to  refuse  Thomas  for 
some  time  the  privilege  of  describing  the  basic  process  in 
its  journal. 

(G).  CLAPP-GRIFFITHS  CONVERTER.—  The  last  to  fall  into 
this  trap  is  no  less  competent  a  person  than  the  very  experi- 
enced and  judicious  Capt.  R.  W.  Hunt,  who  lauds  the  ex- 
cellent quality  of  phosphoric  low-carbon  Bessemer  steel 
made  in  the  Clapp-Griffiths  converter  :  and,  though  I  do 
not  find  that  he  says  so  in  so  many  words,  he  evidently 
thinks  that,  for  given  composition,  phosphoric  steel  pro- 
duced in  this  converter  is  incomparably  superior  to  steel  of 
identical  composition  produced  in  the  ordinary  converter, 
but,  as  is  perfectly  patent  on  examination,  without 
proper  ground  for  such  a  conclusion.  Passing  by  the  sur- 
prising fact  that  this  steel,  even  with  1-10$  phosphorus, 
rolls  in  a  "practical  manner"  which  will  be  considered  un- 
der the  effects  of  phosphorus  on  hotshortness,  and  taking 
only  his  strongest  cases,  he  reports  steel  with  0'08  carbon 
and  0*50  phosphorus  to  0-12  carbon  and  0'55  phosphorus 
which  shows  good  static  ductility  ;  and  one  with  0-18  car- 
bon and  0'85  phosphorus  which  shows  fair  static  ductility 
for  its  tensile  strength.  He  reports  but  one  case  with 
over  0-13  carbon,  No.  22  Table  28,  and  this  was  surpris- 
ingly brittle.  In  short  he  too  has  rediscovered  for  the 
Nth  time  that  phosphorus  affects  the  ductility  of  low- 
carbon  steel  relatively  little,  and,  so  far  as  I  can  see, 
nothing  more. 

Let  us  now  examine  his  results  in  detail  and  see 
whether  they  indicate  that  his  phosphoric  steel  is  really 
less  brittle  than  that  of  other  observers,  and  whether 
therefore  there  is  any  ground  for  supposing  that  the 
use  of  this  converter  any  more  than  of  Sherman's  and 
Brown's  nostrums  even  partially  neutralizes  phosphorus. 
The  three  most  noticeable  cases  which  he  reports  are 
numbers  21,  24  and  30  in  Table  28.  If  they  are  no  better 
than  other  steels  of  like  composition,  we  need  not  examine 
his  poorer  cases. 

No.  21  (Clapp-Griffiths)  with  0'12  carbon  and  0-55  phos- 
phorus, has  actually  less  ductility  and  much  less  tensile 
strength  than  No.  41  (Brown),  though  the  latter  has  both 
more  phosphorus  and  more  carbon,  and  should  therefore 
be  more  brittle.  No.  24  (C.  G.)  has  about  4^  more 
tensile  strength  but  less  than  half  of  the  elongation  of  No. 
44  (Brown),  though  the  latter  has  somewhat  more  phos- 
phorus and  much  more  carbon,  and  should  therefore  be 


eldem,  1879,  II. ,  p.  355. 


72 


THE    METALLURGY    OF    STEEL. 


more  brittle.  No.  30  (C.  G.)  has  the  same  elongation  but  de- 
cidedly less  tensile  strength  than  No.  41  (Brown),  though 
the  latter  exceeds  it  somewhat  in  phosphorus  and  very  much 
more  carbon,  and  should  therefore  be  decidedly  more  brittle. 
I  frankly  confess,  however,  that  while  I  have  no  ground  for 
doubting  Brown's  results  beyond  their  inherent  improba- 
bility, and  while  I  find  them  harmonious  and  observe  that 
they  show  the  characteristics  of  phosphoric  steel  reported 
by  others,  I  do  not  know  how  trustworthy  they  are. 

There  is,  however,  every  reason  to  trust  the  Terre  Noii-e 
results  3,  12  and  15.  The  only  Clapp-Griffiths  steel  di- 
rectly comparable  with  these  without  making  any  allow- 
ances whatsoever  is  No.  22,  which  has  the  same  carbon 
and  phosphorus  as  Terre  Noire  No.  12,  yet  is  astonishingly 
brittle  while  the  Terre  Noire  steel  is  admirably  ductile: 
the  former  has  0'62$  elongation  and  O'OO  contraction  :  the 
Terre  Noire  has  26$  elongation  with  46'7$  contraction. 
But  comparing  the  best  Clapp-Griffiths  steels  with  the 
Terre  Noire  and  making  any  reasonable  allowance  for  dif- 
ferences in  composition,  I  can  not  lind  that  the  former  are 
superior  to  the  latter.  Clapp-Griffiths  21  and  30  have 
less  elongation  and  decidedly  less  contraction  and  tensile 
strength  than  Terre  Noire  12,  which  with  about  4-5ths  as 
much  phosphorus  has  2 '5  to  3  times  as  much  carbon.  Now 
I  for  one  should  expect  this  Terre  Noire  (12)  steel  to  be 
more  brittle  than  the  Clapp-Griffiths  (21  and  30),  because 
with  but  little  less  phosphorus  it  has  so  very  much  more  car- 
bon, which  so  greatly  exaggerates  the  effect  of  phosphorus. 
Or,  to  look  at  it  a  little  differently,  if  0'40$  phosphorus  in 
Terre  Noire  steel  No.  12  has  absolutely  no  effect  on  its 
ductility  (its  elongation  is  13$  above  the  usual  upper  limit 
for  elongation  for  steels  of  this  carbon :  see  Table  6  §  28), 
lam  not  surprised  to  learn  thatO'50  and  0'55$  phosphorus 
in  Clapp-Griffiths  steel  21  and  30  permits  their  elongation 
to  remain  within  20$  of  (but  below)  the  usual  upper 
limit  for  their  carbon :  nor  do  I  see  that  it  redounds  to  the 
credit  of  the  Clapp-Griffiths  converter  that  '85$  phos- 
phorus in  No.  24  Clapp-Griffiths  steel  drags  the  elongation 
down  64$  below  the  usual  upper  limit  and  actually  48$ 
below  the  usual  lower  limit  for  elongation  for  its  carbon. 
(See  Table  6,  §  2^.)  Making  similar  allowances  I  find  these 
best  Clapp-Griffiths  steels  no  better  if  as  good  as  Terre 
Noire  2 and  3,  which,  be  it  remembered,  are  not  picked, 
but  represent  the  averages  of  hundreds  of  heats. 

Again  Clapp-Griffiths  Nos.  21  and  30  have  about  the 
same  elongation  but  much  less  contraction  than  the  Rus- 
sian rail  No.  48,  though  they  have  at  once  decidedly 
less  phosphorus  and  only  half  as  much  carbon  as  it :  while 
No.  48  (Russian)  with  twice  as  much  carbon  and  within 
21$  as  much  phosphorus  has  2 '5  times  as  great  elongation 
and  over  6  times  as  great  contraction  as  the  Clapp-Griffiths 
No.  24.  I  think  these  facts  imply  that  phosphorus  has  af- 
fected the  Clapp-Griffiths  far  more  than  the  Russian  steel. 
The  Russian  results  are,  however,  so  tainted  with  suspicion 
that  I  attach  no  weight  to  them. 

The  Trenton  steels  are  not  closely  comparable  with  the 
Clapp-Griffiths  steels,  because  their  elongation  and  contrac- 
tion are  not  given,  and  because  their  phosphorus  is  much 
below  that  of  the  three  most  surprising  specimens  of  Clapp- 
Griffiths  steel.  But  the  fact  that  No.  51,  Trenton,  with  -21$ 
of  carbon  and  '345$  of  phosphorus,  was  "remarkably 
tough"  is  liable  to  cool  the  ardor  of  the  worshipers  of 
Clapp-Griffiths, 


In  short,  carefully  comparing  the  Clapp-Griffiths  steels 
with  those  of  identical  composition  among  the  Terre 
Noire,  Heaton,  R.  Brown  and  Russian  phosphoric  steels, 
and  making  liberal  allowances  when  their  compositions 
are  not  identical,  I  find  in  each  of  the  last  three 
classes  instances  as  good,  and  among  the  R.  Brown, 
Russian  and  Terre  Noire  steels  instances  decidedly 
better  than  the  best  Clapp-Griffiths  cases  as  regards 
ductility :  while  the  worst  Clapp-Griffiths  cases  are  much 
worse  than  the  worst  Terre  Noire,  and  about  the  same  as 
the  worst  Heaton.  And  I  am  profoundly  convinced  that  no 
unbiased  person,  bearing  in  mind  the  capriciousness  of  the 
effects  of  phosphorus  on  ductility  and  its  much  greater 
effect  on  high  than  on  low-carbon  steel,  can  find  any  war- 
rant in  the  data  at  hand  for  believing  that  phosphorus  is 
one  whit  less  injurious  in  Clapp-Griffiths  than  in  other 
steel,  or  that  its  effects  are  neutralized  by  the  Clapp- 
Griffiths  converter  to  a  higher  degree  or  in  any  other 
way  than  that  which  is  equally  open  to  the  ordinary 
Bessemer  and  open-hearth  processes,  nay  has  long  been 
practiced  in  them,  and  which  consists  essentially  in  keeping 
the  carbon  and  probably  the  other  foreign  elements  low. 

This  error  neither  surprises  us  nor  reflects  on  Captain 
R.  W.  Hunt  if  we  remember  that  he  was  apparently  in 
ignorance  of  many  of  the  results  previously  obtained  with 
phosphoric  steel,  and  that  such  eminent  observers  as  Fair- 
bairn,  Mallet,  Miller  and  Tessie  du  Motay,  dazzled  by  the 
false  glitter  of  this  tinsel,  mistook  it  for  gold  much  as  he 
has.  Nor  does  the  adoption  of  the  converter  by  several 
manufacturers  vouch  for  its  efficacy  :  the  history  of  met- 
allurgy, aye  and  of  recent  metallurgy,  is  simply  strewn 
with  the  corpses  of  foredoomed  processes  which  the 
"genuine  practical  "  manufacturer  has  adopted  to  his 
sorrow  :  he  is  as  fallible  as  others. 

§  129.  PHOSPHORUS  AND  FORGEABLENESS. — Iron  in  gen- 
eral cannot  be  forged  at  a  temperature  closely  bordering 
on  its  melting  point,  and  slow  cooling  without  forging 
from  this  temperature  to  a  lower  but  still  exalted  one  in- 
duces coarse  crystallization  and  a  consequent  lack  of 
cohesion  which  renders  iron  extremely  tender  in  forging. 
As  phosphorus  appears  to  lower  the  melting  point  of  iron, 
and  as  it  greatly  exaggerates  the  tendency  to  coarse  crys- 
tallization, it  is  not  surprising  that  phosphoric  iron  and 
steel  must  be  forged  lightly  when  at  very  high  tempera- 
tures, and  are  prone  to  crack  and  even  fall  to  pieces. 

It  is  the  general  belief  that  at  lower  temperatures,  say 
from  a  yellow  to  a  dull  red  heat,  the  influence  of  phos- 
phorus on  forgeableness  is  relatively  very  slight:  there 
are  those  who  even  consider  moderately  phosphoric  steels 
as  unusually  easy  to  forge.  I  shall  shortly  endeavor  to 
show  that  it  is  uncertain  whether  the  highest  proportion 
of  phosphorus  ordinarily  met  with  in  commercial  steel 
has  any  serious  influence  on  its  forgeableness  under  the 
usual  conditions  of  manufacture.  Such  uncertainty  could 
hardly  exist  were  its  influence  serious  and  constant. 

The  following  evidence  shows  that  while  in  many  cases 
it  has  been  possible  to  forge  highly  phosphoric  steel  with 
care,  in  others  in  which  the  high  percentage  of  phos- 
phorus appears  to  be  the  sole  abnormal  condition,  forging 
has  been  impossible.  The  evidence  is  discordant,  steel 
with  '88$  of  phosphorus  rolling  well,  while  that  with  '24, 
•38  and  '52$  rolls  badly.  This  harmonizes  with  the  capri- 
cious effects  of  this  element  on  ductility,  and  calls  to 


PROPORTION    OF    PHOSPHORUS    PERMISSIBLE. 


130. 


mind  the  marked  differences  observed  in  its  chemical  be- 
havior during  solution  by  acids.     (See  §§  101,  123.) 

(i).  1-10$  PIIOSPHORLS.  R.  W.  Hunt*  found  that 
Bessemer  (Clapp-Grifflths)  steel  with  1'10$  of  phosphorus, 
•004  of  silicon,  '5  of  manganese,  and  '05  of  sulphur  rolled  in 
a  "practical  manner."  lie  seems  to  regard  this  as  due  to 
some  influence  of  the  Clapp-Griffiths  converter,  but  as 
steel  with  0--J,0'8S  and  0'98$  phosphorus  had  previously 
been  successfully  rolled,  as  I  know  of  no  evidence  that 
steel  of  this  composition  produced  in  non-Clapp-Griffiths 
converters  will  not  roll  in  a  "practical  manner,"  and  as 
I  know  that  much  Clapp-GrifRths  steel  with  moderate 
amounts  of  phosphorus  has  cracked  badly  in  rolling,  I 
find  little  ground  for  his  belief. 

(2).  -98^  PHOSPHORUS.  M.  White  has  shown  me  a 
small  bar,  about  •£"  x  £",  which  he  assures  me  contains 
0'98^  phosphorus  and  was  rolled  from  a  2"  X  2"  ingot. 
It  evidently  had  cracked  a  great  deal  in  rolling,  yet  it  had 
rolled  and  held  together. 

(3).  88^  PHOSPHORUS.  Z.  S.  Durfee  states  that  steel 
with  '8S^  of  phosphorus  hammered  and  worked  "beauti- 
fully" when  above  a  low  red  heat.b 

(4).  -40$  PHOSPHORUS.  E.  Williams  in  1856  or  1857 
found  Bessemer  steel  with  -40  phosphorus  non-hotshort, 
or  at  least  rolled  it  into  perfectly  sound  rails.0 

(5).  '35$  PHOSPHORUS.  It  is  stated  that  steel  with  this 
percentage  of  phosphorus  was  rolled  into  rails  for  the 
South  Austrian  Railway  with  perfect  ease.d 

(6).  '35$  PHOSPHORUS.  Slade  informs  me  that  the 
Trenton  phosphoric  steel  (see  §  128,  D.)  with  phosphorus 
from  -11  to  '35^  (in  one  case  phosphorus  '27  with  only 
•07  manganese  '12  carbon  '02  silicon)  rolled  perfectly,  with 
the  reductions  employed  for  other  steel,  at  any  heat  not 
above  an  orange  color ;  "It  would  not  fly  even  when 
heated  to  a  true  white  heat,  bat  after  having  been  brought 
to  this  heat  it  was  redshort  when  the  temperature  fell  to 
an  orange  color,  but  all  right  again  when  down  to  a  blood 
red . " e  I  have  observed  this  in  non-phosphoric  lo w-ca  rbon 
steel  as  well :  I  should  attribute  it  to  the  extraordinary 
lack  of  manganese  rather  than  to  the  presence  of  phos- 
phorus. 

(7).  '524^  PHOSPHORUS.  Wendel  found  that  Bessemer 
steel  with  '498  to  '524$  of  phosphorus  but  otherwise  of 
normal  composition  fell  to  pieces  in  rolling,  whether  a 
high  or  low  temperature  were  employed.  As  he  subse- 
quently found  the  same  behavior  in  steel  with  but  '20% 
phosphorus,  some  may  doubt  that  the  phosphorus  was 
the  cause,  or  at  least  that  it  was  the  sole  cause  of  the  hot- 
shortness.* 

(8).  '38$  PHOSPHORUS.  The  Sherman  phosphoric  steel 
relied  at  Boston  in  1877,  containing  '24  to  '38  of  phos- 
phorus, rolled  badly :  after  diligent  inquiry  I  fail  to  learn 
whether  it  was  unforgeable  at  all  temperatures  or  only  at 
high  ones. 

(9).  The  Terre  Noire  phosphoric  steel  is  rumored  to 
have  cracked  very  badly  when  rolled  into  rails. 

So  much  for  excessive  proportions  of  phosphorus  :  how 
is  it  with  the  comparatively  small  proportion  actually 


a  Trans.  Am.  Inst.  Min.  Engrs.,  XIV. ,  pp.  140-1,  1886. 

l>Eng.  and  Mining  Jl.,  1874,  I.,  p.  358. 

c  Journ.  Iron  and  St.  Inst.,  1880,  II. ,  p.  574. 

dldem,  1875,  I.,  p.  347. 

e  Private  Communication,  Jan.  12th,  1887. 

t  Trans,  Am.  Inst.  Min.  Eug.,  IV.,  p.  366,  1876, 


employed  commercially,  say  from  0  to  0'17j»?  Percy 
considers  that  phosphorus  does  not  interfere  with  hot 
malleableness :  Ledebur  that  it  does  not  except  at  very 
high  temperatures.8  It  is  a  general  belief  or  perhaps  super- 
stition among  American  Bessemer  men  that  phosphorus 
makes  steel  hotshort,  an  increase  of  0  '01^  phosphorus  being 
considered  by  some  sufficient  to  produce  this  effect :  yet  I 
learn  from  a  most  competent  authority  at  an  Illinois 
works,  which  has  probably  turned  out  as  much  phosphoric 
steel  (say  phosphorus  O'lO  to  0'17)  as  any  in  the  country, 
that  the  most  careful  observation  does  not  show  that  an 
increase  of  phosphorus  from  O'lO  to  0'14  has  ever  affected 
the  hot-malleableness  of  their  steel.  And  from  the  chemist 
of  another  Illinois  works  famed  for  its  phosphoric  steel 
and  for  the  cracked  flanges  of  its  rails,  I  learn  that  pro- 
longed investigations  designed  to  discover  the  relations 
between  composition  and  the  rolling  properties  of  their 
steel,  not  only  established  no  relation  between  phos- 
phorus and  hotshortness,  but  did  not  even  make  him 
believe  that  phosphorus  ever  caused  bad  rolling. 

Others  may  have  convincing  evidence :  I  for  one  consid- 
er it  improbable  that  the  proportion  of  phosphorus  which, 
in  view  of  its  causing  brittleness,  is  permissible  in  com- 
mercial steel,  has  an  important  effect  on  forging  power. 

WELDING  is  thought  to  be  favored  by  the  presence  of 
phosphorus :  the  United  States  test  board11  found  that, 
arranging  the  welded  wrought-iron  chains  in  order  of 
merit,  their  phosphorus  was  as  follows :  Best,  0'23^ :  '18 : 
•07:  -20:  -18:  '19:  -17:  '19:  -17:  '25:  rlfifc  worst  weld- 
ing. 

THE  MODULUS  OF  ELASTICITY  of  sixphosphoric  Heaton 
steels  tested  by  Fairbairn  (Nos.  13  to  18,  Table  28)  was  nor- 
mal, maximum  30,000,000;  minimum  26,580,000;  aver- 
age 28,603,000.  Phosphorus  is  currently  reported  to  di- 
minish the  modulus  ;  but,  finding  no  evidence  to  support 
this  view  I  regard  it  as  a  popular  superstition.  If  it  were 
true,  then  phosphoric  steels  with  their  high  elastic  limit 
should  be  very  springy. 

§  130.  PERCENTAGE  OF  PHOSPHORUS  PERMISSIBLE  FOR 
VARIOUS  USES. — As  the  effects  of  phosphorus  are  inten- 
sified by  the  presence  of  carbon,  and  probably  also  by  un- 
disturbed slow  cooling,  so  the  proportion  of  this  element 
which  can  be  tolerated  in  steel  for  a  given  purpose  must 
vary  greatly ;  it  is  hard  to  give  rules  of  wide  applica- 
bility. 

A.  WELD  vs.  INGOT  METAL. — The  effects  of  phosphorus 
are  considered  much  more  severe  in  ingot  than  in  weld 
metal,  partly  because  the  sum  of  the  other  foreign  elements 
(carbon,  silicon,  manganese)  is  usually  very  much  greater 
in  the  former,  and  possibly  partly  because  the  slag  inter- 
calated in  weld  metal  mechanically  lessens  brittleness  by 
creating  a  condition  slightly  approaching  that  of  a  wire 
rope,  i.  e.,  by  giving  pliancy  and  interrupting  the  growth 
of  incipient  cracks.  But  I  attach  little  weight  to  this 
hypothesis,  for  had  the  slag  this  effect  to  a  notable  degree, 
then  the  modulus  of  elasticity  of  weld  metal  should  be 
much  lower  than  that  of  ingot  metal,  i.  e.,  it  should  be 
less  stiff.  Actually  their  moduli  are  practically  identical. 
Finally,  as  phosphorus  appears  to  make  steel  brittle  by 
inducing  coarse  crystallization,  the  intercalated  slag  may 
partially  counteract  it  by  directly  obstructing  the  growth 


e  Handbueh  der  Eisenhiittenkunde,  p.  247. 

h  Trans.  Am.  Inst.  Mining  Engrs.,  1878,  VI.,  p.  116, 


74 


THE    METALLURGY    OF     STEEL. 


of  large  crystalline  faces,  and  by  offering  so  many  points 
from  which  crystallization  simultaneously  commences  that 
the  crystalline  faces  interrupt  each  other  before  attaining 
injurious  size. 

The  comparatively  mild  effect  of  phosphorus  on  weld 
metal  is  sometimes  explained  by  supposing  that  much  of 
it  here  exists  as  phosphate  in  the  slag  :  this  may  explain 
it  in  part,  but  probably  in  small  part.  We  find  ductile 
weld  irons  containing  0'24$  of  phosphorus  and  but  0'5$ 
of  slag :  if  this  is  of  the  composition  of  common  tap  cinder 
it  is  not  likely  to  hold  more  than  10$  of  phosphoric  acid, 
which  would  account  for  but  0-G25  of  phosphorus  per  100 
of  metal.  Indeed,  the  slag  produced  in  puddling  such 
iron  may  hold  as  little  as  l-7$  of  phosphoric  acid,  which 
would  account  for  but  0'004$  of  phosphorus.  Few  pub- 
lished analyses  of  tap  cinder  show  over  S$  of  phosphoric 
acid :  bat  one  out  of  42  analyses  of  wrought-iron  given 
by  IlolJey  shows  more  than  1-7$  of  slag,  which,  if  hold- 
ing 9,%  of  phosphoric  acid,  would  account  for  but  0'0?$ 
of  phosphorus. 

KARSTEN  thought  that  0'3  phosphorus  in  weld  metal 
did  not  cause  coldshortness :  that  with  0  5  phosphorus 
iron  might  yet  be  worked,  and  that  even  with  0-6  it  might 
be  bent  to  a  right  angle,  but  that  with  0'8  phosphorus 
it  was  decidedly  coldshort.  Yet  Eggertz  found  1"  sq. 
bars  of  weld  iron  with  0'25  to  0-3  phosphorus  very  cold- 
short, which  again  illustrates  the  capriciousness  of  phos- 
phorus, if  indeed  both  these  observers  are  right. 

BAILS. — Weld  iron  rails  often  have  0'45  phosphorus, 
and  0-4$  is  not  thought  to  be  injurious.  Bell  gives  one 
with  0-67$.  American  steel  rails,  which  ordinarily  con- 
tain 0-3  to  0-5  carbon,  rarely  have  more  than  0-16  phos- 
phorus. The  unsurpassed  Bethlehem  rails  have  but  -07 
phosphorus,  and  those  of  other  Eastern  mills  rarely  contain 
more  than  -09  or  0-095$.  The  highest  proportion  which  I 
have  met  in  a  steel  rail  with  over  0-3  carbon  is  0-24$, 
together  with  carbon  -38  :  silicon  -03  sulphur  -07  and 
manganese  -87.  This  I  believe  was  a  European  rail. 
Rails  2  and  2a  in  Table  30,  the  former  a  bad  the  latter  an 
excellent  rail,  both  have  0-24  phosphorus.  I  know  of 
American  steel  rails  with  0-14  phosphorus  and  say  -35 
carbon  which  were  pronounced  "  excellent"  by  their  pur- 
chasers. 

For  851  cases  of  steel  rails  examined  by  Sandberg  the 
normal  limits  for  phosphorus  appeared  to  be  '05  and  -10$. 
No  less  than  23$  of  them,  however,  had  more  than  '10%  of 
phosphorus,  and  11$  of  them  less  than  '05$  of  this 
metalloid.81 

If  we  can  believe  Beck-Guerhard  (I  cannot)  Russian 
rails  have  as  much  as  0-67  phosphorus.  Table  28  gives  six 
phosphoric  rails  reported  by  him,  of  which  the  most  re- 
markable have  -28  carbon  with  '33  phosphorus  (No.  46), 
and  '23  carbon  with  '67  phosphorus  (No.  48).  Though 
behaving  well  under  static  stress,  their  track  record  is 
surprising.  No.  48  was  greatly  damaged  after  41  months' 
service,  during  which  12  tons  (737  poods)  had  passed  over 
it.  Another,  No.  47,  broke  after  2  months'  service,  dur- 
ing which  a  total  weight  of  900  Ibs.  (25  poods)  had  passed 
over  it,  presumably  a  hand  car.b  Unless  the  pood  has 


a  Trat-o  Am.  Inst.  Min.  Eng.,  X.,  1882,  p.  410. 

t>  The  Secretary  of  the  Iron  and  Steel  Institute  assures  me  that  the  incompr»- 
hensible  numbers  which  I  have  quoted  are  those  given  by  the  Russian  Commission, 
and  uot  misprints.  (Private  communication.) 


some  other  meaning  than  that  assigned  it  by  the  text 
and  the  encyclopaedias  (about  '017  ton),  Russian  train- 
dispatchers  are  to  be  envied.  Dudley  would  limit  the 
phosphorus  in  rails  to  0-10$.°  Boiler  plate  steel  has  ordi- 
narily not  above  '04  to  *05  phosphorus  :  yet  I  know  one 
instance  of  boiler  plate  made  at  an  American  works 
whose  reputation  for  this  product  is  probably  unequa^d, 
which  contained  '07  phosphorus,  and  many  other  cases 
of  admirable  boiler  plate  with  this  amount. 

Steel  boiler  plates  of  this  composition  are  in  very  ex- 
tensive use,  and  are  mercilessly  punched  and  flanged  cold 
without  subsequent  annealing  or  reaming,  and  it  is  next 
to  certain  that  they  actually  behave  admirably  in  service, 
for  otherwise  more  frequent  failures  of  steel  boilers  in 
manufacture  or  use  would  have  occurred.  Boiler  plate 
with  0'31$  phosphorus  and  0'12  carbon  has  moreover  been 
pronounced  "remarkably  tough"  by  so  conscientious  an 
engineer  as  F.  J.  Slade,  (see  §  128  D.) ;  but  this  was  manu- 
factured in  such  small  quantity  that  we  can  draw  little 
inference  as  to  its  trustworthiness  under  the  trying  condi- 
tion of  actual  service.  The  effects  of  phosphorus  are  so 
capricious  that  we  cannot  infer  complete  trustworthiness 
from  a  few  instances  of  good  behavior. 

CUTTING  TOOLS  should  apparently  be  very  free  from 
phosphorus  (say  with  not  over  '03$).  Indeed  the 
reputed  superiority  of  tool  steel  made  from  Danne- 
mora  ore  is  by  many  attributed  to  its  freedom  from 
phosphorus.  Of  18  tool  steels  tested  by  Smith,  the 
only  three  with  over  '03  phosphorus  were  among 
the  worst,  their  value  being  from  40  to  60$  of  the 
maximum :  yet  one  steel  with  -024  phosphorus  had 
the  best  record  in  slotting  ;  and  its  average  for  all  cutting 
purposes  was  81$  of  the  maximum.  The  value  was  meas- 
ured by  the  weight  of  the  shavings  which  a  tool  would 
turn,  plane,  etc.,  without  dressing."1 

I  am  informed  that  the  saws  of  one  of  the  most  cele- 
brated American  makers  formerly  contained  as  much  as 
0'09$  of  phosphorus,  but  that  their  quality  has  been 
materially  improved  by  limiting  the  phosphorus  to  '027, 
and  raising  the  carbon  from  "90  to  1'10$. 

TABLE  80. — PHOSPHORUS  IN  VARIOUS  IRONS  AND  STEELS.    (SEE  TABLES  28  AND  29.) 


Carbon. 

a 
8 

En 

Manga- 
nese. | 

ii 

""§. 

•=§ 

<£•§. 

Purpose,  etc. 

1 

•16 

(  Kails,  usual  upper  limit  for  phosphorus. 

2. 

•28 

•05 

24 

•24 

•04 

j  Bad   German    rail.     Pourcel,  Trails.  Am.   Inst.    Mining 

2a 

•21 

•05 

•33 

•24 

•08 

Engrs.,  XI.,  p.  201 
Rail  removed  after  12  years  wear  on  an  American  railway. 

R.  W.  Lodge,  private  communication. 

3. 

•16 

•04 

•60 

•07 

06 

Ingot 

Boiler  plate,  usual  upper  limit  for  phosphorus. 

4. 

•15 

•67 

10 

metal. 

Wire  rods,  common. 

5. 

•12 

•67 

10 

Structural  steel,  common. 

10® 

6 

•10 

01 

•37 

•12 

•05 

1  Nail  plate,  common  . 

7. 

0  90 

30 

•35 

•09 

Saws,  formerly  made  by  a  celebrated  maker. 

8 

no 

80 

35 

•027 

I     "     now            "      "  the  same           *• 

9. 
0. 
11. 

•10 
•04 
•13 

16 
12 

14 

•07 
'6' 

•67 
•195 
•16 

•07 
•01 
0 

Weld 
iron. 

1  Iron  rails,  unusually  phosphoric,  p.  42S  t  Bell,  Manuf. 
-<  Best  Yorkshire  boiler  plate.           1       AQA\       Iron 
j     "           •'         railroad  axles.       |  I>-  ***  j  and  Steel. 

§131.  PHOSPHORUS  UNITS. — For  conciseness  Dudley 
would  measure  the  brittleness  due  to  a  given  percentage  of 
carbon,  silicon  or  manganese  in  terms  of  that  caused  by  '01$ 
phosphorus  :  he  suggests  provisionally  assigning  to  -02$ 
silicon,  '03$  carbon  and  "05$  of  manganese  respectively  an 
effect  equivalent  to  that  of  O'Ol  phosphorus,  and  con- 
veniently designates  each  of  these  quantities  as  a  phos- 
phorus unit.6  When  we  discover  what  quantity  of  each 

c  Trans.  Am.  Inst.  Mining  Engrs.,  IX.,  p.  356. 

a  Report  U.  S.  Board  on  Testing  Iron,  etc.,  1881,  II.,  p.  59S  :  Thurston,  Matls. 
of  Engineering,  II.,  p.  434. 
e Trans,  Am.  Inst.  Min.  Engrs.,  VII.,  p.  197,  1879. 


CHROME    STEEL.      §  137. 


75 


of  these  elements  is  equivalent  to  01$  of  phosphorus,  this 
clever  conception  will  be  of  great  value,  and  it  may  be  very 
useful  to-day  if  cautiously  employed.  But,  as  the  values 
assigned  to  the  phosphorus  unit  are  purely  conjectural,  it 
is  liable  to  be  wildly  misleading  if  used  beyond  the  nar- 
row limits  for  which  its  talented  author  designed  it. 
Thus,  while  four  irons  with  0 '60$  carbon,  '40  silicon,  \% 


manganese  and  -20$  phosphorus  respectively  and  contain- 
ing nothing  beyond  iron  and  one  impurity,  might  possibly 
be  equally  brittle,  it  is  extremely  improbable  that,  if  an  iron 
initially  contained  0-50$  carbon  and  nothing  else  it  would 
be  rendered  as  brittle  by  an  addition  of  ]  %  manganese  or  of 
•5%  manganese  +  '20  silicon,  or  of  -40  manganese-)-  '16  sili- 
con -+-  -12$  carbon  as  by  an  addition  of  '20$  phosphorus. 


§  136.  IRON  AND  CHROMIUM. 

SUMMARY. — In  1820  Berthier*  publicly  described  chrome 


steel,  whose  value  he  recognized,  and  his  method  of  pre- 
paring it,  substantially  that  employed  to-day.  Chromium 
appears  to  combine  with  iron  in  all  proportions,  probably 
often  tending  to  form  heterogeneous  compounds  :  to  be 
readily  oxidized  when  thus  alloyed  :  to  raise  the  satura- 
tion point  for  carbon :  to  increase  the  hardness,  especially 
that  of  the  hardened  steel,  and  perhaps  also  the  tensile 
strength  and  elastic  limit :  and  to  lessen  the  welding  power. 
It  does  not  confer  on  carbonless  iron  the  power  of  being 
hardened  by  sudden  cooling :  it  does  not  diminish  but  per- 
haps increases  this  power  conferred  by  carbon  simulta- 
neously present :  it  does  not  very  seriously  dimmish  hot 
malleableness  or  ductility  under  impact  or  under  quiescent 
load.  Chromic  oxide  is  liable  to  cause  flaws  in  chrome 
steel,  which  is  more  easily  burnt  than  chromeless  steel. 

Chrome  steel  is  rather  hard  when  annealed  and  intensely 
so  when  quenched:  is  readily  forged:  is  not  peculiarly 
brittle :  will  not  truly  weld,  but  can  be  made  to  cohere 
(even  to  wrough  t-iron  it  is  said)  with  a  tenacity  valuable 
for  many  purposes.  Its  manufacture  is  a  promising  field, 
but  only  for  those  competent  to  control  it  scientifically. 

§  137.  THEIR  METALLURGICAL  CHEMISTRY. 

A.  FERRO-CHROME. — Chromium    appears  to    combine 
with  iron  readily  and  in  all  proportions,  at  least  up  to  80%. 
Ferro-chrome,  i.  e.  highly   chromiferous  iron,   may  be 
readily  prepared  as  stated  by  Berthier,"  by  very  strongly 
heating  the  mixed  oxides  of  iron  and  chromium  in  brasqued 
crucibles,  adding    charcoal    powder    if   oxide  of  chro- 
mium predominates,  and  fluxes  (e.  g.  borax  and  glass)  to 
scorify  earthy  matter  and  to  prevent  oxidation :  the  pres- 
ence of  iron  or  of  its  oxides  facilitates  the  reduction  of  the 
chromium,  which  demands  a  higher  temperature  than  that 
of  iron.    This  is  said  to  be  substantially  the  method  em- 
ployed at  Brooklyn"  and  at  Unieux  (France),  where  chrome 
steel  has  been  for  years  produced  on  a  large  scale.     It  has 
also  been  made  at  Sheffield.     Of  late  12$  f  erro-chrome  pro- 
duced in  the  Cowles  electric  furnace  has  been  offered  for 
sale.   Ferro-chrome  has  also  been  made  in  the  blast-furnace 
atTerre-Xoire,  but  it  is  stated  with  not  over  40$  chromium. 

B.  CHROME  STEEL  also  is  made  to-day  substantially  by 
Berthier's  process,  by  simply  melting  f  erro-chrome  with 
wrought -iron  or  steel  in  plumbago  crucibles.0 


CHAPTER    VII. 

CHROMIUM,     TUNGSTEN,    COPPER. 

[Foe  later  information  see  Appendix  I.] 

C.  OXIDATION. — Chromium, even  when  alloyed  with  iron, 
is  very  readily  oxidized.      In  puddling  chromiferous  cast- 


a  Annales  des  Mines,  1st  series,  VI.,  p.  573:  Ann.  Chim.  Pbys.,  3d  series,  XVII., 
p.  55. 

b  Percy,  Iron  and  Steel,  p.  185. 

c  Ferro-chrome  is  said  to  be  made  at  Brooklyn  by  melting  finely  pulverized 
chrome  ore  with  charcoal  in  common  graphite  crucibles,  about  45$  of  ferro- 
chrome  resulting,  which  holds  30$  of  chromium  and  3$  of  carbon.  Prom  0'25 
to  2%  of  this  product  is  melted  with  Swedish  or  bloomary  wroughc-iron  in  70  Ib. 
charges  in  crucibles  in  common  crucible  furnaces,  which  melt  6  rounds  per  24 
hours  with  a  consumption  of  2  Ibs.  of  anthracite  to  1  of  steel :  (Stahl  und  Eisen, 
II.,  p.  165,  1882). 


iron  its  chromium  is  largely  scorified,  and,  by  forming  a 
thick  slag,  prevents  the  puddled  ball  from  welding  (this 
appears  distinctly  due  to  the  oxide  of  chromium  in  the 
slag  and  not  to  the  metallic  chromium  in  the  metal).  Thus 
Riley  found  that  adding  \\%  of  cast-iron  which  contained 
about  1%  of  chromium  greatly  delayed  the  puddling  of 
good  gray  forge  iron :  the  chromium  was  found  in  the 
slag  soon  after  fusion.  Equal  parts  of  this  chromiferous 
cast-iron  and  of  hematite  pig  puddled  with  difficulty,  and 
the  slag  was  so  viscid  that  the  puddled  balls  could  not 
be  formed  into  blooms. d 

The  Bessemer  process,  possibly  because  its  slags  are  acid, 
seems  less  prone  to  remove  chromium  than  puddling.  A.t 
one  time  the  acid-Bessemer  steel  of  Harrisburg  had  occa- 
sionally as  much  as  0'59$  of  chromium.8 

The  readiness  with  which  chromium  oxidizes  has  sug- 
gested the  use  of  ferro-chrome  instead  of  spiegeleisen  as 
a  recarburizer  for  the  Bessemer  process.  But  its  efficacy  is 
very  doubtful.  The  oxides  of  manganese  arising  from 
the  reaction  between  the  oxygen  of  the  blown  steel  and 
the  manganese  of  the  spiegeleisen  are  fusible  and  scorifi- 
able :  they  coalesce  and  rise  to  the  surface  of  the  molten 
metal.  Chromic  oxide,  infusible  and  well-nigh  unscorifi- 
able,  would  probably  remain  mixed  with  the  steel,  break 
up  its  continuity  and  impair  its  forgeableness.  Indeed, 
even  in  the  crucible  process,  in  which  chromium  has  com- 
paratively little  chance  to  oxidize,  chromic  oxide,  formed 
while  the  steel  is  molten,  is  liable  to  cause  deep  inerad- 
icable veins  in  chrome  steel,  especially  if  its  carbon  be  low 
or  ita  chromium  high.*  Even  in  heating  chrome  steel  a 
very  strong  and  adherent  scale  forms  which  renders  weld- 
ing next  to  impossible. 

Chromium  is  said  to  hasten  the  rusting  of  iron. 

D.  CARBON,  SILICON,  SULPHUR. — Chromium  raises  the 
saturation  point  for  carbon,  probably  even  more  power- 
fully than  manganese  does  :  ferro-chromes  Nos.  1  and  11 
in  Table  31  have  11  and  6 '2$  carbon  with  80  -and 
chromium  respectively.    Like  manganese  it  prevents  the 
separation  of  graphite. 

Ferro  chrome  often  contains  over  2%  of  silicon.  Chromium 
does  not  necessarily  exclude  sulphur  from  iron,  for  ferro- 
chrome  3,  Table  3 1 ,  with  67-15$  chromium  has  0  -3$ sulphur. 

E.  KEKN. — I  find  neither  result  nor  promise  in  his  pro- 
posal to  substitute  chrome  iron  ore  and  calcined  limestone 
for  ferro-manganese  in  the  crucible  process.85 


a  E.  Riley,  Journal  of  the  Iron  and  Steel  Institute,  1877.  I ,  p.  104. 

e  A.  S.  McCreath,  private  communication,  March  19,  1887. 

*  Brustlein,  Journal  of  the  Iron  and  Steel  Inst.,  1886,  II.,  p.  776.  After  pro- 
longed study  I  cannot  quite  assure  myself  that  I  understand  the  passage  on  which 
this  statement  is  based. 

g  Metallurgical  Review,  I.,  p.  489. 


76 


THE    METALLURUY    OF    STEEL. 


TABLE  <<!.— COMPOSITION  of  FEBEO-CIIEOJLE. 


No  

1 

f, 

3. 

4 

ft 

6. 

7. 

8. 

9 

10 

11. 

12. 

80 

7fi+ 

67- 

no 

M-f 

4S@52 

42  ± 

30  ± 

"7  + 

W 

18  ± 

16  ± 

11 

5-4 

7©8 

7  S± 

4'7± 

s-s 

6'2± 

2'7± 

8  -30 

often  >  2 

2-l± 

0  4 

05 

04 

yes 

yes 

Magnet  attracts... 

no 

no 

no 

vcs 

1.  Fnieux.  2*  Percy,  Iron  and  Steel,  p.  1$G:  Imperfectly  fused:  yellowish  pray  white: 
renter  lillod  with  minute  acicular  crystals.  Attacked  with  difficulty  by  acids.  3,  Boussin.gau.lt. 
Journ.  Iron  and  St.  Inst.,  1SS6,  II.,  p.  81,"-.  4*  lierthier,  Percy,  loc.  cit.:  well  rounded  button  : 
full  of  large  bubbles  lined  with  prismatic  crystals:  whiter  than  platinum  :  attacked  with  great 
difficulty  even  by  nitro-hydrochloric  acid,  5,  Percy.  Inc.  cit.  B,  Usual  composition  of  Unienx 
I'eiTo-ehroine.  7,  Unicux.  silky  when  chilled.  8*  I'nieux  :  when  slowly  cooled  a  mass  of  needles. 
5*»  Percy,  loc.  cit.,  well-fused  :  tin-white,  finely  granular,  attacked  with  difficulty  by  acids.  JO. 
tTnieux:  fracture  white,  aeicular.  J  1,  Unieux:  fracture  brilliant  acicular  when  slowly  cooled, 
silky  when  chilled.  12,  Unieux:  fracture  when  slowly  cooled  gray,  small  square  facets  :  silky 
when  chilled.  Unicux  specimens  from  Urustlein,  Journ.  Iron  and  St,  Inst.,  1SSC,  II.,  p.  770. 


§  138.  INFLUENCE  OF  CHROMIUM  ON  THE  PHYSICAL 
PROPERTIES  OF  IRON. 

A.  TENSILE  STRENGTH. — It  is  usually  stated  that  chro- 
mium raises  the  tensile  strength.  What  evidence  I  have 
collected  while  it  does  not  disprove  certainly  does  not 
warrant  this  statement.  Plotting  in  Figure  3,  §  27,  those 
steels  of  Table  32  whose  composition  and  tensile  strength 
are  given,  with  tensile  strength  as  ordinate,  carbon  as 
abscissa,  I  find  that  in  six  cases  the  tensile  strength  about 
equals  the  normal  strength  of  chrome-less  steels  of  like 
percentage  of  carbon,  in  three  cases  it  is  slightly  higher 
and  in  three  slightly  lower.  Of  the  three  with  unusually 
high  tensile  strength,  one  (No.  1 )  has  4.%  of  chromium  :  a 
calculation  based  on  this  instance  alone  gives  chromium 


but  slight  influence,  about  400  pounds  increase  of  tensile 
strength  per  Q-\%  of  chromium  per  square  inch.  The 
second  (No.  7  unhardened)  is  rather  stronger  than  the 
average  of  chromeless  steel  of  like  carbon  content,  but 
the  difference  is  too  slight  to  build  on,  especially  as  a  har- 
dened piece  from  the  same  bar  was  decidedly  weak.  The 
percentage  of  chromium  of  the  third  (No.  13,  with  -25$ 
of  chromium)  is  so  low  that  we  hesitate  to  ascribe  to  it  the 
high  tensile  strength  of  the  steel.  These  cases  are  here 
summarized.* 

Tensile  K'rength  compared  with  other  steels  of  like  carbon  content. 

, High. v  ,—  • Normal. , . Low. , 

Number  in  Table  32.    1    7  unhardened.     13      2     4          6  9    12    29  7  hardened.    8     9'5 

Chromium 4'00  0-.r>3  0-252-2  1-2    -22@-64  -33  '29    ?  -S8          -SO     -33 

Carbon 1-10  1'03  O'TO  0-6  0  34  -Sl@'99  -901-82  -7±      103          '91     '84 

From  the  other  instances,  Nos.  16  to  28,  no  safe  infer- 
ences can  be  drawn:  so  much  " chrome  steel "  contains 
little  or  no  chromium  that  we  cannot  safely  assume  its  pres- 
ence where  it  is  not  explicitly  given.  Excepting  tungsten 
steel  No.  10,  Table  34,  §  141,  I  know  of  none  whose  tensile 
strength,  when  not  raised  by  hardening  or  cold-forging, 
equals  that  of  chrome  steel  No.  21  (Ib7,915  pounds  per 
square  inch).  It  is  not  explicitly  stated  that  this  had  not 
been  hardened,  but  this  is  to  be  inferred  from  the  context. 
The  strength  of  the  hardened  bars  Nos.  3  (199,000  pounds), 
18  (202,900  pounds)  and  30(213,342  pounds)  is  decidedly 


a  I  here  leave  No.  6  out  of  consideration,  not  knowing  which  of  the  composi- 
tions given  corresponds  to  the  tensile  strength.  For  none  of  them  would  the 
tensile  strength  be  high. 


TABLE  32. — CHROME  STEEL. 


Number. 

Observer,  source,  etc. 

Composition. 

Physical  properties. 

Bent  before  break- 
ing. 

Chromium. 

Combined 
carbon. 

Graphite. 

$ 

S 

H 

1 

cfi 

1 

.J* 
=g£>o  . 
gl&5 

fij 

3 

Elastic  limit. 
Lbs.  persq. 
ta. 

Klongation 

Reduction 
of  area  % 

£' 

Diameter  of 
piece. 
Inches. 

* 

In. 

1 
1-5 
2 
3 
4 
4'5 
C 
6 

7 

8 
9 
95 
10 
11 

12 
18 

14 
15 
16 
17 
IS 
19 
20 
21 
22 
23 
24 
25 
26 
27 
28 
29 
30 
81 
82 
83 

4- 

2'9± 
2'2 
2  2 
1  2 

'99± 
•45@'92 
•22@'Gi 

•88 

•50 
•88 
•88 
•88 
•36 

•29 

•25 

0 
0 

1-10 
1-  t 
0'6 
06 
•84 
1-   f 
•84@1  19 
•81®  '99 

1-03 

•91 

•90 
•84 
•94 
•98 

1  32 

•70 

•60 
•31 

177,800 

177,000± 

75 

103,000 
199,000 
88,180 

67,500 
199,000 
53,300 

It- 
s' 

1- 

67+ 

A.  A   Blair  and  I>  Smith,  P                   

•01©-03 
•01@"02 

•03 

1  28 

115,922 

"                     •>         F                                            

104,756 

•17 

•05 



J  157,000  a 
I  116,000b 
122,300 

0-6 
0-6 
15'7 

4" 
4" 

0 
0 

25 
15  5 

•53  octagon. 
•58      ' 

1  89 
•22 

•08 
•09 

•98 

184,000 
110,572 

2- 

4" 

0 

40- 

•43  square. 

•01 

Brooklyn  St  Louis  Bridge  (*)  Blair     

t.  •               .1          ••        (j\    •' 

•15 

•15 

•78 

J  124,000  a 
}  127,000^ 

145,400 

6' 
9- 

5'5 

8-5" 
3-5" 

4 
2 

»j 

1-5 
65 
25  a 
30  c 

•63  round. 
•63     " 

<•          IA             ••           «             "           •«                        

tjnieux,  unburdened 
'*         quenched  from  yellow 
"                          "     bright  cherry  >  same  bar,  Barbier,  Boussingault.  4 
'•               "            "     cherry 
"     dark  red          J                                                             ( 

108,700 
191,000 

85.446 

IS' 
1-2 

50 
2 
6 
68 
63 

60 

b6  octagon. 

202.900 
104,260 
100,000 
187,915 

'  62,806'  ' 
55,000 

2- 
14- 
IT1 

168,765 
166,360 
129,630 
126,870 
124,890 
157,600 

"        Kirkaldy's  test                               

87,000 
71,000 
68,000 
M.OOO 

7  6 
6'2 
7  2 
11 

80- 
59- 
59- 
47' 
57- 
67" 
68- 
29  2 

|     ..         ..      ;  .:"•;•:'::.  ::::.::.:::: 

:     ..   .  .. 

152,200 
102,200 
213,300 

69',300 
199,000 

is  5 

6  2 

8" 
3" 

•7± 
'7± 

1  04 
•92 
61 

•68 
•44 

•46 

•01 
•01 
0 

•05 
•02 
•03 

•15 

•14 
•12 

«>        « 

1.  Unhardened,  Unieux.  1'S,  Faraday  and  Stodart.  Forged  well,  with  no  disposition  to  crack  :  hard,  as  malleable  as  pure  iron,  gave  a  very  fine  damask.  The  composition  here  given  is  inferred 
from  their  statements  that  they  melted  tog-ether  1600  grs.  of  steel,  whose  carbon  is  roughly  assumed  at  1%,  and  48  grs.  of  pure  chromium  ;  and  further  that  "  in  all  the  experiments  made  in  tho 
laboratory  the  button  produced  was  weighed,  and  if  it  fell  short  of  the  weight  of  both  metals  put  into  the  crucible  it  was  rejected  as  imperfect."  Phil.  Trans.  Royal  Soc.,  1622,  pp.  267,  258.  2  and 


SJ.  Unieux,  2  unhardened,  8  the  same  steel  annealed  from  bright  redness  after  oil-hardening."  4-  Unieux.  4*5,  Faraday  and  Stodart,  loc.  cit.,  good,  forged  well,  with  no 
hard,  but  not  so  hard  as  No.  1'5.  The  remarks  concerning  No.  1-5  apply  to  No.  4  5,  mutatis  mutandis.  S  and  6.  Kept,  of  U.  S.  Bd.  to  Test  Iron,  etc.,  II.,  p.  590.  Thurston,  Mat'ls  of 
Kn"ineering,  II..  p.  4.34.  7.  Brooklyn  "  Adamantine"  chrome  steel,  a,  unhardem-d.  b,  quenched  in  oil  from  dull  redness.  Hunt  and  Clapp  and  the  author.  8.  Dfihh-n,  Ledebur,  Handhurh, 
p  261.  J».  One  of  the  hardest  brands  of  Brooklvn  chrome  steel,  Hunt  and  (Jlapp  and  tho  author.  H'B.  Kept.  U.  S.  Bd.  to  Test  Iron,  II.,  p.  590.  1O  and  1 1.  A.  A.  Blair.  Said  to  be  from 
staves  of  St.  Louis  Bridge  :  private  communication,  May  80,  1887.  1  2  and  13.  Brooklyn  chrome  si  eel.  Hunt  and  Clapp  and  the  author.  13  is  styled '-No.  1  A."  a,  Unhnrdrncd:  h,  har- 
dened in  oil  from  dull  redness.  14  and  1  ft.  Brooklyn  (?)  chrome  steel,  naid  1 1  be  from  staves  of  St.  Louis  Bridge.  A.  A.  Blair,  private  communication,  May  30,  1837.  1  6  to  !4O.  Unieux. 


p.  807. 


CxiEtTx  STEELS.— Excepting  Nos.  27,  28.  and  SI  to  83,  described  by  Brastleln  and  Boussingault,  Ann.  de  Chtm.  et  Phys.,  5th  Ser.,  XT.,  aid  .Tour.  Iron  and  St.  Inst.,  1886,  II..  p  807. 
liitooKLYN  CHBOME  STEELS.— Nos.  7,9,  12,  and  13,  obtained  by  the  author  from  the  makers  or  their  Boston  agents,  anil  tested  by  him  :    Messrs.  Hunt  and  Clapp,  of  Pittsburgh,  Pa.,  have  been  si 
kind  as  to  analyze  these  steels  gratuitously  for  this  work.     In  tho  bending  tests,  these  steels  were  held  lirmly  in  a  vise  uud  struck  with  moJoilM  force  with  a  sledge  till  they  broke.    The  beading  wa 


measured  after  fracture. 
a.  As  received  from  the  makers,    b.  Alter  quenching  in  oil  from  dull  redness. 


c.  After  annealing  from  cherry  redness.    Several  chromiferous  phosphoric  steels  arc  described  In  Table  28. 


CHROME    STEEL ;      PHYSICAL    PROPERTIES.      §  138. 


77 


high  :  but  we  have  too  few  recorded  cases  of  the  tensile 
strength  of  hardened  high-carbon  steel  to  justify  our  term- 
ing it  extraordinary,  or  the  inference  that  it  has  been  raised 
by  chromium.  §  54,  I,  gives  cases  in  which  the  tensile 
strength  of  hardened  steel  rises  to  248,000  and  314,800 
pounds,  and  that  of  wire  to  432,000  pounds:  hardened 
steel  No.  2:),  Table  8,  has  211, 072  pounds  tensile  strength, 
and  hardened  steel  of  Park  Bro.  &  Co.  is  reported  with 
227,500a  pounds  tensile  strength.  These  four  are  appar- 
ently chromeless. 

B.  THE  ELASTIC  LIMIT,  it  is  stated,  is  raised  by  chro- 
mium even  more  than  the  tensile  strength  :    this  however 
is  only  true  of  one  of  the  cases  which  I  have  met,  No.  1, 
Table  33,  with  4$  chromium,  whose  elastic  limit  is  nearly 
identical  with  its  tensile  strength,   177,000  pounds  per 
square  inch.     The  elastic  ratio  of  the  others  is  either  nor- 
mal or  (as  in  Nos.  18  and  19)  unusually  low. 

C.  DUCTILITY. — If  we  compare  the  steels  in  Table  32 
with  the  numbers  given  in  Table  6A,  §  28A,  we  find  that, 
considering  their  tensile  strength,  the  elongation  of  three 
of  them,  Nos.  4,  7  and  9,  is  decidedly  low,  that  of  eleven  of 
them  is  about  normal,  and  that  of  four  of  them,  Nos.  1,  2, 
8  and  23,  is  decidedly  high.     In  a  later  chapter  combina. 
tions  of  tensile  strength  with  elongation  which  equal  if 
they  do  not  greatly  excel  these  will  be  given.     Compar- 
ing them  with  Table  &  and  Figure  5,  §  2d,  we  note  that, 
considering  their  carbon  content,  the  elongation  of  three, 
Nos.  2,  8  and  12,  is  high,  that  of  two,   4  and  7,  is  low, 
while  that  of  the  remaining  ones  whose  composition  is 
given  is  about  normal.     Q  here  is  little  in  these  numbers 
to  suggest  that  chromium  either  favors  or  precludes  an 
unusually  high  combination  of  strength  and  toughness. 

As  regards  ductility  under  shock  our  data  are  equally 
contradictory.  Boussingault,  who  investigated  chrome 
steel  perhaps  more  thoroughly  than  any  other  pecuniarily 
disinterested  person,  considered  that  its  resistance  to  im- 
pact was  far  greater  than  that  of  other  steels."  He  cites  an 
octagonal  bar  (No.  23,  Table  32),  whose  inscribed  diameter 
was  0 '87  inch:  when  notched  0'08  inch  deep  and  grasped 
in  a  vise  with  this  notch  'OS  inch  above  its  jaws,  it  bent 
60°  under  20  blows  of  an  eleven-pound  sledge  before 
breaking.  This  is  certainly  good  resistance :  unfortunate- 
ly it  is  not  stated  that  it  was  positively  known  to  con- 
tain chromium.  Holtzer's  twelve-inch  chrome  steel  pro- 
jectiles shattered  a  hard  sixteen-inch  Brown  compound 
steel  armor  plate,  and  were  found  entire  at  the  back.0 
Here  too  we  are  not  positively  informed  that  they  con- 
tained an  important  quantity  of  chromium.  Unfortunate- 
ly in  other  cases  chrome  steel  has  shown  poor  resistance 
to  impact.  I  found  that  four  Brooklyn  chrome  steels,  7,  9, 
12  and  13,  Table  32,  bent  from  1-5°  to  40°  under  the  blows 
of  a  sledge  before  breaking  :  none  behaved  well,  two  be- 
haved wretchedly.  A  bar  of  chromeless  Pittsburgh  cru- 
cible cutlery  steel  of  about  1$  carbon,  0'4  inches  square, 
bent  93 '5°  under  like  conditions  before  breaking. 

McCreath  informs  me  (partly  from  memory)  that,  at  the 
Pennsylvania  Steel  Works,  Bessemer  rails  with  from  '12  to 
•64$  chromium  passed  the  drop  test  when  their  carbon  was 
from  '25  to  -30$,  but  often  broke  under  it  when  their  car- 


a  W.  S.  Shock,  quoted  in  Trautwine's  Civil  Engineer's  Pocket  Book,  p.  179, 
1872. 

b  Ann.  Chim.  et  Phys.,  5th  ser.,  XV. 
«  Engineering,  April  1st,  1887,  p.  306. 


bon  was  from  '40  to  -50$:  e.  g.,  one  with  '41  chromium 
and  -28  carbon  passed  :  two  with  "59  and  '41  chromium 
and  -50  -(-  and  28  -(-  carbon  respectively  broke.d  Here  too 
chromium  appears  to  have  injured  the  shock-resisting 
power. 

D.  HARDNESS,  HARDENING  AND  ANNEALING. — Chro- 
mium is  said  to  increase  the  hardness  of  iron  both  in  the 
ordinary  condition  and  when  hardened.  Unhardened 
chrome  steels  are  slightly  harder  and  more  difficult  to  cut 
than  chromeless  steels  of  like  carbon  content,  and  their 
hardness  increases  with  the  percentage  of  chromium. 
Steel  with  4'24$e  chromium  scratched  glass  (presumably 
when  unhardened).  Ferro-chromes  2,  4  and  5,  Table  33, 
with  54  to  16%  chromium  scratched  glass. 

Chromium  does  not  appear  to  give  iron  the  power  of 
becoming  harder  when  suddenly  cooled.  At  Unieux  in- 
got iron  with  \%  chromium  could  still  be  easily  filed  after 
quenching  from  cherry-redness.*  '  Wire  with  1*24$  chro- 
mium and  0'31$  carbon  acquired  no  more  elasticity  on 
oil-quenching  than  similar  metal  without  chromium.* 
But  chromium  does  not  prevent  metal  which  also  contains 
carbon  from  hardening.  Steel  13,  Table  32,  when  unhard- 
ened was  slightly  harder  than  ordinary  unhardened  tool 
steel.  Quenched  in  running  cold  water  from  blood-red- 
ness it  was  much  softer  thanMushet's  tungsten  steel,  and 
could  be  filed,  though  with  difficulty.  Quenched  from 
an  orange  heat  it  had  a  porcelanic  fracture,  scratched 
glass,  was  very  slightly  indented  by  Mushet's  tungsten 
steel,  but  slightly  indented  imperial  (Tungsten)  steel, 
Hadfield's  manganese  steel  and  glass-hard  cutlery  carbon 
steel.  It  could  be  filed,  but  with  great  difficulty  :  even 
Mushet's  steel  is  slightly  attacked  by  the  file.8 

Steels  5,  6  and  9 '5,  Table  32,  tested  in  competition  with 
fourteen  lots  of  the  best  American  and  British  steels, 
though  not  notably  harder  than  their  competitors  judging 
from  the  pressure  required  to  produce  the  first  percepti- 
ble compression,  on  the  whole  excelled  them  in  efficiency 
as  cutting  tools,  as  gauged  by  the  weight  of  standard  iron 
cut  by  each  under  fixed  conditions  without  re-sharpening. 
The  greatest  weight  cut  by  the  best  chromeless  steel  was 
but  80-99$  of  that  cut  by  the  best  chrome  steel,  No.  5  : 
while  No.  6  also  slightly  excelled  the  best  carbon  steels. 
The  chrome  steel  No.  9 '5  was  excelled  by  five  of  the 
chromeless  steels,  the  best  of  which  excelled  it  by  22$. h 
Unfortunately  they  were  not  compared  with  tungsten 
steels  which  probably  excel  them. 

Eight  specimens  of  chrome  steel  (which  include  Nos. 
23  to  26,  Table  33)  gave  Kirkaldy  the  following  results  :l 


Crushing  strength  ..../ 

Length  8  diams. 

Lbs.  persq.  in 73,000@106,000 


Elastic. , 

12  diams. 
69,000@97,000 


, Ultimate . , 

8  diams.  12  diams. 

99,411@184,144        77,041@10S,090 


This  combination  of  tensile  and  compressive  strength 
with  static  ductility  is  certainly  extremely  good,  but  not 
enough  examples  are  at  hand  to  justify  our  pronouncing 
it  extraordinary  :  63, 000  and  112, 320  Ibs.  per  square  inch 
(8  diameters)  were  the  highest  elastic  and  ultimate  com- 


d  Private  communication,  March  19th,  1887. 

0  Percy,  Iron  and  Steel,  p.  187. 

*  Boussingault,  Journal  of  the  Iron  and  Steel  Inst.,  1886,  II.,  p.  8]  1. 

g  J.  H.  H.  Corbin  (Silliman's  Jl.,  1869,  3d.  Ser.,  XL VIII.,  p.  348)  reports  that 
Brooklyn  chrome  steel  with  1'66$  chromium  and '98;?  carbon  was  as  hard  as 
quartz  when  hardened  and  as  felspar  when  unhardened  :  I  have  never  met  steel 
which  would  scratch  quartz, 

h  Rep.  U.  S.  Board  on  Testing  Iron,  etc.,  II.,  p.  593  :  Thurston,  Matls.  of  Engi- 
neering, II.,  p.  434. 

1  Circular  of  Chrome  Steel  Co.,  1874. 


78 


THE    METALLUKGY    OF    STEEL. 


pressive  strength  which  Kirkaldy    found    in    Fagersta 
Bessemer  steel  of  1*2$  of  carbon.3 

FOE  HARDENING,  the  lowest  quenching  temperature 
which  will  give  sufficient  hardness  should  be  employed, 
which  appears  to  be  the  highest  compatible  with  preserv- 
ing a  fine  fibrous  fracture.  It  may  be  accurately  ascer- 
tained by  heating  a  bar  differentially  by  conduction  from 
one  end,  quenching,  and  examining  the  fracture  at  differ- 
ent points.  The  point  where  a  fine  fiber  replaces  a  coarse 
granular  one,  an  index  of  too  high  temperature,  was  at  the 
proper  temperature  when  quenched.  This  temperature  is 
near  dull  redness.  If  chrome  steel  which  is  to  be  hard- 
ened has  for  forging  been  heated  beyond  its  proper  quench- 
ing temperature,  it  should  cool  in  air  below  that  point 
and  be  again  heated  to  it,  lest  the  interior  be  too  hot  at  the 
instant  of  quenching :  the  Chrome  Steel  Company  states 
that  thus  alone  can  chrome  steel  be  injured.  For  anneal- 
ing it  should  be  heated  to  barely  visible  redness  (a  higher 
temperature  might  lead  to  detrimental  coarse  crystalliza- 
tion), and  if  practicable  it  should  cool  extremely  slowly. 

The  foregoing  are  the  instructions  of  the  Brooklyn 
Chrome  Steel  Company. 

E.  FORGING. — From  what  information  I  can  obtain  and 
from  the  results  of  my  own  incomplete  trials  I  judge  that 
chrome  steels  forge  more  readily  than  tungsten  steels, 
and,  when  they  do  not  contain  more  than  about  '50%  of 
chromium,  nearly  as  well  as  ordinary  carbon  steels  of  like 
percentage  of  carbon. 

Faraday  and  Stodart  found  that  chrome  steel  with  \±% 
chromium  (and  presumably  about  \%  carbon)  forged  well, 
and  one  with  3 ±%  chromium  (and  presumably  1±$  carbon) 
"  was  as  malleable  as  pure  iron."b  Brustlein  states  that 
chrome  steel  forges  quite  as  well  as  ordinary  carbon  steel, 
but  is  more  easily  burnt  under  oxidizing  conditions  tit  a 
yellow  heat  :c  the  Brooklyn  Chrome  Steel  Company  states 
that  it  may  be  forged  like  any  other  good  steel  :d  Rolland 
that  it  works  advantageously  at  a  temperature  approach- 
ing whiteness. e  Even  with  12$  of  chromium  and  2%  of 
carbon  iron  may  be  forged.'  Brooklyn  chrome  steels  7, 
9,  12  and  38  forged  well  between  a  light  yellow  and  a  dull 
red  heat,  in  some  cases  even  enduring  light  blows  at 
slightly  scintillating  whiteness.  I  here  condense  my  ob- 
servations, adding  for  comparison  some  results  obtained 
with  tungsten  steel.  See  Table  34A,  §  141. 


depreciate  it,  admits  that  it  is  "difficult,  if  not  impossi- 
ble, to  weld  two  pieces  of  steel  which  contain  a  notable 
proportion  of  chromium,"  owing  to  the  formation  of  an 
unscorifiable  scale  of  oxide.8  With  repeated  trials  at 
different  temperatures  and  closely  following  the  maker's 
directions  a  skillful  blacksmith  was  unable  to  weld  for 
me  steel  No.  13,  which  contains  but  0'25$  of  chromium. 
It  would  stick  together  and  could  be  bent  back  and 
forth  at  dull  redness  without  separating :  but  on  twisting 
the  steel  when  cold  it  parted  at  the  weld,  the  perfectly 
bright  clean  surfaces  showing  that  no  true  weld  had 
occurred.  The  pieces,  however,  adhered  with  a  tenacity 
sufficient  for  many  purposes.  We  would  naturally  ex- 
pect this  tenacity  to  decrease  with  increasing  proportion 
of  chromium,  and  from  Brustleiu's  statements  I  infer  that 
it  does,  and  probably  rapidly. 

G.  HOMOGENEOUSNLSS. — Several  facts  indicate  that 
chrome  steel  is  liable  to  be  exceedingly  heterogeneous. 
The  tensile  strength  of  two  test  pieces  cut  from  the  same 
bar  of  Brooklyn  chrome  steel  tested  at  West  Point  dif- 
fered by  21,990  pounds  :  that  of  two  others,  cut  from  the 
same  bar  after  heating,  differed  by  24,680  pounds.11 

The  specific  gravity  of  two  pieces  cut  from  another  test 
bar  varied  from  7 '8556  to  7-8161,  or  by  -0395.  In  carbon 
steel  a  variation  of  about  Q'25%  of  carbon  would  be  re- 
quired to  produce  such  a  difference  in  tensile  strength,  and 
of  about  0-50$  of  carbon  to  produce  such  a  variation  in 
specific  gravity.  For  comparison  I  here  tabulate  a  few 
instances  of  deviation  of  specific  gravity. 

Difference  between  the  mean  sp.  gr.  of  the  heaviest  and  lightest  of  18  lots 
of  tool  steel :  1 0'0506 

Difference  between  sp.  gr.  of  steel  ingots  of  1-079  and  0'539#  of  carbon  :  i    0-036 

Difference  between  the  sp.  gr.  of  hammered  bars  of  1-079  and  0'539;£  of 
carbon  :  i 0-019 

Differenceinsp.gr.  due  to  hardening  steel  of  1 -005i8  carbon  from  red- 
ness :  1 0-037 

Maximum  variation  in  pieces  cut  from  the  same  piece  of  Bessemer  steel : 
Miller  ;k 0'015 

Do.  do.  for  open-hearth  steel :  Kent :  k O'OOSl 

Greatest  difference  between  two  pieces  cut  from  the  same  bar  of  Brooklyn 
chrome  steel,  West  Point 0-0395 

Only  moderate  differences,  however,  existed  between  the 
specific  gravities  of  duplicate  pieces  cut  from  the  other 
bars  of  chrome  steel  tested. 

On  etching  the  polished  surface  of  bar  13,  Table  32,  with 
dilute  sulphuric  acid,  irregular  bright  white  spots  ap- 
peared, 0-12  inch  in  diameter  and  less,  apparently  unacted 


TABLE  82A.— FORGING  TEMPERATURES  OF  BROOKLYN  CHROME  STEEL. 


Nos.  In 
Table  32. 

Composition. 

Temperature. 

Chromium. 

Carbon. 

Manganese. 

Tungsten. 

Scintillating 
white. 

White. 

Light  yellow. 

Yellow. 

Full  red. 

Cherry  red. 

Dull  red. 

Black. 

7 
9 
12 
18 
Mushet's 

•58 
•83 
•29 
•25 

:ungst< 

1-08 
•90 

1-32 
•70 

n  steel  7' 

•17 
1-89 
•15 

":98 
•78 

Crumbles  badly.  .  . 
Crumbles  

Crumbles  badly.  .  . 
Crumbles  a  little.. 
Forges  pretty  well 

Forges  well  
Forges  

Forges  well  ... 
Forges  well.  . 

Forges  well.  .  . 

Forges  well.  .  . 

Forges  

Hammer  hardens  and  cracks. 

Forges  a  little. 
Hammer  hardens. 

Crumbles  a  little.. 

Forges  well  

Cracks. 

Forges  well... 
Forges  well  .  .  . 

Forges  well..  . 

Forges  well... 

Forges  
Cracks  

g 

F.  WELDING. — The  Chrome  Steel  Co.  state  that  chrome 
steel  ' '  welds  readily  either  to  iron  or  to  itself,  and  will 
not  separate  at  the  weld :  "  but  here  the  suspicion  of  in- 
terest arises.  Brustlein,  who  as  the  (I  believe)  chief  Eu- 
ropean maker  of  chrome  steel  should  not  knowingly 


a  Kiraldy's  Experiments  on  Fagersta  Steel,  Series  A3,  test  B  1083. 

b  Phil.  Trans.  Royal  Society,  1823,  p.  267. 

c  Journ.  Iron  and  St.  Inst.,  1886,  II.,  pp.  775,  830. 

a  Circular. 

e  Ann.  Mines,  1878, 13,  p.  153. 

t  Brustlein,  Journ.  Iron  and  St.  Inst.,  1886,  II.,  p.  774. 


on  by  the  acid.  On  digestion  with  acid  these  spots  grew 
into  projecting  lumps,  as  the  surrounding  matrix  was  dis- 
solved. These  may  be  segregations  rich  in  chromium : 
certain  chromium-iron  alloys  resist  acids.  This  segrega- 
tion is  a  possible  explanation  of  the  apparent  chromeless- 


8  Idem,  p.  776. 

h  Circular  of  Chrome  Steel  Company. 

1  Kept.  U.  S.  Bd.  on  Testing  Iron,  etc.,  II.,  p.  593. 

i  Metcalf,  Treatment  of  Steel,  p.  37. 

k  Miller,  Trans.  Am.  Inst.  Mining  Engineers,  XIV.,  p.  583,  1886. 


CHROME    STEEL.      §  139. 


79 


ness  of  "chrome  steel."  If  so  segregated  as  to  escape 
ordinary  sampling,  how  beneficial  chromium  must  be! 

H.  FUSIBILITY. — Chromium  raises  the  melting  point  of 
iron  :  with  more  than  Q8fc  of  chromium  ferro-chromes  are 
"with  difficulty  fusible  at  the  highest  temperatures  of 
the  blast-furnace."8  Chrome  steel  must  be  teemed  at  a 
very  high  temperature,  since  according  to  Boussingault  it 
solidifies  incomparably  faster  than  other  steels. 

MAGNETISM. — Even  with  Q5%  chromium  ferro-chrome  is 
according  to  Brustlein  attracted  by  the  magnet :  Percy 
however  found  that  one  with  54'6^±  chromium  was  not 
thus  attracted. 

STRUCTURE  :  DAMASKING. — Chromium  tends  to  pro- 
duce an  acicular  structure  in  iron,  especially  if  the  metal 
be  slowly  cooled  and  if  it  be  also  rich  in  carbon. b  Thus 
No.  8  in  Table  31  "  is  a  mass  of  minute  needles":  No.  11 
is  brilliantly  acicular,  yet  the  fracture  of  No.  12  shows 
only  small  square  facets,  though  it  diifers  from  No.  11 
chiefly  in  having  much  less  carbon. 

A  slight  application  of  dilute  sulphuric  acid  to  the  pol- 
ished surface  of  chrome  steel  produces  at  least  in  certain 
cases  a  very  beautiful  damask,  which  Berthier  observed, 
and  which  Faraday  and  Stodart0  ascribed  to  the  elongation 
of  the  crystals  by  forging.  I  cannot  develop  this  damask 
on  steel  13,  nor  could  J.  H.  H.  Corbin  produce  it  on  a 
Brooklyn  chrome  steel  containing  1'tjQfo  chromium  and 
0-98^  carbon. d 

The  fracture  of  chrome  steel  in  the  normal  condition 
(i.  e.,  neither  hardened  nor  annealed)  closely  resembles 
that  of  chromeless  steel  of  the  same  carbon  content :  when 
quenched  it  becomes  extremely  fine,  and  if  the  steel  be 
the  rich  in  chromium  porcelanic,  like  that  of  tungsten 
steel.  If  long  exposed  to  a  yellow  oxidizing  fire  it  ac- 
quires a  coarse,  square,  crystalline  structure  and  becomes 
worthless. 

§  139.  THE  STATUS  OF  CHROME  STEEL. — The  admirable 
properties  of  chrome  steel,  its  combination  of  hardness 
with  forgeableness,  long  ago  attracted  Faraday,  Berthier, 
Percy  and  Boussingault.  There  seems  to  belittle  doubt 
that,  where  extreme  hardness  coupled  with  a  fair  degree 
of  forgeableness  is  required,  it  is  preferable  to  carbon 
steel.  Now  how  is  it  that  a  material  with  such  valuable 
properties,  in  spite  of  the  eclat  due  to  its  adoption  for  the 
Illinois  and  St.  Louis  bridge  (!)  finds  itself  to  day,  some 
sixteen  years  after  that  event,  in  little  demand  and  in  ill 
favor  ?  I  have  little  doubt  that  this  is  because  its  manu- 
facture, which  demands  unusual  skill  and  intelligence, 
has  in  the  past  largely  fallen  into  incompetent  hands : 
arid  that  the  poor  management  of  this  promising  industry 
has  for  a  time  deprived  the  world  of  a  most  valuable 
material,  both  directly  and  indirectly  by  giving  it  a  bad 
name. 

Though,  owing  to  the  proneness  of  chromium  to  oxi- 
dize, the  manufacture  of  chrome  steel  calls  for  unusually 
close  chemical  control,  it  is  stated  that  at  Brooklyn  no 
competent  control  is  exercised,  and  that  the  ferro-chrome 
is  not  even  analyzed,  a  like  quantity  of  it  being  employed, 
irrespective  of  its  composition,  to  produce  steel  of  given 
quality.  This  is  a  very  serious  charge,  but  one  for  which 


a  Boussingault,  op.  cit.,  p.  381. 

bFrom  Brustlein's  statements  the  opposite  might  be  interred  :  but  Boussingault's 
statement  on  this  point  appears  unequivocal.     Op.  cit.,  p.  815, 
c  Loc.  cit. 
cit. 


my  observations  made  during  a  recent  visit  quite  pre- 
pared me.  The  irregularity  and  chromelessness  of  chrome 
steel  is  a  matter  of  frequent  complaint.  Many  experi- 
enced chemists  have  found  either  no  chromium  or  the 
merest  traces  in  chrome  steel  sold  in  the  American  and  I 
believe  also  in  the  British  market.  Among  these  are 
Abel,8  Snelus,' A.  E.  Hunt8  and  A.  A.  Blair."  G.  W. 
Maynard*  with  repeated  careful  analyses  could  find  no 
chromium  in  the  chrome  steel  of  the  St.  Louis  bridge : 
Hunt  could  find  none  even  in  the  slag  from  the  Brooklyn 
Chrome  Steel  Works. 

What  now  is  chrome  steel  ?  Finding  no  satisfactory 
definition  I  suggest  this : — "  Steel  whose  physical  proper- 
ties are  influenced  more  by  the  chromium  than  by  the 
other  non-ferrous  elements  which  it  contains."  Our  pres- 
ent knowledge  does  not  permit  close  discriminations  :  but 
I  may  safely  say  that  while  steels  1  to  4-5  and  31  to  33  in 
Table  32  are  chrome  steels,  12  to  13  clearly  are  not,  their 
name  to  the  contrary  notwithstanding,  and  that  numbers 
7  to  11  occupy  debatable  ground. 

Beyond  this  the  grossly  exaggerated  statements  of  the 
properties  of  chrome  steel  which  have  been  widely  circu- 
lated, are  well  calculated  to  lead  to  disappointment  and 
improper  treatment  even  where  true  chrome  steel  is  sup- 
plied, and  still  more  when  chromeless  steel  masquerades 
in  its  place.1 

The  present  limited  employment  of  chrome  steel, 
coupled  with  the  prevalent  belief  that  the  Illinois  and  St. 
Louis  bridge  was  built  of  it,  would  lead  us  to  regard  it  as 
a  material  of  the  past,  not  of  the  future,  and  to  believe  that, 
in  spite  of  the  skill  and  experience  acquired  by  the  manu- 
facture of  enormous  structural  masses,  in  spite  of  the  con- 
trol gained  over  its  quality  in  producing  such  vast  quanti- 
ties with  rigidly  specified  properties,  it  had  not  been  able 
to  hold  its  own,  but  had  been  driven  by  carbon  steel  from 


e  Am.  Journ.  Science,  3d  Series,  XIII.,  p.  424,  1877. 

t  Journ.  Iron  and  St.  Inst.,  1874,  I.,  p.  87. 

s  Private  communication. 

h  Private  communication. 

t  Journ.  Iron  and  St.  Inst.,  1874,  I.,  p.  88. 

J  I  reluctantly  feel  compelled  to  call  attention  to  a  most  astonishing  report  by 
three  officials  of  the  U.  S.  Navy,  one  ot  them  a  chief  engineer,  widely  dis- 
seminated through  the  circular  of  the  Chrome  Steel  Co.  There  is  hardly  a  state- 
ment in  it  which  can  be  reconciled  with  those  of  other  and  competent  observers. 
They  state  ( 1)  that  "  chrome  steel  is  not  a  carbon  steel  but  an  alloy  of  chromium 
with  iron  "  :  in  the  great  majority  of  the  analyses  of  American  chrome  steel  which 
I  have  seen  the  carbon  exceeds  the  chromium.  2.  "  It  is  of  a  uniform  texture  in 
large  or  small  masses."  The  indications  are  that  it  is  unusually  heterogeneous. 
3.  "It  is  exceedingly  tough  when  hardened":  so  it  is,  just  about  as  tough  as 
glass.  The  four  varieties  which  I  have  examined  are,  when  hardened,  as  brittle 
as  other  hardened  steel.  4.  "  It  will  do  from  three  to  four  times  more  work  in 
all  the  various  kinds  of  tools  than  carbon  steel."  The  elaborate  tests  of  D.  Smith 
show  that  while  it  on  the  whole  slightly  excels  carbon  steel  in  efficiency  when 
employed  for  cutting,  in  many  cases  carbon  steel  excels  it :  e.  g.  in  drilling,  car- 
bon steel  of  one  lot  excelled  the  three  chrome  steels  with  which  it  was  compared, 
excelling  two  of  them  by  about  100;?.  5.  "  It  can  be  welded  and  worked  at  the  same 
degree  of  heat  and  with  the  same  ease  that  wrought -iron  can — without  danger  of 
ever  being  destroyed  by  overheating."  This  statement  is  simply  incredible  and  is 
opposed  by  Brustlein's  observations  and  my  own,  and  by  the  instructions  of  the 
Chrome  Steel  Company  to  forge  the  steel  like  that  of  any  other  gocd  brand,  and, 
in  welding,  to  tap  it  lightly  and  increase  the  force  of  the  blows  gradually  as  it  is 
liable  to  fly.  If  it  welded  as  easily  as  wrought-iron  such  instructions  would  bo 
superfluous. 

In  a  less  widely  circulated  version  of  their  report  they  state  that  "  chromium  is 
a  non-oxidizable  metal."  Actually  chromium  when  hot  decomposes  aqueous 
vapor,  and,  under  certain  conditions,  oxidizes  with  grrat  facility,  taking  fire  in 
the  air  even  at  a  heat  below  redness.  I  am  fully  persuaded  that  no  steel  ever 
possessed  the  combination  of  qualities  which  they  describe,  and  that  such  exaggera- 
tions are  calculated  to  restrict  rather  than  to  extend  the  use  of  this  valuable  sub- 
stance, by  leading  would-be  employers  to  injure  it  by  too  severe  usage,  and  in 
other  obvious  ways.  A  single  proved  misstatement  is  but  too  apt  to  inspire  dis- 
gust and  complete  incredulity. 


80 


THE    METALLURGY    OF     STEEL. 


ground  already  won.  I  gladly  refute  this  story :  no  such 
retreat  has  occurred :  the  bridge  was  built  of  chromeless 
steel." 

To  sum  up,  I  believe  that  the  employment  of  chrome 
steel  has  been  greatly  restricted  by  the  unfortunate  reputa- 
tion which  it  has  acquired  through  irregularity  in  its  com- 
position and  through  exaggerated  statements  of  its  valuable 
properties,  leading  to  too  severe  treatment,  disappointment, 
disgust.  These  have  been  intensified  by  the  extensive 
sale  as  "chrome  steel"  of  material  which  has  either  no 
chromium  or  too  little  to  entitle  it  to  this  name  :  applied 
to  this  these  exaggerations  are  the  more  exaggerated  and 
prejudicial. 

Fain  would  I  praise,  not  censure.  I  am  induced  to  write 
the  foregoing  by  the  hope  that  a  plain  statement  of  these 
sufficient  reasons  for  the  present  disappointing  status  of 
chrome  steel,  due  not  to  its  faults  but  to  its  unfortunate 
treatment,  may  contribute  to  its  acquiring  the  far  better 
position  to  which  I  am  confident  that  it  is  entitled.  That 
it  will  rapidly  approach  this  I  am  encouraged  to  believe 
by  what  I  can  learn  of  the  spirit  of  its  makers  in  France, 
Jacob  Holtzer  et  Cie. 

§  140.  THE  FCTOKE  OP  THE  SPECIAL  STEELS. — This  of 
the  past :  what  of  the  future  ?  Chrome  steel  appears  to 
lie  between  carbon  and  manganese  steels  on  the  one  hand 
and  tungsten  steel  on  the  other.  More  costly,  harder  and 
less  easily  forged  than  the  former,  it  is  cheaper,  when  hot 
more  forgeable  and  when  cold  more  ductile  and  less  hard 
than  the  latter:6  manganese  steel  however  excels  it  in 
toughness. 

Three  natural  fields  suggest  themselves  for  chrome  steel. 
First,  where  extreme  hardness  is  needed  and  where  tung- 
sten and  manganese  steels  are  excluded  by  the  difficulty 
of  forging  them,  as  in  the  case  of  cutting  tools  and  abra- 
sion-resisting pieces  of  complex  form.  Second,  where 
extreme  hardness  must  be  coupled  with  fair  resistance  to 
shock,  as  in  the  case  of  armor  piercing  projectiles  :  here 


a  The  Chrome  Steel  Co.,  referring  in  their  circular  to  this  bridge  say  "  Capt. 
J.  D.  Eads  did  adopt  our  '  chrome  steel '  for  this  wonderful  structure,  as  the  only 
steel  made  that  would  withstand  the  requisite  pulling  and  thrusting  stress,  as  will 
be  seen  by  his  (Bads')  report  to  that  company,  dated  October,  1871."  I  find  no 
warrant  for  this  statement  in  Eads'  report.  He  indeed  expresses  his  preference 
for  chrome  steel,  but,  expressly  stating  (p.  12)  that  he  "  did  not  feel  justified  in  as- 
suming that  crucible  carbon  steel  of  the  qualities  and  forms  required  could  not  be 
readily  made,  when  he  was  assured  of  the  contrary  by  some  of  the  most  eminent 
steel-makers  of  America  "  and  by  the  managers  of  Krupp's  and  of  Petin  Godet 
&  Co.'s  works,  he  says  (p.  1 1)  that  "  it  seemed  but  fair  to  state  the  qualities  which 
the  steel  should  possess,  without  prescribing  the  method  of  manufacture"  :  i.  e. ,  the 
contractors  were  simply  required  to  supply  steel  of  given  properties,  and  were  at 
liberty  to  supply  either  carbon  or  chrome  steel.  Actually  they  supplied  chrome- 
less  steel,  which  was  accepted.  Eads  had  evidently  been  completely  deceived  on 
the  subject,  for  he  states  (p.  11)  that  chromium  "has  little  or  no  affinity  for 
oxygen,  while  carbon  has  a  great  affinity  for  it,  and,  by  the  application  of  heat  it 
is  liable  to  be  burnt  out  of  the  steel : "  while  in  fact  all  the  evidence  goes  to  show 
that  chromium  in  steel  is  much  more  oxidizable  than  carbon.  Eads  further  states 
that  the  company  which  was  to  manufacture  steel  for  the  bridge  had  bought  the 
right  to  make  chrome  steel  for  it,  and  had  assured  him  that  no  other  kiud  would 
be  made.  This  assurance,  a  word  which  seems  to  fit  this  case,  was  not  kept.  Mr. 
W.  F.  Durfee  informs  me  (private  communication,  June  15th,  1887)  that  "there 
was  no  chromium  used  in  the  materials  for  the  St.  Louis  bridge,  which  was  all 
made  under  my  supervision,  with  the  exception  of  the  sheet  steel  envelope  of  the 
tubes.  This  was  made  by  Park  Brothers  of  Pittsburgh,  and  I  have  been  assured 
that  no  chromium  was  used  in  that.  Before  I  assumed  the  charge  of  the  works 
there  had  been  some  experiments  made  with  chrome  steel,  and  the  ccmpany  had 
purchased  the  right  to  use  it,  and  these  facts  have  probably  given  rise  to  the  story 
that  the  bridge  was  made  of  chrome  steel,  which  is  not  a  fact."  (The  italics  are 
bis.)  I  here  call  attention  to  Maynard's  failure  to  find  chromium  in  this  steel,  and 
to  analyses  14  and  15  Table  32,  by  Blair,  of  steel  said  to  be  from  this  bridge. 

t>  Tungsten  steel  is  certainly  harder  than  much  of  the  chrome  steel  of  commerce, 
but  I  do  not  know  that  highly  cbromiferous  steel  may  not  be  as  hard  or  even 
harder  than  tungsten  steel, 


tungsten  steel  appears  to  be  excluded  by  its  brittleness  and 
badly  handicapped  by  its  cost :  but  manganese  steel, 
incomparably  tougher  and  but  slightly  softer  than  hard- 
ened chrome  steel,  may  offer  it  serious  competition,  while 
some  tungsten-manganese  steel,  borrowing  extreme  hard- 
ness from  tungsten  and  toughness  from  manganese,  may 
prove  a  yet  more  formidable  competitor.  The  combined 
hardness  and  toughness  of  manganese  steel  should  pre- 
eminently fit  it  for  armor  plate.  Third,  where  extreme 
hardness  in  the  finished  piece  or  in  some  portion  of  it 
must  be  combined  with  the  power  of  being  toughened  or 
softened  by  annealing,  as  in  the  case  of  pieces  which  must 
be  machined  or  engraved,  or  of  which  one  part  must  be 
very  hard  and  another  very  tough.  Here  the  fact  that 
tungsten  and  manganese  steels  can  be  but  slightly  softened 
by  annealing  appears  to  exclude  them. 

It  is  very  doubtful  whether  the  tensile  strength  of 
chrome  and  tungsten  steels,  high  as  it  often  is,  is  greater 
than  that  attainable  in  carbon  steel ;  and,  as  the  latter 
for  given  tensile  strength  is  certainly  less  treacherous 
and  brittle  than  tungsten  steel,  and  probably  both  more 
uniform  in  composition  and  more  homogeneous  than 
chrome  steel,  the  employment  of  these  special  steels  where 
tensile  strength  alone  or  chiefly  is  sought,  is  hardly  to  be 
looked  for.  Manganese  steel,  however,  may  commend  itself 
where  unusual  tensile  strength  coupled  with  great  tough- 
ness is  demanded. 

Naturally  where  we  can  sacrifice  but  a  little  of  the 
forgeableness  of  chrome  steel  we  may  add  tungsten  to 
gain  hardness,  or  manganese  to  gain  toughness.  (See 
Nos.  9  and  12,  Table  32.)  But  too  little  evidence  of  the 
effect  of  crossing  these  alloys  exists  to  permit  definite 
statements. 

In  the  past  the  employment  of  these  steels  has  been 
restricted  by  irregularity  in  their  composition  and  by 
ignorance  on  the  part  of  both  maker  and  user  of  the  com- 
position best  suited  to  special  purposes.  The  solution  of 
the  difficult  problem  of  adapting  to  their  uses  these  al- 
loys, whose  properties  seem  to  vary  with  their  composition 
according  to  most  complex  and  unguessed  laws,  has  been 
chiefly  entrusted  to  men  utterly  unfitted  for  it  by  nature 
and  training.  Groping  in  the  dark,  often  with  neither 
adequate  chemical  nor  physical  testing,  their  jealousy  and 
narrowness  have  too  often  thrown  Chinese  walls  around 
their  establishments,  keeping  knowledge  out  far  more  than 
in.  Each  crucible  steel  maker,  hugging  his  own  ignorance 
lest  his  trivial  secrets  or  his  lack  of  them  should  leak  out, 
often  refused  to  advance  lest  his  neighbor  should  advance 
too.  The  introduction  of  the  special  steels  has  been  fur- 
ther hampered  by  their  need  of  special  treatment  at  the 
hands  of  the  smith,  ever  loth  to  learn,  for  learning  con- 
fesses previous  ignorance.  As  none  of  them  can  for  general 
purposes  compete  with  carbon  steel,  he  has  in  general  been 
called  on  to  employ  them  only  in  special  cases,  so  isolated 
that  he  remains  skilless  in  their  use.  But  the  light  of  a 
brighter  day  o'ertops  our  Chinese  walls :  technical  schools 
train  steel  makers  of  a  different  spirit,  and  investigators 
who  can  not  be  restrained  from  learning  and  telling:  arti- 
sans' schools  and  the  rapidly  increasing  specialization  of 
artisan's  labor  will  give  us  smiths  of  a  different  type. 
To-da  y  the  forces  which  make  for  the  use  of  special  steels 
wax,  the  old  opposing  ones  wane. 

I  here  endeavor  to  indicate  roughly  to  the  eye  the  rela- 


TUNGSTEN    AND     IRON.       §  141. 


81 


five  toughness,  hardness,  etc.,  of  these  three  special  steels 
and  of  hard  high-carbon  steel.     With  our  present  knowl 
edge  such  statements  must  be  somewhat  conjectural. 

TABLE  33  B. 


Hardness 

Toughness 

Tensile  strength 
Forging  power. 
Welding     " 
Annealing  " 


1  UNGNTEN!.'.' 


(iJAKHON  !.' 
CARBON!!! 

Carbon 

CARBON!!! 

CARBON. 


CHROME!!* 

CARBON 

CHROMIUM!! 

Chromium 


CHROMIUM  ! 
MANGANESE 


CARBON ! 

Chromium 
TUNGSTEN!!) 

Manganese  't 
Chromium 
Manganese 

CHROMIUM 


lfangmiete(f 

Manganese 

TunpsU-n 
Tungsten 
Tungsten 
Tungsten 


"  It  is  not  intended  to  assert  that  rich  chrome  steel  may  not  be  as  hard  as  tung 
sten  steel. 


§  141.  IKON  AND  TUNGSTEN  were  first  alloyed  by  the 
brothers  d'Elhuyarin  1783,  and  later  by  Berthier.  Though 
metal  sold  at  one  time  as  tungsten  steel  contained  no  tung 
sten,  it  is  certain  that  it  is  now  largely  employed  in  tin 
manufacture  of  the  harder  grades  of  crucible  steel.   Mush 
et's  "Special,"   " Imperial "  and  " Crescent  Hardened ' 
are  brands  of  tungsten  steel  now  sold  in  the  American 
markets. 

COMBINATION. — Tungsten,  itself  exceedingly  infusible, 
unites  with  iron  apparently  in  all  proportions,  at  least  up 
to  80%.  Ferro-tungsten  is  apparently  readily  obtained, 
often  as  a  dark,  heavy,  slightly  sintered  mass,  by  long 
and  strongly  heating  wolframite,  (FeMn)  WO4,  or  scheel- 
ite,  CaWO4,  preferably  with  iron  or  iron  oxide,  in  brasqued 
crucibles,  after  roasting  to  expel  sulphur  and  arsenic,  wash- 
ing, and  finally  pulverizing.  It  has  been  made  in  the  blast- 
furnace, but  a  demand  for  its  production  on  so  large  a  scale 
in  the  near  future  seems  hardly  probable.  When  made 
from  wolframite  it  inevitably  and  not  undesirably  contain 
manganese.  As  tungsten  raises  the  melting  point  of  iron, 
alloys  with  more  than  40$  of  it  are  rarely  made.  Ferro- 
tungsten  has  been  reported  for  sale  in  the  European  market 
with  20  to  50  (?)  %  tungsten  and  1'B  to  6$  manganese. 

Tungsten  steel  is  made  by  the  crucible  process,  ferro- 
tungsten  of  known  composition  being  added  to  the  ordi 
nary  charge.      Instead  of  this  Mushet  recommended  a 
mixture  of  roasted  wolframite  and  pitch,  which  could 
hardly  give  so  uniform  a  product. 

Bernoulli  prepared  tungsten  steel  by  melting  tungstic 
anhydride,  W03,  with  turnings  of  gray  cast-iron,  whose 
graphite  he  found  reduced  tungsten  to  the  metallic  state, 
though  combined  carbon  alone  did  not.* 

CONDITION  OF  TCNGSTLN. — Ferro-tungstens  appear  to 
consist  of  a  matrix  of  iron  within  which  various  alloys 
are  crystallized.  Schneider,  digesting  ferro-tungsten 
No.  6,  Table  35,  in  hydrochloric  acid  (which  dissolved  about 
60$  of  the  whole,  though  only  traces  of  its  tungsten),  ob- 
tained a  residue,  magnetically  separable  into  two  por- 
tions :  one,  constituting  90$  of  the  whole,  contained  24  to 
31$  iron  and  1  -4  to  1  6$  carbon  ;  was  not  attracted  by  the 
magnet ;  gained  about  26$  in  weight  when  heated  in  air ; 
but  was  again  readily  reduced  by  hydrcgen  to  an  alloy 
whose  iron  was  insoluble  in  hydrochloric  acid.  The  other, 
containing  68'1$  iron,  4'1$  carbon  and  27$  tungsten,  was 
attracted  by  the  magnet.  He  appears  to  consider  these 
residual  substances  as  mechanical  mixtures  of  iron  and 
tungsten  :  but  their  easy  magnetic  separation  from  each 
other  and  the  fact  that,  after  oxidation  and  subsequent 
reduction,  the  iron  of  one  remained  insoluble  in  acid, 
strongly  suggest  chemical  union.6 


a  eoggendorff's  Aunalen,  1860,  CXI.,  p.  581. 

t?  Oest.  Zeitschrift ;  1885,  XXXIII,  p.  257.     Stahl  uud  Eisen,  1885,  p.  333. 


TllM. I.  98.       l-'l  BIO    I 


1. 

2. 

3. 

4. 

5. 

6. 

Tungsten.  .    

37 

77  -g 

Iron   

63 

ir.-.( 

r:-  1 

Manganese  .  . 

58 

Silicon  

•61 

0-S8 

Phosphorus  

1-17 

n  c:> 

1  88 

I .  Brilliant,  bard,  lamellar,  more  brittle  than  common  iron;  2.  lianl.  brittle,  lamellar ;  fuses 
"illy  in  ilu- liii:li<->t  ]ir:it  <•!'  l'iini:n-t-s,  ami  3.  i.lalinuiii  j^ray,  hard,  brittle  lanu-lhr  oomnletelr 
luMblc,  I'.i-rtliiiT.  I'eri-y.  Iron  and  Steel,  p.  IMI.  4  Hanover,  examined  ty  Ledebur;  /.  Terre- 

Notre,  aoeonUne  t<>   K.-rpi-l.-y;    l.,-iM,m-,  llandliuch,   ]..  -X',.    u.  Austrian  Alpine  Mining  Co 
.lotn-u    Iron  :,IH|    St.  I,,.-!  ,  lss(.  I  ,  ,,.  280.     (feet.    X.rit.,    XXXIII.,  p.  207.     This   is   incorrectly 
ijuoteil  in  .stalil  mill  KiM-n,  \  ..  p.  :tw.  an  ••  <)-.  4  \V   •_'>•-.!  Fe  " 


TABLE  34. — TUNGSTEN  STEEL. 


Source,  etc. 

Composition. 

Tensile 
strength. 
Pounds 
per  square 
Inch. 

Elon- 
gation. 
*. 

W. 

Fe. 

C. 

2-15 
1  24 
1-99 
1  70 

2-06 
16 

Si. 

Mn. 

n» 

1  04 
•19 
1  26 

2-66 

2-11 

P. 

1.  Schneider  

11-03 
9  99 
7-81 

•26 
0-33 
•09 
0-82 

•05 
•16 

•097 
04 

1 

2.  Mushct's  special... 

8. 

146,400 

6 

4.    Engliih  

8  25 
G-73 
6-88 

5.  "Crescent  Hardened,"  Pittsburgh.  ... 
6.  "Imperial,"  Pittsburgh  

1  76,100  a 
'(  94,000  b 

0 

T.           "          (another  bar)  

(67,000 
(91,000 

0 

S.  Ledebur.. 

8'81 
S-74 
645 
8  05 
2-71 
1-94 

95:8S 
96-37 

•42 
•88 
1-20 

•76 
•76 
•21 

2-57 
2-48 
•35 

9        •'        

10.  Styrian  

190,000 

0-75 

1  1  .  Bochura  

12.        "        

1-48 

•19 

tr 
•44 

13.        "        

14.  De  Fenffe  

153,300 
166  500 

15.     "      "     

1.  L.  Sconeidcr.  Oest.  Zeit.,  1SS5.  XXXIII..  p  257 ;  Journ.  Iron  and  St  Inst.,  1SS4,  I ,  p.  231). 
2.  Hard  English  Mushefs  Steel,  Metallurgical  Kev.,  II.,  p.  441.  3.  The  same,  tested  by  the 
author.  4.  Ledel.ur.  Handbuch,  p.  263.  6.  Made  by  Miller,  Metcalf  &  Parkin,  tested  by  the 
author.  6  and  1 ,  Made  by  Park  Bros.  &  Co.  and  tested  by  the  author.  8,  !»  and  10.  Lede- 
bur, loc.  cit.  II  and  I  2 .  Percy.  Iron  and  Steel,  p.  194.  J  3  .  Ledebur,  loc.  cit.  14  and  15. 
Kev.  Univ  ,  1860,  p.  88.  a.  As  received  from  the  makers,  b.  Quenched  in  oil  from  very  dull 
redness. 

I  have  to  thank  Messrs.  Hunt  and  Clapp,  Pittsburgh,  Pa.,  for  the  compositions  of  numbers  5,  • 
6  and  7,  which  they  kindly  analyzed  for  this  work. 


EFFECTS  ON  THK  PHYSICAL  PKOPEETIES  OF  IKON.  TEN- 
SILE STRENGTH.— While  steels  3, 10, 14  and  15  in  Table  34 
suggest  that  tungsten  raises  the  tensile  strength,  steels  5 
and  7,  which  differ  from  3  and  10  chiefly  in  having  much 
more  manganese,  are  decidedly  weak. 

HAKDNESS. — Tiingsten  renders  iron  intensely  hard. 
Mushet' s  steel,  No.  3  Table  34,  is  the  hardest  which  I  have 
met,  indenting  hardened  chrome  steel  No.  13,  Table  32. 
It  is  slowly  and  slightly  attacked  by  a  very  sharp  file.  I 
found  hardened  chrome  steel  slightly  harder  than  Crescent 
hardened  steel  and  Imperial  steel  (both  unhardened  and 
tungstiferous).  All  these  readily  scratch  glass.  These  two 
tungsten  steels  as  already  pointed  out  differ  chiefly  from 
Mushet' s  in  composition  in  having  more  manganese.  The 
specimens  of  Mushefs  steel  which  I  have  examined  do 
not  scratch  quartz,  but  a  rich  ferro-tungsten  made  by  Ber- 
nouilli  is  said  to  have  scratched  quartz  readily.  Tungsten 
steel  is  thought  harder  than  chrome  steel :  but  I  do  not 
know  that  it  has  been  proved  to  be  harder  than  rich 
chrome  steel.  Weight  for  weight  tungsten  probably  does 
not  increase  the  hardness  as  much  as  carbon,  and  perhaps 
not  as  much  as  chromium  ;  Metcalf  found  that  dies  with 
1  '37$  carbon  and  '78$  tungsten  wore  much  faster  than 
tungstenless  ones  with  2'37$ carbon.0  Steel  may  however 
contain  a  much  larger  proportion  of  tungsten  (at  least  10$) 
than  of  carbon  without  losing  its  power  of  being  forged. 

DUCTILITY. — Tungsten  steel  is  exceedingly  brittle. 
When  bars  3,  5  and  7  were  grasped  in  a  vise  and  struck 
with  a  sledge  with  gradually  increasing  force,  though 
they  appeared  to  be  resilient,  they  broke  without  the 
'east  perceptible  set,  and  in  certain  cases  flew  into  many 
small  pieces  at  the  point  of  fracture  like  glass.  It  is 
lence  not  only  unfit  for  structural  purposes,  but  even  for 
ools  subject  to  shock,  such  as  rock-drills,  cold-chisels, 


Trans.  Am,  lust.  Mining  Engrs.,  IX.,  p.  549,  1881, 


82 


THE    METALLURUY     OF     STEEL. 


etc.  Even  the  chattering  of  a  lathe  is  said  to  be  liable  to 
crack  it  :a  yet  it  is  successfully  used  for  the  knives  of 
nail-cutting  machines.  The  chief  normal  use  of  these 
steels  is  for  the  tools  of  lathes,  planers,  etc.,  designed  for 
heavy  cuts. 

FOKGIXG  AND  WELDING. — Tungsten  steel  can  be  forged 
only  between  a  cherry-red  and  a  low  yellow  heat,  and 
then  with  a  difficulty  which  restricts  its  use  to  pieces  of 
simple  shape.  I  here  condense  the  results  of  my  observa- 
tions in  forging  i>.  Only  general  conclusions  can  be 
drawn  from  these  tests,  as  the  smith  was  not  skilled  in 
the  use  of  tungsten  steel.  The  "Crescent"  appeared  to 
forge  better  than  the  "Imperial"  at  a  low  yellow,  the 
"Imperial"  better  than  the  "Crescent"  at  a  dull  red. 
This  may  have  been  because  the  Crescent  contains  more 
carbon,  because  of  unobserved  differences  in  the  conditions 
of  forging,  or  because  of  some  peculiarities  of  these  par- 
ticular bars.  The  general  lesson,  the  limited  range  of 
forging  temperature,  is  unmistakeable. 


molten  or  solid  :  but  when  these  metals  are  mixed  in  more 
nearly  equal  quantities  they  often  tend  t;>  split  Tip  into 
alloys,  on  the  one  hand  more  ferruginous  and  on  the  other 
more  cupriferous.  These  may  or  may  not  be  of  definite 
composition :  they  separate  more  or  less  completely  by 
gravity,  the  copper  concentrating  downwards.  Thus 
Richec  found  in  an  alloy  made  from  94'1$  of  copper  and 
5  '9$  of  iron,  microscopic  gray  spots  :  melting  90$  of  cop- 
per with  10$  of  pure  iron  he  obtained  an  ingot  which, 
after  prolonged  fusion  at  a  high  temperature,  had  four 
times  as  much  iron  in  its  upper  as  in  its  lower  portion : 
while  Percy,d  in  an  alloy  containing  80$  of  iron  (with  20$ 
of  copper  ?)  found  copper-red  particles,  -which,  especially 
towards  the  bottom  of  the  mass,  were  occasionally  visi- 
ble to  the  naked  eye.  These  were  probably  in  Riche's 
case  a  more  ferruginous,  and  in  Percy's  a  more  cupre- 
ous alloy.  "When  the  segregated  portion  becomes  more 
considerable  its  particles  coalesce  and  the  separation  is 
more  complete.  But  even  when  the  proportions  of  the 


TABLE  34  A. — FOBGINC,  PROPERTIES  OF  TUNGSTEN  STEEL. 


Composition. 

Temperature. 

\V. 

Mn. 

O. 

Light  yellow. 

Yellow 

Orange  . 

Full  red. 

Low  rt'd. 

Black  . 

T'Sl 
6-73 

6  SSa 

0-19 
2  '66 

2'lla 

1-99 
2-06 

l-6a 

Cracks  badly  
Crumbles  badly  
] 

Forges     
liends  fairly  

Bends  well  •< 

Bends      anil       hammers 
close  together  without 

>  Cracks  in  bending, 
j  Breaks  when  bent    flt 

Cracks  after  5  or  G  light 
blows. 
1 
1  Forges  better  than  the 
preceding 

Bfnds  well   .    ..... 

Imperial  

Forges  but  cracks  in 
bending  

L.. 

fUent  double  and  hain- 
1      mered  close  at  very 
\      dull     red      without 
I     cracking     ....     .... 

"    1 

f 

a  This  is  the  composition  of  a  bar  similar  to  the  one  forged. 


Imperial  steel  is  said  to  be  weldable,  but  with  extreme 
difficulty  :  I  doubt  if  it  can  be  truly  welded  by  ordinary 
methods.  Prof.  Elihu  Thomson,  by  his  electric  welding 
process,  welded  for  me  small  bars  of  both  Mushet's 
and  Imperial  steel  so  perfectly  that  I  could  not,  by  the 
most  severe  tests,  detect  the  point  of  juncture  :  Mushet's 
steel,  twisted  till  it  flew  apart,  revealed  no  trace  of  the 
welded  surface. 

HARDENING. — Even  slightly  tungstiferous  steels  are  said 
to  be  very  prone  to  crack  in  hardening.  I  can  detect 
no  increase  of  hardness  on  quenching  Mushet's  steel.  1 
found  two  bars  of  Imperial  steel  slightly  softer  after  sud- 
den than  after  slow  cooling ;  it  here  resembles  manganese 
steel ;  indeed  it  has  a  notable  proportion  of  manganese. 
Mushet's,  "Crescent  Hardened"  and  "Imperial"  steels 
are  employed  without  quenching,  which  indeed  would  be 
dangerous.  Quenched  or  unquenched  they  readily  scratch 
glass,  but  not  quartz :  as  their  hardness  is  not  impaired 
by  heat,  they  may  be  driven  much  faster  than  carbon  steel 
when  used  as  machine  cutting  tools. 

DETERIORATION. — Chernoff  states  that  after  a  few  heat- 
ings tungsten  steel  becomes  oxidized  and  loses  its  special 
properties.1" 

MAGNETIZATION. — Tungsten  steel  is  said  to  be  excep- 
tionally retentive  of  magnetization. 

§  142.  IRON  AND  COPPER.  A.  COMBINING  POWER. — It 
is  stated  that  iron  and  eopper  unite  in  all  proportions. 
The  alloys  of  iron  with  a  little  copper  and  of  copper  with 
a  little  iron  appear  to  be  homogeneous  and  stable  whether 

a  A.  Willis  (Journ.  Iron  and  St.  Inst.,  1880,  1.,  p.  92)  considers  that  tungsten 
hardens  steel  without  making  it  brittle  :  and  M.  Boker  (Stahl  und  Eisen,  VI.,  p. 
4Ji),  states  that  it  enables  us  to  obtain  steel  of  greater  hardening  power  together 
•with  increased  toughness.  If  this  be  true  at  all,  it  can  only  apply  to  comparatively 
small  percentages  of  tungsten  :  the  four  tungsten  steels  which  I  have  examined 
are  astonishingly  brittle. 

I*  Revue  Universelle,  1877,  I.,  p.,  400, 


two  metals  are  nearly  equal,  this  separation  does  not 
always  occur,  or  at  least  is  not  always  perceptible.  Thus 
Percy  (loc.  cit. )  could  detect  no  segregation  in  an  alloy  - 
containing  20$  of  iron  (and  80$  of  copper?)  These 
facts  suggest  that  copper  and  iron  unite  chemically  in 
many  but  not  in  all  proportions,  and  hence  that  if  either 
copper  or  iron  be  added  to  a  homogeneous  alloy  of  both, 
a  new  homogeneous  alloy  arises  if  the  new  composition 
permits :  if  not,  the  metals  rearrange  themselves  in  al- 
loys of  some  chemically  possible  composition,  separat- 
ing more  or  less  completely  by  gravity,  perhaps  during, 
perhaps  prior  to  solidification. 

The  presence  of  carbon  still  further  diminishes  the  ten- 
dency of  copper  and  iron  to  unite.  If  copper  and  car- 
buretted  iron  be  intimately  mixed  they  again  separate 
almost  completely,  apparently  the  more  fully  the  more 
carbon  is  present.  Thus  Mushet  found  that,  though  5$ 
of  copper  formed  on  apparently  homogeneous  alloy  with 
steel,  yet  when  the  copper  reached  10$  minute  segregations 
appeared  ;  if  25$  of  copper  were  present  much  of  it  sank 
to  the  bottom  and  occurred  in  knots  and  streaks.  With 
white  cast-iron  the  tendency  to  segregation  was  stronger : 
if  5$  of  copper  were  added  to  gray  cast-iron,  copper-colored 
specks  concentrated  at  the  bottom  of  the  ingot,  with  9$ 
of  copper  deep-red  leaves  separated,  and  with  16 '7$  a 
separate  copper  button  formed  beneath  the  cast-iron." 
Melting  10$  of  cast-iron  with  90$  of  copper,  Riche'  found 
uncombined  iron  at  the  top  of  the  ingot :  while  at  Perm8 
(Urals)  ferruginous  copper  ore  smelted  in  blast-furnaces 
19  feet  high  yielded  4  parts  of  copper  containing  about 


cThurstou,  Matls.  of  Engineering,  III.,  p.  184. 
<3  Iron  and  Steel,  p.  150. 

o  L.  &  E.  Philosophical  Magazine,  3d  series,  \  I.,  p.  81,  1835. 
*  Thurston,  loo.  cit. 

B  Rivot,  Prindpes  Gc-neYaux  du  Traitement  des  Minerals,  I.,  p.  89,  and  Percy, 
Iron  and  Steel,  p.  153. 


IRON    A3TD     COPPER.       §  142. 


,  of  iron,  and  3  parts  of  cast-iron  containing  12  -Qir/0  of 
copper  and  3'03>'  of  carbon.  This  cast-iron,  when  remelted, 
yielded  an  upper  stratum  of  iron  with  0-25  to  2#  of  copper 
and  a  lower  cne,  tapped  from  beneath  the  upper,  and  con- 
sisting of  copper  with  2<)£  of  iron.  So  too  Percy,8  melt- 
ing spiegeleisen  of  £^,  of  manganese  with  pure  copper  in 
Intel  clay  crucibles,  obtained  cast-iron  containing  2-5^'  of 
copper  together  with  copper  containing  3-67  to  4'87fc  of 
iron  and  1  '16  to  2-82^  of  manganese.  The  iron  salamanders 
obtained  in  copper  smelting  occasionally  contain  as  little  as 
]  -;V?b  of  copper,  and  I  have  produced  black  copper  with  not 
over  3  to  4$  of  iron  in  contact  with  these  salamanders. 

Owing  to  its  low  affinity  for  oxygen  all  the  copper  con- 
tained in  iron  ore  must  necessarily  be  reduced  in  the  blast- 
furnace :  but  if  much  copper  is  present  most  of  it  may  be  ex- 
pected separate  by  gravity,  so  that  the  iron  would  not  hold 
more  than  perhaps  2^  of  it.  But  the  copper  which  it  retains 
should  adhere  tenaciously  to  the  iron  through  all  stages  in 
its  manufacture,  and  should  concentrate  in  the  steel,  which 
might  tlmshave  2-5^  of  copper,  necessitating  great  dilution. 

EFFECTS  OF  COPPF.K  :  UEDSHORTNESS. — The  chief  effect 
of  copper,  like  that  of  sulphur,  is  to  render  steel  redshort 
and  to  destroy  its  welding  power :  but  its  influence  has 
been  greatly  exaggerated.  Steel  may  contain  0  85  and 
according  to  Choubly  0'96^  of  copper  without  serious  red- 
shortness,  and  W.  W.  Scranton"  habitually  makes  Besse- 
mer T  rails  with  0-51  to  0'66£',  which  he  states  are  so  non- 
redshort  that,  in  spite  of  their  thin  flanges  and  the  ex- 
ceptionally low  temperature  at  which  they  are  finished* 
only  from  1  '25  to  2  '5%  of  them  are  sufficiently  cracked  to  be 
classed  as  second  quality.  Eggertzd  indeed  stated  that  0-5^ 
of  copper  rendered  steel  worthless,  but '  it  is  evident  from 
Table  35  that  this  can  only  be  true  under  special  conditions 
if  at  all.  I  know  not  what  percentage  of  copper  is  re- 
quired to  produce  redshortness,  but  2%  appears  to  destroy 
hot-malleableness  completely,  for  Billings,"  melting  2%  of 
copper  with  a  remarkably  pure  weld-iron,  found  the  result- 
ing alloy  so  redshort  that  in  forging  it  crumbled  into 
grains  :  and  Mush et  reports  steel  melted  with  5^  of  copper 
as  "useless  for  forge  purposes."' 

The  evidence  as  to  the  effects  of  copper  on  weld  metal 
are  less  harmonious.  The  illustrious  Karsten8  found  that 
0-286$  of  copper  (remaining  from  \%  introduced  into  the 
charcoal  refining  hearth)  sensibly  affected  the  welding 
power  of  weld  metal :  Stengel11  reports  that  puddled  iron 


a  Op.  cit.,  p.  140. 

bKerl,  Grundriss  der  Metallhuttenkunde,  p.  171. 

c  Private  communication. 

a  Wagners  Jahresbericht,  1862,  p.  9. 

e  Trans.  Am.  Inst.  Mining  Engineers,  V.,  p.  450,  1877. 

f  Phil.  Mag.,  loc.  cit. 

g  Percy,  Iron  and  Steel,  p.  148. 

h  Idem,  p.  151. 


with  0-018  sulphur  and  O^p;  of  copper  was  slightly  red- 
short  :  of  thirteen  wrought-irons  for  chain  cables  tested 
by  the  U.  S.  Board  to  test  metals  one  with  0-32  to  0-43$ 
of  copper  stood  lowest  but  one  in  welding  power.1  Clearly 
these  weld  metals  are  injured  far  more  than  ingot  metal  is 
by  the  same  proportion  of  copper.  In  other  cases  the  in- 
fluence of  copper  is  less  severe  than  in  the  preceding, 
though  still  perhaps  more  severe  than  on  ingot  metal. 
Thus,  of  the  only  two  other  cupreous  irons  among  the 
thirteen  just  referred  to,  one  with  0-17$  of  copper  stood 
highest  but  one  in  welding  power,  and  one  with  0 -31$  stood 
well  in  this  respect.  So  too  Eggertz  reports  that  0-a^of 
copper  produces  only  traces  of  redshortness  in  weld  metal. d 
Holley  suggests  that  the  excellent  welding  of  the  iron  with 
0 '3 1  copper  may  possibly  be  due  to  the  simultaneous  pres- 
ence of-34  nickel  and  '11  cobalt.1  These  incomplete  data 
suggest  that  the  influence  of  less  than  0-2$  of  copper  is  not 
likely  to  be  appreciable  in  weld  iron,  that  of  '30$  not  neces- 
sarily injurious,  and  that  of  '34$  at  least  occasionally  serious. 

INFLUENCE  OF  MAKGANESE. — Whether  manganese 
counteracts  the  effects  of  copper  like  those  of  sulphur  is 
not  known  :  but  from  the  fact  that  Nos.  3,  6,  7, 13  and  14 
in  Table  31  are  not  redshort,  though  they  have  -85,  '3.r), 
•31,  '96  and  *48^  of  copper  respectively  with  but  '51,  '07, 
trace  '46  and  '53^  of  manganese,  it  is  not  probable  that 
the  presence  of  this  metal  is  as  imperative  in  cupreous  as 
in  sulphurous  iron  and  steel.  No.  1 4  shows  that  the  co- 
existence of  much  phosphorus  and  copper  does  not 
necessarily  cause  redshortness. 

OTHER  EFFECTS  OF  COPPER. — It  is  not  known  whether 
the  highest  proportion  of  copper  which  commercial  iron 
contains  has  any  sensible  effect  beyond  those  just  dis- 
cussed. We  have  the  following  information  concerning 
the  alloys  of  copper  with  iron.  All  refer  to  alloys  of 
practically  carbonless  iron  with  pure  copper,  except 
Mushet' s,  which  were  of  steel  (apparently  crucible  steel) 
with  copper,  and  possibly Kinman's. 

%  Cu .  Description  of  the  alloys . 

'2± Extremely  redshort :  weak  when  cold a 

5± Useless  for  forge  purposes  :  cannot  take  an  edge  b 

9±    Hard  and  brittle b 

16'7 Apparently  stronger  than  the  two  preceding b 

2I)± Extremely  brittle,  crystalline  granular,  fracture  pale  coppery  gray o 

25 Separated :  bottom  of  soft  malleable  copper b 

41  •  75 Very  brittle  ;  fracture  uneven  and  crystalline;  strongly  magnetic c 

50±   ....  Very  brittle  and  fine-grained  :  strongly  magnetic 0 

67  to  89.  .Harder  but  not  appreciably  less  ductile  than  copper  (?) d 

80± Less  ductile  than  the  following  one  :  strongly  magnetic o 

S3'4±. .  .Decidedly  redshort :  much  harder  and  tougher  than  copper c 

94± Extremely  ductile  :  stronger  than  copper  e 

94     Harder  than  copper  ;  inignetic d 

a,  Billings,  loc.  cit.;  b,  Mushet,  loc.  cit.;  c,  Percy,  loc.  cit.;  d,  Blnman,  Matls.  of  Engineering, 
Thurston,  III.,  p.  183;  e,  Eiche,  idem. 

While  the  alloys  of  copper  with  a  little  iron  hold  out 
some  promise  (sterro- metal,  a  brass  with  1'77  to  4^  iron 
and  0-15  to  1  -5%  tin  has  much  higher  tensile  strength  than 
brass  proper)  alloying  iron  with  small  quantities  of  cop- 
per is  not  an  alluring  field. 


1  Trans.  American  Inst.  Mining  Engrs.,  VI.,  p.  101,  1879. 


TABLE  35. — EFFECT  OF  COPPER  ON  HOT-MALI.EABLENE 
Cupriferous  steel  known  to  bo  non-rcdshort. 


No. 

Cu. 

C. 

Si. 

Mn. 

P. 

s. 

Reference. 

Rolled  into. 

Behavior  in  rolling1. 

1 

•45 

•28 

•14 

•78 

•06 

06 

A 

Rails                 

Perfect.                                                                                      [sliirhtly. 

8 

•86 

•28 

09 

•71 

•05 

•06 

A 

Almost  perfect  :  tbo  end  mado  from  the  top  of  the  Ingot  cracked 

3 

•86 

•81 

•05 

•51 

•06 

•11 

A 

«« 

Very  good  ;  slight  cracks  which  closed  up  Liter. 

4 

•88 

•68 

'10 

•16 

tr 

B 

e 

•80 

46 

•11 

•18 

0 

B 

6 

•85 

•62 

•09 

•07 

0 

B 

u          K        d 

It                        U               (« 

7 

•Ql 

"08 

•]7 

tr 

•25 

'005 

c 

Welded  well       Others  of  similar  composition  welded  rather  poorly. 

8. 

17 

•02 

•14 

•03 

•is 

•007 

O 

Welded  admirably. 

9 

"062 

37 

•05 

•10 

•10 

D 

Rolled  well. 

in  i 

•61® 

•83® 

•03® 

1  •»."'<«. 

•05® 

•os@ 

'-     D 

Steel  within   these  limits    gave  1-25   to  2'5#  of   ieoon<l    -juiility 

IU.   j 

11 

•66 
•21 

•88 

•08 
•038 

1'26 

•06 

"10 

•02 

E 

Puddled  iron                               .  .                   

Some  tendency  to  redshortness. 

12* 

'80 

F 

Extremely  Blight  redshortness. 

13 

•96 

49 

•15 

•46 

•or 

04 

G 

Steel  

Perfect. 

14.. 

-48 

•64 

•12 

•43 

•19 

1.1 

G 

Perfect. 

A 

Scran to 


=  Wasum,  Stahl  und  Risen,  1882,  p.  192.     1!  =  Kern,  Metallurgical  Review,  II..  p  519.    C  =  Holley,  Transactions  of  the  American  Institute  of  Mining  Engineers,  VI.,  p.  115.     I) 
nton,  private  communication.     E  =  Stengel,  Percy,  Iron  and  Steel,  p.  151 .     F  =  Willis,  Journal  Iron  and  Steel  Inst.,  1SSO,  I.,  p.  93.    G  =  Choubley,  idem,  18S4,  I.,  p.  248. 


W.  W. 


84 


THE    METALLURGY     OF     STEEL. 


CHAPTER    VIII. 
THE  METALS  OCCURRING  BUT  SPARINGLY  IN  IRON. 


§  145.  A.  ZINC. — The  alloys  of  this  metal  with  a  little 
iron  appear  to  be  tolerably  stable.  In  galvanizing,  i.  e. 
zincing  iron,  the  molten  zinc  gradually  attacks  the  iron 
vessels,  and  a  zinc-iron  alloy  collects  at  the  bottom."  Sev- 
eral analyses  of  it  give  from  3  to  9  -4$  of  iron.  The  alloys 
of  iron  with  a  little  zinc  are  extremely  unstable,  evolving 
their  zinc  when  heated,  readily  and  apparently  com- 
pletely. 

Parry's  experiments  prove  that  the  vapor  of  zinc  and 
of  other  metals  may  be  temporarily  absorbed  but  is  appar- 
ently feebly  retained  by  iron.  Cast-iron,  previously 
heated  in  vapor  of  zinc,  cobalt,  cadmium,  bismuth  and 
magnesium  (each  separately),  after  being  cooled,  cleaned 
with  acid  and  filed  bright,  gave  metallic  sublimates  when 
re-heated  in  vacuo.  Gray  cast-iron,  when  fused  in  closed 
crucibles  with  zinc,  bismuth  and  tin  (each  separately)  be- 
came white,  and,  on  heating  in  vacuo  after  cleaning  with 
acid,  gave  distinct  sublimates.  Gray  and  white  cast-irons 
made  from  zinciferous  ores  gave  faint  sublimates  when 
heated  in  vacuo.  Some  of  the  zinc  and  cobalt  sub- 
limates were  spectroscopically  shown  to  contain  these 
metals  :  the  others  were  not  examined.  In  one  case  iron 
gained  '05%  in  weight  when  heated  in  zinc  vapor. b 

In  cast-iron  made  from  zinciferous  ores  Percy  found  no 
zinc  and  Karsten  but  traces. c  In  smelting  zinciferous  iron 
ores  in  Virginia,  green  zinc  flames  escape  for  days  at  a 
time  from  the  tap  hole  and  from  the  cinder-notch.  Me- 
tallic zinc  escapes  through  the  cracks  in  the  hearth,d  and 
here  as  well  as  in  smelting  zinc  residues  for  spiegeleisen 
(Franklinite)  at  Newark,"  N.  J.,  pieces  of  zinc  sometimes 
float  on  both  slag  and  iron  as  they  run  from  the  furnace, 
burning  with  a  green  flame  and  leaving  deposits  of  zinc 
oxide.  Occasionally,  at  Newark,  after  about  a  ton  of  cad- 
mia  has  passed  through  the  furnace,  the  "  cast"  is  cov- 
ered with  zinc  oxide,  and  the  casting-house  is  filled  with 
zinc  fume :  yet  after  removing  the  crust  of  sand  and  zinc 
oxide  no  zinc  can  be  found  in  the  cast-iron  °  on  which  zinc 
has  been  seen  burning,  and  among  many  analyses  of  the 
slag  I  learn  of  but  one  which  shows  zinc.  An  old  analysis 
of  New  Jersey  spiegeleisen  (1860±)  gives  0'3$  of  zinc:f 
this  is  probably  an  error  :  it  is  said  that  both  sampling 
and  analysis  were  formerly  improperly  conducted. 

As  metallic  zinc  volatalizes  far  below  the  temperature  at 
which  iron  and  slag  escape  from  the  blast-furnace,  its 
floating  ar.d  burning  on  the  cast-iron  at  first  suggests  that 
a  zinc-iron  alloy  forms  in  the  furnace,  somewhat  as  in 
Parry's  experiment,  owing  to  the  pressure  of  the  zinc 
vapor,  but  decomposes  and  evolves  its  zinc  when  the 
pressure  falls  on  its  escape  from  the  furnace.  But  the 
true  explanation  doubtless  is  that  the  metallic  zinc,  vola- 
tilized within  the  furnace,  in  escaping  through  the  walls 
condenses  in  the  damp  clay  stoppings  of  tap-hole  and 
cinder-notch1-':  indeed,  metallic  zinc  will  often  drip  out 


a  Percy,  Iron  and  Steel,  p.  153.     Ledebur,  Haudbuch,  p.  267. 

b  Journ.  Iron  and  St.  Inst.,  1874,  I.,  p.  96. 

c  Percy,  loc.  cit. 

<1H.  Firmstone,  Trans.  Am.  Inst.  Mining  Engineers,  VII.,  p.  93,  1879. 

•  Geo.  C.  Stone,  private  communications,  July  25-38,  1887. 

*  Karl,  Grundriss  der  Eisenbuttenkunde.  p.  43. 

8H.  Firmstone,  piivate  communication,  July  29,  1887. 


when  these  stoppings  are  picked  at,  and  in  one  case  it  is 
reported  to  have  collected  in  a  little  pool  beneath  the  tap- 
hole,  and  to  have  boiled  furiously  when  the  cast-iron  ran 
upon  it,  burning  the  men.6  A  little  of  this  condensed 
metallic  zinc,  picked  up  by  the  cast-iron  or  slag,  would 
natiirally  float  and  burn  as  described. 

Zinc  added  by  G.  H.  Billings  to  pure  molten  ingot  iron 
volatilized  till  but  traces  remained :  the  resulting  ingot  was 
slightly  redshort,h  perhaps  owing  to  lack  of  manganese. 

Zinc  appears  to  render  iron  brittle  at  a  red  heat.1  Ihus 
a  piece  of  tough  galvanized  iron  wire  was  heated  to  redness 
so  quickly  that  the  coating  of  zinc  melted  and  apparently 
penetrated  into  the  interior  of  the  metal  instead  of  vola- 
tilizing. On  attempting  to  bend  it  while  hot  it  readily 
broke  off  short,  exhibiting  a  uniform  blue-gray  fracture 
— as  though  the  zinc  had  penetrated  into  the  interior  of 
the  iron.  When  again  cooled  it  became  tough,  and,  on  re- 
heating it  long  enough  to  completely  volatilize  the  zinc,  its 
hot-shortness  ceased  j  It  is  stated  that  iron  wire  in  molten 
zinc  will  often  break  off  short,  though  the  part  outside  the 
bath  remains  tough. 

Ledeburk  has  verified  the  observation  that  molten  gray 
cast-iron  becomes  hard  and  inclined  to  whiteness  if  zinc 
be  immersed  in  it,  though  little  if  any  zinc  is  retained. 
This  is  possibly  due  to  the  expulsion  of  silicon. 

The  consideration  of  sterro-metal,  a  brass  with  1.77  to 
4$  of  iron,  belongs  rather  to  the  metallurgy  of  copper 
than  of  steel. 

B.  TIN  AND  IRON  unite  readily,  as  the  firm  union 
effected  in  making  tin-plate  shows,  and  in  all  proportions, 
forming  apparently  homogeneous  alloys :  but  tin,  or  more 
probably  a  highly  stanniferous  alloy,  liquates  when  alloys 
containing  more  than  about  35%  of  tin  are  heated  to  or 
slightly  above  the  melting  point  of  this  metal,  till  the 
more  or  less  definite  alloy  Fe4Sn  holding  about  35$  of  tin 
remains.1 

Luckily  tin  occurs  but  very  rarely  in  iron  ores,  for  it  de- 
stroys the  ductility  and  f  orgeableness  of  iron.  Some  think  it 
even  more  deleterious,  weight  for  weight,  than  phosphorus. 
A.bout  (Y52%  of  tin,  added  to  the  charge  in  the  puddling 
furnace  according  to  Sterling's  patent,  caused  copious 
white  fumes  and  rendered  the  iron,  which  also  emitted 
white  fumes,  extremely  difficult  to  forge  and  weld.1  Kar- 
sten1 found  that  '19$  of  tin  made  charcoal  weld  iron 
very  brittle  at  a  strong  (i.  e.  welding?)  heat,  and  ex- 
tremely cold-short :  Billings'"  found  that  '73$  of  it  ren- 
dered a  very  tough  ingot  iron  decidedly  cold-short,  and  so 
hot-short  that  at  a  white  heat  it  flew  under  the  hammer 
into  particles  so  minute  as  to  scintillate.  Cast-iron 
melted  with  2  to  5%  of  tin  is  reported  as  very  hard  and 
fragile ;  with  5%  producing  a  bell  of  pretty  good  tone  : 
with  9-09$  as  fusible,  extremely  fluid,  non-rusting,  whiter 
than  cast-iron,  acquiring  a  beautiful  polish  and  having  as 


h  Trans.  Am.  Inst.  Mining  Engrs.,  V.,  p.  454,  1877. 

t  Kerl,  Grundriss  der  Eisenhuttenkunde,  p.  24. 

1  W.  H.  Johnson,  Proc.  Royal  Society,  XXIII.,  p.  172,  1875. 

k  Loc.  cit.     Cf.  Parry's  experiment  above. 

l  Percy,  Iron  and  Steel,  p.  161. 

mTrans.  Am.  Inst.  Min,  Engrs,,  V.,  p.  450,  1877. 


TIN,     LEAD,     TITANIUM,  ARSENIC.       §  146. 


good  a  tone  as  bell-metal.  The  tin-iron  alloys  thus  inter- 
est the  iron  founder  more  than  the  steel  maker.  De- 
scriptions of  a  few  better  known  alloys  are  here  condensed. 


TABLE  86.— TIN  IRON  ALLOYS. 


1. 
2. 
3. 

4. 
5. 
6. 
7. 

8. 
9. 
10. 

11. 


Nollner 

Deville  and  Caron . 

Berthicr 

Berthier,  Percy . . . . 

Herve     

fi.  H.  Billings 

Karsten 


Rinman 

Percy 


II 


80  be 

67 '8c 

SO1 

85'1 

09 

0-73 

0-19 

90-9 
76'9 
9  09 


a  S  l  a      5' 


Cniyish  white,  very  brittle,  fracture  granular. 

Brittle,  pulverizable.  magnetic. 

Hard  and  brittle,  slightly  granular. 

Very  cold-short,  extremely  red  and  white  short. 

Very  tender  at  strong  heat,  difficult  weldable, 

extremely  cold  short. 
Apparently  uniform  :  very  malleable. 
Pretty  homogeneous,  semi-malleable. 
Very  hard  brittle,  dense:  rust-proof,  fusible,  very 

fluid,  can  be  highly  polished. 
A  bell  of  this  al'oy  had  a  pretty  good  tone. 
Very  hard,  fragile,  low  tenacity. 


a  Percy,  Iron  and  Steel,   p.  160.    b  Billings,   Trans.   Am.  Inst.   Mining  Engrs.,   V.,  p.  450. 
c  Calculated  composition. 

C.  IRON  AND  LEAD. — It  is  apparently  possible  but  ex- 
tremely difficult  to  alloy  these  metals,  and  no  valuable 
properties  have  been  notedin  their  alloys.  I  know  of  no 
successful  attempt  to  alloy  them  directly.  By  reducing 
litharge  with  an  excess  of  pure  iron  at  a  very  high  tem- 
perature Karsten  obtained  an  iron  containing  on  an  aver- 
age 2  '06$  of  lead  :  Biewend  obtained  an  iron  containing 
3'24^  of  lead  by  heating  a  slag  rich  in  lead  and  iron  in  a 
brasqued  crucible :  beneath  an  iron  blast-furnace  a  crys- 
tallized alloy  containing  88 ~7Q%  of  lead  and  11  "14$  of  iron 
has  been  found.  The  wrought-iron  ladles  used  in  Pattin- 
sonizing  eventually  become  permeated  with  lead.a 

Percy  was  unable,  either  by  Karsten' s  method  or  other- 
wise, to  obtain  a  decided  alloy  of  lead  and  iron.  Lead 
added  by  Billings  to  molten  ingot  iron  completely  vola- 
tilized, traces  only  remaining.11  Metallic  lead  usually  con- 
tains a  minute  quantity  of  iron. 

The  lead  of  plumbiferous  iron  ores  separates  in  the 
blast-furnace  hearth  from  the  cast-iron,  carrying  with  it 
any  silver  present,  and  thus  sometimes  forming  an  im- 
portant bye-product. 

TITANIUM,  a  metal  so  oxidizable  that  it  decomposes  boil- 
ing water,  often  occurs  in  gray  cast-iron, c  existing  at  least 
in  part  as  carbide,  much  as  suspected  by  Riley  in  1872. 
(See  §  13).  It  has  been  found  in  spiegeleisen  ;  it  is  said  to 
occur  rarely  or  never  in  other  white  cast-iron,  but  the  com- 
plete absence  of  graphite  from  the  very  titaniferous  cast- 
iron  quoted  below  strongly  suggests  whiteness.  Nor  is  it 
found  in  commercial  wrought-iron  and  steel,  ior  it  is  in- 
evitably oxidized  along  with  the  other  electro-positive 
elements  of  the  cast-iron  from  which  they  are  made :  in- 
deed it  can  probably  only  be  introduced  into  any  malleable 
variety  of  iron  (except  possibly  the  most  highly  carbu- 
retted  steels)  by  a  tour  deforce,  nor  is  there  reason  to  be- 
lieve that  if  introduced  it  would  be  beneficial.  It  is  indeed 
possible,  though  apparently  extremely  difficult,  to  obtain 
titaniferous  steel  by  melting  titanic  acid  and  iron  or  iron 
oxicle  with  charcoal  in  crucibles  :  Sefstromd  thus  obtained 
a  very  hard  but  malleable  iron  wilh  4-78$  of  titanium  :  it 
may  even  be  questioned  whether  this  metal  did  not  closely 
approach  cast-iron.  Though  many  competent  chemists 
have  sought  it,  I  find  no  other  record  of  its  detection  in 
wrought-iron  or  steel.  A  titaniferous  "plate  iron"6 


a  Percy,  Iron  and  Steel,  p.  168. 

b  Trans.  Am.  Inst.  Mining  Engineers,  V. ,  p.  454,  1877. 

c  Riley,  Journ.  Chem.  Soc.,  1873,  XXV.,  p.  552  :  Journ.  Iron  and  St.  Inst., 
1880, 1.,  p.  190. 

d  Ledebur,  Handbuch  der  Eisenhiittenkunde,  p.  265. 

e  Iron  and  St.  Insfc.,  1880,  I.,  p.  190  :  A.  H.  Allen,  private  communication,  May 
23d,  1887. 


quoted  by  A.  H.  Allen  turns  out  to  be  nothing  but  cast- 
iron,  probably  white  or  nearly  white,  containing 


Combined  carbon . .  ! 
Graphite tr 


Silicon  1  09 

Titanium 4'15 


Sulphur '086 

Phosphorus  ..   'OS1 


M;inir:inesc   ...     1  87 
Iron - 


Faraday  and  Stodart  stated  that  though  their  crucibles 
sufficed  for  fusing  rhodium  and  (imperfectly)  platinum, 
they  could  not  bear  the  temperature  needed  for  reducing 
titanium.'  In  an  undoubted  sample  of  Mushet'  s  "  '1  itanic 
steel"  which  I  obtained  personally  from  the  maker's 
American  agents,  and  which  was  stamped  as  such,  neither 
Shimer  nor  H.  L.  Wells  could  detect  titanium,  though 
they  have  made  its  determination  a  special  study.8 

Percy"  states  that  chemists  of  skill  and  repute  have 
failed  to  find  titanium  in  "titanic  steel":  and  later 
Riley,1  Greenwood3  and  others  have  found  this  steel  free 
from  titanium.  (Cf.  Appendix  I.) 

§  146.  A.  ARSENIC  behaves  towards  iron  much  as  sul- 
phur does. 

COMBINATION. — They  unite  readily  and  in  all  propor- 
tions. Iron  heated  in  contact  with  alkaline  arsenite  and 
charcoal,  or  arsenious  acid  and  nitrogenous  animal  mat- 
ter, acquires  an  arsenical  case-hardening.  Ordinary  cast- 
iron  occasionally  contains  small  unimportant  quantities 
of  arsenic  :  but  non-European  irons  have  occasionally 
contained  large  quantities.  Thus  Berthier  found  9  •&% 
(with  VS%  carbon)  and  27$  (with  \%  carbon)  in  cannon- 
balls  from  Algiers,  free  from  sulphur,  manganese,  copper 
and  silicon.  The  former  was  easily  pulverized  ;  the  lat- 
ter, still  more  fragile,  could  be  split  diametrically,  re- 
vealing a  fracture  like  that  of  marcasite  nodules.*  Percy 
found  16'2^  arsenic  in  a  cannon-ball  from  Sinope.1 

In  roasting  mispickel -bearing  ores  the  arsenic  is  expelled 
in  large  part,  but  not  completely,  as  part  forms  non-volatile 
arsenate  of  iron,  which  is  reduced  in  the  blast-furnace. 
Simple  heating  to  whiteness  does  not  completely  expel 
arsenic.  It  is  not  known  whether  arsenic  can  be  scorified 
by  other  metals  as  sulphur  is  by  manganese  in  iron-smelt- 
ing. Even  the  violently  oxidizing  conditions  of  the  basic 
Bessemer  process  do  not  always  completely  remove  arsenic, 
for  Ledebur  found  '013$  of  it  in  a  basic  rail.111 

Parry  found  that  hot  iron  readily  absorbed  vapor  of 
arsenic,  which  it  retained  on  heating  in  vacuo.  Iron 
behaves  in  the  same  way  towards  phosphorus,  but  after 
absorbing  vapors  of  zinc,  cobalt  and  certain  other  metals 
it  again  evolves  them  on  heating  in  vacuo.  Riley,  how- 
ever, observed  a  strong  smell  of  arsenic  on  working  arsen- 
ical steel,  which  indicates  that  his  metal,  unlike  Parry's, 
evolves  its  arsenic  at  least  in  part  when  heated." 

EFFECTS. — Arsenic  appears  to  lower  the  saturation  point 
for  carbon  :  to  give  iron  a  white  fracture,  to  destroy  its 
power  of  welding,  and  make  it  redshort  and  sometimes 
brittle  at  higher  temperatures  :  a  larger  proportion  of 
arsenic  renders  iron  coldshort  also.  We  have  few  quan- 
titative data  as  to  its  effects  :  Lundin' s  analyses,  too  scanty 
to  build  on,  indicate  that  in  wrought-iron  they  begin  to  be 


l  Phil.  Trans.  Royal  Society,  1823,  p.  254. 

e  Private  communications,  P.  W.  Shimer  and  H.  L.  Wells,  April  7th  and  May 
14th,  1887.  Wells  states  that  his  method  (by  hydrogen  peroxide)  would  probably 
detect  "01  and  would  certainly  detect  -02$  of  titanium. 

h  Iron  and  Steel,  p.  158. 

1  Journ.  Chem.  Soc.,  XVI.,  p.  387  ;  1872,  XXV..  p.  562. 

i  Greenwood,  Steel  and  Iron,  p.  396. 

k  Annales  des  Mines,  3rd  Ser.,  XI.,  1837,  p.  501. 

1  Percy,  Iron  and  Steel,  p.  76. 

mStahlund  Eisen,  1884,  IV.,  p.  640. 

n  Compare  §  145  A.    Journ.  Iron  and  St.  Inst.,  1874, 1.,  pp.  96,  97,  101. 


86 


THE    METALLURGY    OF    STEEL. 


serious  at  some  point  between  '045  and  "09$.     Here  are 
his  results.8 


Arsenic. 

Sulphur. 

Quality  of  the  \vrought-iron. 

By  silver  plate. 

By  barium  chloride. 

•09* 
•046 

0-08* 
0-015 

0-042* 
0  022 

Very  unforgeable. 
The  best  in  every  respect. 

Here  the  amount  of  sulphur  is  too  trifling  to  have  caused 
redshortness.  Riley  reports  that  steel  so  arsenical  as  to 
smell  strongly  of  this  metal  when  forged,  yet  worked 
pretty  well,  but  was  brittle  and  useless."  The  wrought- 
iron  of  Alais,  rendered  unweldable  by  arsenic,  has  been 
successfully  made  into  open-hearth  steel. c 

B.  ANTIMONY  unites  with  iron  readily,  and  probably  in  all 
proportions  ;  even  a  minute  quantity  of  it  makes  iron  hard 
and  both  red-  and  cold-short.    Fortunately  it  is  not  often 
present  in  iron  ores.     It  is  not  wholly  removed  in  the  manu- 
facture of  wrought-iron,  nor  on  exposing  antimony-bearing 
iron  to  a  steel-melting  heat.     Of  \%  of  antimony  added  by 
Karsten  to  cast-iron  in  the  charcoal  hearth,  the  bar-iron 
produced  contained  -23$. d    Of  \%  added  by  G.  H.  Billings6 
to  almost  pure  molten  ingot-iron,  enough  remained  after  20 
minutes'  exposure  to  a  steel-melting  heat  to  ruin  the  metal. 

Karsten' s  weld  iron  with  '23$  antimony  was  ex- 
tremely red-  and  cold-short :  another  bar  iron,  in  which  he 
found  '114$  of  antimony,  was  worthless.  Billings'  anti- 
monial  iron  was  decidedly  cold-short,  and  so  redshort  that 
it  crumbled  to  pieces  whether  hammered  or  rolled. 

C.  BISMUTH.— Of  1%  of  this  metal  added  by  Karsten  to 
cast-iron  while  being  refined  in  the  charcoal  hearth,  '081$ 
was  retained  by  the  bar  iron  :  its  sole  effect  was  to  make 
the  iron  work  ' '  raw. ' ' f    Of  0  -5$  added  by  Billings  to  molten 
ingot  iron  only  traces  remained  in  the  solidified  metal, 
which  was  decidedly  red-short.     It  contained  -08%  of  car- 
bon.15    Hot  iron  absorbs  vapor  of  bismuth,  evolving  it 
when  heated  in  vacuo.h 

D.  VANADIUM  occurs  occasionally  in  cast-iron,  in  which 
Riley1  has  found  0-  686$  of  it ;  Sefstrom  discovered  it  in  the 
bar-iron  and  refinery  slags  from  the  Taberg  (Swedish) 
ores.J     I  know  no  data  concerning  its  influence. 

According  to  Witz  and  Osmondk  it  concentrates  in  cer- 
tain slags,  notably  in  those  the  basic  Bessemer  process  ; 
these  taken  collectively  contain  large  quantities  of  this 
rare  metal,  whose  recovery  they  propose. 

§  147.  MOLYBDENUM  produces  with  iron  alloys  analo- 
gous to  those  of  iron  with  tungsten,  according  to  Berthier, 
one  with  2%  of  molybdenum  being  fusible,  extremely  hard 
and  brittle,  but  tenacious  :'  yet  Billings  found  that  1$  of 
this  metal  rendered  good  iron  extremely  redshort  and 
utterly  worthless.111  Some  Mansfeld  copper-smelting  sala- 
manders consist  chiefly  of  iron-molybdenum  alloys ;  as 
much  as  28  "49$  of  molybdenum  is  reported  in  them.n 


a  Stabl  und  Eisen,  1884,  p.  485,  from  Jernkontorets  Ann.,  1884,  II. 
b  Journ.  Iron  and  Steel  Inst.,  1874, 1.,  p.  101. 
cidem,  1885,  I.,  p.  278. 
d  Percy,  Iron  and  Steel,  p.  169. 

e  Trans.  Am.  Inst.  Mining  Engrs.,  1887,  V.,  p.  453. 
t  Percy,  Iron  and  Steel,  p.  170. 

K  Trans.  Am.  Inst.  Mining  Engineers,  V.,  p.  453,  1877. 
l>  Cf.  §  145  A. 

1  Riley,  Journ.  Chem.  Soc.,  XVII.,  p.  21,  1864;  XXV.,  p.  544,  1872. 
i  Watts.  Diet.  Chem.,  V.,  p.  983. 

k  Journ.  Iron  and  St.  Inst.,  1883,  II.,  p.  770,  from  Comptes  Rendus,  XCV.,  I., 
p.  42. 

I  Percy,  Iron  and  Steel,  p.  195. 

mTraus  Am.  Inst.  Mining  Engrs.,  V.,  p.  454,  1877. 
n  Kerl.  Orundriss  der  Metall-Hiittenkunde,  p.  171. 


§  148.  NICKEL  AND  COBALT  are  frequently  present  in 
cast-iron,  though  rarely  if  ever  in  important  amount,  and 
are  retained  when  it  is  converted  into  wrought-iron  and 
steel. 

A.  NICKEL  alloys  with  iron  readily  and  probably  in  all 
proportions  :  meteoric  iron  usually  contains  from  1  to 
20%  of  it.0    The  largest  amount  which  I  have  met  in  a 
commercial  iron  is  -35$,  which,  together  with  -11^  cobalt 
and  '31$  copper,  had  no  traceable  effect  on  the  weld  iron 
which  contained  it,    unless,    as   Holley  pointed  out,  it 
counteracted  the  copper  present :  for  the  metal  welded 
well.     (See  §  142.) 

EFFECTS. — Nickel  appears  to  make  iron  redshort :  in  cer- 
tain proportions  and  under  certain  conditions,  both  unde- 
fined, it  appears  to  make  it  brittle.  Billings"  found  an 
alloy  with  '66$  nickel  and  -72%  carbon  redshort  ;  and  one 
with  •'1 32  nickel  and  -07  carbon  very  redshort,  the  differ- 
ence being  attributed  to  its  lower  carbon  content :  both 
were  forgeable  at  higher  temperature  :  one  with  &%  nickel 
and  but  little  carbon  was  extremely  redshort.  These  al- 
loys were  almost  absolutely  free  from  elements  other  than 
those  here  mentioned. 

The  following  proportions  of  nickel  have  been  found  in 
iron  :  0'35^q  :  0-66$* :  \%* :  3$,'  as  malleable  as  pure  iron  : 
5$8:  6$,r  almost  as  ductile  and  tenacious  as  pure  iron: 
6-36$u:  7  to  8$":  7'87$u:  8'21$u :  8-3&v  semi-ductile: 
10$'  more  brittle  than  pure  iron.  The  irons  whose 
proportion  of  nickel  is  here  given  in  heavy  faced  type  are 
ductile,  the  rest  appear  to  be  at  least  comparatively 
brittle.  The  influence  of  nickel  appears  to  be  very 
capricious :  why  0'66,  1,  and  5%  of  it  should  greatly 
impair  ductility  while  0'35,  3,  and  6$  do  not,  is  not 
known. 

Meteoric  irons  with  6 -36, 7'87  and  8 '21$  nickel  are  reported 
as  hard  to  file,  and  one  with  8'59$  nickel  as  easily  filed." 
The  nickel-iron  alloys  are  reported  to  rust  less  easily  than 
iron  :  Faraday  and  Stodart  found  this  true  of  an  alloy  of 
iron  with  10$  of  nickel,  but  not  to  the  extent  previously 
alleged :  while  10$  of  nickel  alloyed  with  steel  greatly 
accelerated  rusting.  (Cf.  Appendix  I.) 

B.  COBALT. — Of  the  effects  of  cobalt  on  iron  we  have 
still  less  knowledge.     Billings  found  ingot-iron  with  '33 
cobalt    (but     otherwise    almost    perfectly    pure)    solid, 
tough  and  decidedly  weak  when  cold,  and  somewhat  red- 
short^    As  it  contained  no  manganese  its  redshortness 
may  have  been  due  to  what  we  call  oxygenation.     Alloys 
of  53-29  and  12'79$  cobalt,  with  46-71  and  87-21$  iron  re- 
spectively, made  in  Percy' s  laboratory  were  brittle.*    Hot 
iron  absorbs  vapor  of  cobalt,  evolving  it  when  heated  in 
vacuo.y 

§  149.  IKON  AND  ALUMINIUM  may  according  to  Deville 
be  alloyed  in  all  proportions :  among  others  the  following 
allovs  have  been  described. 


0  System  of  Mineralogy,  J.  D.  Dana,  p.  18. 
P  Trans.  Am.  Inst.  Mining  Eugrs  ,  V.,  p.  448,  1877. 
q  Holley,  Trans.  Am.  Inst.  Mining  Engrs.,  VI.,  p.  115. 
r  G.  H.  Billings,  Idem,  V.,  p.  448. 
8  Percy,  Iron  and  Steel,  p.  171. 
'  Faraday  and  Stodart,  Percy,  Iron  and  Steel,  p.  171. 

u  Boussingault  and  De  Rivero,  Meteoric  Irons,  "  The  Useful  Metals  and  Their 
Alloys,"  p.  27S. 
"  Berthier. 

wTrans.  Am.  Inst.  Mining  Engrs. ,  V.,  p.  454. 
*  Percy,  Iron  and  Steel,  p.  173. 
y  Compare  §  145  A. 


NICKEL,     COBALT,     ALUMINIUM.      §  149. 


87 


TABLE  ST.— ALLOYS  OF  IRON  AND  ALUMINIUM. 


to. 

Observer. 

Composition. 

Al. 

C. 

Si. 

Faraday  and  Stodartj 

•012® 
•0095 
•50 
•52 

•so 

2-30 
tf'41 

2-30 
•20 

'"•io 

2-26 
"5-95 

G.  H.  Billings 

Ilogers  

Calvert  anil  Johnson.. 

12  00 

Properties,  etc. 


•Wootz. 

'ast-iron. 
Solid,  homogeneous,  forges  well  at  red  heat. 

crumbles  at  yellow. 
Resembled  best  llombay  wootz, 

White,  close-grained,  very  brittle. 
Very     hard,    but    forgeablo  and  weldable 
rusts. 


1.  Quarterly  Jour,  of  Science,  etc.,  T,  p.  2S8  :  Percy,  Iron  and  pteel,  p.  188.  2.  Ledebnr, 
ll:iri(llmcli  dcr'Eisenhuttenkumle,  p.  205,  from  Annak's  des  Mines,  XV.,  p.  18").  Ccst-iron  from 
Champignenlle.  3.  Trans.  Am.  Inst.  Mining  Kngrs.,  V.,  p.  4.r>'>.  1-T7.  Produced  by  fusing  12 
parts  of  emery,  18  of  alumina,  1  of  pulverized  charcoal  and  36  of  pure  iron  turnings  :  after  heat- 


heating  pure  alumina  witli  pure  highly  carburetted  iron  in  a  close  crucible.  Close  granular  texture. 
1,  Obtained  by  heating  to  whiteness  8  equivalents  of  chloride  of  aluminium.  40  of  fine  iron  filings 
and  8  of  lime  :  it  was  extremely  hard  and  rusted  when  exposed  to  damp  air,  but  could  be  forged 
and  welded.  Philosophical  Magazine,  X.,  p.  242, 1S55 ;  Percy,  op.  cit.,  p.  181.  "Aluminium," 
liichards,  p.  210. 


A.  ALUMINIUM  AND  WOOTZ. — As  Faraday  found  from 
•0128  to  '0695^  of  aluminium  in  wootz,8  and  as  he  ob- 
tained a  product  with  "all  the  appreciable  characters  of 
wootz"  by  melting  "good  steel"  with  enough  of  an  iron- 
aluminium  alloy  to  yield  by  calculation,   -40%  of  alumin- 
ium," he  ascribed  the  damask  of  wootz  to  the  presence  of 
aluminium."    But  the  wootz-like  character  of  his  product 
was  probably  accidental,  if  not  imaginary,  for  Henry,  a 
most  trustworthy  analyst,  Karsten  and  Eammelsberg  find 
no  aluminium  in  wootz. 

The  alloys  of  iron  with  a  larger  proportion  of  aluminium 
appear  to  be  brittle,  and  hold  out  little  promise. 

B.  MITIS  CASTINGS. — Without  special  additions  non-car- 
buretted  iron  evolves  gas  so  copiously  in  setting  that  its 
castings  are  very  porous  :  its  freezing  point  is  so  high  that, 
even  when   cast  at  the   highest   temperature  ordinarily 
attainable,  it  sets  so  rapidly  that  it  can  only  be  cast  into 
rather  thick  forms  :    yet,  if  '05  to  -\%  of  aluminium  be 
added  just  before  teeming,  it  yields  solid  castings  of  aston- 
ishingly attenuated  shapes,  and  still  retains  its  great  duc- 
tility. So  says  P.  Ostberg,  and  one  most  trustworthy  metal- 
lurgist assures  me  that  a  slight  addition  of  aluminium  does 
check  the  escape  of  gas  from  non-carburetted  iron,  and 
another  that  it  renders  it  extremely  fluid.0    Indeed,  the 
remarkable  castings  which  Ostberg  has  exhibited,   and 
which  he  assures  us  have  not  been  annealed,  combine  the 


a  Quarterly  Journal  of  Science,  Literature  and  the  Arts,  9,  p.  320,  1820. 

» Idem,  7,  p.  288,  1819  :  Percy,  Iron  and  Steel,  p.  183.  Metallurgical  Review, 
I.,  p.  175. 

o  Trans.  Am.  Inst.  Mining  Engrs. ,  XIV. ,  p.  773, 1886 .  R .  W.  Davenport  has  per- 
sonally conducted  direct  comparative  tests  under  rigidly  similar  conditions,  which 
leave  no  doubt  as  to  this  effect  of  aluminium.  A  large  charge  of  unrecarburized, 
non-carburetted,  wild,  effervescing  ingot  iron,  holding  about  0'08$  of  carbon,  was 
tapped  from  an  open-hearth  furnace  simultaneously  into  two  similar  ladles,  into 
each  of  which  small  red-hot  lumps  of  ferromanganese  were  thrown  at  the  same 
time,  introducing  0'7  of  manganese  per  100  of  steel,  while  one  ladle  also  received 
1  of  ferro-aluminium,  or  sufficient  to  introduce  -064$  of  aluminium,  '024$  of  sili- 
con and  0-01$  of  manganese.  After  a  few  minutes  both  lots  were  teemed  into 
similar  sand  castings  of  a  few  hundred  pounds  weight  each,  and  into  common 
ingot  molds.  The  aluminium-treated  steel  lay  perfectly  dead  and  "piped"  in  the 
ingot  molds,  and  yielded  a  practically  solid  sand  casting:  the  other  rose. in  the 
molds  and  had  to  be  stoppered,  and  yielded  a  very  porous  sand  casting. 

On  another  occasion  he  added  1$  of  ferro-aluminium,  or  enough  to  yield  "04  of 
aluminium  and  '10  of  silicon  per  100  of  metal,  to  both  oxygenated  rising  metal 
obtained  by  melting  wrought-iron  alone  in  crucibles,  and  to  crucible  steel  which, 
owing  to  the  presence  of  carbon  and  manganese,  evolved  no  important  quantity 
of  gas.  This  addition  prevented  the  evolution  of  gas  from  the  former,  making  it 
pipe  when  teemed,  and  appeared  to  thin  it,  or  at  least  it  poured  easily:  but  it 
appeared  to  stiffen  the  latter  and  to  make  it  hard  to  pour.  In  no  case,  however, 
has  he  been  able  to  find  aluminium  in  the  castings  themselves.  (Private  communi- 
cation, Sept.  10th,  1887.) 


ductility  of  the  most  carbonless  iron  with  the  thinness 
and  solidity  of  the  most  carburetted  and  brittle  castings. 
Such  additions  of  aluminium,  however,  appear  to  render 
molten  carburetted  iron  thicker  rather  than  thinner.6 

Note  that  we  have  two  distinct  effects,  increased  fluid- 
ity, and  increased  solidity  and  freedom  from  blowholes. 
These  are  not  necessarily  connected,  or  dependent  on  the 
same  proximate  cause. 

What  now  is  the  rationale  of  these  effects  of  alumin- 
ium ?  Ostberg  states  that  the  addition  of  '05  to  -\%  of 
aluminium  lowers  the  melting  point  by  say  300  to  500° 
F. :  hence  the  thin  castings.  Further,  that  it  is  while  be- 
ing raised  from  its  melting  point  to  a  temperature  enough 
higher  to  permit  casting  that  steel  acquires  the  gases 
which  it  later  evolves  while  setting,  and  that  the  addition 
of  aluminium  immediately  after  fusion,  depressing  the 
melting  point,  enables  us  to  teem  at  once,  and  so  nearly 
eliminates  the  opportunity  for  absorbing  gases.  Finally, 
aluminium  renders  the  metal  so  fluid  that  it  releases  what 
gas  it  has,  which,  in  his  view,  appears  to  be  entangled  as 
in  a  net.  He  speaks,  however,  with  a  degree  of  positive- 
ness  which  neither  his  nor  our  present  knowledge  justi- 
fies, and  which  awakens  suspicion.4  I  vainly  request 
his  evidence :  without  it  such  statements  carry  no 
weight. 

Now  (1)  it  is  not  shown  that  the  melting  point  is  actually 
lowered  in  the  mitis  process  ;  (2)  there  is,  moreover,  reason 
to  doubt  that  aluminium  even  tends  to  produce  this  spe- 
cific effect  of  lowering  the  melting  point ;  and  (3)  were  it 
known  to  lower  the  melting  point  too  little  of  it  is  present 
to  plausibly  explain  a  fall  of  the  melting  point  sufficient 
to  account  for  the  startling  effects  produced.  (4)  Finally, 
a  fall  in  the  melting  point  is  incompetent  to  explain  all 
the  phenomena.  In  brief,  our  aluminium  is  not  shown  to 
be  qualitatively  competent  and  is  shown  to  be  almost  cer- 
tainly quantitatively  incompetent  to  explain  the  phenom- 
ena in  this  particular  way.  The  following  paragraphs 
evidence  these  statements  seriatim. 

1.  A  rise  in  the  metal's  temperature  explains  the  phe- 
nomena quite  as  easily  as  a  fall  in  its  melting  point. 

2.  I  vainly  seek  in  the  writings  of  Deville,  Faraday  and 
Calvert  and  Johnson,  who  have  all  investigated  the  iron- 
aluminium  alloys,  any  intimation  that  aluminium  lowers 
the  melting  point  of  iron  in  this  remarkable  way,  a  point 
which  these  in  two  cases  illustrious    observers   would 
hardly  overlook.     Moreover,  as  just  stated,  the  addition 
of  ferro-aluminium  to  molten  carburetted  steel  appears  to 
stiffen  it,  doubtless  by  diluting  its  heat. 

3.  On  diligent  inquiry  among  those  best  informed,   I 
learn  of  no  determination  of  aluminium  in  mitis  castings, 


d  He  states  unreservedly  that  to  gradually  heat  steel  above  its  melting  point  as 
n  "  killing"  is  most  injurious:  that  practically  no  gases  are  absorbed  by  solid 
steel,  (though  Parry  has  observed  by  direct  measurement  that  gray  cast-iron  ab- 
sorbed 14  times  its  own  volume  of  hydrogen  at  bright  redness  and  22  times  its  vol- 
ume at  whiteness ;  the  volume  of  gas  being  measured  at  tlie  usual  tem- 
jerature  Journ.  Iron  and  St.  Inst.,  1874,  I.,  p.  94)  :  and  that  increasing  the 
luidity  of  molten  iron  causes  it  to  evolve  its  gases.  Here  he  asserts  now  what  is 
probably  fal'e,  now  what  is  only  con jecturable  or  at  best  probable.  Hisfurt'jer 
statement  that,  apparently  in  two  or  three  years,  the  mitis  inventors  have 
jad  time  to  conduct  the  most  exhaustive  and  elaborate  experiments  with  every 
conceivable  metal,  metalloid  and  alloy,  certainly  does  not  indicate  a  careful  weigh- 
ng  of  words.  The  previous  protracted  labors  of  many  a  physicist  and  metallur- 
gist, probably  collectively  representing  scores  of  years,  had  been  able  to  conquer 
ixhaustively  but  a  fraction  of  this  ground.  As  Davenport  finds  that  silicon  gives 
it  least  approximately  as  good  results  as  aluminium,  some  may  infer  that  Ostberg 
regards  silicon  as  in  some  sort  inconceivable, 


88 


THE    METALLURGY    OF    STEEL. 


though  several  complete  analyses  by  Riley  are  given  :a 
here  indeed  the  presence  of  aluminium  might  have  been 
purposely  suppressed.  Competent  chemists  have  vainly 
soiight  it  in  them  :  Davenport  could  find  it  in  no  instance: 
and  I  am  credibly  informed  that  Ostberg  admits  that  it 
has  never  been  detected.  The  effects  described  are  pro- 
duced even  when  only  0'06$  of  aluminium  is  added.  Now 
the  proportion  of  aluminium  actually  present  in  common 
steel  often  varies  from  0  to  0-034$,  without  producing  any 
noticeable  effect :  are  we  to  believe  that  the  further  addi- 
tion of  another  0'03$  is  to  so  intensely  affect  the  proper- 
ties of  the  metal  ?  It  may  indeed  be  questioned  whether 
even  this  amount  remains  in  the  mitis  casting  :  for  alu- 
minium, though  difficult  to  oxidize  at  low  temperatures, 
oxidizes  readily  at  higher  ones,  and  it  may  well  be  oxi- 
dized by  the  oxygen  of  the  oxygenated  metal  which 
forms  the  basis  of  these  castings.1" 

If  it  be  present  why  does  no  one  find  it  ?  The  analyti- 
cal methods  are  not  perfected?  Perhaps  not  for  O'OOl^ 
of  aluminium.  But  so  eminent  an  analyst  as  A.  A.  Blair, 
who  has  given  the  subject  special  attention,  informs"  me 
that  he  considers  it  impossible  that  0'03$  of  aluminium 
should  escape  detection  when  properly  sought  in  iron  or 
steel,  and  that  the  limit  of  error  should  not  exceed  a  few 
thousandths  of  one  per  cent.  Can  we  believe  that  enough 
aluminium  remains  to  influence  the  physical  properties 
appreciably  ?  Must  we  not  rather  conclude  that  it  is 
almost  or  quite  wholly  scorified  ?  and  if  scorified,  can  we 
believe  that  the  fact  of  its  former  brief  presence  can  alter 
the  melting  point  after  its  departure  ?  The  supposition 
appears  to  me  very  improbable. 

4.  A  fall  in  the  melting  point,  by  increasing  the  fluidity, 
enables  the  gases  present  to  escape  ?  Then  when,  as  in 
Davenport's  experiment,  already  boiling  metal  receives 
ferro-aluminium,  it  should  immediately  boil  the  more 
tumultuously  :  actually  it  at  once  grows  quiet.  Hence 
the  ferro-aluminium  clearly  acts  by  enabling  the  metal  to 
retain  in  solution  gas  which  otherwise  would  have  con- 
tinued to  escape,  and  not  by  promoting  its  release.  And 
this  is  a  direct  consequence  of  a  lowered  melting  point  ? 
Or  perhaps  of  the  conjunction  of  some  planets  ? 

DAVENPORT'S  EXPLANATION*  is  that  the  aluminium 
attacks  the  oxygen  present  in  the  oxygenated  metal,  its 
combustion  raising  the  temperature."  This  is  indeed  quali- 
tatively competent  to  explain  why  oxygenless  carburetted 
steel  is  stiffened  while  oxygenated  metal  is  thinned  by  ferro- 
aluminium  ;  and  as  the  addition  of  0'06$  of  aluminium 
might  remove  0'47$  of  ferrous  oxide  by  such  a  reaction  as 

2A1  +  6FeO  =  3FeO,  A1ZO8  +  3Fe 

and  as  the  removal  of  this  quantity  of  ferrous  oxide 
might  well  check  the  evolution  of  gas,  it  may  be  regarded 
as  quantitatively  competent  to  explain  the  quieting  effect. 

a  Pamphlet  of  the  United  States  Mitis  Company,  containing  what  purports  to 
be  a  paper  read  by  T.  Nordenfelt  before  the  British  Iron  and  Steel  Institute,  May, 
1885  :  yet  strangely  enough  I  have  been  unable  to  find  in  Ihe  journal  of  that 
society  any  reference  to  such  a  paper  :  the  words  "  Mitis"  and  "  Nordenfelt "  are 
not  even  indexed  in  its  journal  for  1885  and  1886.  Ostberg  (loc.  cit.)  refers  to 
this  paper  as  "  read  before  the  British  Iron  and  Steel  Institute." 

b  According  to  Deville  aluminium  does  not  decompose  metallic  oxides  at  a  red 
heat  :  an  alloy  of  aluminium  and  copper  yields  cupric  oxide  when  heated  in  a 
muffle  :  an  alloy  of  lead  and  aluminium  can  be  cupelled.  But  above  redness 
aluminium  takes  the  properties  of  silicon  and  reduces  the  oxides  of  copper  and 
lead,  yielding  aluminates. 

c  Private  communication,  September  39th,  1887. 

<J  Private  communication,  a  nte  cit. 

c  Even  initially  clean  vi  rought-iron  might  easily  absorb  enough  oxygen  from  the 
furnace  gases  during  melting  to  account  for  the  oxidation  of  the  aluminium. 


But  is  the  combustion  of  the  small  quantity  of  alu- 
minium employed  quantitatively  competent  to  raise  the 
temperature  of  the  metal  enough  to  account  for  its  in- 
creased fluidity  ?  Calculemus.  Thomsen  calculates  that 
aluminium,  in  uniting  with  oxygen  and  water  to  form 
aluminium  hydrate  thus,  A13,  O3,  3H2O,  generates  388,920 
calories,  or  about  7,097  calories  per  kilo  of  aluminium.' 
This  may  be  more  or  less  than  the  heat  generated  by  the 
oxidation  of  aluminium  to  alumina  :  but  assuming  that  it 
equals  it,  our  O'OG^  of  aluminium  would  generate  425 -8 
calories  per  100  kg  of  metal,  which  would  raise  the  tem- 
p?rature  by  27°,  were  we  to  assume  its  specific  heat  as 
0'16,  or  say  one  eighteenth  as  much  as  it  rises  in  the  Bes- 
semer process. 

The  heat  which  is  thus  evolved  is  on  the  one  hand 
lessened  by  that  absorbed  by  the  simultaneous  deoxida- 
tion  of  the  iron,  whose  oxygen  the  aluminium  seizes,  and 
on  the  other  increased  by  that  evolved  by  the  union  of 
alumina  with  the  residual  ferrous  oxide.  Moreover,  by 
stopping  the  escape  of  gas,  the  aluminium  prevents  a  small 
quantity  of  heat  from  becoming  latent  through  vapori- 
zation. Finally,  the  radiation  of  heat  is  somewhat  slower 
from  a  quiescent  than  from  a  bubbling  liquid,  as  they 
know  who  stir  their  soup.  All  things  considered,  it 
may  not  be  unreasonable  to  claim  that,  directly  and  in- 
directly, our  '06$  of  aluminium  may  raise  the  tempera- 
ture of  our  steel  by  from  25°  to  30°  C.  (77°  to  86°  F.) 
which  may  be  considered  sufficient  to  account  for  the  in- 
crease of  fluidity,  which  was  probably  not  great :  for 
Davenport  speaks  of  it  very  guardedly  as  "  an  apparent  in- 
crease" only.  A  rise  of  100°  C.  (180°  P.),  which  wouldimply 
the  combustion  of  only  0'22^  of  aluminium,  might  well 
account  even  for  the  extreme  thinness  of  Ostberg' s  castings: 
and  this  quantity  may  easily  have  been  added  to  them. 

Now  the  attenuated  castings  testify  that  the  ingot 
iron  which  composes  them  was  unusually  far  above  its 
freezing  point  when  cast :  either  its  freezing  point  was 
lowered  (Ostberg' s  theory)  or  its  temperature  raised  by 
the  aluminium  (Davenport' s).  The  former  theory  is  hardly 
tenable :  the  latter  is  made  to  account  for  all  the  phe- 
nomena by  a  series  of  assumptions  which,  while  in  no  case 
preposterous,  perhaps  not  even  unreasonable,  still  by  no 
means  command  acceptance.  It  seems  to  me  improbable, 
though  possible,  that  the  oxidation  of  so  small  a  quan- 
tity of  aluminium  would  cause  such  a  rise  in  tempera- 
ture. I  doubt  if  as  much  as  426  calories  would  be  avail- 
able for  raising  the  temperature  of  the  iron,  and  I  think 
it  probable  that  the  specific  heat  of  this  iron  at  its  melting 
point  is  considerably  above  that  here  taken.  These  are 
grave  difficulties  which  Davenport's  explanation  has  to 
contend  with,  [t  appears  to  me  decidedly  the  less  im- 
probable of  the  two :  but  the  true  explanation  may  be 
yet  unguessed. 

C.  ALUMINIUM  IN  COMMERCIAL  IRON. — Though  the  di- 
rect reduction  of  alumina  by  the  usual  reducing  agents, 
hydrogen  and  carbon,  is  extremely  difficult,  Faraday  and 
Billings  seem  to  have  effected  its  reduction  in  presence  of 
a  great  excess  of  iron  by  means  of  carbon.  Hence  the  fre- 
quent presence  of  small  quantities  of  aluminium  in  com- 
mercial cast  iron  is  hardly  surprising.  Difficultly  oxidized 
below  redness,  at  higher  temperatures  it  behaves  like  sil- 
icon :  and,  like  silicon,  a  little  of  it  may  survive  the  oxi- 

t  Thermochemische  Untersuchungen,  III.,  p.  339. 


ALUMINUM,     THE    NOBLE    METALS,     CALCIUM,     MAGNESIUM,     ETC. 


dizing  processes  of  refining  and  be  found  in  the  resulting 
steel  or  wrought-iron.  A.  A.  Blair  has  examined 
very  many  irons  and  steels  for  aluminium,  which  he 
reports  "nearly  always  exists  as  such  in  steel,"  but  he 
has  never  found  more  than  a  few  thousandths  of  one 
per  cent,  say  '032$.  He  has  been  unable  to  connect  its 
presence  with  any  peculiarity  in  the  properties  of  the 
metal,  or  with  any  particular  mode  of  manufacture.8 

Percy  quotes  and  questions  an  analysis  of  cast-iron  con- 
taining 0 -97$  of  aluminium. b  Part  of  the  aluminium  of  cast- 
iron  probably  exists  r.s  alumina  in  slag.  Karsten  detected 
but  traces  of  aluminium  in  iron  and  steel,  and  those 
rarely.0  Alumina,  which  he  added  to  cast-iron  which  was 
being  refined  in  the  charcoal  hearth,  was  wholly  slagged. d 

§  150.  MEKCUKY  does  not  amalgamate  with  iron  directly, 
hot  or  cold,  but,  by  immersing  sodium  amalgam  in  ferrous 
sulphate  solution  and  probably  by  other  indirect  means, 
iron  amalgams  apparently  of  feeble  stability  may  be 
formed.0 

§  151.  Faraday  and  Stodart  stated  that  "the  metals 
which  form  the  most  valuable  alloys  with  steel  are  silver, 
platina,  rhodium,  iridium  and  osmium,  and  palladium."* 
The  scanty  subsequent  investigations  into  this  group  of 
alloys  have  not  tended  to  confirm  their  statement.  With 
to-day's  knowledge  of  the  influence  of  other  elements  on 
iron  they  would  probably  have  interpreted  their  observa- 
tions quite  differently. 

(A.)  IRON  AND  PLATINUM  appear  to  combine  readily  in 
all  proportions,  platinum  melting  even  below  the  fusing 
point  of  steel  when  in  contact  with  that  metal.  Their  al- 
loys are  considered  of  no  technical  importance,  Faraday 
and  Stodart  to  the  contrary  notwithstanding.  Melting 
Indian  steel  and  0'99$  of  platinum  they  obtained  an  alloy 
which,  though  not  so  hard  as  that  obtained  by  melting  the 
same  steel  with  0'2$  of  silver,  was  considerably  tougher, 
and  they  prophesied  its  extensive  use  in  spite  of  the  cost 
of  platinum.8  Their  prophecy  is  not  yet  fulfilled. 

They  obtained  alloys  of  steel  (A)  with  50%  of  platinum, 
beautiful,  with  the  finest  imaginable  color  for  a  mirror, 
taking  a  high  polish,  non-tarnishing  and  malleable  ;  (B) 
with  11$  of  platinum,  taking  a  high  polish,  finely 
damasked,  and  free  from  rust  after  many  months  expos- 
ure.'1 They  were  probably  in  error  in  attributing  the  ex- 
cellent qualities  of  platinum  as  of  silver  steel  to  the  pres- 
ence of  the  noble  metal. 

Billings  found  that  platinum  increased  the  hardness  of 
steel  less,  but  diminished  its  forgeableness  more,  than  a  like 
proportion  of  carbon  did.  A  pure  ingot  iron  with  '08$ 
carbon  and  '82$  of  platinum  was  extremely  redshort  and 
white-short :  otherwise  pure  steel  with  4$  of  platinum  and 
nearly  2$  of  carbon  was  slightly  redshort,  and  inferior 
in  quality  to  steel  of  like  composition  less  the  platinum.1 

B.  PALLADIUM  in  steel  in  the  ratio  1  :  100  produces  ac- 


a  Private  communication,  May  10,  1887  :  Kept,  of  U.  S.  Board  Test  on  Testing 
Metals,  II.,  p.  590.  Am.  Jl.  Science,  XIII.,  p.  424,  1877  :  Thurston,  Matls.  of 
Engineering,  II.,  p.  434. 

b  Percy,  Iron  and  Steel,  p.  543. 

e  Percy,  Iron  and  Steel,  p.  185. 

dCorbin  (Silliman's  Journal,  2d  Ser.,  XLVIIL.p.  348,  1869),  reports  2-38$ 
aluminium  with  1-66$  chromium  and  "98$  carbon  in  chrome  steel;  but  this  is 
hardly  credible.  Blair  finds  no  more  aluminium  in  chrome  than  in  other  steels. 

e  Percy,  op.  cit.  p.  174. 

l  Phil.  Trans.  Royal  Society,  1822,  p.  254. 

B  Idem,  p.  257. 

h  Percy,  Iron  and  Steel,  p.  177.    These  are  the  calculated  compositions. 

I  Trans,  Am,  Inst.  Mining  Engrs,,  V.,  p.  452,  1887, 


cording  to  Faraday  and  Stodart  an  alloy  "truly  valu- 
able," especially  for  instruments  demanding  a  perfectly 
smooth  edge. 3 

RHODIUM,  uniting  with  iron  in  all  proportions,  forms  with 
steelalloys  "perhaps  the  most  valuable  of  all"  accordingto 
Faraday  and  Stodart,  remarkably  hard,  forgeable,  and 
hardening  without  cracking.  Steel  with  50$  of  rhodium  has 
when  polished  "the  most  exquisite  beauty"  and  "the  finest 
imaginable  color"  for  mirrors,  and  long  resists  tarnishing. J 

C.  OSMII  M-lKioiUM-iron  alloys  of  the  following  com- 
positions have  bf  en  prepared. 

3$  osmium-iridium  with  pure  iron  ;  forgeable,  long  re- 
sists rusting,  distinctly  blue,  hardens  when  quenched  from 
redness,  though  no  carbon  could  be  detected  in  it.  Fara- 
day and  Stodart.k  Calculated  composition. 

2'98$  osmium-iridium  with  Swedish  iron  containing  not 
more  than  -07$  of  carbon.  Very  homogeneous,  not  har- 
dened by  quenching ;  Boussingault.1 

2-98$  iridium  replaced  the  osmium-iridium  of  the  pre- 
ceding alloy  with  like  results  ;  Boussingault.1 

Note  that  osmium-iridium  conferred  the  power  of  har- 
dening on  Faraday's  alloy,  but  not  on  Boussingault' s. 

D.  GOLD  alloys  with  iron:    of  the  value  of  its  alloys 
with  steel  Faraday  and  Stodart  were  doubtful. 

E.  SILVER  does  not  alloy  with  iron  readily  if  at  all.    On 
exposing  steel  and  0  62$  of  silver  foil  to  a  white  heat  for 
three  hours  in  a  crucible  filled  with  crushed  glass,  Faraday 
and  Stodart  found  the  silver  fused  and  adhering  to  the 
steel,  but  none  had  combined.     After  many  trials  they 
found  that  steel  would  take  up  but  0'2$  of  silver :  when 
more  was  present  part  was  found  as  a  metallic  dew  lining 
the  interior  of  the  crucible,  and  the  fused  button  itself 
was  a  mere  mechanical  mixture  of  the  two  metals.     But 
0-2$  of  silver  appeared  to  unite  perfectly  with  the  steel, 
yielding  a  product  harder  than  either  the  best  cast-steel 
or  wootz,  and  with  no  disposition  to  crack  in  forging  or 
hardening."1    They  thought  that  silver  greatly  benefited 
steel,  but  were  probably  completely  deceived. 

Of  0'5$  of  silver  added  by  Billings  to  molten  ingot  metal 
only  traces  were  found  in  the  solidified  ingot,  while  glo- 
bules of  silver  were  found  above  it.n  Of  l'5$of  silver 
added  by  Karsten  to  cast-iron  in  the  charcoal  refinery, 
but  '034$  was  retained  by  the  bar  iron,  which  was  unsound, 
laminar  and  very  redshort.0 

IRON  WITH  THE  METALS  OF  THE  ALKALINE  EARTHS. — 
It  is  very  doubtful  whether  any  class  of  iron  made  by 
ordinary  methods  can  contain  calcium,  magnesium, 
barium  or  strontium  as  such  :  nor  is  it  certain  that  any  of 
these  metals  can  be  alloyed  with  iron  even  experimentally. 
The  small  quantities  occasionally  reported  probably  exist 
as  oxide  or  silicate  in  the  mechanically  held  slag.  Gay 
Lussac  and  Thenard  were  unable  to  reduce  calcium, 
barium  or  strontium  from  their  oxides  by  heating  with 
charcoal  and  iron  :  Berzelius  failed  to  reduce  calcium  in 
this  way,  though  he  obtained  "indications"  of  an  alloy 
of  iron  and  magnesium. p 


i  Percy,  Iron  and  Steel,  p.  180,  from  Phil.  Trans.,  1822,  p.  256.  Calculated 
composition. 

k  Percy,  Iron  and  Steel,  p.  181. 

I  Journ.  Iron  and  Steel  Inst.,  1886,  II.,  p.  812,  from  Ann.  de  Chimio  et  Phya, 
5th  Ser.,  XV. 

mPhil.  Trans.  Royal  Society,  1822,  p.  255. 

i  Trans.  Am.  Inst.  Mining  Engineers,  V.,  p.  454,  1877. 

"Percy,  Iron  and  Steel,  p.  175. 

P  fercy,  Iron  and  Steel,  p.  196.    A  famous  analysis  of  spiegeleisen  by  Freseniua 


90 


THE    METALLURGY    OF     STEEL. 


Hot  iron  absorbs  vapor  of  magnesium,  evolving  it  when 
heated  in  vacuo.a 

POTASSIUM  AND  SODIUM,  however,  are  reduced  from 
their  hydrates  by  iron  at  a  white  heat,  and  from  their  car- 
bonates by  carbon :  hence  their  reduction  in  the  blast- 
furnace and  their  retention  by  the  metal  through  the 
refining  processes  is  not  impossible  on  a  priori  grounds, 
especially  if  the  refining  be  accompanied  by  basic  slags. 
By  strongly  heating  iron-filings  with  bitartrate  of  potash, 
alloys  containing  74-6  and  81-4$  of  iron  and  25 '4  and 


IS  '58$  of  potassium  respectively  have  been  produced, 
which  closely  resemble  wrought-iron,  can  be  forged  and 
welded,  are  so  hard  as  to  be  barely  fileable,  and  oxidize 
rapidly  in  air  or  water.'  By  long  exposing  iron  turnings 
at  a  high  temperature  to  vapor  of  potassium  Gay-Lussac 
and  Thenard  obtained  a  flexible  iron-potassium  alloy, 
which  was  occasionally  soft,  sectile  and  even  scratched 
with  the  nail.g  These  metals  have,  however,  rarely  been 
detected  in  iron,  perhaps  because  rarely  sought.  Their  in- 
fluence on  commercial  iron  is  unknown,  if  indeed  it  exists. 


CHAPTER     IX. 
IRON  AND  OXYGEN. 


§  155.  THE  OXIDES  OF  IRON. 

A.  SUBOXIDE. — Bell  obtained  strong  indications  of  the 
existence  of  an  oxide  lower  than  ferrous  oxide,  perhaps 
of  the  composition  Fe2O.b 

B.  FERROUS  OXIDE,   FeO,  though  it  may  be  isolated 
according  to  Debray  by  passing  equal  volumes  of  carbonic 
acid  and  oxide  over  red-hot  ferric  oxide,  and  though  ac- 
cording to  Liebig  it  may  be  obtained  mixed  with  spongy 
iron  by  igniting  ferrous  oxalate  in  a  closed  vessel,   yet 
absorbs  oxygen  with  such  avidity  that  it  is  not  easily 
produced."    A  powerful  base,  its  silicates  and  phosphates 
are  of  great  importance  in  the  slags  of  iron  metallurgy. 
Ferrous  silicate  is  formed  with  evolution  of  oxygen  by  the 
action  of  silica  on  ferric  oxide  at  high  temperatures'1 : 
stable  at  moderately  high  temperatures,  at  extremely  high 
ones  it  readily  absorbs  oxygen  from  the  air. 

C.  FERRIC    OXIDE,   Fe2O3,    frequently  giving    up  its 
oxygen  to  organic  matter  even  at  ordinary  temperatures, 
at  higher  ones  becomes  a  strong  oxidizing  agent,  being  re- 
duced to  magnetic  oxide  with  evolution  of  oxygen  when 
heated  alone  to  its  very  high  melting  point,  and  at  appa- 
rently much  lower  temperatures  when  heated  in  contact 
with  metallic  iron.     It  is  readily  and  completely  reduced 
by  hydrogen,  by  carbon  and  by  ammonia  :   its  reduction 
by  carbonic  oxide  is  probably  never  quite  complete  unless 
carbon  intervenes,  though  the  contrary  is  generally  stated, 
for  Bell  found  that  both  spongy  iron  and  ferric  oxide  when 
heated  at  bright  redness  and  cooled  in  this  gas  yielded  a 
product  containing  from  '8  to  \%  of  the  oxygen  required 
to  form  ferric  oxide.6    Even  large  lumps  of  ferric  oxide 
may  be  nearly  if  not  quite  completely  reduced  by  contact 
with  lump  carbon,  the  carbonic  oxide  formed  by  the  surface 
action  doubtless  penetrating,  then  carrying  oxygen  from 
the  interior  oxide  outwards,  being  again  reduced  to  car- 
bonic oxide  by  the  surrounding  carbon,  and  so  on.    In  the 
interior  of  lumps  of  ore  which  had  been  heated  in  lump 
charcoal,  I  have  found  particles  of  malleable  spongy  iron 


gave  '063  potassium,  traces  of  sodium,  '045  magnesium,  '091  calcium  and  traces 
of  lithium.  (Kerl,  Grundriss  der  Eisenhiittenkunde,  p.  43.)  Karsten  found  '1774 
calcium  in  wrought-iron,  which  was  deficient  in  weldability  and  tenacity,  though 
neither  red-  nor  coldshort.  (Percy,  Iron  and  Steel,  p.  197.)  Kerl  quotes  seven  cast- 
irons  which  contain  from  '02  to  '46^  of  calcium  and  from  •  00  to  '25$  of  magnesium. 
(Op.  cit.,  pp.  27  to  43.)  Percy  quotes  but  doubts  an  analysis  of  cast-iron  with  -97$ 
aluminium,  1  '37$  calcium  and  0'43$  magnesium.  (Iron  and  Steel,  p.  543.)  Con- 
cerning slag  in  cast-iron  see  foot-note  to  §  189. 

a  Compare  §  145,  A. 

b  Journ.  Iron  and  St.  Inst,  I.,  1871,  p.  106. 

c  Watts,  Dictionary  of  Chemistry,  1871,  III.,  p.  393, 

<1  Percy,  Iron  and  Steel,  p.  30. 

t  Jour.  Iron  and  St,  Inst.,  1871,  I.,  p.  113, 


so  placed  that  they  had  been  apparently  (though  not  cer- 
tainly) completely  surrounded  by  gangue,  and  so  cut  off 
from  contact  with  outer  iron  which  was  being  deoxidized. 
Both  at  high  and  low  temperatures  ferric  oxide,  like 
alumina,  at  least  occasionally  acts  as  an  acid.  Percy 
completely  melted  mixtures  of  ferric  oxide  and  lime,  twice 
obtaining  masses  of  interlacing  acicular  crystals  contain- 
ing 73-39$  of  ferric  oxide  and  24-5$  of  lime  (FesO3CaO  = 
Fe2Ca04),  which  may  be  regarded  as  magnetic  oxide  whose 
ferrous  oxide  is  replaced  by  lime.h  The  neutral  carbon- 
ates of  potash  and  of  soda  are  not  decomposed  by  heat 
alone :  but  their  carbonic  acid  is  expelled  when  they  are 
strongly  heated  with  ferric  oxide.1  A  compound  of  the 
formula  4CaO,  FeaO8  =  Ca4FeaO7  may  be  precipitated 
from  certain  solutions  as  a  snow-white  powder,  though 
containing  nearly  50$  of  ferric  oxide.3 

D.  IRON  RUST,  consisting  essentially  of  hydrated  iron 
oxide,  varies  in  composition  with  the  conditions  under 
which  it  forms.     According  to  Malletk  it  tends  in  propor- 
tion to  the  duration  of  reaction  to  approach  the  formula 
2Fe2O3,  3H2O  (limonite),  mixed  with  more  or  less  (usually 
less)  ferrous  carbonate,  FeCO3,  and  when  very  old  it  ap- 
pears to  lose  water  and  approach  the  composition  of  hema- 
tite, Fe2O3.     When  formed  far  beneath  the  surface  of 
water  it  consists  of  black  hydrated  magnetic  oxide.1    Iron 
rust  often  contains  minute  quantities  of  ammonia. 

E.  FERROSO-FERRIC  OXIDES. — Oxides  of  many  and  per- 
haps all  compositions  intermediate  between  ferrous  and 
ferric  oxide  form :   magnetic  oxide  FesO4  =  Fe8O3,  FeO, 
and  probably  scale  oxide  Fe809  =  6FeO,  Fe2O3  are  of 
definite  composition :  the  others  may  be  viewed  as  chem- 
ical compounds  of  ferrous  and  ferric  oxide  in  continuously 
varying  proportions. 

These  oxides  are  in  general  unstable,  on  slight  provo- 
cation taking  up  oxygen  or  letting  it  go,  and  passing 
readily  from  a  lower  to  a  higher  state  of  oxidation  or  vice 
versa :  they  thus  act  as  carriers  of  oxygen,  assisting 
oxidation  in  oxidizing  operations  and  reduction  in  reduc- 
ing ones.  This  is  probably  true  of  their  silicates  also. 

THE  MAGNETIC  is  in  many  respects  the  most  stable  oxide 
of  iron.  At  ordinary  temperatures  it  resists  the  action  of 


*  Calvertand  Johnson,  Phil.  Mag.,  4th  Series,  X.,  p.  343, 1855. 

g  Percy,  Iron  and  Steel,  p.  196. 

h  Metallurgy,  Fuel,  New  Edition,  1875,  p.  78. 

l  Percy,  Iron  and  Steel,  p.  17. 

j  Idem,  p.  19. 

kRept.  British  Ass.,  1843,  p.  11. 

1  Percy,  Iron  and  Steel,  p.  38. 


OXYGEN     IN     MOLTEN     IRON.       §  158. 


91 


the  weather  and  of  many  reagents.  A  coating  of  this 
oxide,  such  as  is  produced  in  blueing,  Barffing,  etc.,  pro- 
tects metallic  iron  from  rusting,  while  ferric  oxide  on  the 
one  hand  hastens  the  rusting  of  iron  with  which  it  is  in 
contact,  and  ferrous  oxide  on  the  other  itself  rapidly  ab- 
sorbs oxygen.  While  at  moderately  high  temperatures,  as 
when  ignited  in  air,  magnetic  oxide  is  converted  into  fer- 
ric oxide,  at  still  higher  ones  it  is  spontaneously  formed 
by  the  decomposition  of  ferric  oxide  by  heat  alone. 

The  facts  that  magnetic  oxide  is  so  comparatively  stable  : 
that  ferrous  oxide  is  so  powerful  a  base  :  that  in  certain 
cases  both  at  high  and  low  temperatures  ferric  oxide  acts 
as  an  acid,  and  in  certain  of  them  forms  compounds  sim- 
ilar to  magnetic  oxide,  (e.  g.,  the  compound  FeaCaO4  al- 
ready described),  and  in  others  even  isomorphous  with  it 
(e.  ff.,  franklinite  Fe2ZnO4  —  ZnO,  FeaO3) :  that  the  ses- 
quioxides  analogous  to  ferric  oxide,  viz.  alumina  and 
chromic  oxide,  form  with  ferrous  oxide  compounds  iso- 
morphous with  magnetic  oxide,  (ceylonite  Al3FeO4  = 
FeO,  A12O3  and  chrome  iron  ore  Cr^Fe04  =  FeO,  CraO3), 
in  the  latter  of  which  chromic  oxide  may  reasonably  be 
regarded  as  an  acid  :  that  ferric  oxide  and  alumina  often 
replace  part  of  the  chromic  acid  in  this  mineral :  and  that 
in  other  cases  both  alumina  and  chromic  oxide  act  as 
acids,  strongly  suggest  that  in  magnetic  oxide  we  have  a 
true  salt,  a  f errite,  ferric  oxide  its  rather  mild  acid,  ferrous 
oxide  its  powerful  base.  This  view  harmonizes  with  the 
fact  that,  when  magnetic  oxide  is  attacked  in  a  closed  ves- 
sel by  not  more  than  enough  hydrochloric  acid  to  dissolve 
its  ferrous  oxide,  the  latter  alone  dissolves,  hydrochloric 
acid  appearing  to  displace  ferric  oxide  much  as  it  would 
carbonic  acid. 

F.  SCALE  OXIDE. — FegO0  =  6FeO,  Fe.jO3.  Exposed  to 
air  or  to  furnace  gases  at  a  red  or  higher  heat,  iron  ac- 
quires a  coating  intermediate  in  composition  between 
ferrous  and  ferric  oxides,  often  divisible  into  two  or  three 
layers  more  or  less  arbitrarily  chosen  :  the  outer  is  always 
the  most  highly  oxidized,  the  inner  though  probably  of 
indefinite  composition  sometimes  approximates  the  for- 
mula Fe8O0.  The  following  percentages  of  ferric  oxide  in 
iron  scale  have  been  published,  chiefly  by  Percy:*  The 
heavy  faced  figures  represent  the  compositions  Fe8O9  and 
Fe304. 


TABLE  40. — PERCENTAGE  OP  FERRIC  OXIDE  IN  IRON  SCALE. 

26  1 9  inner  layer.  I  36  60*  I  47  67  middle  layer.        I  89  •  27  velvet  scale. 

27'O4FeO9  I  37  49  all  layers.  |  52  01       "         ••  |  98  63  outer  layer. 


27  OS  incer  layer. 
35  77  outer    " 


I  40  51  middle  layer. 
46-77  inner        " 


|  52  01 

159-00       "          ' 

I  6S-97  >'e30 


I  98-80 
99  68 


*  G.  W.  Maynnrd,  Trans.  Am.  Inst.  Mining  Engrs.,  X.,  p  281, 1S82. 

Gr.  FERKIC  ACID,  Fe03,  though  never  isolated,  may  be 
supposed  to  exist  in  the  ferrates  of  the  alkalies  and  of 
baryta,  which  form  in  the  dry  and  the  wet  way.  It  is 
conceivable  that  similar  salts  may  form  in  metallurgical 
operations. 

§  156.  OXYGEN  IN  COMMERCIAL  IRON. — Even  when  cold 
iron  can  probably  retain  but  a  fraction  of  one  per  cent 
of  hydrogen  or  of  carbonic  oxide,  which  are  readily  ex- 
pelled and  which  modify  it  comparatively  little. 

Of  nitrogen  it  can  permanently  hold  more  than  \\%, 
which  alters  its  properties  more  profoundly  :  sometimes 
readily  evolving  at  least  a  portion  of  it,  e.  g.  on  boring,  at 
others  it  retains  it  far  more  tenaciously,  but  it  always  re- 
leases it  at  a  white  heat  completely  or  nearly  completely. 
In  ferric  acid  iron  may  be  conceived  to  unite  with  over  46'% 

» Iron  and  Steel,  pp.  SI  et  seq. 


of  oxygen,  of  which  it  retains  27 •$%  at  the  highest  tempera- 
tures, which  completely  obliterates  its  metallic  nature. 
Though  the  properties  of  iron  are  thus  more  deeply  af- 
fected by  oxygen  and  nitrogen  than  by  hydrogen  and 
carbonic  oxide,  yet  it  is  by  a  much  larger  percentage 
of  the  former  two,  and  it  is  not  clear  that,  weight  for 
weight  they  affect  it  more  than  the  latter  two  :  indeed  in 
this  respect  the  glass-hardness  produced  by  '26$  of  hydro- 
gen (No.  29,  Table  56,  §  170)  probably  outweighs  in  in- 
tensity the  effect  of  the  same  proportion  of  any  other  ele- 
ment. 

The  ratio  of  the  chemical  to  the  physical  force  con- 
cerned in  the  retention  of  these  substances  appears  to  be 
lowest  in  case  of  hydrogen  and  carbonic  oxide  and  com- 
paratively high  in  case  of  at  least  that  part  of  the  nitro- 
gen which  forms  the  white  brittle  nitride :  while  the 
union  of  iron  with  oxygen  is  typically  chemical,  llence 
it  is  not  to  be  expected  that  oxygen  would  be  given  off, 
nor  is  it  as  the  three  other  gases  are  when  metallic  iron  is 
heated  in  vacuo,  or  when  it  solidifies  in  casting :  and  I 
find  it  in  but  two  of  the  many  recorded  analyses  of  gasts 
obtained  on  boring,  (No.  13,  porous  steel,  and  No.  34,  from 
a  blister  iu  puddled  iron,  in  Table  54,  §  171).  The  follow- 
ing table  gives  the  proportion  of  oxygen  found  in  com- 
mercial and  unrecarburized  iron,  etc.  Further  details  of 
the  composition  of  certain  of  these  irons  are  given  in 
Table  43. 

§  157.  EFFECT  OF  OXYGEN. — At  the  end  of  the  Bessemer 
process  the  metal  usually  absorbs  a  certain  proportion  of 
oxygen,  which  renders  it  unforgeable,  and  which  is  re- 
moved by  addition  of  carbon,  manganese,  etc.,  though 
under  certain  conditions  unrecarburized  Bessemer  metal  is 
so  free  from  oxygen  as  to  be  f  orgeable.  It  is  s  tated  that  more 
than  '\%  of  oxygen  appreciably  affects  forgeableness,  but 
that  in  smaller  proportion  it  is  often  harmless :  I  do  not, 
however,  think  that  we  have  evidence  sufficient  to  warrant 
precise  statements.  That  a  small  quantity  of  oxygen  does 
not  necessarily  cause  redshortness  is  shown  by  the  fact  that 
steel  No.  5,  Tables  42  and  70  A,  after  receiving  2$  of 
ferromanganese  was  non-redshort,  though  it  still  retained 
some  '025$  of  oxygen,  as  calculated  from  the  data  of  the 
spiegel  reaction  which  occurred  when  it  was  further  recar- 
buiized  with  spiegeleisen,  and  which  was  accompanied  by 
flame  and  rather  active  boiling." 

When  carelessly  heated  ingot  and  weld  iron  may  absorb 
oxygen,  of  which  Tucker  finds  '063$  in  burnt  steel :  but 
"  burning,"  while  often  accompanied  by  absorption  of 
oxygen,  apparently  consists  essentially  in  structural 
change  due  to  overheating,  which  may  be  almost  com- 
pletely effaced  by  purely  physical  means  (cautious  heat- 
ing and  forging).  The  oxygen  which  causes  redshortness 
in  unrecarburized  and  in  burnt  steel  is  not  to  be  confounded 
with  the  comparatively  inert  oxygen  of  the  slag  mechan- 
ically held  in  weld  iron  ( •&%  of  oxygen  is  thus  reported, 
No.  13,  Table  41). 

§  158.  OXYGEN  IN  MOLTEN  IRON. — Molten  iron  like  mol- 
ten copper  can  retain  a  small  quantity  of  oxygen,  which  has 
been  assumed  to  exist  as  magnetic  oxide,  though  in  the  pres- 
ence of  so  vast  an  excess  of  metallic  iron  ferrous  oxide  would 
be  more  naturally  expected.  Indeed,  part  or  all  of  the 
oxygen  may,  like  hydrogen  or  carbon,  be  united  with  the 
whole  of  the  metal.  The  quantity  of  oxygen  which  molten 


bMuller,  Stahl  und  Eisen,  IV.,  p,  73,  188*. 


92 


THE    METALLURGY    OF    STEEL. 


TABLE  41.— OXYGEN  IN  COMMERCIAL  IKON  AND  UNKECARBURIZED  STEEL. 


No. 

1.. 

2.. 
8.. 

4.. 
5  . 

6. 

7.. 

8 
9.. 

10.. 

11.. 
12.. 
13.. 
14.. 
15.. 
15  5 
16 
11 

Observer. 

Ledebur.. 
it 
Bender... 

King.  ..  . 
Muller..  . 

Tucker  .  .  . 
Ledebur  .  . 

Tucker  .  . 
Percy    . 
Ledehur.. 

Kern  
Parry  .... 
Ledebur.  . 

Mode  of 
determination. 

Description  of  metal. 

Oxygen. 

% 

•068 
•111@-126 

•34 

•898 
(•958) 

•48S± 
(0'79±) 

•086 
(•!<94) 

•03@-2u 
(•09®  -28) 
0-58 
(1-76@1'79) 

•6S@1  74 

•171(2r214 
•063 
•017 
•507®  '524 
•082 
•025®  '037 
•13  @'55? 
0 
•177 
2  04  ? 

Volumes 
per  vol. 
metal. 

Ignition  in  hydrogen 
Spiegel-reaction 

Unrecarburized    basic     Bessemer 
metal  not  fully  dephosphorized  .  . 
Do.  do.,  fully  dephosphorized.  ... 
Unrecavburized  lully  decarlmrized 

3-91 
6'38@7-24 

19-55 

Spiegel  -reaction 

Unrecarburized  fully  decarbur-j 
ized  acid  Bessemer  metal  \ 

Spiegel  -reaction 
method  

Do.do.,  slag  not  pres- 

Unrecarburized  basic  Bessemer  j 
metal  fully  dephosphorized.  .  .  ( 

Do    do                                 '           -1 

•     "  '  • 

Do.  do.  slag  present 
Fusion  with  charcoal 

Not  stated 

Unrecarburized  oxygenated  basic 
(?)  Bessemer  metal  
Unrecarburized    basic    Bessemer 

39  ®100- 

9'83@14. 
3  62 
1  00 
•29  16@30'13 
1  84 
1-44®  2-13 

Fusion  with  charcoal 
Ignition  in  hydrogen 

Not  stated 

Commercial  steel  

Ignition  in  hydrogen. 

0 

18. 

Parry  

land  2.  15  grammes  of  the  metal  previously  dried  in  nitrogen  at  200°  C,  arc  heated  to  red - 
ness  in  a  current  of  hydrogen  for  45  minutes  :  the  water  formed  is  collected  by  phosphoric  an- 
hydride and  weighed.  (Stahl  und  Eisen,  II.,  p.  193,  1882  :  Journ.  Iron  and  St.  Inst.,  1882,  I.,  p. 
883  ) 

3  and  4.  Unrecarburized  Bessemer  metal  is  heated  in  hydrogen,  and  the  water  thus  formed 
is  caught  in  chloride  of  calcium.  This  is  checked  by  the  loss  of  weight  which  the  iron  simul- 
taneously undergoes,  '335$  after  allowing  for  loss  of  sulphur.  It  is  further  checked  by  the  loss  of 
manganese,  carbon  and  silicon  occurring  on  recarburizing,  which  represents  the  action  of  .398±^ 
of  oxygen,  of  which  a  portion  may  have  been  furnished  by  the  atmosphere  or  by  the  slag,  See 
No  10  in  Tables  42,  48,  70  A.  (Dingler's  Polyt.  Journal,  CCV.,  p.  531,  1872  ;  from  Berg- und 
Hiitt  Zeit.  1872,  No.  81  ) 

5 .  In  calculating  these  results  I  have  been  obliged  to  assume  the  composition  of  the  ferro-man- 
ganese  employed  :  but,  as  it  amounted  to  only  -228^  of  the  product,  the  error  thus  introduced  is 
unimportant.    Trans.  Am.   Inst.  Mining  Engineers,  IX.,  p.  258, 1881.     See  No.  11  in  Tables  42, 
43,  70  A. 

6.  (Zeit.  Tereins  Deutscher  Ing.,  XXII.,  p.  3S5.)    See  No.   9  in  Tables  42,43,70  A.    The 
metal  was  recarburized  in  the  usual  way. 

7  .  To  prevent  the  action  of  the  slag  and  to  lessen  that  of  the  atmospheric  oxygen,  the  metal 
was  completely  separated  from  the  slag  and  recarburized  in  common  ingot  moulds.  SeeNos.l 
to  4,  Tables  42,  43,  70  A.  (Stahl  und  Eisen,  IV.,  pp.  72-3, 1884.) 

S  .  The  after-blown  metal  was  recarburized  in  the  converter  with  1%  of  ferro-manganese,  and 
thru  transferred  to  common  ingot  moulds,  separated  from  slag  and  further  recarburized.  Iha\e 
been  obliged  to  assume  that  the  ferro-raanganese  contained  the  same  proportion  of  manganese  as 
in  other  experiments  of  Mlillcr,  viz.:  10%,  See  Nos.  5  and  6,  Tables  42,  4?,  70  A.  (Stahl  und 
Eisen,  IV  ,  pp.  72-8, 1884.) 

9.  The  metal  ia  melted  in  a  crucible  brasqued  with  pure  charcoal,  and  the  oxygen  inferred 
from  the  loss  of  weight,  after  allowing  for  the  change  in   the  percentage  of  carbon.     (Journ .  Iron 
and  Steel  Inst.,  1881,  p.  205.) 

10.  3  specimens  of  after-blown  basic  Bessemer  metal  taken  from  the  converter  held '244,  187 
and  -ITljJ  of  oxygen.    See  Nos.  A  B  C  in  Table  43.    (Handbuch  der  Eisenhiittenkunde,  I.,  p. 
276). 

11.  Same  conditions  as  No.  9. 

1  2*  Oxygenated  iron  was  prepared  by  melting  in  a  clay  crucible  pure  ferric  oxide  mixed  with 
a  quantity  of  lamp-black  theoretically  sufficient  to  reduce  82. 2^  of  it.  150  grains  of  the  resulting 
very  soft  file-clogging  product  were  ignited  in  hydrogen  during  80  minutes,  and  the  resulting 
water  caught  and  weighed.  (Percy,  Iron  and  Steel,  p.  15.) 

K!,  14*  Same  conditions  as  No.  1. 

16.  About  100  grammes  of  steel  in  lumps  of  10  to  15  grammes  each,  were  ignited  in  dry 
nitrogen  for  an  hour,  the  oxygen  evolved  being  caught  in  pyrogallic  acid  and  weighed.  5  speci- 
mens yielded '054  -087,  '025,  -040  and -031^  of  oxygen.  (Chemical  News,  XXXVI..  p.  20.  1877  ) 

I5'5.  It  is  not  definitely  stated  whether*these  represent  Unrecarburized  or  recarburized  com- 
mercial steel.  If.  as  is  strongly  suggested  by  the  context,  they  refer  to  the  latter,  they  must  be 
taken  very  guardedly,  especially  as  Parry  does  not  describe  his  method  of  determining  oxygen. 
(Journ.  Iron  and  St.  Inst.,  1881,  I.,  p.  190.) 

16.  Conditions  and  reference  the  same  as  for  number  1. 

1  7.  Jahrbuch  Berg-  und  Huttenwesen  Konig.  Sachscn,  1883,  p.  21 ;  Handbuch  der  Eisen 
huttenkunde,  p.  276.  See  No.  E,  Table  48. 

18.  "Overblown  burnt  steel  pave  7'4#  iron  oxide."  As  Parry  evidently  regards  the  oxide 
present  as  magnetic  oxide,  this  implies  V'Mf  of  oxygen.  Overblown  steel  is  one  thing;  burnt 
steel  quite  another:  "  overblown  burnt "  steel  literally  means  steel  which  had  been  overblown, 
and  later  had  been  burnt :  I  think  however  that  Parry  here  rcfu-s  to  simply  overblown  metal. 
Journ.  Iron  and  St.  Inst ,  1881, 1.,  p  190. 

The  numbers  in  parentheses  are  calculated  on  the  assumption  that  manganese  reacts  thus: 
Mn  -f-  O  =  MnO  The  corresponding  unenclosed  numbers  are  calculated  on  the  assumption 
that  it  reacts  thus:  Mn  +  Fe3<>4  =  SFeO  +  MnO.  In  both  cases  the  silicon  is  assumed  to  react 
thus  ;—  Si  -(-  SFeO  =  2Fe  +  FeSiOs. 


iron  can  retain  when,  as  in  the  "after  blow"b  of  the  basic 
Bessemer  process,  it  has  an  opportunity  to  saturate  itself, 
is  a  question  of  practical  importance.  Very  different  pro- 
portions are  found  by  the  same  analytical  method  in 
different  specimens  of  after-blown  steel ;  the  proportions 
found  by  different  methods  in  different  specimens  differ 
still  more  widely,  from  '034  indicated  by  Muller' s  data 
and  '111$  found  by  Ledebur,  to  1 '74^  found  by  Tucker. 
"Overblown  burnt  steel,"  whatever  that  may  be,  gave 
Parry  7'4$  of  iron  oxide,  apparently  magnetic,  which 
would  imply  2  '04%  of  oxygen. a  His  method  of  determina- 
tion is  not  stated.  Sources  of  error  inherent  in  these 
methods  can  apparently  account  for  so  small  a  part  of 
these  differences  that  we  may  reasonably  conclude  not 


a  No.  18,  Table  41. 


that  our  methods  are  defective  (indeed  in  cases  3  and  4, 
Table  41,  dissimilar  methods  applied  to  the  same  sample 
give  harmonious  results),  but  that  the  proportion  of  oxygen 
even  in  after-blown1*  steel  varies  within  wide  limits.  We 
know  not  whether  this  is  because  even  in  after-blowing 
the  metal  saturates  itself  but  slowly  with  oxygen,  or 
because  the  power  of  retaining  oxygen  varies  with  the 
temperature  and  other  variables. 

DISCUSSION'  OF  ANALYTICAL  METHODS  AND  RESULTS."— 
In  the  SPIEGEL-REACTION  METHOD  we  deduce  the  propor- 
tion of  oxygen  in  the  blown  metal  from  the  quantity  of 
manganese,  carbon  and  silicon  which  are  oxidized  when  a 
recarburizer  is  added  to  it.  In  seven  spiegel  reactions  de- 
scribed by  Muller  and  in  two  which  I  have  calculated 
from  data  of  Bender  and  King,  from  '034  to  '782$  of  oxy- 
gen react,  if  we  assume  that  the  manganese  acts  thus  ; 

hypothesis  A  ;  Mn  +  FeO  =  Fe  +  MnU  : 
and  from  '089  to  1  '78^  if  we  assume  that  it  acts  thus  ; 

hypothesis  B  ;  Mn  +  Fe3O4  =  3FeO  +  MnO. 
The  apparent  percentage  of  oxygen  found  by  this  method 
is  liable  to  be  exaggerated  by  the  oxidizing  action  of  the 
slag  and  of  the  atmosphere,  and  to  be  depressed  by  the 
mechanical  retention  of  silica  and  of  oxide  of  manganese 
by  the  solidified  metal,  for  these  substances  would  be 
mistaken  in  analysis  for  unoxidized  silicon  and  manga- 
nese. When  the  former  source  of  error  is  eliminated  by 
completely  removing  the  slag  and  recarburizing  in  ingot 
moulds,  Mailer's  data  in  three  cases  imply  from  '034  to 
•254$  of  oxygen  on  hypothesis  A,  and  from  -089  to  '281$ 
on  hypothesis  B:  when  it  is  not  eliminated  I  find  from 
•086  to  '782$  of  oxygen  on  hypothesis  A,  and  from  '394 
to  1'78$  on  hypothesis  B.  Table  42  summarizes  these 
calculations. 

Muller' s  reaction  9  on  hypothesis  A  gives  but  '086  and 
on  hypothesis  B  but  '394$  of  oxygen :  here  the  oxidizing 
action  of  the  slag  had  full  play :  these  numbers  exceed 
those  in  which  it  was  eliminated  (Muller' s  reactions  1,  2 
and  4)  by  so  little  that  we  may  infer  that  its  influence  may 
bo  slight,  at  least  in  the  acid  Bessemer  process. 

Let  ns  now  consider  the  influence  of  the  second  of  the 
above  sources  of  error.  The  quantity  of  silica  and  of 
oxide  of  manganese  which  forgeable  steel  can  retain  is 
probably  small.  In  Muller' s  reaction  1  only  -042$  of  sili- 
con is  present  in  blown  metal  plus  recarburizer,  so  that  the 
depressing  effect  of  silica  may  here  be  neglected.  If  the 
recarburized  steel  retained  even  as  much  as  \%  of  oxide  of 
manganese  this  would  depress  the  apparent  oxygen  by 
only  0'22$ :  so  that  we  may  safely  conclude  that  this  spe- 
cimen of  blown  steel  had  not  much  more  than  '14  -f-  '22  — 
•36 fo  of  oxygen. 

Were  the  recarburized  steel  to  retain  a  portion  of  its 
oxygen  unacted  on  by  the  recarburizer,  this  would  consti- 
tute a  third  source  of  error,  depressing  the  apparent  be- 
low the  true  percentage  of  oxygen.  But  in  the  cases  here 
presented  error  from  this  source  is  probably  not  serious, 
as  each  steel  retains  after  recarburizing  from  -48  to  1  '60% 
of  silicon,  manganese  and  carbon  collectively,  with  which 
a  large  quantity  of  oxygen  could  hardly  coexist. 

It  is  as  yet  uncertain  whether  in  the  spiegel-reaction 

b  In  the  basic  Bessemer  process  as  usually  conducted,  after  the  nearly  complete 
removal  of  the  carbon,  silicon  and  manganese,  much  phosphorus  still  remains:  by 
continuing  the  operation  this  in  turn  is  oxidized,  and  this  portion  of  the  process  is 
termed  the  "  after-blow." 

c  The  methods  here  discussed  are  briefly  described  in  the  note  to  Table  41. 


OXYGEN    IN    MOLTEN    IRON.      §  158. 


93 


TABLE  42. — OXYGEN  ix  OXYGENATED  BKSSKMF.K  MKTAL,  AS  INFEKKKD  KIUIM  TIIK  SIMK<;EI.   UKA<  rm\. 

f  Hypothesis  A  ;  the  reactions  are  Assumed  to  be  Mn  -f  O  =  Mm  t  ;  81  -f-  3FoO  =  2Fe  -f  FeSiOs  ;  C  -f-  O  =  CO.  1 

•'          B;  "  "      Mn  -f  Kc304  =  3FeO  -f-  MnO;  Si -f  tfFcO  =  2Fe  -f-  Fe8K>i;  C  f  O  =  CO.  J 

These  cases  are  numbered  to  correspond  ID  those  in  Table  71) A  and  43 


1, 

2. 

4. 

5. 

6. 

7. 

9. 

10. 

11. 

Observer                                   • 

Muller. 

Muller. 

Muller. 

Miiller. 

M  filler. 

Muller. 

Muller. 

Bender. 

King. 

M  n  C'  and  Si 
removed  by  reaction. 

O     roiTr- 
spondilltf 

Mn  C  and  Si 
removed  by  reaction. 

1)  I-01TI-- 

spondin^ 

n  C  and  Si 
ed  bv  reaction. 

O   corre- 
sponding 

d 

5 

sl 
H£ 
** 

of 

O    corre- 
sponding 

n  r  ami  Si 
•ed  bv  reaction. 

O    corre- 

Spomlilli: 

In  C  and  Si 
•ed  by  reaction. 

O  CO  re- 
sponding 

n  Cam!  Si 
•ed  by  reaction. 

O    corre- 
sponding 

• 

O  «orre- 
Bpondinf,'. 

In  C  and  Si 
veil  by  reaction. 

')      n.nv- 

siMUhlirii: 

By  LvpothesiB 
A. 

<£ 
— 
o    . 

.a' 
£ 

1 

L 

jq' 
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Silicon  removed  

1*2  and  4,  oxygenated  basic  Bessemer  metal,  recarbnrized  in  iron  moulds  to  avoid  the  action  of  the  sla<*  1  was  rec.irburized  with  spiegeleisen,  2  with  ferro-silicon  4  with  terro-silfeo-man- 
ganese.  5  and  6,  oxvjrenated  basic  Bessemer  metal  is  lirst  reearburized  with  '2%  of  ferro-maiifranese  in  the  converter,  and  then  more  fully  rec.irburized  in  iron  moulds,  to  avoid  the  action  of  the  slag, 
No.  5  receiving  spiegeleisen.  No  li  ferro-silicon .  Assuming  that  the  ferro-nianf-ariesc  holds  10%  of  manganese  and  W  of  carbon,  we  find  that  the  following  quantities  of  carbon,  silieon  and  man- 
ganese were  removed  on  the  addition  of  the  first  and  second  recarburizers  respectively. 

. Number  5. .  , Number  6 , 

C*  SI*  Mn*  C*  81*  Mn* 

On  adding  ferro-manganese  there  is  removed '1     ±  1'4    ±  "1     ±  1'4    ± 

On  adding  the  second  recarburizer  there  Is  removed '019  'Oil  — 011  -002  '032  — -036 


Total,  approximately '119  'Oil 

7,  oxygenated  basic  Bessemer  metal  is  recarburized  with  ferro-silicon  and  ferro-manganese  in  the  ladle,  to  diminish  the  action  of  the  slag. 
Ized,  probably  in  the  usual  way  with  spiegeleisen  added  in  the  converter. 


1-389  -102  -082  1'864 

9,10,  and  11,  acid  Bessemer  metal  is  recarbur- 


manganese  acts  in  accordance  with  hypothesis  A  or  B  or 
with,  some  third  formula,  or  sometimes  according  to  one 
sometimes  according  to  another.  Hypothesis  A  gains 
color  from  the  fact  that  the  results  obtained  by  Bender 
with  the  hydrogen  method  accord  with  it :  to  hold  hypo- 
thesis B  we  must  assume  that  Bender  by  the  hydrogen 
method  found  only  about  one-third  of  the  oxygen  pres- 
ent. This  however  is  rather  slender  foundation  for  hypo- 
thesis A,  and  neither  hypothesis  is  excluded  by  the  other 
results  recorded  in  Table  41. a  We  are  also  in  doubt  as  to 
the  formula  in  accordance  with  which  silicon  is  oxidized, 
though  we  probably  err  little  in  assuming  that  it  is 

3FeO  +  Si  =  2  Fe  +  FeSiO3. 

Till  these  formulae  are  known  the  spiegel-reaction  method 
can  only  give  us  a  rough  notion  of  the  percentage  of  oxy- 
gen present  when  the  quantity  of  manganese  reacting  is 
large :  but  when,  as  in  Nos.  1,  2  and  4,  very  little  man- 
ganese reacts,  its  results  should  not  be  far  wrong.  It  is 
difficult  to  believe  that  in  these  cases  anything  approach- 
ing the  1  -74%  of  oxygen  found  by  Tucker  can  have  been 
present. 

HYDROGEN  MKTIIOD. — It  may  be  held  that  in  the  30  to 
60  minutes  usually  employed  hydrogen  is  not  likely  to 
completely  remove  oxygen  from  the  interior  of  the  parti- 
cles of  even  fine  iron  filings :  we  are  led  to  hope  that  this 
source  of  error  need  not  be  serious  by  the  fact  that  the 
hydrogen  method  gave  Bender  (Xos.  3  and  4,  Table  41) 
almost  the  same  result  as  the  spiegel-reaction  method : 
but  these  two  methods  here  support  each  other  but  feebly. 
In  view  of  the  small  percentage  of  oxygen  found  by  the 
latter  method  in  Muller' s  reactions  1  and  4,  which  cannot 
be  far  wrong,  serious  suspicion  of  Ledebur's  hydrogen- 
method  results  (No.  2,  Table  41),  low  as  they  are,  is  hardly 
justified. 

TUCKER'S  METHOD. — The  proportion  of  oxygen  found 
by  this  method  in  afterblown  steel,  •.  8  to  1  -74$,  is  much 
higher  than  those  which  I  have  met  obtained  by  the  hydro- 

a  This  question  could  easily  be  settled  by  recarburizing  different  portions  of  the 
same  afterblown  metal  (1)  with  pure  carburetted  ircu,  (~)  with  very  rich  ferro- 
manganese  and  (3)  with  very  rich  ferro-silicon. 


I 


gen  method,  or  by  the  spiegel  reaction  method  if  inter- 
preted by  hypothesis  A :  but  the  latter  method  on  hypoth- 
esis B  finds,  in  Mailer's  reactions  5  and  ti,  1'79  and  1'1Q% 
of  oxygen. 

Of  the  three  sources  of  error  which  suggest  themselves 
in  connection  with  Tucker' s  method  none  is  likely  to  have 
had  serious  influence.  1.  Its  results  might  possibly  be 
slightly  depressed  by  absorption  of  gases  from  the  atmos- 
phere :  but  they  are  so  high  that  suspicion  of  having  been 
depressed  does  not  aris?.  2.  They  might  be  exaggerated 
by  the  expulsion  from  the  molten  metal  of  hydrogen,  ni- 
trogen, carbonic  oxide  and  sulphur  initially  present  along 
with  the  oxygen  :  but  the  proportion  of  sulphur  in  after- 
blown  basic  steel  is  small,  and  the  largest  recorded  pro- 
portions of  the  three  other  substances  which  I  have  met 
in  commercial  irons,  say  '01,  '06  and  '05%  respectively, 
would  collectively  affect  Tucker's  high  results  but  slightly, 
would  explain  but  a  fraction  of  the  difference  between  his 
and  Ledebur's.  3.  They  might  possibly  be  exaggerated 
by  the  removal  of  manganese,  silicon,  etc.:  but  these  ele- 
ments are  almost  completaly  absent  from  afterblown  steel. 
Further,  the  facts  that  when  applied  to  steel  reasonably 
believed  to  be  approximately  free  from  oxygen  it  indi- 
cated the  presence  of  but  '02$  of  that  element ;  that,  ap- 
plied to  steel  mixed  with  a  known  weight  of  oxide,  its  re- 
sults "  left  nothing  to  be  desired"  ;  and  that  they  are  har- 
monious, '064,  '062  and  "u66$  of  oxygen  in  a  sample  of 
burnt  steel,  and  1'7J,  T74  and  1'69$  in  one  of  blown 
metal,  furnish  positive  evidence  of  good  character.  Hence 
I  infer  that  the  steels  treated  by  Tucker  probably  con- 
tained an  unusual  proportion  of  oxygen  :  it  is  hardly  con- 
ceivable that  the  steel  in  which  he  found  from  1-(J9  to 
1-74$  of  oxygen  should  actually  have  held  anything  like 
as  little  as  those  in  which  the  spiegel-reaction  method 
finds  at  most  '089  and  -124$,  and  those  in  which  the  hy- 
drogen method  finds  but  •11@<12^,  making  all  possible  al- 
lowances and  supposing  that  all  the  possible  errors  com- 
bined to  swell  the  apparent  percentage  in  one  case  and  to 
depress  it  in  the  others. 

To  SUM  Ur,  while  none  of  these  methods  inspires  abso- 


94 


THE    METALLURGY     OF     STEEL. 


lute  trust,  we  yet  have  strong  reasons  for  believing  that 
the  results  of  Tucker's  method  closely  approximate  the 
truth,  and  no  serious  reason  for  believing  that  those  of 
the  hydrogen  method,  or  of  the  spiegel-reaction  method 
when  but  little  manganese  and  silicon  react,  are  far  wrong. 
But,  when  much  manganese  enters  into  the  reaction,  the 
uncertainty  as  to  whether  hypothesis  A  or  B  be  correct 
leaves  the  latter  method  no  pretence  to  accuracy. 

§  159.  OXYGEN  WITH  CARBON. — Though  carbon  silicon 
and  manganese  remove  oxygen  from  molten  steel,  a  small 
proportion  of  these  elements  and  of  oxygen  may  coexist :  it 
is  stated  that  '1  to  '%%  of  carbon  and  as  much  manganese 
can  exist  with  some  hundredths  of  one  per  cent  of  oxygen, 
while  the  coexistence  of  very  considerable  quantities  of 
oxygen  and  a  little  carbon  is  illustrated  by  Table  43. 
Muller  describes  thoroughly  blown  steel  which  contained 
•605$  of  silicon :  that  it  simultaneously  contained  oxygen 
is  inferred  from  the  violent  development  of  carbonic  oxide 
on  subsequently  adding  spiegeleisen  to  it.a 


a  Iron,  1883,  p.  18. 


TABLE  43.— OXYGEN  WITH  CARBON,  ETC.,  IN  IRON. 
(This  table  is  numbered  to  correspond  with  Tables  70  A  and  42.) 


1 

B 
& 

A... 
B.. 
C  .. 
1.. 

? 

Description. 

Mode    of  deter- 
mining   oxygen. 

Composition. 

0. 

C. 

•037 
•123 
•051) 
•029 
•IKS 

Si. 

•001 
0 
0 
•016 

•  ; 

Mn. 

P. 

•038 
•077 
•085 

S. 

•059 
•Ui>S 
•057 

Cu. 

•046 
•095 
•061 

Ni. 
and 
Co. 

•064 
•140 

•no 

Afterblown  basic  metal  
"      Ledebur. 

•244 
•187 
•171 
118a 
•2Ma 

0 
tr 
0 

•iss 
•Kin 

"      Muller.  .. 

Spiegel-reaction. 

4 
T.  . 
9.. 

10.. 
11.. 
D.. 
E.. 

Decarburized  acid  Bessemer  metal; 
Muller  

«(          t< 

ii          ii 

034a 
•782a 

•086a 
•898a 
•438a 

•041 
•177 

•033 
•002 

•046 
•08 
•034 

•039 
•052 

•021 

•002 

•122 

•212 
•083 

•248 

•07S 

Decarburized  acid  Bessemer  metal; 
Bender  

Recarburized  acid  Bessemer  metal: 
King..   . 

•din 

•014 
0 

•10 

•858 
0 

Partly  recarburized  basic    Besse- 
mer metal  ;  Muller.  .   
Weld  metal  ;  Ledebur. 

•223 

tr' 

:450 

:i,57 

a  Calculated  on  hypothesis  A  ;  on  hypothesis  B  the  percentage  of  oxygen  is  larger.  See  head- 
ing to  Table  42. 

A.  B,  C,  Handbueh  der  Eisenhuttenkunde,  p.  276.  Nos.  1  to  11 ,  see  corresponding  numbers 
in  Table  70  A.  D,  Stahl  und  Eisen,  IV.,  p.  72,  1884. 


§  160.  CORROSION  OF  IRON. — The  readiness  with  which 
iron  oxidizes,  familiar  to  all  through  its  exasperating  prone- 
ness  to  rust,  deemed  a  token  and  penalty  for  the  blood  it 


TABLE  44.— Loss  OF  IRON  BY  CORROSION,  IN  POUNDS  Pnu  SQUARE  FOOT  OP  SURFACE  PER  ANNUM. 


Number. 

Observer. 

Metal. 

Exposed  to 
weather. 

Immersed  in  cold 
pure  sea  water. 

Immersed  in  cold 
foul  sea  water. 

Immersed  in  hot  sea 
water. 

Immersed  in 
fresh  water. 

Immersed  in  cold  sea  water  in 
voltaic  contact  with 

In 

acidulate' 
water. 

Uneon- 
flned. 

Con- 
fined. 

Sewage 
bear- 
ing. 

Bilge 
water. 

P.  and  O. 
steamer. 

Boiler 
with 
zinc. 

Boiler 
impure 
water. 

$l& 
Ifil 

Pure 
river. 

Foul 
river. 

<i 
*j  — 

10     W  M 

.tog  S 
K  %~ 

Scale- 
bearing 
iron. 

Copper 

Bronze 

1.. 

2.. 
8.. 
4. 
B. 
6.. 
T.. 
8.. 
11 

Mallet. 
Andrews. 

Green  sand. 
Chilled, 
Planed, 
Painted. 
Standard, 
Aver,  of  17, 
Zinced. 
Steel,  average 
Cast-iron 

Cast-iron  J 

Wrought-iron.  -j 
of  7  

•059 
•02 
•098 
•013 
•081 
•188 
0 
•117 

•069 
•073 
•098 
•082 
•089 
•121 
•089 
•107 

:208 
•215 
•198 
•207 
•168 
•198 
•225 
•173 
•212 
1-45 
2-07 
2-90 

•OSS 
•024 
•023 
•019 
•022 
•021 
•081 
•027 
•024 
•025 

•078 
•064 
•258 
•183 
•128 
•215 
•088 
•214 

•063 
•117 
•270 
•048 
•277 

•01 
•01 
012 
•010 
•021 
•018 

•028 
•029 
•080 
•060 
•057 
•158 

•22 

•88 

•44 

•58 

.... 

•OOK 
•013 

•041 
•125 

•036 
•080 

•086 

•J22 

12.. 
18.. 
14.. 
15.. 
16.. 
17.. 
18.. 
19.. 
20.. 
23 
24.. 
27.. 
28.. 
29.. 
80.. 
81.. 
82.. 
83 
34.. 
85.. 
36 
37.. 
88.. 
89.. 
40.. 
41.. 
42.. 
43.. 
44.. 
45.. 
46.. 
47.. 

Parker. 

Gruner. 

(i 

Farqu- 
barson. 

Thwaite's 
averages. 

M 

Wrought-iron 

•053 

•118 

Bessemer,       )                           ( 
Open-hearth.  >  Soft  steel  -( 
Crucible.        (                          j 
Bessemer,      \                         i 
Open-hearth,  VHard  steel..  ..-< 
Crucible.         j                         1 
Landore,                      ~\ 
Brown,                           Igoft     1 
Bolton,                           fatcel.] 
Steel  Co.  of  Scotland.  J 
Taylor,       •) 
Leeds.        1 
Bowling,     [•  Wrought-iron...-! 
Farnley, 
Lowmoor,  J 
Grey,                 "1 

Sp'logeletaen,     [  Cast-iron....  | 
Charcoal. 
Soft  steel,  1 

:206 
•254 
•214 
•222 
•169 
•155 
•150 
•167 
•166 
28®  -87 

•56®'75 

•085 
•036 
•086 
•086 
•081 

•059 
•073 
•081 
•060 
•070 

•108 
•074 
•109 
•111 

•117 

•480 
•560 
•544 
•509 
•475 
•527 
•518 
•578 
•589 

•284 
•810 
•250 
•258 
164 
•191 
•198 
•217 
•209 

•120 
•147 
•117 
•182 
•061 
•066 
•052 
•069 
•087 

•666 
•755 
•785 
•789 
•609 
•657 
•598 
•708 
697 

19-87 
11-12 
1-87 
1 
12@-50 
1@1'S7 
2 
5-12 

•41@'83  | 

•118 
•126 
•121 
•107 
•070 
•089 

| 

Manganese  st 

1  Wrought-ir 
"I  Soft  steel  . 

eel  annealed...  f 
'     hardened.  J 
>n  

•22 
•046 

1  Wronght-ir 
I  Steel,  misce 
1  Cast-iron  . 
I        "      gal 

>n  

•188 
•1ST 
054 

.  -022 

•215 
•214 

•072 
•088 

ian  rous  

ranized  

.... 

I  to  8.  Five  apparently  exactly  similar  sets  of  specimens,  each  consisting  of  11  pieces  of  green-sand  castings,  5x5x1,  apparently  retaining  their  skin,  6  of  them  unprotected  (No.  1),  5  of  them 
painted  or  varnished  (No.  4);  5  specimens  of  unprotected  chilled  cast-iron  5  X  5  X  Ii  four  of  them  differing  from  four  of  the  preceding  only  in  being  chilled  (No.  2);  1  of  unprotected  gray  cast-iron 
(No.  3)  with  its  skin  removed  by  planing;  and  1  of  unprotected  wrought-iron  (Ne.  5)  about  5  x  3  X  0'875.    These  were  exposed  as  follows.    (1)  In  clear  sea  water  at  46°  to  58°  F.  for  732  days:  (2) 
In  foul  sea  water,  close  to  the  mouth  of  the  Great  Kingston  main  sewer  at  46°  to  58°  F.  for  732  days.  (3)  In  pure   sea  water  at  115°  F.,  for  117  days:  (4)  In  clear  unpolluted  water  of  the  Iliver  Liffey, 
at  32°  to  68°  F.  for  732  days:  (5)  In  foul  river  water  with  much  organic  matter,  in  the  same  river  at  Dublin,  the  bottom  soft  putrid  mud,  temperature  36°  to  Cl°  F.,  for  732  days:  (6)  To  the  weather  on 
the  summit  of  an  exposed  building  in  Dublin,  for  539  days.    In  addition  these  were  simultaneously  exposed  to  condition  (1)  64  pieces  of  unprotected  green-sand  cast-iron,  apparently  retaining  their 
skin,  and  mostly  either  5"  X  5"  X  1"  or  6"  X  5"  X  0.25"  (No.  1);  and  to  all  the  conditions  except  (3)  apparently  exactly  similar  sets  each  consisting  of  17  pieces  of  wrought-iron  of  various  kinde 
(No.  6),  7  of  steel  (No.  8)  (blister,  shear,  spring,  etc.,  apparently  all  of  high-carbon  steel)  and  one  of  galvanized  wrought-iron  (No.  7).  all  except  the  last  apparently  unprotected.     Moreover,  bars  of 
the  ''standard  "  wrought-iron  (No.  5)  were  immersed  in  cold  sea  water  in  contact  with  copper,  zinc,  and  various  brasses  and  bronzes  (i.  e.  copper-zinc  and  copper-tin  alloys).     [Tables  III.  and 
VII.,  pp.  286,  299,  Kept  British  Asso.,  1840;  Tables  I.  to  XIII.  inclusive,  pp.  30  to  51.  Idem,  1843.] 

I 1  to  £O.   Thomas  Andrews,  Proc.  Inst,  Civ.  Engrs..  LXXXII.,  p.  281,  1885.    In  these  experiments  the  metal  was  immersed  in  confined  cold  sea  water  in  glass  or  wooden  vessels,  the  sea  water 
being  generally  changed  every  month  and  the  los;.  by  evaporation  being  frequently  made  good  by  addition  of  distilled  water.     In  every  ca>e  the  rusting  proceeded  very  much  more  slowly  than  in  the 
experiments  of  other  observers  in  which  the  water  was  unconfined.    This  suggests  that,  by  the  reaction  between  the  metal  and  the  sea  water,  the  latter  rapidly  loses  its  corrosive  power.    Should  this 
be  true,  it  might  possibly  betaken  advantage  of  by  preventing  the  circulation  of  the  sea  water  surrounding  important  submerged  structures.    The  simple  immersion  in  cold  sea  water  lasted  878 
days:  that  in  contact  with  bright  wrought  iron  plates  lasted  770  days:  those  in  contact  with  scale-bearing  iron  plates  and  with  copper  plates  each  112  days.      These  are  the  periods  at  the  ond  of  which 
the  results  in  Table  44  were  obtained.      In  certain  cases  the  experiments  were  further  prolonged,  with  results  on  the  whole  similar  to  those  here  given.      If  I  understand  him  correctly,  the  results  in 
the  column  headed  "  Scale-bearing  iron"  are  the  losses  suffered  by  bright  iron,  etc.,  when  a  bright  plate  of  each  kind  was  galvanically  connected  with  a  similar  but  scale-bearing  plate  of  the  same 
metal,  each  of  tliese  couples  being  immer&ed  in  a  separate  jar,  and  all  being  coupled  together  in  series. 

43  to  33.  Parker,  Journ.  Iron  and  St.  Inst ,  1881,  I  .  p.  39      On  each  of  six  glass-coated  rods  were  placed  22  discs  4'5  inches  in  diameter  and   about  0*05  inch  thick.    Each  set  contained  one 
bright  and  or,e  scale-bearing  disc  from  each  of  seven  lots  of  wrought-iron  and  of  four  lots  of  rnfld  steel,  from  11  different  makers.    The  results  obtained  with  two  lots  of  "  common  "  wrought-iron  are 
omitted  in  the  table.    One  set  was  suspended  for  455  days  on  a  London  roof :  a  second  was  attached  under  water  to  the  Brighton  pier  for  437  days:  a  third  was  submerged  for  240  days  in  bilge  water 
in  an  Eastern  trading  vessel.    Threo  sets  were  submerged  in  marine  boilers,  one  of  which  contained  zinc  and  was  blown  off  as  seldom  as  possible;  the  immersion  lasted  3G1  days:  the  M-eond  was  in  a 
"  IN-ninsular  and  Oriental"  steamship,  and  was  blown  out  at  each  terminal  port  and  filled  afresh  with  salt  water;  the  immersion  lasted  264  days:  the  third  was  in  a  steam  collier  using  Tyne  water, 
probably  acidulated  by  local  chemical  works;  the  immersion  lasted  836  days      In  this  boiler  corrosion  was  extremely  rapid,  both  for  iron  and  steel. 

34  to  41.  Gruner,  Revue  Universelle,  XIII.,  p.  659,  1SS3,  Twenty-eight  polished  plates  of  steel  and  cast-iron  of  different  degrees  of  hardness  and  purity,  each  3'937  inches  square,  were  exposed 
under  three  sets  of  conditions.  One  set  was  exposed  to  moist  air  for  20  days,  a  second"  was  immersed  in  sea  water  for  9  days,  a  third  was  immersed  in  water  acidulated  with  0  5£  of  concentrated  sul- 
phuric acid  for  three  days.  In  air  chrome  steels  corroded  more  and  tungsten  steel  less  than  common  steel.  In  sea  water  hardened  steels  corroded  less  than  the  same  steels  when  annealed,  the  soft 
steels  less  than  the  manganese  and  chrome  steels,  and  tungsten  steel  less  than  common  steel  of  like  carbon  content.  It  will  be  noticed  that  in  these  experiments  the  corrosion  is  very  much  more  rapid 
than  in  the  others,  possibly  because  the  exposures  wer  j  BO  brief.  These  results  are  so  unexpected  that  if  published  by  a  less  trustworthy  author  they  might  be  questioned. 

42,43.  Farquharson,  Journ.  Iron  ami  St.  Inst., '882, 1.,  i».  204:  Proc.  Inst.  Nav.  Architects  April,  1882.  His  results  differ  from  those  of  Andrews  in  that  the  rusting  of  steel  was  greatly 
retarded  while  in  Andrews'  experiments  it  was  very  slightly  hastened  by  contact  with  wrought-iron.  In  both  the  rusting  of  wrought-iron  is  hastened  by  contact  with  steel.  Six  plates  of  wrought- 
iron  and  six  of  steel  were  immersed  in  sea  water  in  F-ort=^o"th  harbor.  England,  for  six  months,  three  of  each  being  simply  immersed,  the  remaining  three  being  coupled  together  *n  pairs,  each 
wrought-iron  plate  being  coupled  to  one  of  steel.  The  steel  was  apparently  soft. 

44  1"  47.  Avenges  deduced  by  II.  II.  Thwaite  from  several  thousand  results  of  Mallet,  Calvert  and  others.     Journ,,  Iron  and  St.  Inst,,  1SSO,  II.,  p.  668. 
The  composition  of  Parker's  and  Andrews'  steels  is  given  in  Table  47,  §  164. 


CORROSION    OF    IRON,     INFLUENCE    OF    DIFFERENT     MEDIA. 


163. 


with  the  fineness  of  its  subdivision,  and  with  the  tempera- 
ture. It  is  affected  by  contact  with  substances  of  differ- 
ent potential,  zinc  and  highly  zinciferous  brasses  retard- 
ing, bronzes,  copper,  tin,  lead  and  iron  scale  hastening 
corrosion.  While  it  is  doubtless  affected  by  the  metal' s 
composition,  we  have  as  yet  very  little  information  as  to 
what  compositions  favor  and  what  oppose  corrosion. 
Skin-bearing  cast-iron  resists  corrosion  better  than 
wrought-iron  and  steel,  and  the  hard  close-grained  cast- 
irons  better  than  the  softer  and  more  open  ones.  If  its 
skin  be  removed,  however,  cast-iron  cannot  yet  be  said  to 
resist  corrosion  better  than  malleable  iron.  Nor  can  we 
say  which  class  of  malleable  iron  resists  corrosion  best : 
soft  steel  plates  are  thought  to  retain  their  scale  more 
tenaciously  than  wrought-iron,  which  hastens  their  corro- 
sion :  if  this  be  removed  there  is  probably  no  important 
difference  in  the  rates  at  which  they  corrode. 

Individual  peculiarities  of  the  specimens  experimented 
on  and  slight  differences  in  the  conditions  affect  the  rapid- 
ity corrosion  to  an  astonishing  degree  ;  this  necessitates 
extreme  caution  in  drawing  inferences  from  even  direct  com- 
parative tests  :  accurate  conclusions  can  only  be  drawn 
from  the  averages  of  many  determinations.  Moreover, 
the  relative  corrosion  of  two  classes  of  iron  under  one  set 
of  conditions  gives  no  safe  indication  as  to  what  it  will  be 
under  another  set. 

The  chief  ulterior  sources  of  the  oxidation  of  iron  are 
atmospheric  oxygen,  free  or  dissolved  in  water,  its  own 
oxides  (sometimes  as  in  puddling  and  pig  washing  ulte- 
rior sources,  sometimes  as  in  Bessemerizing  mere  carriers 
of  oxygen),  and  more  rarely  water. 

Table  44  condenses  the  results  obtained  by  several  ex- 
perimenters, as  regards  the  rate  of  corrosion  of  various 
classes  of  iron  under  different  conditions. 

§161.  INFLUENCE  OF  SURFACE  EXPOSURE; 
ISM. — Finely  divided  iron,  e.  g.  that  prepared  by  reducing 
precipitated  ferric  oxide  by  hydrogen,  is  said  to  be 
pyrophoric  when  quite  cold ;  that  made  in  Percy's 
laboratory,  however,  would  only  ignite  when  sensibly 
warm  to  the  hand,  and  sometimes  only  when  heated 
above  100°  C.  Dropped  into  hot  air  it  burns  brilliantly. 
In  pure  water  from  which  air  is  excluded  it  is  not  oxidized 
at  21°  C  (70°  P.)  and  it  is  said  to  begin  to  oxidize  at  55°  C. 
(131°  F.).a 

§  162.  INFLUENCE  OF  TEMPERA TUKE. — Pure  dry  oxygen, 
inert  on  compact  iron  at  21°  C.  (70°  F.)  is  said  to  begin  to 
oxidize  it  appreciably  at  or  above  200°  C.  (392°  F.):  at 
redness  they  unite  with  vivid  incandescence. 

ATMOSPHERIC  OXYGEN  at  a  white  heat  burns  .ron  vivid- 
ly, with  marked  rise  of  temperature,  especially  if  blown 
upon  it.     At  a  still  higher  temperature  compact  iron  scin- 
tillates as  it  burns  in  air. 
PURE  WATER  deprived  of  air  appears  to  be  absolutely 


Steam  converts  iron 
even    at    about    the 


has  shed,  in  general  increases  with  its  heterogeneousness,  inert  even  on  finely  divided  iron  at  21°  C.  (70°  F.),b  and 

on  compact  iron  even  at  100°  C.c 
superficially  into  magnetic  oxided 
melting  point  of  lead,  and  at  and  above  redness  this  ac- 
tion goes  on  rapidly. 

COMMON  PURS  FRESH  WATER,  containing  dissolved  air, 
in  very  shallow  open  vessels  attacks  iron  more  rapidly  at 
100°  C.  than  at  a  lower  temperature  according  to  Mallet : 
but,  presumably  in  comparatively  deep  vessels  to  which 
air  has  less  ready  access,  it  corrodes  fastest  between  79° 
and  88°  C.  (175  and  190°  F.),c  probably  because  at  higher 
temperatures  the  water  contains  comparatively  little  car- 
bonic acid  and  free  oxygen. 

ORDINARY  SEA  WATER  does  not  appear  to  corrode  iron 
materially  faster  when  hot  or  even  boiling  than  when 
cold  (Table  44), e  perhaps  because  when  hot  it  can  dis- 
solve but  very  little  air.  In  many  direct  comparative  tests 
hot  sea  water  corrodes  iron  faster,  in  many  others  slower 
than  cold  sea  water.  In  one  set  of  exposures  (Parker's) 
every  one  of  the  nine  specimens  which  were  immersed  in 
boiling  sea  water  in  a  boiler  containing  zinc,  corroded 
much  less  rapidly  than  the  exactly  similar  ones  in  cold 
pure  sea  water,  and  even  much  slower  than  those  simply 
exposed  to  the  weather.  It  is  not  clear  how  the  zinc  acted 
here :  the  usual  conditions  of  galvanic  action,  actual  con- 
tact or  connection  through  some  metallic  conductor,  were 
lacking,  for  the  iron  discs  were  completely  insulated : 
there  was  no  communication  between  iron  and  zinc  save 
through  the  sea  water  itself,  which  indeed  is  a  much  bet- 
ter conductor  than  fresh  water.'  The  corrosion  of  the 
zinc  may  have  satisfied  the  more  actively  corroding  com- 
ponents of  the  water,  or  the  salts  of  zinc  may  have  them- 
selves retarded  the  corrosion  of  the  iron. 

If,  as  Mallet  implies, g  hot  sea  water  attacks  galvanized 
iron  more  energetically  than  cold,  it  is  probably  because 
it  is  the  more  destructive  towards  its  zinc  coating. 

163.  INFLUENCES  OF  DIFFERENT  MEDIA.  A  s 
GENERAL. — Neither  pure  oxygen  nor  water  nor  carbonic 
acid  alone,  nor  oxygen  with  carbonic  oxide  appears  able 
to  start  rusting  at  the  prdinary  temperature.  But  either 
oxygen  and  water  or  carbonic  acid  and  water  can  start  it. 
The  action  of  deposited  and  indeed  of  liquid  water  in 
general  is  far  more  energetic  than  that  of  vapor  of  water, 
and  the  degree  of  concentration  of  the  carbonic  acid  and 
oxygen  influence  the  power  of  starting  rust.  Thus  the  di- 
luted oxygen  and  carbonic  acid  of  the  atmosphere  when  in 
conjunction  with  liquid  water  are  able  to  start  rusting,  but 
apparently  not  when  simply  acting  with  the  undeposited 
aqueous  vapor  of  the  atmosphere  ;  either  pure  oxygen  or 
pure  carbonic  acid  may  produce  slight  rusting  with  aqueous 
vapor  even  when  no  water  appears  to  be  deposited  ;  while 
with  liquid  water  pure  oxygen  energetically  attacks  iron 
at  the  ordinary  temperature.  In  ordinary  cases  rusting  is 
probably  induced  by  the  joint  action  of  the  atmospheric 


a  Percy,  Iron  aud  Steel,  p.  13. 

This  pyropborism  has  been  ascribed  to  the  condensation  of  hydrogen  employed 
for  deoxidizing  in  the  pores  of  the  spongy  iron,  which,  like  spongy  platinum,  is 
thought  to  determine  the  union  of  this  gas  with  atmospheric  oxygen  :  nor  is  this 
disproved,  as  has  been  thought,  by  the  fact  that  the  mixture  of  spongy  iron  and 
ferrous  oxide  which  is  obtained  by  igniting  ferrous  oxalate  in  closed  vessels,  is 
also  pyrophoric:  for,  if  this  bo  free  from  hydrogen,  may  not  its  pyrophorism  be  as- 
cribed to  the  finely  divided  unstable  ferrous  oxide  which  it  contains »  The  influ- 
ence of  surf  ace  exposure  is  perhaps  illustrated  by  the  fact  that  while  finely  divided 
iron  ceases  to  be  pyrophoric  if  previous  to  exposure  to  the  air  it  is  heated  beyond 
427°  C.,  yet  if  intimately  and  uniformly  mixed  with  3$  of  silica  or  alumina,  which 
should  protect  its  porosity,  it  is  pyrophoric  even  if  reduced  at  a  red  heat, 


»>  Percy,  Iron  and  Steel,  p.  26. 

c  Mallet,  Kept.  Brit.  Ass.,  1840,  p.  229. 

d  Idem,  1843,  p.  12.  It  is  not  stated  whether  this  occurs  when  the  steam  is 
wholly  free  from  air. 

"  Mallet  states,  Idem,  1840,  p.  226,  that  cast-iron  corrodes  more  rapidly  at  46" 
!.  (115°  F.)  than  at  8'@14°  C.  (46°  @  58°  F.).  I  cannot  reconcile  this  with  his  nu- 
merical results  (Table  44).  Eight  out  of  12  specimens  of  cast-iron,  of  which  1 1  ap- 
>arently  retained  their  skin,  oxidized  more  rapidly  in  cold  than  hot  sea  water, 
he  average  loss  being  30$  greater  in  the  former. 

t  The  electric  resistance  of  distilled  water  is  about  2,300  times  as  great  as  that 
if  a  saturated  solution  of  sodium  chloride, 

gldem,  1843,  p.  13, 


96 


THE    METALLURGY    OF    STEEL. 


oxygen  and  carbonic  acid  with  deposited  or  ordinary 
liquid  water.  These  two  gases  are  usually  present  in  both 
fresh  and  salt  water :  if  they  be  absent  iron  immersed  in 
water  remains  bright  indefinitely. 

Thus  Percy  found  that  bright  iron  gave  no  sign  of  rust- 
ing even  after  one  or  two  years,  when  immersed  in  boiled 
distilled  water  in  a  sealed  tube  containing  hydrogen,  and 
that  the  fractures  of  iron  in  the  often  opened  cases  of  the 
London  museum  of  practical  geology  remained  perfectly 
bright  during  twelve  years,  which  he  ascribes  to  the  com- 
plete prevention  of  dew  by  the  method  employed  for 
warming  the  museum.*  Mallet  too  found  that  fresh 
water  deprived  of  air  did  not  corrode  iron  in  a  closed 
vessel,  even  at  100°  C.b 

Calvert,  exposing  clean  iron  blades  for  four  months 
under  different  conditions,  obtained  the  following  re- 
sults :° 

TABLE  45. —CALVERT'S  EXPERIMENTS  ON  RUSTING. 

In  dry  oxygen  and  ammonia No  oxidation. 

41  damp    '*  

dry  oxygen  alone " 

damp  oxygen i  In  thrco  experiments  only  one  blade  slightly 

'  dry  carbonic  acid No  oxidation. 

•  damp  carbonic  acid  I  In  4  out  of  S  cases  a  slight  precipitate  of 

I     iron  carbonate  formed. 

•  dry  carbonic  acid  and  oxygen No  oxidation. 

(  Ox'dation  most  rapid,  ft  few  hours  suffic- 
"  damp  carbonic  acid  and  oxygen -^     ing  :  iron  turned  dark-green,  then  brown- 


(  OxMatior 

.  -!     ing  :  in 

(     ochre. 


In  a  bottle  containing  distilled  water  and  oxygen,  the 
submerged  portion  of  a  clean  iron  blade  rapidly  rusted, 
the  protruding  part  remained  for  weeks  unoxidized  :  but 
when  the  oxygen  was  mixed  with  carbonic  acid  the  pro- 
truding part  as  well  rapidly  "  showed  the  result  of  chem- 
ical action." 

The  influence  of  air  on  rusting  is  further  indicated  by 
the  facts,  elsewhere  alluded  to,  that  hot  sea  water,  in  spite 
of  being  hot  and  in  spite  of  its  high  electric  conductivity, 
usually  corrodes  iron  no  faster  than  when  cold,  apparently 
because  it  has  so  little  solvent  power  for  air :  and  that 
Mallet's  experiments  convinced  him  (1)  that  fresh  water 
corrodes  iron  most  rapidly  at  from  175°  to  190°  F.,  which 
is  approximately  the  temperature  at  which  it  releases  its 
dissolved  air  most  rapidly  ;  (2)  that  the  rate  of  corrosion 
in  water  is  directly  proportional  to  the  volume  of  dissolved 
air  for  given  temperature  ;  and  (3)  that  for  given  initial 
proportion  of  dissolved  air,  the  rate  of  corrosion  in  still 
water  is  inversely  as  the  depth  of  immersion  within  limits, 
as  is  naturally  the  proportion  of  air  which  diffuses  down- 
ward to  replace  that  consumed  by  the  corrosion.*1 

Rust  ordinarily  contains  but  little  carbonic  acid,  (Calvert 
found  but  "9  and  '617$  of  iron  carbonate  in  two  specimens), 
whose  role  in  the  oxidation  of  iron  is  not  clear.  It  may 
simply  start  the  rust :  or  the  iron  may  first  form  carbonate, 
which  later  turns  to  hydrated  ferric  oxide. 

B.  SUBAEEIAL  RUSTING,  as  we  have  seen,  is  probably 
not  induced  by  the  atmospheric  oxygen  and  carbonic  acid 
without  the  intervention  of  deposited  water :  but  once 
started  it  appears  to  proceed  without  further  deposition 
of  water,  iron  rust  being  so  strongly  electro-negative  as  to 
determine  oxidation,  and  acid  fumes,  sulphuretted  hydro- 
gen, chlorine,  etc.,  suffice  to  start  it  without  deposition  of 
water. 


a  Percy,  Iron  and  Steel,  pp.  26,  27. 

h  Mallet,  Kept.  Brit.  Ass.,  1840,  p.  289. 

c  Journ.  Iron  and  St.  Inst.,  1871,  I.,  p.  615,  fr.  Trans.  Manchester  Lit.  and 
Phil.  Soc. 

d  Mallet,  Rept.  Brit.  Ass.,  1840,  pp.  228-9.  It  is  not  clear  how  far  these  con- 
clusions are  based  on  direct  comparative  tests,  and  how  far  on  general  observa- 
tion and  a  priori  reasoning. 


While  subaerial  rusting  is  probably  very  much  slower 
than  subaqueous  in  cold  dry  climates,  yet  as  the  amount 
of  corrosion  is  probably  nearly  proportional  to  the  time 
that  the  iron  is  actually  wet  by  the  weather,  as  dew,  rain 
and  snow  appear  to  be  very  highly  charged  with  oxygen 
and  carbonic  acid,  and  as  the  thinness  of  the  film  of  water 
on  objects  exposed  to  the  weather  is  so  favorable  to  rapid 
rusting,  (iron  covered  with  a  thin  film  of  water  or  ' '  wet 
and  dry"  rusts  very  much  faster  than  when  deeply  im- 
mersed), it  is  hardly  surprising  that  Table  44  contains  many 
instances  of  corrosion  by  pure  sea,  and  by  both  pure  and 
foul  fresh  water,  which  are  less  than  the  corresponding 
weather  corrosions.  But  as  this  wet  and  dry  condition 
which  favors  the  corrosion  of  iron  so  greatly  is  not  espe- 
cially injurious  to  coatings  applied  to  protect  it,  so  when 
zinced,  painted  or  varnished,  iron  appears  from  Mallet's 
experiments  (4  and  7,  Table  44)  to  rust  much  less  when 
exposed  to  the  weather  even  in  damp  climates  than  when 
immersed  in  sea  water,  but  yet  usually  more  than  in  pure 
river  water. 

Iron  ships  are  found  to  corrode  more  deeply  along  the 
water  line  than  where  constantly  wet  or  constantly  dry, 
illustrating  the  power  of  this  wet  and  dry  state  to  accelerate 
rusting. 

C.  SUBAQUEOUS  RUSTING. — The  much  smaller  propor- 
tion of  air  and  carbonic  acid  which  sea  water  usually  con- 
tains tends  to  render  it  less  corrosive  than  common  fresh 
water  ;  but  this  is  probably  in  most  cases  outweighed  by 
influence  of  the  higher  electric  conductivity  and  of  the 
saline  contents  of  sea  water.8 

The  ratio  of  its  corrosive  action  to  that  of  fresh  water 
on  various  kinds  of  wrought-iron,  cast-iron  and  steel,  ac- 
cording to  Mallet's  numerous  direct  determinations,  while 
it  occasionally  rises  to  20 : 1  and  falls  to  2'5 : 1,  yet  in  gen- 
eral lies  with  rather  surprising  regularity  between  about 
6  : 1  and  9  : 1. 

D.  SEWAGE,  ETC.,  according  to  Mallet's  experiments, 
greatly  increases  the  corrosive  action  of  fresh  water,  and 
rather  more  for  wrought  than  for  cast-iron.       It  also 
increases  that  of  sea  water  on  irons  other  than  skin-bear- 
ing cast-iron,  but  much  less  than  in  case  of  fresh-water. 
Owing  to  this,   foul  fresh  water  corrodes  unprotected 
wrought-iron  and  steel  and  galvanized  wrought-iron  faster, 
and  both  painted  and  planed  cast-iron  nearly  as  fast  as 
pure  sea  water.      So  too  while  the  presence  of  sewage 


e  Mallet  states,  op.  cit.,  1840,  pp.  233-4,  that  the  relative  corroding  power  of 
sea  water  is  increased,  in  the  case  of  wroughMron,  by  the  fact  that  the  coating  of 
rust  which  forms  in  it  is  comparatively  pulverulent,  while  that  which  forms  iu  fresh 
water  adheres  more  tenaciously,  acting  as  a  cloak  to  binder  further  oxidation  :  and 
that  while  this  is  also  true  of  cast-iron,  it  is  to  a  much  smaller  degree,  since  the  fresh 
water  oxide  coating  adheres  to  it  much  less  tenaciously  than  to  wrought  iron.  On 
the  other  hand,  according  to  the  same  writer,  the  relative  corroding  power  of 
fresh  as  compared  with  sea  water  on  galvanized  iron  is  increased  by  the  greater 
power  of  the  former  to  perforate  its  zinc  coating.  Indeed,  in  one  set  of  experi- 
ments he  found  that  cast-  and  wrought-iron  and  steel,  when  in  voltaic  contact 
with  zinc,  wore  all  corroded  faster  by  fresh  than  by  sea  water,  the  former  holding 
one  volume  of  air  and  carbonic  acid  in  eight,  the  latter  one  in  seventy.  (Op.  cit. , 
p.  255.)  It  will,  however,  be  noted  that  this  is  not  true  of  the  zinced  wrought- 
iron  No.  7,  Table  44. 

In  comparing  the  ratio  of  the  corrosive  action  of  sed  water  to  that  of  fresh  water, 
as  given  by  Mallet  iu  Table  44,  we  observe  that  it  is  7'5  :  1  in  case  of  galvanized 
wrought-iron,  and  in  case  of  ungalvanized  cast-iron  wrought-iron  and  steel  respect- 
ively about  7  '5  : 1,  8'9  :  land  8  : 1.  In  brief  the  difference  between  the  rate  of  corro- 
sion in  fresh  and  in  salt  water  is  about  the  same  for  one  class  of  iron  as  in  another. 
It  is  true  that  in  earlier  and  briefer  exposures  Mallet  found  that  this  ratio  was  about 
4  :  1  to  6  : 1  for  cast-  and  8  : 1  for  wrought  iron,  i.  e.  that  the  sea  water  was  espe- 
cially severe  on  the  latter  metal.  But  these  results  refer  to  but  a  single  pair  of 
exposures  of  wroughtiron,  while  those  in  Table  44  lines  5  and  6  refer  to  18  pairs 
of  exposures,  aud  carry  weight  proportionally. 


CORBOSION    OF    IRON :    INFLUENCE   OF    COMPOSITION.      §  164. 


97 


invariably  greatly  hastens  the  corrosion  of  both  cast  and 
wrought-iron  in  fresh  river  water,  yet  it  affects  skin-bear- 
ing cast-iron  much  less  than  most  other  varieties,  increas- 
ing its  corrosion  about  threefold,  while  it  raises  that  of 
painted  and  of  planed  cast-iron  about  six  and  sevenfold 
respectively,  that  of  galvanized  wrought-iron  about  eight- 
fold, and  that  of  unprotected  wrought-iron  and  steel  about 
eleven-  and  tenfold.  Turning  now  to  sea  water,  we  find  that 
in  ]  3  out  of  Mallet' s  22  pairs  of  immersions  of  skin-bearing 
cast-iron  of  which  only  11  are  given  in  Table  44,  the  presence 
of  sewage  retards  corrosion,  and  on  an  average  the  foul 
sea  water  corrodes  it  less  rapidly  than  the  clear.  Sewage 
however  about  doubles  the  corrosive  action  of  sea  water 
on  painted  and  on  planed  cast-iron,  on  galvanized  and  on 
unprotected  wrought-iron,  and  on  unprotected  steel,  in- 
creasing the  corrosion  by  from  43  to  158  per  cent. 

The  preceding  paragraph  refers  to  Mallet' s  results,  which 
are  on  the  whole  corroborated  by  those  of  Parker  (23  to 
33,  Table  44)  and  C.  O.  Thompson.  Parker's  11  wrought- 
irons  and  steels  are  invariably  corroded  faster  by  bilge  than 
by  pure  sea  water,  on  an  average  nearly  thrice  as  fast. 
Thompson  found  that  while  the  waste  of  gas  works  did 
not  appear  to  increase  the  corrosive  action  of  pond  water 
initially  somewhat  polluted  by  stables,  etc.,  sewage  in- 
creased it  37$  in  case  of  wrought-iron  and  76$  in  case  of 
cast-iron.  Here  sewage  hastens  the  corrosion  of  cast  more 
than  of  wrought-iron,  the  reverse  of  Mallet's  results." 

E.  SULPHUROUS  ACID. — W.  Kent  found  in  the  rust  of 
railway  bridges,  whose  iron  is  reported  to  corrode  very 
rapidly,  traces  of  chlorine,  much  soot,  carbonic,  sul- 
phuric and  traces  of  sulphurous  acid,  supposed  to  arise 
from  the  products  of  the  combustion  of  pyritiferous  coal 
in  the  locomotive.  As  carbon  is  electro-negative  to  iron 
and  apt  to  condense  passing  vapors,  he  attributes  to  it 
and  to  carbonic  and  sulphxirous  acids  the  rapid  corrosion. 
He  further  found  that  an  aqueous  solution  of  sulphurous 
acid,  in  a  closed  vessel,  corroded  iron  energetically,  form- 
ing ferrous  sulphate." 

§  164.  INFLUENCE  OF  THE  COMPOSITION  OF  IKON.— The 
influence  of  other  elements  combined  with  iron  on  its  oxi- 
dation at  high  temperatures  will  be  considered  later. 

It  is  stated"  that  at  ordinary  temperatures  combined 
carbon,  and  probably  silicon  and  to  a  smaller  extent  phos- 
phorus, retard  the  corrosion  of  iron.  Manganese  is  said 
to  increase  the  rusting  tendency  of  malleable  iron,  but  to 
diminish  that  of  cast-iron.  But  it  seems  to  me  very  doubt- 
ful whether  such  sweeping  statements  are  justified  by  the 
present  state  of  our  knowledge. 

To  study  the  effect  of  combined  carbon,  I  number  the 
irons  of  each  of  several  sets  of  experiments  in  order  of 
their  combined  carbon,  1  having  the  most,  and  place  them 
in  Table  46  in  order  of  the  rapidity  of  corrosion,  the  fast- 
est corroding  standing  first.  Were  it  true  that  corrosion  is 
inversely  as  the  combined  carbon,  they  should  stand  in 
inverted  sequence,  say  6,  5,  4,  3,  2,  1.  To  illustrate  simul- 
taneously the  relative  corrodibility  of  cast  and  malleable 
iron  the  former  appears  in  heavy-faced  type. 

In  not  one  of  these  16  sets  do  the  numbers  happen  to 
stand  in  inverted  sequence,  and  this  might  easily  happen  if 
they  were  arranged  at  random.  Indeed,  comparing  the 


a  Trans.  Am.  Inst.  Mining  Engineers,  IX.,  p.  S68,  1881. 

b  Journ.  Franklin  Inst. ,  XCIX.,  p.  437,  1875. 

c  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  278. 


sum  of  the  first  half  of  the  digits  of  each  case  with  that 
of  the  last  half  (e.  g.  in  case  number  1  comparing  3  +  4  =  7 
with  1  -f-  2  =  3)  we  find  that  in  eight  out  the  sixteen  cases 
of  this  table  their  first  half  is  less  than  their  last ;  and 
adding  together  all  of  these  first  halves  we  find  that  their 
gross  sum  is  le&s  than  that  of  the  last  halves.  To  one  rash 
enough  to  draw  an  inference  from  such  conflicting  data, 
this  would  mean  that  combined  carbon  hastened  corrosion."1 

The  eight  cases  in  which  the  last  half  of  the  digits  ex- 
ceeds the  first  include  the  immersions  with  scale-bearing 
and  copper  plates,  one  case  of  immersion  in  acidulated 
water,  and  all  but  one  of  the  cases  of  simple  immersion  in 
cold  sea  and  bilge  water. 

It  is  impossible  to  explain  away  these  facts  by  the  in- 
fluence of  manganese  and  silicon.  Thus  number  16  Table 
44  is  numbered  ",  th  in  order  of  combined  carbon  among  An- 
drews' irons  in  Table  46.  As  it  has  decidedly  high, 
manganese  and  very  low  combined  carbon  it  should  be  one 
of  the  quickest  to  corrode,  while  actually  it  is  the  slowest. 
Many  another  anomaly,  "grateful — comforting,"  will  re- 
ward the  patient  digger. 

TABLE  46. — COMBINED  CARBON  AND  RAPIDITY  OP  CORROSION. 


c' 

^ 

Observer. 

Exposed  to  or  immersed  in 

Numbered  after  proportion   of    com- 
bined carbon.  1  highest,  placed  in 
order  of  corrosion,  fastest  first. 

1 

•2 
t 
4 

S 

t 

7 
8 

9 

in 
11 

IS 

13 

14 
IB 
It 

17 
15 

8.4,1.2. 
(2.8)  l.a 
1  (2,  3).a 
11,6,  8.  T,  3.  9,1,  S,  10,  3,  4. 

1,6.8.2,4,8,8,7. 
3,  2,  4,  1. 
8,  1,  4,  2. 
1,  8,  4,  2. 
3,  4,  2,  1. 
8,  4,  1,  2. 

5  6,7,1,8,8,4. 
6,3,  1,5,8,7. 

1,8,5,6,8,7. 
3,  1.  2. 
5,8,4,6,2,1. 
2,  J,8.a 
3.  4.  1,  2. 
1  ,  6,  8,  5,  8,  7. 

Cold  sea  water,  simple  immersion    . 
Cold  bilge  water,  "              " 

Mallet    .... 

Andrews  
Parker.  

M 

it 

Cold  sea  water,  in  contact  with  bright 

H 

Cold  sea  water,  in  contact  with  scale- 

Cold  sea  water,  in  contact  with  cop- 

Adamson  

,i               it 

Parker  

Mean  of  all  conditions       

a.  Gruner  does  not  give  the  combined  carbon  of  his  irons,  but  three,  Bpiegeleisen,  hard  manga- 
nese steel  and  soft  steel,  arc  selected,  since  there  can  be  littlu  doubt  that  of  these  the  splegeleisen 
lias  the  most  and  the  soft  steel  the  least  combined  carbon. 

Heavy-fact'd  type  re-presents  cast-iron.  Where  two  numbers  are  placed  in  parentheses  I  do  not 
know  which  of  the  two  corrodes  fastest. 

The  numbers  in  lino  12  are  derived  from  the  specimens  11  to  20  of  Table  44,  but  refer  to 
exposures  prolonged  beyond  the  point  at  which  the  results  in  column  16  of  Table  44,  "scale 
bearing  iron,"  were  obtained. 

Line  14,  Jour.  Iron  and  St.  InstM  1878,  II.,  p.  398. 

Line  15,  Ledebur,  Handbuch,  p.  279. 


The  following  tables,  calculated  from  the  results  of 
Parker  and  of  Andrews,  are  thought  to  bring  out  the 
anomalous  relation  between  corrosion  and  composition : 

TABLE  47  — PARKEB'S  AND  ANDREWS'  EXPERIMENTS  ON  RUSTING. 


Parker's  experiments. 

Percentage  of 

Relative 
corrosion 
mean  of  all 
conditions. 

Carbon. 

Silicon. 

Manga- 
nese. 

Phos- 
phorus. 

Sul- 
phur. 

Copper. 

•18 
•12 
•19 

•10 

•013 
tr 
•060 

•082 

•64 
•11 
•52 

•26 

•077 
•056 
041. 

•057 

•074 
•077 
•068 

•085 

•015 
tr 

tr 

tr 

1  00 
1-19 
1-05 

1-07 

Brown  &  Co  's  steel  ... 
Bolton  &  Co  's  steel.. 
Steel  of  Steel  Co.  of 
Scotland  

Andrews'  experiments. 

Percentage  of 

Relative  loss  by  corrosion   in  sea 
water,  wrought-iron  =  100. 

•  •  :  |  Graphite. 

Combined  car- 
bon. 

Silicon. 

Manganese. 

Phosphorus. 

•j 

% 
~5 

CO 

ft 

a 
|| 

B  « 

ic 

Immersion  in  galvanic 
circuit  with 

a 

A  &     • 
IP 

,    60 

SB  e 

g's  ? 

"Z 

H 

1... 
2 

s'.'.. 

4... 
5... 
6... 

7. 

Soft  Bessemer  steel  ... 
Soft  open-hearth  steel  
Soft  c  .st-steel               
Hard  Bessemer  steel  

•15 
•17 
•46 
•51 
•72 
1-41 
2-01 

•01    -54 
•07      68 
•07    -IS 
•071-15 
081-24 
12      86 
•41  0'65 

06 
•08 
•21 
•09 
14 
•OS 
0-45 

•11 

•12 

•02 
11 

•lu 
•06 
•25 

941 
1  004 
1-290 
1  169 
1-032 
1-189 

1  301 
1-4S9 
1  332 
1  284 
1-105 

•971 
•764 
1-210 
1-126 
1  133 

•791  5 
•861  4 
1-031  7 
1  00    2 
1  016  1 
6 

1-001 
1-029 
1  215 
1-144 
1-071 
1  189 
1-204 

Hard  cast-steei  

1:50 

1-572 

1-128 

1  098  8 

d  Reversing  the  order  of  Gruner's  doubtful  numbers,  S  and  3,  would  reverse  the 
balance. 


98 


THE    METALLURGY    OF    STEEL. 


JS'ot  to  needlessly  multiply  cases,  note  how  No.  7  of 
Andrews'  which,  greatly  excelling  all  others  in  both  com- 
bined carbon  and  silicon  and  with  but  a  moderate  propor- 
tion of  manganese  should  corrode  the  slowest  of  all,  ac- 
tually corrodes  the  fastest  when  in  contact  with  copper, 
and  when  in  contact  with  bright  vvrought-iron ;  and 
is  one  of  the  most  corrodible  under  the  third  set  of  con- 
ditions. 

Numbering  the  irons  of  Table  47  in  order  of  their  man- 
ganese, 1  having  the  most,  and  arranging  them  in  order 
of  corrosion,  the  fastest-rusting  first,  then  if  as  is  believed 
manganese  hastens  rusting,  they  should  stand  in  se- 
quence, say  1,  2,  3,  4,  etc.  Actually  they  are  more  nearly 
in  inverted  than  in  direct  sequence.  Parker's  stand  4,  3, 
2,  1 ;  Andrews'  stand  3,  7,  2,  6,  1,  4,  5. 

Doubtless  composition  does  influence  the  rapidity  of 
corrosion  ;  but  we  may  surmise  that  structure  and  proxi- 
mate rather  than  ultimate  composition  are  the  important 
factors  The  local  pitting  of  steel  plates,  the  most  dan- 
gerous form  of  corrosion,  indicates  the  local  segregation  of 
readily  corroding  compounds,  or,  if  I  may  so  style  them, 
electro-positive  "minerals"  :  Mallet  indeed  concluded  that 
the  homogeneousness  of  cast-iron  influenced  its  rate  of 
corrosion  far  more  than  did  its  chemical  composition." 

STKUCTURE. — Experience  in  the  management  of  chemi- 
cal manufacturing  works,  in  which  the  very  rapid  corro- 
sion of  all  iron  work  due  to  the  presence  of  acid  fumes 
and  to  various  similar  causes  gives  unusual  opportunities 
for  observation,  seems  to  indicate  clearly  that  hard,  com- 
pact, close-grained  cast-iron  resists  corrosion  better  than 
the  softer,  open,  dark  gray  irons  ;b  numbers  2  and  3  better 
than  number  1.  Mallet  indeed  reaches  the  opposite  con- 
clusion from  his  small  scale  tests,0  but  I  find  little  justifi- 
fication  for  his  belief.  Taking  the  average  of  all  his  condi- 
tions of  exposure  (hot,  cold  and  foul  sea  water,  pure  and 
foul  fresh  water,  and  damp  air),  his  number  1  irons  in 
both  series  corrode  about  30$  faster  than  those  of  lower 
grade  under  identical  conditions. 

In  pure  sea  water  the  rates  of  corrosion  are  nearly  ident- 
ical in  his  experiments,  the  average  corrosion  in  four  expos- 
ures of  number  1  iron  being  about  4$  greater  than  that  in 
fourteen  exposures  of  harder  iron.  It  is  uncertain  whether 
the  greater  corrodibility  of  the  softer  irons  is  due  chiefly 
to  structure,  to  composition,  or  to  composition  as  governing 
structure,  or  to  the  greater  resisting  power  of  their  skin. 

SIZE. — Immersing  26  pairs  of  specimens  of  cast-iron, 
each  consisting  of  one  block  5  inches  X  5  inches  X  1  inch, 
and  of  a  similar  one  5  inches  X  5  inches  X  0'25  inch,  in  pure 
sea  water  for  387  days,  Mallet  found  that  the  thin  piece  in 


a  Op.  cit. ,  1843,  p.  4.  Mallet  considered  that  chilled  cast-iron  corroded  faster 
than  that  cast  in  green  sand  :  and  this  he  attributed  to  the  heterogeneousness  of 
the  former,  citing  in  support  of  this  the  fact  that  its  rusting  was  tubercular,  which 
he  considers  an  unfailing  index  of  heterogeneousness  (Idem,  1840,  p.  234).  In 
earlier  and  briefer  exposures  chilled  iron  nearly  always  corroded  much  faster  than 
similar  unchilled  iron  in  foul  sea  water  ;  but  I  am  inclined  to  attribute  this  to  in- 
dividual peculiarities  of  certain  of  the  specimens.  For  in  the  same  series  there  was 
little  difference  between  the  rates  of  corrosion  of  chilled  and  nnchilled  irons,  other- 
wise similar,  in  pure  sea  water,  and  in  river  water  pure  or  foul  :  while  in  the 
later  series,  whose  results  are  given  in  Table  44,  we  find  that  even  in  foul  sea  water 
the  chilled  iron  corroded  slower  than  the  unchilled  :  and  that  iu  cold  pure  sea 
water  and  in  river  water,  wh<  ther  fresh  cr  foul,  their  corrosion  was  closely  simi- 
lar, while  chilled  iron  corroded  about  twice  as  fast  in  hot  sea  water  yet  only  half 
as  fast  in  damp  air  as  similar  unchilled  iron. 

b  Several  very  experienced  and  intelligent  managers  of  chemical  works  assure  me 
that  their  experience  fully  agrees  with  this  statement.  It  seems  to  be  true  both  of 
corrosion  by  air  slightly  charged  with  acid  fumes,  aiid  by  brine. 

c Op  cit.,  1843,  p.  5. 


every  case  corroded  faster,  and  generally  very  much  faster, 
than  its  companion.  On  reimmersing  them  for  732  days, 
in  21  out  of  the  2(5  pairs  the  thin  piece  still  corroded 
faster  than  the  thick,  but  the  difference  was  less  marked 
than  before,  while  in  five  pairs  the  thick  piece  corroded 
somewhat  the  faster.  He  attributed  this  to  the  greater 
heterogeneousness  of  the  thin  piece  :  but  the  slow  cooling 
of  the  thick  piece  should  give  better  opportunity  for 
segregation  during  solidification,  and  the  difference  seems 
more  naturally  attributable  to  a  difference  in  the  structure 
of  the  metal,  or  in  the  thickness  or  adhesiveness  or 
corrodibility  of  its  skin,  due  to  different  rates  of  cooling. 

§165.  CAST-  IMN  vs.  STEEL  AND  WROUGHT-IRON. — In 
general  cast-iron  corrodes  much  less  readily  than  malle- 
able iron,  but  this  is  certainly  in  large  part  and  perhaps 
wholly  due  to  its  tenaciously  held  skin.  Thus  in  Table 
44  Mallet's  skin-bearing  cast-irons  under  all  conditions 
corrode  less  than  his  wrought-iron  and  steels,  though  in 
pure  river  water  the  difference  is  comparatively  slight. 
But  the  planed  cast-irons  of  Mallet,  Andrews  and  Gruner 
on  the  whole  corrode  rather  faster  than  unprotected 
wrought-iron  and  steel.  Mallet  and  Gruner  indeed  find  that 
planed  cast-iron  corrodes  more  slowly  than  malleable  iron 
when  simply  exposed  to  the  weather  :  but  it  corrodes  on 
the  whole  decidedly  faster  than  malleable  iron  in  cold  sea 
water,  whether  simply  immersed  or  in  voltaic  contact  with 
copper  or  with  scale-bearing  wrought-iron.  In  three  out 
of  the  four  groups  in  figure  9  the  corrosion  of  cast-iron  out- 
strips that  of  malleable  iron. 

In  Gruner' s  experiments  the  planed  cast-iron  corrodes 
in  sea  water  from  about  2  to  3 '5  times  as  fast,  and  in 
acidulated  water  from  0'8  to  14  times  as  fast  as  the  fastest 
corroding  carbon  steel. 


•80.05 
1 


Ttg.t. 

Andrews' 

EXPERIMENTS 

on 
RUSTING 


le  bearing-plttttt 
Copperplate* 


.40 


100 


Scftle  of  time,weeka. 

INFLUENCE  OP  TIME  AND  OF  GALVANIC  CONTACT  WITH  ELECTRO- 
NEGATIVE SUBSTANCES  ON  RUSTING  IN  SEA  WATER. 

§  166.  THE  RELATIVE  CORROSION  OF  W  ROC  Gin -I  RON 
AND  STEEL  is  a  question  whose  economic  importance,  I 
hope,  justifies  the  length  at  which  I  shall  consider  it.  I  first 
present  the  results  of  experiments  on  a  small  scale,  then 
those  of  actual  experience  in  use  in  land  and  marine  boil- 
ers, ships'  hulls,  etc. 

As  already  indicated,  there  is  probably  no  important 
difference  in  the  rate  at  which  these  two  classes  of  iron 
corrode  under  ordinary  conditions.  It  is  true  that  our 


THE    RELATIVE    CORROSION    OF     WROUGHT-IRON    AND    STEEL.      §  166. 


09 


small  scale  tests  indicate  that  under  certain  conditions 
steel  corrodes  much  faster  than  iron :  but  at  least  undei 
some  of  these  this  is  opposed  by  experience  on  a  large 
scale.  It  is  to  be  observed,  however,  that  if,  as  is  prob- 
able, the  two  metals  corrode  equally  per  square  foot  of 
surface  per  annum,  steel  suffers  more  per  unit  of  strength. 
A  steel  plate  of  the  same  strength  as  an  iron  one  is  con- 
siderably thinner  ;  and  if  each  loses  the  same  thickness  in 
the  same  time,  the  steel  plate  becomes  finally  considerably 
weaker  than  the  iron  one.  Hence,  where  serious  corrosion 
is  to  be  expected,  it  is  not  prudent,  in  substituting  steel 
for  wrought-iron,  to  reduce  the  thickness  proportionally 
to  the  increased  strength  of  the  metal.  And  where  trans- 
verse as  well  as  tensile  stress  is  to  be  resisted,  it  is  also  to 
be  remembered  that  a  steel  piece,  whose  cross-section  is 
such  that  it  is  tensilely  just  as  strong  as  a  thicker  one  of 
wrought-iron,  is  by  no  means  as  strong  transversely. 

While  it  would  hardly  have  been  surprising  had  a  de- 
cided difference  in  the  corrodibility  of  these  two  classes  of 
iron  been  proved  to  exist,  I  do  not  know  that  there  is  any 
strong  reason  to  expect  such  a  difference  on  a  priori 
grounds.  We  have  seen  that  there  is  comparatively  little 
difference  between  the  corrodibility  of  wrought-  and  of 
skinless  cast-iron,  though  their  compositions  differ  so 
greatly.  As  steel  resembles  wrought-iron  much  more 
closely  in  composition  than  cast-iron,  no  serious  differ- 
ence in  corrodibility  need  be  expected  on  the  score  of 
composition.  Beyond  this,  wrought-iron  differs  from 
steel  in  having  a  small  quantity  of  slag  mechanically  in- 
tercalated, which  if  any  thing  should  hasten  its  corrosion. 
Beyond  this  there  appears  to  be  a  decided  difference  in 
their  structure,  due  at  least  in  part  to  the  presence  of 
that  slag  in  the  one  and  its  absence  from  the  other.  But 
I  do  not  know  that  this  difference  is  of  a  kind  which 
should  be  expected  to  affect  corrodibility. 

It  appears  tolerably  certain  that  the  mild  steel  of  to-day 
compares  more  favorably  with  wronght-iron  in  corrodi- 
bility than  that  formerly  made.  This  may  be  due  to 
former  neglect  to  remove  its  scale,  or  to  present  greater 
regularity  in  the  proportion  of  manganese  and  perhaps  of 
other  elements  which  tend  to  segregate,  and  which,  if 
even  occasionally  present  in  excessive  proportions  would, 
by  assisting  segregation,  lead  to  the  formation  of  spots 
differing  in  potential  from  the  mass  of  the  metal,  and  thus 
leading  to  aggravated  local  corrosion.  Or,  again,  care- 
lessness in  recarburizing  may  have  formerly  led  to 
heterogeneousness  and  difference  of  potential. 

A.  SMALL  SCALE  TESTS  indicate  that  in  cold  sea  water, 
whether  pure  or  foul,  and  whether  it  be  simply  immersed 
in  it  or  in  galvanic  contact  with  bright  wrought-iron,  with 
scale-bearing  iron,  or  with  copper,  as  well  as  in  pure  fresh 
water,  steel  corrodes  at  about  the  same  rate  as  wrought- 
iron.  The  data  are  not  always  harmonious  :  but  where 
they  are  discordant  those  which  point  to  steel  as  the  more 
corrodible  are  so  far  offset  by  others  pointing  in  the 
opposite  direction  as  to  strongly  suggest  that  there  is  no 
important  difference.  But  in  hot  sea  water,  e.  g.  in  marine 
boilers,  and  when  exposed  to  the  weather,  our  small  scale 
tests  indicate  that  steel  is  decidedly  the  more  corrodible 
of  the  two  :  while  our  rather  scanty  data  concerning  the 
effect  of  acidulated  water  and  sewage-bearing  river  water 
point  rather  to  wrought-iron  as  somewhat  the  more  cor- 
rodible. This  is  summed  up  in  Table  47  A. 


TABLE  47  A.— RELATIVE  CUKKODHIN  UK  WKUUKHT-IRON  AM>  STEEL,  SHALL  S<  AI.K  Ti:si«. 


Conditions  ol  exposure. 


A.  In  pun-  mlil  M';I  water — 

1.  simple  immersion 

ii.  ^tfel  and  bright  wrought 
iron  in  galvanic  contact. 

{scale- 
bearing 
iron.  .. 
copper. 
li.  Hot  sea  water. . . 


C.  Exposed  to  the  weather 


D.  In  foul  sea  water 

E.  In  pure  fresh  water. 
V.  In  foul      ••         "     . 

O.  In  acidulated     "     .... 


Relative  corrodibility. 


Corrode  nearly  equally 

Probably  little  difference  . 

Nearly  identical 


tct'l  iniu-ti  the  more  corrodible, 
perhaps  by  fiO£ 

Soft    steel   corrodes   decidedly 
faster  than  wrought-iron . . . 

Nearly  identical 


keel  rather  the  less  corrodible. 
< ••  •!  decidedly  the  less  corrodi- 
ble... 


(Duality  of  evideni-e. 


Abundant   and    tolerably  har- 
monious. 
Contradictory. 


Scanty ;  tolerably  harmonious. 

Very     harmonious,     tolerably 
-.bundant. 

Harmonious     scanty. 

Harmonious ;  inoderatelv  abun- 
dant. 
Rather  scanty. 


Scanty. 


In  extensive  experiments  by  D.  Phillips*  mild  steel 
appeared  to  corrode  much  more  rapidly  than  wrought- 
iron  in  marine  boilers,  but  his  results  are  so  tainted  with 
suspicion  that  I  do  not  produce  them  here,  believing  that 
very  little  weight  should  be  attached  to  them.  Bessemer" 
points  out  that  were  steel  to  corrode  in  practice  at  the  rate 
stated  by  Phillips,  a  boiler  plate  three-eighths  of  an  inch 
thick  would  be  completely  destroyed  in  8 '5  years,  the 
coat  of  paint  alone  remaining,  a  result  it  is  needless  to 
say  directly  contradicted  by  abundant  experience.  In- 
deed, it  is  stated  that  when  Phillips'  experiments  were 
prolonged,  the  committee  which  had  them  in  charge  con 
eluded  that  there  was  no  difference  in  the  Kites  of  corro- 
sion of  wrought-iron  and  mild  steel.0 

In  other  and  apparently  more  trustworthy  experiments, 
Phillips  exposed  plates  of  wrought-iron  and  steel,  each 
carefully  insulated  with  glass,  and  here  his  results  agree 
in  general  more  nearly  with  those  of  other  observers,  the 
orrosion  of  the  two  metals  being  nearly  identical  in  cold 
sea  and  rain  water,  while  that  of  steel  exceeded  that  of 
wrought-iron  on  exposure  to  the  weather,  though  in  a 
much  higher  proportion  than  in  Parker's  experiments. 

DETAILED  EVIDENCE. — Let  us  now  briefly  run  through 
;he  evidence.4 

1.  SIMPLE  IMMERSION  IN  COLD  SEA  WATER. — The  re- 
sults obtained  by  Mallet,  Andrews,  Parker,  and  Farqu- 
larson,  and  Thwaites'  averages  agree  fairly  in  showing 
that  both  metals  corrode  at  about  the  same  rate.     The 
greatest  difference  is  in  Andrews'  results,  in  which  steel 
orrodes  about    19$    faster  than  wrought-iron ;  but  as 
jonly  two  specimens  of  wrought-iron  are  here  represented, 
and  as  the  difference  in  large  part  is  due  to  the  exception- 
ally rapid  corrosion  of  one  out  of  the  six  specimens  of 
steel,  it  is  referable  to  individual  peculiarities.     In  Mal- 
et's  results  wrought-iron  corrodes  11$  faster  than  steel. 
Parker's  (and  apparently  Farquharson's)  results  refer  to 


a  Proc.  last.  Civ.  Bug.,  LXV.,  p.  73.  Engineering,  1881, 1.,  p.  313. 
It  appears  that  in  certain  cases  copper  plates  were  present  with  the  steel  and 
wrought-iron  ones  experimented  on  by  Phillips,  aud  the  latter  metals  were  often 
leld  by  uninsulated  brass  or  copper  rods,  yet  the  influence  of  these  electrc-nega- 
ive  metals  was  ignored.  Further,  in  the  experiments  conducted  with  hot  water, 
he  steel  plates  were  placed  above  the  wrought-iron  ones,  and  consequently  in 
lotter  water,  which  might  be  expected  to  corrode  more  energetically.  What 
rust  can  we  put  in  such  work  ?  The  untrustworthiness  of  his  methods  and  re- 
ults  was  fully  exposed  by  Abel,  Siemens  and  others,  in  the  discussion  which  fol- 
owed  the  reading  of  his  paper, 
b  Journ.  Iron  and  St.  List.,  1881, 1.,  p.  76. 

c  Wright,  Engineer-in-Chief  of  the  Admiralty,  Proc.  Inst.  Civ.  Eng.,  LXV.,  p. 
04. 

d  In  the  following  discussion  some  discrepancies  will  be  observed  between  the 
lumbers  given  and  those  which  might  be  deduced  from  Table  44.  This  is  because 
he  numbers  in  that  table  give  only  the  more  important  results  obtained  by  the 
several  observers,  while  those  in  the  following  discussion  often  refer  to  a  larger 
number  of  results,  which  include  those  in  this  table. 


100 


THE    METALLURGY    OF    STEEL. 


soft  steel,  Mallet's  to  hard  steel,  and  Andrews'  partly  to 
each. 

2.  UNDER  GALVANIC  ACTION  IN  COLD  SEA  WATER  there 
is  little  reason  to  suspect  an  important  difference  between 
the  corrodibility  of  wrought-iron  and  steel.     The  cases  in 
which  steel  corrodes  the  faster  are  pretty  well  offset  by 
others  in  which  wrought-iron  is  the  more  corrodible. 

a.  When  wrought-iron  and  steel  are  galvanically  con- 
nected in  cold  sea  water,  Andrews'  results  indicate  that  the 
steel  corrodes  slightly  faster  than  the  wrought-iron,  and 
both  metals  decidedly  faster  than  when  simply  immersed. 
Farquharson's  results  indicate  just  the  reverse,  that  the 
corrosion  of    steel,  slightly    more    rapid   than    that    of 
wrought-iron  when  insulated,  is  almost  completely  arrested 
by  connection  with  wrought-iron,  the  rapidity  of  rusting 
of  the  latter  being  nearly  doubled.   This  appears  opposed 
to  common  experience,  and  may  be  due  to  some  peculiarity 
of  the  material  employed.     Andrews'  ten  sets  of  experi- 
ments harmonize  among  themselves,  as  do  Farquharson's 
three  sets. 

b.  When  similarly  immersed  in  galvanic  contact  with 
copper,  Andrews'  results  indicate  that  wrought-iron  rusts 
about  10%  faster  than  steel.      Similar  result  were  ob- 
tained by  a  longer  exposure  of  68  weeks,  during  which 
steel  lost  by  rusting  about  Q%  less  than  wrought-iron. 
But  this  difference  is  so  slight  that  it  may  easily  have 
been  due  to  some  individual  peculiarity. 

c.  When  similarily  immersed  in  contact  with  scale- 
bearing  plates,  Andrews'  results  in  Table  44  indicate  that 
steel  corrodes  faster  than  wrought-iron  :   but  when  their 
exposure  was  farther  prolonged  this  result  was  reversed, 
and  the  corrosion,  of  the  wrought-iron  exceeded  that  of  the 
steel  by  about  Q%. 

3.  IN  SIMPLE  IMMERSION  IN  COLD  WATER  OTHER  THAN 
PURE  SEA  WATER  there  appears  to  be  little  difference  be- 
tween the  corrosion  of  these  two  metals.  In  pure  river  water, 
in  sewage-bearing  sea  water  and  in  bilge  water  they  cor- 
rode at  approximately  equal  rates,  and  in  the  case  of  foul 
river  water  alone  does  any  important  difference  arise, 
wrought-iron  here  corroding  22%  faster  than  the  hard 
steels  of  Mallet's  experiments. 

4.  IN  SIMPLE  IMMERSION  IN  HOT  SEA  WATER  soft  steel 
appears  to  corrode  decidedly  faster  in  Parker's  experi- 
ments than  wrought-iron,  although  when  the  same  steels 
and  wrought-irons  were  immersed  in  pure  cold  sea  water 
and  in  bilge  water  the  two  metals  corroded  at  practically 
uniform  rates.     In  two  of  his  boilers  the  slowest  corrod- 
ing steel  corroded  8%  and  34$  faster  respectively  than  the 
fastest  corroding  wrought-iron,  while  in  the  third  boiler 
but  one  of  the  wrought-irons  corroded  faster  than  the 
slowest  corroding  steel.     The  average  corrosion  of  the 
four  steels  exceeds  that  of  the  seven  wrought-irons  by  22, 
34  and  98$  in  the  three  boilers  ;  the  average  of  these  three 
excesses  is  5 1  %.     The  difference  here  is  too  marked  and 
too  constant  to  be  readily  accounted  for  by  individual  pecu- 
liarities, and  certainly  seems  to  indicate  that  soft  steel 
corrodes  faster  than  wrought-iron  in  hot  sea  water. 

5.  ON  EXPOSURE  TO  THE  WEATHER  Mallet's  hard  steels 
corrode    more    slowly    than    his    wrought-irons :    while 
Parker's  soft  steels   uniformly  corrode  faster  than  his 
wrought-irons,  on  an  average  41$  faster,  the  slowest  rust- 
ing steel  corroding  22$  faster  than  the  fastest  rusting 
wrought-iron.     As  Mallet's  wrought-irons,  which  were  ex- 


posed  in  Dublin,  corrode  at  a  rate  not  very  different  from 
that  at  which  Parker' s  did  in  London,  this  would  go  to  show 
that  in  the  weather  hard  steels  corrode  more  slowly  than 
soft,  though  such  an  inference  should  be  used  cautiously. 
6.  IN  ACIDULATED  WATER. — In  addition  to  Gruner's 
results  in  Table  44,  those  in  Table  47  B  are  offered. 

TABLE  47  B.— CORROSION  BY  ACIDULATED  WATER. 


Composition. 

Relative  loss. 
Wrought-iron  =  100. 

Graph. 

Com. 

car. 

Si. 
•05 

Mn. 

p. 

S. 

I 

•38 
•11 
1-01) 
4-5 
8-0 
tr 
0  5 

1-01 
0-50 

•07 
•04 

•02 
•03 

25- 
9- 

75- 
16- 
22- 
81- 
48' 
12S- 
98- 

Tool  steel 

2'  5 

1-8 

10- 

1-0 

White  cast-iron  

•70 
80 
•60 

3T) 
3. 

Steel 

9... 

1  and  a.  Adamson,  Jonrn.  Iron  and  St.  Inst.,  1878,  II.,  p.  398.  3  to  1.  Ledebur,  Handbuch 
der  Eisenhuttenkunde,  p.  27!!,  BITS  und  Huten.  Zeitung,  1S77.  p.  280. 

8*  H.  M.  Boies,  private  communication,  Aa<r.  Sth,  1887.  Four  plates,  one  each  of  steel  and 
wrought-iron  unprotected  and  one  of  each  t'alvani/.cd  (•'  coated  with  zinc  or  something  of  the 
kind  ")  were  suspended  in  boilers  nsinrr  Lucknwanna  IJivcr  water  for  from  one  to  two  months,  at 
the  Kushdale  Powder  Mills,  Pennsylvania.  This  water  is  reported  to  contain  sulphuric  acid,  from 
tho  mine  water  of  the  adjacent  anthracite  mines,  and  is  extremely  corrosive.  Each  plate  was  im- 
mersed twice,  with  results  which  1  here  condense,  in  loss  per  100  of  weight  of  the  orifdnal  plates 
[>er  annum.  Note  that  while  the  unprotected  steel  at  first  corroded  faster  than  the  wroujtht- 
ron,  the  tables  were  turned  later.  It  would  be  rash  to  draw  conclusions  from  auch  data  as  to 


which  tnetai  was  the  more  corrodiblc. 
Loss  JUT  cent,  per  annum. 

Steel  unprotected   

Wrought- iron  unprotected 

Steel  zinced 

Wrought-iron  zinced 


First  immersion.  Second  immersion. 
25  50 

86  28 

95  4'7 

11  6'S 


9.  Bars  of  wrought-iron  and  steel  were  immersed  during  6  5  months  in  the  acid  water  issuing 
from  the  pits  of  the  Bonifacius  Coal  Mining  Company,  and  the  loss  by  corrosion  ascertained.  Iron 
Age,  August  18th,  1887. 


As  far  as  this  evidence  goes  it  tends  to  show  that 
wrought-iron  is  attacked  by  acidulated  water  faster  than 
steel. 

B.  CORROSION  IN  ACTUAL  PRACTICE.— It  may  justly  be 
objected  to  the  preceding  evidence  that  it  is  based  on 
comparatively  small  scale  experiments,  that  it  is  often 
contradictory,  and  that  no  one  of  the  sets  of  conditions 
accurately  represents  those  of  actual  use.  Since  in  such 
a  question  as  this  experience  on  a  large  scale  is  the  court 
of  last  resort,  let  us  see  what  its  verdict  is. 

Steel  boilers  used  by  Platt  Brothers  for  over  twenty 
years  (presumably  with  fresh  water)  did  not  corrode 
noticeably  except  while  temporarily  fed  with  acid-bearing 
water.8  Walker  for  years  vainly  sought  difference  of 
behavior  in  boilers  whose  flues  were  part  iron,  part  steel. b 
Denny  reported  that  but  one  steel  vessel  built  by  his  firm 
had  shown  a  symptom  of  corrosion.0  The  periodical 
examination  by  Lloyd's  surveyors  of  the  majority  of  their 
1100  marine  steel  boilers,  indicates  that,  though  reported 
to  corrode  more  irregularly,  they  on  the  whole  resist  cor- 
rosion about  as  well  as  their  iron  ones.d  Steel  vessels  are 
reported  afloat  after  over  20  years,  and  after  14  and  15  they 
have  shown  no  unusual  corrosion.6  The  inner  side  of 
steel  plates  of  the  Stad  Vlissinger,  though  inaccessible, 
unscraped  and  unpainted,  appeared  after  about  ten  years' 
service  in  quite  as  good  condition  as  when  new.*  At  Seraing 
steel  boilers  after  about  seven  years'  use  are  reported  to 
have  deteriorated  less  than  iron  ones  ;  indeed  no  pitting 
or  corrosion  could  be  detected,  and  no  important  repairs 
had  been  made.8 

On  the  other  hand,  not  a  few  cases  of  very  serious  corro- 
sion of  soft  steel  are  reported.  In  one  case  steel  marine 


a  Jour.  Iron  and  St.  Inst.,  1881,  I.,  p.  67. 

b  Idem,  p.  70. 

c  Idem,  p.  63. 

dldem,  p.  53-71. 

o  Martell,  Jeans,  Steel,  p.  743. 

f  Parker,  Journal  Iron  and  St.  Imt.,  1879, 1.,  pp.  75,  76. 

«  Engineering,  1879, 1.,  p.  40,  Report  by  Lloyd's  surveyor. 


THE    RELATIVE    CORROSION    OF    WROUGHT-IRON    AND    STEEL.      §  166. 


101 


boiler  tubes  lost  about  70%  of  their  weight  in  nine  months, 
while  the  adjoining  iron  tubes  were  almost  uninjured  :a  in 
another,  three  steel  tubes  in  an  iron  marine  boiler, 
whose  other  tubas  were  of  iron,  pitted  so  badly  that  they 
had  to  be  removed  after  about  a  fortnight's  use."  The 
steel  plated  Tromblon  pitted  so  rapidly  and  was  so 
nearly  perforated  in  several  places  that  it  was  deemed 
prudent,  nine  months  after  launching,  to  remove  her  from 
the  water  till  actually  needed  for  service,  though  during 
that  brief  time  she  had  been  thrice  docked,  and  painted. 
The  steel  plates  of  the  Epee  too  corroded  fast  and  deep, 
but  it  was  possible  to  keep  her  afloat  in  the  brackish  com- 
paratively cool  waters  of  L'Orient.b  In  spite  of  unusually 
careful  removal  of  scale  from  the  Iris,  she  showed  signs 
of  corrosion  after  a  brief  stay  in  the  Mediterranean,"  and 
another  steel  vessel  corroded  seriously  in  the  warm 
brackish  Irrawaddy." 

Not  satisfied  with  this  evidence,  which  belongs  chiefly 
to  a  period  when  mild  steel  was  a  comparatively  new  and 
untried  material,  I  have  endeavored  to  ascertain  the  pres- 
ent views  of  those  whose  position  should  enable  them  to 
form  the  most  valuable  opinions,  and,  to  this  end,  I  have 
addressed  the  chief  American  and  many  of  the  chief  Brit- 
ish shipbuilders,  many  American  makers  and  users  of 
locomotive  boilers,  and  others.  If  a  really  important  dif- 
ference between  the  corrodibility  of  the  wrought-iron  and 
steel,  which  are  used  to  so  great  an  extent  under  identical 
conditions,  existed,  it  would  not  be  likely  to  escape  ob- 
servation on  our  best  railways,  where  the  lives  of  the  boil- 
ers and  fire-boxes  are  carefully  ascertained,  and  a  decided 
majority  of  those  consulted  might  be  expected  to  agree  as 
to  which,  was  the  more  corrodible.  If  on  the  other  hand 
no  such  important  difference  existed,  we  should  expect 
that,  while  owing  to  personal  prejudices,  to  individual 
peculiarities  of  the  particular  specimens  of  metal  em- 
ployed, to  un weighed  differences  in  the  conditions  of 
trial,  some  would  consider  the  one,  some  the  other  metal 
the  more  corrodible,  the  majority  should  either  be  un- 
decided, or  believe  that  the  two  metals  corroded  at  ap- 
proximately the  same  rate.  This  was  so  fully  the  case  as 
to  raise  a.  very  strong  presumption  that  there  is  no  very 
serious  difference  in  the  corrodibility  of  these  two  classes 
of  iron.  Still,  while  fashion  in  opinion  is  not  sufficiently 
strong  to  conceal  a  really  serious  difference,  such  a  differ- 
ence for  instance  as  Parker  found  in  the  corrodibility  of 
wrought-iron  and  steel  in  his  small  scale  tests  in  marine 
boilers,  51$,  yet  it  might  well  cover  up  smaller  differences, 
say  of  ten  per  cent  or  even  more. 

A  condensed  statement  of  the  answers  received  is  pre- 
sented in  Table  47  C. 

Discrssiox  OF  OPINIONS. — I  intend  to  publish  elsewhere 
a  more  elaborate  statement  of  the  replies  received  than 
would  be  appropriate  here,  and  I  will  now  indicate  only  n 
few  points  of  possible  importance. 

In  the  case  of  locomotive  boilers  several  believed  confi- 
dently that  steel  was  less  corrodible  than  iron  :  but  in  case 
of  marine  boilers  and  hulls  none  were  of  this  opinion : 
and  in  general  the  answers  were  more  favorable  to  steel  in 
the  former  than  in  the  latter  class.  This  appears  to  har- 


aParker,  Journal  I-on  and  St.  In?t.,  1879,  I.,  pp.  75,  76. 

b.M.  B.  Fontaine  Engineering,  XXXI.,  p.  450,    1881,   from  Trans.  Inst.  Nav. 
Architects. 

c  Journ.  Iron  and  Steel  Inst.,  1881,  I.,  p.  69. 
a  Engineering,  XXXI.,  p.  415,  1881. 


TABLE  47  C. — RELATIVE  CORROSION  OF  WROUOIIT-IRON  AND  STEEL.     SUMMARY  OK  REPLIES  TO 
CIRCULAR  OF  KN^I/IKY. 


Opinions  as  to  the  relative  corrodibility  of  soft  steel 
and  wrought-iron. 


Steel  more  corrodible  than  wrought-iron — 

A .  Decided  opinion 

15.  Impression 

O.  Steel  more  corrodible,  yet  steel  boilers  last  longer 

than  iron  

No  difference  in  corrodibility — 

A.  Decided  opinion 

U.  Impression 

C.  No  ditlerence  observed  in  corrosion,  yet  steel 

boilers  last  longer  than  iron  

Steel  less  corrodible  than  wrought-iron — 

A.  Decided  opinion 

C.  Steel  much  more  desirable,  but  not  stated  whether 

it  lasts  longer 

No  opinion  

Summary — 

Steel  mure  corrodible 

No  difference 

Steel  less  corrodible 

tfo  opinion  


Locomotive  boil- 
ers, etc. 


Marine  boilers  and 
hulls. 


monize  to  a  certain  extent  with  the  results  of  small  scale 
tests,  in  which  hot  sea  water  appeared  to  be  relatively  un- 
favorable to  steel. 

Again,  while  several  confidently  believed  that  steel  was 
the  less  corrodible,  yet  only  one  was  decidedly  of  the 
opposite  opinion,  the  three  others  who  regarded  steel  as 
the  more  corrodible  merely  entertaining  an  impression,  or 
at  most  a  belief  which  was  not  a  confident  one,  so  far  as 
could  be  inferred  from  their  letters. 

An  exception  to  this  is  found  in  the  case  of  steel  when 
exposed  to  moist  coal,  in  the  tender  of  the  locomotive : 
here  two  were  decidedly  of  the  opinion  that  steel  corroded 
faster  than  wrought-iron,  and  another  had  the  same  im- 
pression, while  no  opinion  to  the  contrary  was  expressed. 
The  number  who  expressed  this  opinion  was  so  small, 
however,  that  I  attach  no  great  weight  to  it,  but  rather 
regard  it  as  suggesting  further  inquiry.  It  will  be  remem- 
bered that  in  our  small  scale  tests  steel  was  less  corrodible 
than  wrqught-iron  in  acidulated  water. 

To  my  mind  the  most  valuable  opinion  is  that  of  Mr. 
Wm.  Parker,  whose  position  as  chief  engineer-sur- 
veyor of  Lloyd's  register  gives  very  exceptional  oppor- 
tunities for  observation.  He  states  positively  that  steel 
is  no  more  corrodible  than  wrought -iron." 

Several  of  those  who  stated  that  they  found  no  differ- 
ence in  the  corrosion  of  wrought-iron  and  steel  in  hot  and 
cold  sea  water,  qualified  their  statements  by  adding  "pro- 
vided the  scale  be  first  removed  by  pickling  or  otherwise  " 
or  words  to  that  effect.  There  appears  to  be  a  belief  that 
scale  is  more  likely  to  be  injurious  to  steel  than  wrought- 
iron,  and  many  ship-builders  habitually  pickle  steel  plates 
on  this  account. 

Two  who  did  not  think  steel  less  c.irrodible  than  iron, 
yet  believe  I  that  steel  boilers  outlived  wrought-iron  ones. 

Although  no  question  was  raised  as  to  the  general  merits 


<•  "  Experience  has  proved  that  steel  dot's  resist  corrosion  equally  as  well  as  iron, 
and  it  is  used  almost  exclusively  in  the  manufacture  of  marine  boilers."  "  Ninety- 
nine  out  of  every  100  boilers  constructed  under  the  inspection  of  this  society's  sur- 
veyors are  made  of  steel.  In  fact,  the  use  of  iron  for  marine  boiler  making  is  a  thing 
of  the  past.  The  introduction  of  mild  steel  has  allowed  the  working  pressures 
of  boilers  to  b_>  more  than  doubled."  Private  communication,  Aug.  10th,  1887. 

Similar  views  are  expressed  by  Mr.  B.  Martell,  also  of  Lloyd's  Register,  who 
says  (Trans.  Inst.  Hav.  Architects,  XXVII.,  p.  58,  1886)  "  constant  attention  has 
been  given  to  this  subject  (corrosior)  by  the  surveyors  to  Lloyd's  Register,  as  the 
ve:se!s  have  from  time  to  time  come  under  examination.  The  general  opinion  ex- 
Dressed  by  them  is  that,  so  far  as  corrosion  is  concerned,  mild  steel  is  not  more  in- 
juriously affected  than  iron,  provided  the  mill  scale  be  first  cleaned  off  the  sur- 
faces before  coating  the  steel." 


102 


THE    METALLURGY    OF    STEEL. 


of  these  two  classes  of  iron,  many  asserted,  and  often  in 
very  strong  terms,  the  very  great  general  superiority  of 
steel  over  wrought-iron,  and  not  a  single  opinion  to  the 
contrary  was  expressed,  which  is  certainly  striking,  con- 
sidering that  Iliad  no  knowledge  in  general  as  to  the  views 
of  the  persons  addressed,  and  hence  exercised  no  selection, 
conscious  or  unconscious,  in  favor  of  either  metal. 

The  very  rapid  increase  in  the  use  of  steel  for  ship- 
building, and  in  the  ratio  of  steel  to  iron  vessels  built, 
illustrated  by  the  following  table,  goes  to  show  that  ship- 
builders and  users  no  longer  consider  that  steel  is  at  a 
serious  disadvantage  as  regards  corrosion. 

TABLE  47  D.— STEEL  A.ND  IKON  VESSELS  CLASSED  AT  LLOYD'S  REGISTER,  a 


Tear  .  . 

1STS. 

1879. 

1880. 

1881. 

1882. 

1SSR. 

1884. 

18*5. 

Stop!    j  Dumber  
»teel..-j  Tons  

7 
4,170 
435 
517,692 
1  :  116- 

9 

10,000 

848 
470,969 
1  :  29-4 

23 
85,373 
855 
459,994 
1  :18- 

23 
42,407 
452 
696,724 
1  :16-4 

H 

125,841 
525 
851,075 
1  :  6-77 

109 
166,4iS 
614 
9S3,774 
1  :  5-61 

92 
132,457 
618 

661.201 
1  :  4-99 

118 
165,437 
260 
290,429 
1  :  1-76 

Iron..^Tons  

Ratio  steel  :  iron,  tons  .  . 

a  Trans.  Inst.  Nav.  Architects,  XXVII.,  p.  55,  1S86     The  last  line  is  calculated  from  the  data 
there  given.     Vessels  built  on  the  continent,  in  America  and  the  colonies  are  excluded. 

From  our  small  scale  tests  it  might  be  expected  that 
the  contact  of  wrought-iron  and  steel,  like  that  of  any 
dissimilar  classes  of  iron,  would  hasten  the  corrosion  of 
one  if  not  both.  And  in  some  instances  this  has  been  the 
case  ;  it  is  sometimes  the  wrought-iron,  sometimes  the  steel 
whose  corrosion  is  accelerated.  Thus  Martell  found  that, 
after  a  year's  exposure  to  sea  water,  the  steel  plating  of  a 
vessel  riveted  with  wrought-iron  had,  in  the  immediate 
neighborhood  of  the  rivets,  corroded  more  than  the  rivets: 
while  Denny  reports  that,  in  case  of  a  steel  vessel,  the 
forgings  and  certain  covering  plates  of  whose  rudder  were 
of  iron,  the  iron  had  corroded  rather  seriously,  while  the 
steel  with  which  it  was  in  contact  had  not  corroded  at  all. a 

In  the  manufacture  of  screws  a  tendency  on  the  part  of 
soft  Bessemer  steel  to  rust  has  prevented  certain  manu- 
facturers from  substituting  this  material  for  wrought-iron. 
It  seems  that  the  discoloration  in  general  does  not  appear 
immediately  after  cutting  the  threads,  but  begins  a  few 
hours  or  days  afterwards,  and  increases  with  time.  The 
cause  is  obscure.  It  has  been  suggested  that  the  steel 
may  be  harder  than  the  wrought-iron,  and  thus  become 
slightly  hotter  when  the  thread  is  cut,  a  slight  oxidation 
then  occurring,  which  increases  later.  The  screws  do  not 
become  sensibly  warm :  yet  at  the  instant  of  cutting  the 
very  skin  may  be  hot  enough  to  oxidize,  the  temperature 
being  reduced  so  instantaneously  by  conduction  that  the 
warmth  cannot  be  detected.  Oxidation  thus  started  may 
increase  later.  But  the  fact  that  the  surface  of  the  steel 
screw  is  left  somewhat  rougher  by  the  cutting  tool  than 
that  of  the  iron  one  seems  sufficient  to  account  for  the 
facts.  From  the  rough  surface  of  the  steel  the  liquid  in 
which  the  screws  are  cut  would  not  be  so  completely  re- 
moved :  remaining  slightly  moist,  rusting  might  ensue. 
Indeed,  there  is  probably  little  doubt  that  a  smooth  pol- 
ished iron  surface  in  general  rusts  less  readily  than  a 
rough  one." 

§  166  A.  There  is  a  belief  that  the  best  kinds  of  wrought- 
iron  corrode  more  easily  than  the  commoner  kinds,  and 
some  of  our  small  scale  evidence  supports  this  belief,  but 
by  no  means  conclusively.  If  there  were  a  really  impor- 
tant difference  in  favor  of  the  common  wrought-iron, 
then  we  should  expect  that  it  would  nearly  always  corrode 


aProc.  Inst.  Nav.  Architects,  XXIII.,  pp.  146-7,  1882. 

h  Private  communications,  T.  M.  Drown  and  Russell  and  Erwin,  Pecember  6th, 
10th  and  17th,  1887. 


faster  than  the  purer  kinds,  which  is  far  from  true.  Mal- 
let indeed  found  that  the  admirable  Swedish  and  Low- 
moor  wrought-iron  corroded  faster  than  the  common 
varieties  in  sewage-bearing  sea  water  and  when  exposed 
to  the  weather :  but,  on  the  other  hand,  in  river  water  and 
pure  sea  water  the  reverse  occurred.  So,  too,  in  Parker' s 
experiments,  in  which  two  kinds  of  common  and  five  of 
best  wrought-iron  were  exposed  to  six  different  sets  of 
conditions,  while  the  mean  corrosion  of  the  common  was 
less  than  that  of  the  best  irons  under  five  of  the  six  sets  of 
conditions,  yet  the  difference  was  always  slight,  from  5  to 
17%,  and  in  four  out  of  these  five  sets  at  least  one  of  the 
best  irons  corroded  more  slowly  than  at  least  one  of  the 
common  irons.  In  the  sixth  set  the  common  iron  corroded 
slightly  faster  than  the  best.  Were  we  to  strike  a  mean 
of  all  of  Parker's  and  Mallet's  results,  it  might  be  in 
favor  of  the  common  irons :  but,  in  view  of  the  charac- 
teristics of  our  evidence,  such  an  average  carries  little 
weight  unless  based  on  a  vastly  greater  number  of  obser- 
vations than  we  possess. 

§  167.  INFLUENCE  OF  DIFFERENCE  OF  POTENTIAL. — The 
contact  of  more  electro-positive  substances,  such  as  zinc, 
retards,  that  of  more  electro-negative  ones,  such  as  tin, 
lead,  copper,  magnetic  and  ferric  oxides,  accelerates  the 
rusting  of  iron.  Hence  while  galvanizing  even  if  defec- 
tive hinders  the  rusting  even  of  exposed  spots,  tinning 
and  coating  with  magnetic  oxide  probably  greatly  hasten 
the  corrosion  of  unprotected  portions. 

A.  Galvanizing.   In  lines  6  and  7  of  Table  44  we  note  that 
galvanizing  reduces  the  corrosion  of  wrought  iron  under 
all  conditions  of  exposure,  by  from  about  60$  in  case  cf 
foul  sea  and  pure  river  water  to  nearly  75%  in  case  of  foul 
river  water,  completely  preventing  it  in  case  of  exposure 
to  the  weather.     Taking  all  the  conditions  together,  the 
galvanized  wrought-iron  may  be  considered  as  resisting 
corrosion  much  better  than  even  skin-bearing  cast-iron. 

B.  Segregations  within  the   metal   itself,    as  already 
pointed  out,  probably  greatly  hasten  corrosion,  by  creat- 
ing difference  of  potential. 

C.  INFLUENCE  OF  MAGNETIC  OXIDE. — The  magnetic 
and  similar  oxides  of  which  iron  scale  consists,  whose 
stability  is  illustrated  by  the  resistance  of  native  mag- 
netite, iron  sands,  etc.,  to  the  oxidizing  action  of  the  at- 
mosphere, and  of  fresh  and  salt  water  even  when  periodic- 
ally wet  and  dried  by  the  tide  for  countless  centuries, 
protect  iron  which  they  coat  from  oxidation,  but  hasten 
that  of  naked  iron.     Their  protective  action  is  shown  in 
the  comparatively  slow  rusting  of  Russia  iron,  of  blued 
iron,  and  of  castings  which  retain  their  original  skin.  An 
effective  form  is  the  comparatively  thick  coating  of  oxide 
produced  on  a  very  great  scale  by  repeatedly  heating 
iron  to  redness  alternately  in  an  atmosphere  of  carbonic 
oxide  plus  nitrogen  and  in  one  of  mixed  carbonic  oxide, 
carbonic  acid  and  nitrogen  (Bower's  process),  or  better 
still,  by  prolonged  heating  to  redneas  in  steam,  which, 
though  it  acts  more  slowly,  is  said  by  some  to  create  a 
more  tenacious  and  impervious  skin  (Barff '  s  process).    The 
coating  of  oxide  produced  in  this  way  under  favorable 
conditions  is  impervious,  adheres  well,  and  is  a  powerful 
protection.0 


"Percy,  Journ.  Iron  and  St.  Inst.,  1877,  II.,  p.  456  :  Bower,  Idem,  1881,  I., 
p.  166  :  Trans.  Am.  Inst.  Mining  Engrs.,  XI.,  p.  329,  1883  :  Kidder,  paper  be- 
fore Chem.  Soc.  of  Washington,  1885  :  Stahl  und  Eisen,  IV.,  p.  98,  1884. 


INFLUENCE    OF    DIFFERENCE    OF    POTENTIAL    ON    RUSTING.      §  167. 


103 


All  the  parts  of  the  Springfield  United  States  rifles,  ex- 
cepting those  which  are  case-hardened,  the  barrels  and  the 
lock  parts,  fire  coated  with  magnetic  oxide  by  Buffing- 
ton's  procr..-ss  of  suspending  them  for  five  minutes  or  more 
in  pure  molten  niter  containing  manganic  oxide,  at  a  tem- 
perature sufficing  to  ignite  sawdust."  It  was  for  a  time 
applied  to  gun  barrels  also,  but  even  the  very  moderate 
temperature  employed  sometimes  twisted  them. 

It  has,  however,  been  repeatedly  shown  that  iron  scale  is 
strongly  electro-negative  to  iron,  and  that,  while  it  hinders 
the  corrosion  of  those  portions  of  the  iron  which  it  actu- 
ally covers,  its  presence  greatly  hastens  the  corrosion  of 
naked  iron,  whether  in  adjacent  portions  of  the  same 
piece  or  in  separate  pieces  with  which  it  is  galvanically 
connected.  It  thus  acts  like  copper,  but  less  intensely. 
Andrews,  immersing  in  confined  cold  sea  water  bright 
plates  of  wrought-iron,  cast-iron  and  steel,  each  coupled 
galvanically  to  a  similar  but  scale-bearing  plate,  detected 
by  the  galvanometer  a  rapidly  diminishing  electromotive 
force,  from  about  one  third  to  about  one  fourth  of  that 
existing  under  like  conditions  between  similar  bright 
plates  and  copper  plates."  In  experiments  in  Portsmouth 
Harbor,  England,  the  galvanometer  showed  active  galvanic 
action  between  scale-covered  and  naked  portions  of  the 
same  plate  immersed  in  sea  water.  When  cylinders  of 
naked  and  Barffed  (/.  e.  artificially  scale-coated)  iron,  gal- 
vanically connected  by  platinum,  were  immersed  by  J.  H. 
Kidder  in  pure  sea  water,  a  decided  current  was  indicated 
by  the  galvanometer.6 

In  Andrews'  experiments,  which  I  here  summarize,  con- 
tact with  scale -bearing  plates  appeared  to  about  quadruple 
the  corrosion  of  bright  plates,  affecting  it  about  three  fifths 
as  much  as  contact  with  copperplates  did.  Note,  in  these 
harmonious  results,  that  contact  with  scale-bearing  plates 
hastens  corrosion  in  every  case,  increasing  it  from  3-3  to 
4'7  fold.  To  facilitate  comparison  I  have  reduced  the  re- 
sults to  a  uniform  time  of  exposure  of  one  year. 

TABLE    48.— INFLUENCE    OF    IRON    SCALE:    CORROSION   IN    CONFINED   COLD   SEA    WATER. 

ANDREWS. 


In  cold  water. 

In 
London 
air. 

In  marine  boilers. 

Sea. 

Bilge. 

With 

zinc. 

Without 
zinc,  a 

Without 
zinc,  a 

Mean. 

3-8 
06 

2  12 

1-2 
0-5 

•87 

11 

05 

•89 

3-1 
0-9 

1  6s 

1-2 
0-9 
1-08 

1-1 

05 

77 

i:28 

a,  a.     In  these  two  instances  the  scale  was  cither  wholly  or  nearly  wholly  removed  during 
exposure. 

Metal. 

Loss  of  scaleless  steel  and  iron  by  corrosion,  per  square  foot  of  surface 

per  annum. 

In    simple  in- 
sulated   im- 
mersion.   56 
week's. 

Immersed  in  galvanic  circuit. 

Each  plate 
connected 
with  a  bright 

wrou^ht- 
irou  plate 
56  weeks. 

Each  plate  connected  with  a 
similar    but     scale  bearing 
plate. 

Each  plate 
c  innected 
with  a  copper 
plate  for  16 
weeks. 

For  4  weeks. 

For  16  weeks. 

•015 
•014 
•017 
•020 
•018 
•016 
•021 
•017 

•026 
•027 
•027 
•025 
•019 
•080 
•026 

•058 
•052 
•051 
•049 
082 
•OC7 
•068 
061 

058 
•059 
•078 
•081 
•060 
076 
•OS6 
070 

•113 
•103 
•074 
•109 
•111 
•117 
•122 
•107 

Soft  Bessemer  steel. 
Soft  open-hearth  "  . 
Soft  cast  steel  
Hard  Bessemer  steel 
Hard  open-hearth  " 
Cast-iron  
Mean 

Bright  and  scale-bearing  discs,  cut  from  the  same  plates 
and  each  completely  insulated,  were  exposed  by  W.  Parker 
under  identical  conditions  for  from  38  to  65  weeks  to  Lon- 
don air,  cold  sea  and  bilge  water,  and  in  marine  boilers, 
each  set  containing  22  discs  (lines  23  to  33,  Table  44).  Dur- 
ing exposure  the  scale-bearing  plates  lost  part  and  in  some 
cases  all  their  scale.  The  degree  to  which  the  remaining 
scale  hastened  the  rusting  of  the  portions  thus  left  ex- 
posed was  estimated  by  dividing  the  total  loss  of  weight 


a  Bufflngton,  Annual  Kept.  Chf.  Ordnance  U.  S.  Army,  1884,  p.  77  :  private 
communication,  Nov.  15,  1887.  Weightman,  Trans.  Am.  Soc.  Mechanical  Engi 
neers,  1884  :  Iron  Age,  June  11,  1885,  p  1. 

b  Minutes  Proc.  Inst.  Civ.  Eng.,  LXXXII.,  p.  300,  1885. 

o  Paper  read  before  the  Chemical  Society  of  Washington,  April  10,  1885. 


per  square  foot  of  finally  scaleless  surface,  by  the  total 
time  of  exposure.  This  however  brings  the  apparent  much 
below  the  true  influence  of  the  scale  :  for  much  of  the 
scale  doubtless  fell  off  some  time  after  immersion  began, 
so  that  actually  much  less  than  the  total  time  of  immersion 
was  available  for  the  corrosion  of  the  portions  thus  left 
bare.  But  even  if  we  make  no  allowance  for  this  exag- 
geration of  the  apparent  time,  the  corrosion  of  the  naked 
portions  of  these  plates  still  appears  on  the  whole  greater 
than  that  of  the  scaleless  plates.  In  the  case  of  exposure 
to  London  air  and  of  the  marine  boilers  without  zinc  this 
exaggeration  of  the  apparent  time  of  exposure  masks  the 
effects  of  scale.  I  here  condense  his  results. 

TABLE  49.— RATIO  or  THE  APPARENT    EATE    op    CORROSION    OF    THE    NAKED    POKTION    or 
SCALE-BEARING  TO  THAT  OF  SCALELESS  Discs.    PARKER. d 


Fig.  9  also  illustrates  the  influence  of  scale.  The  corro- 
sion curves  for  galvanic  contact  with  copper  and  with 
scale  bearing  iron  are  convex  towards  the  vertical  axis, 
thus  harmonizing  with  the  observed  progressive  diminu- 
tion of  electromotive  force,  while  the  concavity  of  the 
other  curves  illustrates  the  accelerated  corrosion  under 
simple  immersion  or  contact  with  bright  plates. 

Actual  experience  seems  to  fully  bear  out  the  results  of 
these  experiments,  and  it  is  considered  very  important  to 
remove  the  scale  from  the  plates  of  iron  ships,  and  to 
that  end  they  are  sometimes  pickled. 

D.  Copper,  Brass,  etc.     As  copper  is  electro-negative  to 
iron  under  ordinary  circumstances,  while  zinc  is  electro- 
positive, so  we  find  that  while  the  contact  of  zinc  and  of  the 
most  zinciferous  brasses  retards  rusting,  that  of  copper  and 
of  the  common  brasses  rich  in  copper  hastens  it,  the  brasses 
very  rich  in  copper  being  apparently  as  injurious  as  cop- 
per itself  ;  that  of  the  bronzes  (copper-tin  alloys)  hastens 
it  still  more,  and  that  of  pure  tin  more  yet.     Mallet  found 
that  a  brass  consisting  of  15%  of  zinc  and  25%  of  copper 
protected  cast  iron  from  corrosion  as  well  as  pure  zinc, 
while  it  was   not   so  rapidly  corroded  itself  as  zinc  is  : 
whence  he  inferred  that  it  would  form  a  more  permanent 
protection  than  zinc.     He  found  that  during  an  immersion 
of  from  15  to  66  days  in  pure  sea  water,  the  corrosion  of 
cast-iron  was  increased  by  galvanic  contact  as  follow  s  : 

Brasses  containing  less  than  31%  of  copper  retard  corrosion. 

Copper  and  brasses  containing  8  1)<  of  copper  or  more  increase  corrosion  by  ............  10  to    61 

Bronzes  increase  rusting  by  ..................................................  62  to  23' 

Tin  increases  rusting  by  ......................  ................................... 

E.  Iron  on  Iron.    As  there  is  a  decided  difference  of 
potential  between  different  sorts  of  irons,  so  their  mutual 
contact  hastens  the  corrosion  of  the  more  electro-positive 
while  retarding  that  of  the  more  electro-negative.     Thus, 
immersing  similar  blocks  of  very  hard  dense  bright  gray 
and  of  soft  "highly  carbonaceous"  dark  gray  cast-iron 
for  25  months  in  jars  of  confined  sea  water,  A  separately, 
and  B  with  the  hard  in  galvanic  contact  with  the  soft, 
Mallet  found  that  the  average  depth  of  removal  of  metal 
by  corrosion  was  as  follows  : 


Depth  of  corrosion  on  simple  immersion  ......     ...........  hard  iron  ;007'' 

Depth  of  corrosion  when  immersed  in  mutual  contact  ......... 


soft  iron  ;  01" 


The  net  effect  of  the  contact  is  to  greatly  increase  corro- 


d  Journ.  Iron  and  St.  lost.,  1881, 1.,  p.  49. 


104 


THE    METALLURGY    OF     STEEL. 


sion,  as  the  soft  iron  now  loses  nearly  twice  as  much  as 
both  together  lost  when  separately  immersed.     See  p.  100. 
§  168.  PROTECTIVE  COATINGS,  ETC. — Finding  no  data  as 
to  the  relative  protection  against  rusting  afforded  by  gal- 
vanizing, tinning,  barffing,  etc.,  1  have  begun  some  experi- 
ments to  fill  the  gap.    Their  final  results  will  appear  in  an 
appendix  ;  those  obtained  shortly  after  immersion  follow. 
In  comparing  these  protective  coatings,  two  chief  points 
are  to  be  considered,  the  thoroughness  and  permanence 
with  which  they  exclude  air  and  moisture,  and  thus  me- 
chanically prevent  oxidation,  and  their  galvanic  effect. 
Thus,  while  a  coating  of  tin  or  of  magnetic  oxide,  being 
electro-negative  to  iron,  hastens,  while  one  of  zinc  retards 
the  corrosion  cf  unprotected  portions,  yet  the  former  may 
be  so  much  more  impervious  and  enduring  than  the  latter 
that  their  mechanical  advantage  may  outweigh  their  gal- 
vanic disadvantage.     As  .far  as  my  inquiries  have  gone, 
workers  cf  tinned  and  zinced  iron  consider  zincing  as  a 
much  better  and  more  enduring  protection  than  tinning  : 
and  my  results  agree  to  a  certain  extent  with  their  belief. 
Of  the  twenty-three  galvanized  pieces  tested,  fifteen  of 
which  were  sheared  from  sheets  of  galvanized  iron,  and 
therefore  had  no  zinc  on  their  edges,  one  only  showed 
rust,  after  an  exposure  of  from  16  to  18  days  :  the  edges 
of  all  the  sheared  pieces,  even  of  those  in  sea  water,  re- 
maining perfectly  bright  after  18  days  immersion.    All  of 
the  fifteen  sheared  tin  pieces,  including  those  in  distilled 
water,  had  rusted  at  the  end  of  24  hours  :  while  all  the 
unsheared   pieces,    i.   e.    those   which    were   completely 
covered  with  tin,  had  rusted  after  17  hours  immersion 
when  in  sea  water,  and  after  8  days  when  in  Cochituate 
water 

But  when  we  come  to  the  actual  loss  of  weight  (Lines  9 
to  11,  Table  47  F)  we  find  little  difference  between  the 
galvanized  and  tinned  pieces.  The  very  considerable  loss 
of  weight  which  the  galvanized  pieces  undergo  in  Cochit- 
uate and  distilled  water,  indicates  that  a  considerable  pro- 
portion of  their  zinc  is  pretty  rapidly  removed.  As 
with  its  removal  the  conditions  must  change  greatly, 


longer  exposures  are  needed  before  we  can  decide  as  to 
the  relative  protection  afforded  by  zinc  and  tin. 

During  the  brief  immersions  of  my  experiments  the 
other  classes  of  iron  rusted  much  more  than  either  gal- 
vanizt  d  or  tinned  iron  :  whether  the  same  will  hold  true 
in  all  c^ses  after  prolonged  immersion  remains  to  be  seen. 
While  to  judge  by  the  eye  bright  iron  appears  to  rust 
much  more  rapidly  than  the  others,  becoming  completely  or 
nearly  completely  covered  with  rust  in  about  twelve  hours, 
though  a  large  part  of  the  surface  of  the  Russia  and  black 
irons  remained  free  from  rust  after  18  days,  yet  the  actual 
loss  of  weight  by  corrosion  does  not  differ  very  greatly 
among  these  three  classes  ;  the  black  iron  on  the  whole 
corrodes  somewhat  faster  than  the  bright  and  the  Russia. 

Judging  from  the  proportion  of  surface  covered  with 
rust,  the  barffed  iron  appears  on  the  whole  to  resist  rust- 
ing better  than  any  of  the  others,  excepting  the  galvan- 
ized and  the  tinned.  Though  I  cannot  state  confidently 
that  the  barffed  iron  corroded  less  rapidly  than  the  Russia 
in  .sea  water,  in  Cochituate  water  the  difference  was 
marked,  the  Russia  iron  always  showing  signs  of  rust  in 
from  one  to  eight  hours  after  immersion,  while  of  the 
barffed  pieces  one  began  to  rust  after  16\5  hours,  another 
after  47  hours,  and  the  other  two  were  free  from  rust  after 
16  days  immersion. 

The  few  pieces  of  blued  iron  experimented  on  rusted 
with  extraordinary  rapidity,  becoming  about  one-third 
covered  with  rust  in  8'5  hours,  even  in  distilled  water. 

The  nickeled  pieces  also  rusted  very  rapidly,  but  the 
rusting  appeared  to  be  confined  to  certain  spots  :  and,  in 
several  cases  after  a  nickeled  piece  had  become  much 
rusted,  on  removing  the  rust  with  a  cloth  and  rubbing 
the  piece  I  was  unable  to  discover  with  the  naked  eye  the 
spot  at  M  Inch  the  rust  had  formed. 

The  barffed  pieces  undergo  tubercular  rusting,  the  cor- 
rosion being  confined  to  certain  spots,  at  which  the  rust 
piles  itself  up  in  little  knobs.  The  tinned  pieces  also 
occasionally  developed  tubercles  of  rust,  but  to  a  much 
Less  marked  degree. 


TABLE  47  F. — CORROSION  or  GALVANIZED  AND  TINNED  IRON,  ETC. 


Simple  immersion 
in. 

Thin  sheet  iron. 

Barffed  lumps. 

Tinned  nails. 

Galvanized 
staples. 

Blued 

screws. 

Nickeled  screws. 

Galvanized. 

Tinned. 

Eussia. 

Black. 

Bright. 

Length  of  time  immersed  when  J 
rusting  was  first  observed  .  | 

Percentage  of  upper  surface  I 
covered  with  rust  after  18-< 

Sea  water. 
Cochituate     (Bos- 
ton) water. 
Distilled  water. 
Sea  water. 
Cochituate. 
Distilled. 
Sea. 

Cochituate. 

Sea  water. 
Cochituate    water. 
Distilled  water. 

25-5  hrs. 

25-5  hrs. 
24  hrs. 
4 
8 
5 

5'5  hrs. 

7-67  hrs. 
1  hr. 
27 
20 
14 

0  C7  hrs. 

3-25  hrs. 
Ihr. 
10 
62 
27 

3-25  hrs. 

Ihr. 
Ihr. 
100- 
99-5 
100 

4-5  hrs. 
16-5  hrs. 

17  hrs. 
46  hrs. 

16  days. 

17     hrs. 

16  -S  hrs. 
1  •{>(?)  hrs. 

IT)    nib. 

1  All      perfectly  ( 
\  bright,includ--^ 
)    ing  edges.        ( 

Appearance  after  16  days  im-  j 
inersion  ) 

Much  tubercular 
rust. 
Tubercular  rust- 
ing. 

Ends  badly  rust- 
ed. 

Slightly  spotted. 

Almost  perfectly 
clean. 

Perfectly  clean. 

Ileads  completely  covered 
with  rust,  or  nearly  so. 
Heads  much  rusted. 

0-143 
0-177 
0-199 

Loss  of  weight,  Ibs.  per  sq.J 
ft.  of  surface  per  annum  ...  .  "l 

0  00018 
0  tll>2 
0  044 

0  OSO 
0-042 
0  050 

0-136 
0-143 
0-128 

0  138 
0  275 
0-187 

The  pieces  wore  in  all  cases  immersed  in  confined  water,  in  .shallow,  open  porcelain  vessels,  the  water  standing  about  '37  inch  above  the  iron,  and  the  loss  by  evaporation  being  compensated  for 
by  adding  distilled  water,  usually  every  alternate  day.  The  different  pieces  did  not  touch  each  other. 

THIN  SIIKKT  IKON. — In  each  of  the  three  menstrua  five  pieces  each  of  galvanized,  tinned  and  Russia  iron,  four  or  five  of  blaek  iron,  and  two  of  bright  sheet  iron,  each  0*5  inches  square,  were  im- 
mersed. 

OTIIEK  PIECES. — Four  galvanized  iron  staples,  4  and  5  tinned  nails,  4  and  0  barffed  lumps,  and  4  nickeled  screws  were  immersed  in  "  Cochituate"  and  in  sea  water:  and  3  nickeled  and  3  blued  screws 
in  distilled  water. 

Cochituate  water  is  Boston  city  water. 

Previous  to  immersion  the  pieces  were  simply  wiped  clean. 

The  pieces  of  sheet-iron  lay  horizontally,  or  nearly  so,  and  were  raised  above  the  bottom  of  the  vessel  by  thin  wooden  strips.  In  nearly  every  case  the  upper  side  of  these  pieces  rusted  very  much 
more  than  the  under  side. 


CONDITIONS     OF     GASES     IN    IRON.       §  170. 


106 


CHAPTER      X. 
NITROGEN,  HYDROGEN,  CARBONIC  OXIDE. 


§  170.  CONDITION  OF  THESE  SUBSTANCES  IN  IRON.— 
They  may  exist  in  three  if  not  four  fairly  distinct  condi- 
tions :  (1)  in  chemical  combination  of  the  ordinary  type  : 
(2)  in  solution:  (3)  in  adhesion:  (4)  mechanically  retained  in 
pores  which  are  at  least  microscopically  visible,  and  hence 
set  free  when  the  metal  is  comminuted.  In  the  first  three 
conditions  these  substances  are  distinctly  no  more 
gaseous  than  water  and  ice  are :  in  the  fourth  they  are 
gaseous. 

Some  of  these  terms  are  vague  enough  :  in  this  classifica- 
tion I  purposely  avoid  the  still  more  equivocal  ones  alloy- 
ing and  occlusion :  alloying  is  included  under  the  first 
three  conditions,  but  occlusion  may  be  held  to  imply  any 
of  the  four  or  a  combination  of  any  or  all  of  them. 

The  first  condition  may  be  exemplified  by  the  oxygen 
of  iron  oxide  in  minute  particles  dissolved  or  suspended 
in  solid  iron,  or  of  cuprous  oxide  in  molten  copper :  the 
second  by  hydrogen  or  sulphur  apparently  united  with 
the  whole  of  the  mass  of  molten  iron  which  contains  it : 
the  third,  in  which  physical  probably  greatly  preponder- 
ates over  chemical  force,  by  the  oxygen  and  nitrogen  con- 
densed on  the  surface  of  glass  tubes,  from  which  barome- 
ter makers  remove  them  with  the  greatest  difficulty,  or 
by  ammonia  or  carbonic  acid  absorbed  by  charcoal :  the 
fourth  by  bubbles  of  air  in  ice,  or  of  carbonic  acid  escap- 
ing from  champagne.  For  many  readers  the  first  three 
classes  are  resolvable  into  two  :  for  many  of  its  either  hold 
that  solutions  differ  only  in  degree  from  typical  chemical 
unions,  or  maintain  that  solution  and  adhesion  are  one.  I 
will  not  even  assert  that  I  have  in  the  foregoing  examples 
c  jrrectly  stated  the  conditions  of  the  elements.  We  can 
as  yet  rarely  if  ever  fully  discriminate,  in  the  case  of  nitro- 
gen, hydrogen,  etc.,  in  iron,  between  these  first  three  con- 
ditions :  for  our  purposes  they  may  be  regarded  as  a 
single  group,  the  non-gaseous  or  condensed  state,  clearly 
distinguished  from  the  fourth  or  gaseous  condition. 

We  must  free  ourselves  from  the  popular  misconcep- 
tion that  these  substances  can  only  exist  either  in  chemi- 
cal union  of  the  common  type,  i.  e.  in  definite  ratio,  or  as 
gas.  The  case  of  charcoal,  which  at  atmospheric  pressure 
absorbs  as  much  as  90  times  its  own  volume  of  ammonia, 
may  assist  us.  In  view  of  the  similar  retention  of  gases  by 
glass,  we  safely  hold  that  the  charcoal  and  ammonia  are 
not  in  chemical  union  of  the  ordinary  type :  nor  is  the 
ammonia  present  as  a  gas,  for  in  this  case  its  pressure 
should  burst  the  charcoal.  So  too  electro-deposited  iron 
may  hold  248  times  its  own  volume  of  hydrogen,  about 
half  of  which  escapes  when  the  metal  is  exposed  to  the 
air  at  the  ordinary  temperature.  Palladium  absorbs  980 
times  its  own  volume  of  hydrogen,  whose  density  is  thought 
to  be  thereby  increased  about  1 0, 000  times,  so  that  it  doubt- 
less exists  either  as  a  liquid  or  solid. 

While  we  readily  understand  how  solid  or  even  pasty 
iron  may  mechanically  retain  a  very  considerable  quantity 
of  hydrogen,  nitrogen,  etc.,  in  the  gaseous  condition,  it  is 
almost  inconceivable  that  molten  iron  should  hold  an  im- 
portant quantity.  Ice  may  be  as  spongy  as  you  please, 
but  water  can  retain  but  few  and  minute  gas  bubbles. 


These  substances  pass  back  and  forth,  from  the  condi- 
tion of  a  gas  mechanically  held  in  blowholes  to  the  non- 
gaseous  condition  of  adhesion,  so  readily  that,  while  the 
two  conditions  are  very  unlike,  it  is  extremely  difficult  in 
the  case  of  gas  present  in  solid  i;;on  to  decide  how  much 
exists  in  each  state.  If  we  would  collect  the  mechanic- 
ally held  hydrogen  by  exhausting  the  metal,  part  of  that 
in  adhesion  probably  becomes  gasified  the  instant  that 
the  pressure  of  the  initially  gaseous  portion  begins  to 
decline.  Nay,  even  the  mechanical  action  of  the  drill 
with  which  we  seek  the  larger  cavities  may  gasify  part  rf 
the  hydrogen  in  adhesion.  And,  if  there  be  a  real  differ- 
ence of  kind  between  adhesion  and  solution,  hydrogen 
probably  slides  back  and  forth  between  these  states  also 
on  slight  provocation. 

We  readily  see  how  hydrogen,  nitrogen,  etc.,  in  chemi- 
cal combination  .or  solution  may  affect  the  properties  of 
iron :  we  may  also  conceive  that,  when  in  adhesion,  they 
may  have  a  powerful  influence,  owing  to  the  ease  with 
which  they  become  gasified.  If  a  sis  probable,  themetal  con- 
tains numberless  microscopic  or  even  intermolecular  pores, 
when  we  distort  it  we  change  their  size.  Part  of  the  hydro- 
gen in  adhesion  may  be  supposed  to  gasify  and  rush  into 
those  which  we  thus  temporarily  enlarge,  as  fast  as  this 
enlargement  lowers  the  pressure  of  the  gas  already  in 
them.  This  increased  quantity  of  gas  may  subsequently 
oppose  our  effort  to  return  the  metal  to  its  initial  shape, 
and  perhaps  the  more  powerfully  the  larger  the  quantity 
of  hydrogen  in  adhesion.  The  '01$  of  hydrogen  often 
present  in  iron  might  in  this  way  influence  its  properties 
greatly,  more  perhaps  than  if  in  chemical  combination ; 
for,  if  gasified,  its  volume  would  be  ten  times  that  of  the 
steel  at  atmospheric  pressure.  This  is  not  brought  for- 
ward as  the  actual  condition  of  things,  but  merely  as  an 
illustration  of  the  way  in  which  hydrogen,  nitrogen,  etc., 
in  adhesion  might  be  conceived  to  act,  and  as  showing 
£hat  it  is  conceivable  that  they  might  influence  the  prop- 
erties of  iron  without  being  chemically  combined  with  it. 
A  possible  example  will  be  presented  in  §  178. 

But  a  given  weight  of  hydrogen,  etc.,  probably  pro- 
duces by  far  the  most  severe  effects  when  it  passes  from 
the  condensed  to  the  gaseous  state  while  the  metal  is 
plastic.  Unable  to  free  itself  it  collects,  producing  cavi- 
ties or  blowholes :  if  these  occupy  but  one-twentieth  of 
the  volume  of  the  metal  they  may  make  it  perfectly  use- 
less ;  yet  they  could  be  caused  by  gas  which  formed  but 
0  '00005$  of  the  metal  by  weight,  or  one  part  in  2,000,000. 
We  can  hardly  believe  that  so  minute  a  quantity  in 
chemical  combination  could  sensibly  affect  the  properties 
of  the  metal. 

The  gases  present  in  iron  may  be  classified  according  to 
the  time  of  their  escape  as  follows  : 

I.  Gasified  while  the  metal  is  so  liquid  that  no  trace  of 
their  passage  remains. 

II.  Still  retained  at  that  time,  or  formed  later  by  reac- 
tions. 

A.  Gasified  during  plasticity:     form  blowholes  (and 

pipes  2) 


106 


THE    METALLURGY    OF    STEEL. 


1.  Escape  gradiially  from  the  blowholes  through,  the 
walls  of  the  cooling  ingot. 

2.  Redissolve  in  the  metal. 

3.  Remain  in  pores  and  blowholes. 

B.  Remain  dissolved  after  plasticity  has  ceased  or  not 
formed  till  then. 

1.  May  be  extracted  by  heating  in  vacuo. 

2.  Cannot  be  extracted  by  heat  alone. 

This  classification  will  be  considered  at  length  in  §  200. 
Clearly  rigid  discrimination  between  these  classes  is  diffi- 
cult if  not  impossible.  That  gasified  from  the  interior 
of  the  ingot  while  it  is  still  liquid  (class  I. )  may  be  pre- 
vented from  escaping  by  the  already  rigid  exterior,  and 
become  mixed  with  the  gases  of  class  II.,  A,  evolved  from 
the  earlier  solidifying  crust.  Again,  as  we  can  never  lay 
bare  all  the  microscopic  pores,  the  gas  removed  from  solu- 
tion by  heating  in  vacuo  (class  B  1)  may  be  contaminated 
with  that  present  in  pores  (class  A3.) 

Let  us  now  consider  nitrogen,  hydrogen  and  carbonic 
oxide  in  iron  separately,  reserving  for  a  later  chapter  the 
study  of  the  conditions  under  which  they  form  blowholes 
by  being  gasified  in  the  plastic  metal. 

The  following  tables  condense  the  results  obtained  by 
several  investigators  of  the  quantity  and  composition  of 
gas  evolved  by  iron  under  various  conditions. 


§172.  IRON  AND  NITROGEN. — Iron  in  its  ordinary  con- 
dition combines  with  pure"  b  dry  nitrogen  only  with  great 
difficulty :  but  it  readily  absorbs  this  gas  when  heated  in 
ammonia,  and  nascent  iron  may  unite  even  with 
pure  nitrogen,  e.  g.  when  this  gas  is  passed  over  iron 
oxide  while  it  is  being  reduced  either  by  hydrogen  or 
carbon.b 

Commercial  iron  contains  small  quantities  of  nitrogen, 
which  has  been  determined  by  several  investigators,  either 
by  converting  it  into  ammonia,  or  by  collecting  and  measur- 
ing it  after  expelling  it  from  the  iron  either  by  chemical 
means,  by  heating  it  in  vacuo,  or  by  simply  comminuting 
it.  Their  more  important  results  are  summarized  in 
Table  58. 

Of  these  6  and  7  should  represent  the  total  nitrogen  : 
12  should  give  only  that  winch  is  at  least  partly  physically 
retained  and  which  is  not  in  strong  chemical  union  with 
the  iron :  heating  in  hydrogen  should  only  give  that 
which  is  in  chemical  combination,  since  nitrogen  and 
hydrogen  do  not  unite  unless  at  least  one  of  them  be 
nascent :  while  heating  in  vacuo  might  or  might  not  give 
the  chemically  combined  nitrogen.  Dissolving  in  acid 
might  perhaps  convert  both  the  physically  and  the  cliemi- 

a  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  275. 

b  PriSmy,  Comptes  Rendus,  LII ,  p  323,  1861.    Percy,  Iron  and  Steel,  p.  53. 


TABLE  54.— GAS  OBTAINED  BY  BOEING  COLD  STEEL,  IKON,  ETC.,  UNDEB  WATEE,  ETC. 


Number. 

DESCRIPTION-  or  MZTAL. 

i 

o 

Recarburlz- 
ing,  etc. 

Composition  of 
metal. 

Behavior  of  metal  in  casting,  etc. 
Degree  of 

Composition  of  gases. 

"o 
^ 

&.S 

w  o 

& 
"o 

Drill  sharp  or  dull. 

»! 

o 
i  a 

I? 

£ 
'S  j 

!§ 

C. 

Mn. 

Si. 

Scattering. 

Rising. 

Solidity. 

H. 

N. 

CO. 

CO, 

O. 

1.. 
2.. 
8.. 

4.. 
5.. 
5 

Bessemer  rail  steel  a        
"         spring  steel,  bored  u:-der  oil  a  
"         metal  oxygenated  a  

M.. 
M.. 
M.. 

W 

Yes  .  . 
Yes.. 
Not.. 

Yes. 

No... 

•7@-9 
do.... 
do(?). 

do 

•4©-6 
do..  . 
do(f). 

do. 

Rises  quietly  
Rose  quietly  

Porous  

Few  small  holes.  . 
Many  large  blow- 

90-3 

Sl'9 

88-8 
77- 
76-7 
JO-4 
68-8 
78-1 
52-2 
54-9 
92-4 
78-4 
86-6 
85-8 
-7-21 
67-1 
88-T 

85-4 
64-5 

86-4 

54-7 
67' 
43- 

98 

18-1 

10-6 
28- 
26-3 
17  9 
80-5 
20-8 
48-1 
45-5 
5-9 
25-8 
18-8 
14-6 
11-15 
33'3 
10'3 

14-8 
85-4 

12-7 

45-8 
80-8 
28-5 

0 

0 

0-T 
0 
0 
1-8 
0 
0-9 
0 
0 
1-4 
1-8 
•82 
0 
1-65 
1-6 
0 

0-6 
0 

0-4 

0 
2-2 
27-2 
70-42 
4-8 
4-1 
2-5 
89 
2'8 

•48 
•21 

•60 
•45 
•29 
•44 
•165 
•51 
•05 
•073 
•17 
•05 
•54 
•78 
•25 
•21 
11- 

•86 
•20 

•22 

•06 
•25 

•55± 
•15 
•28 
•85 
•085 
•10 
•75 
6- 

S. 
j> 

D. 

S. 

S. 
D. 

Frothed  

M 

Yes 

do 

do 

Slight  

M 

Not 

T.. 

8.. 
9.. 
10 

"        ingot  iron  a  

M.. 

M 

Yes  .. 

Not 

•254- 
'25  + 

Did  not  rise  

Few  blow-holes.  .  . 
Very  porous  

Forged  roil  steel  initially  porous  a  

M.. 
M.. 
M 

Yes  .. 

Yes..  . 

•7®-9 

•4@-6 

Perfectly  solid... 
Solid  '.'.'.'. 

11.. 

12. 
13.. 
14.. 
15.. 
16.  . 
IT 
21.. 

22.. 
23.. 

24.. 

30 
33.. 
.14.. 
8fi.. 
36-5 
87.. 
88.. 
89 

No 

'«  + 
•••+ 

•69 
•40 

•89 
1-08 

ros 

•25  4- 
•26  4- 
•10 
•04 
•09 
1-0 
1-0 

M 

it 

Yes 

':37 

p            t  >  I  v» 

g 

•88 
•46 

•17 
•42 
•42 

Low.. 

Porous  

"         "    b 

8 

»         u    b 

g 

«' 

Solid  steel  b 

s 

Solid  

a 

Basic  Bessemer  steel  recarburized  with  ferro-man- 
ganese  c  

M.. 

M 

Yes.. 
No 

Scatters  — 
Scatters  little  .. 

Moderately  
Rises  slowly  

"     gently  
"         " 

Many  blow-holes  .  . 
Few'  blow-holes.  .  . 

Moderately  porous 
Very     few     blow- 



"           "            "    recarburized   with   ferro-man- 

M 

Yes 

u 

Basic   Bessemer    steel,   recarburized   with    ferro- 

M 

H 

i( 

Open-hearth  steel,  unrecarburlzed  (oxygenated  f)a.  . 

M 

Not 

M 

1.6 
20-85 

0 

•85 

F 

M 

No  blow-holes  

86-5 
81-1 
83-8 
52-1 
62-2 
62-5 
54-5 

9'2 
14-8 
14-2 
44- 
85-6 
44  9 
46-5 

Th                hi           i  f  «•  seconds 

M 

Bessemer  pig  direct  from  cupola  a  

M.. 

M 





No  blow-holes  

M 

40.. 
41.. 

S 

Solid  

g 

Pg, 

In  most  of  these  experiments  the  pas  was  obtained  by  boring  cold  metal  under  water,  as  shown  In  figure  16,  §  217.  The  columns  headed  "  degree  of  scattering,  rising  and  solidity"  refer  to  the  bo- 
bavior  of  the  metal  before  and  during  solidification,  and  to  the  porosity  of  the  cold  solidified  metal. 

The  metal  was  in  general  bored  with  a  sharp  drill,  but  in  two  cases,  Numbers  17  and  41,  the  cutting  edge  was  previously  removed  from  the  drill,  which  then  ground  instead  of  cutting  a  hole  in  the 
metal,  releasing  very  much  more  gas  than  the  sharp  drill,  but  of  essentially  tne  same  composition. 

Muller's  drill  was  so  wide  that  it  cut  out  the  greater  part  of  the  cross  section  of  the  ingot. 

3.  Muller  unquestionably  includes  this  among  the  steels  which  contain  -4  to  fyf  of  silicon  and  '7  to  -9#  of  manganese  :  but  as  Number  4  is  also  included  in  this  class,  it  is  possible  that  Number  8 
may  have  been  included  accidentally. 

6.  Unrecarburized  Bessemer  metal.    When  this  metal  was  subsequently  recarburized  with  spiegeleisen  a  violent  reaction  ensued,  and  perfectly  solid  rail  steel  was  produced. 

7.  Obtained  by  interrupting  the  process  :  t.  f .  not  fully  blown. 
21.  Soft,  recarburized  with  2'5$  of  35^  ferro-manganese. 

23.  Recarburized  with  5£  of  14;6  ferro-silicon  and  2'5£  of  70j!  ferro-mangancse. 

24.  Recarburized  with  5£  ot  11%  ferro-silicon. 

83.  Basic  Bessemer  ingot  iron.     It  behaved  normally  in  the  roughing  rolls,  in  which  it  reduced  to  an   | 1   section.      On  reheating  it  blistered  to  an  extraordinary  degree,  the  web  swelling  out 

nn  both  sides  till  it  was  wider  than  the  flanges      When  cooled  it  was  bored  under  water,  and  the  gas  was  found  to  be  below  the  atmospheric  pressure,  so  that  it  had  to  be  removed  by  an  aspirator.    A 
duplicate  jinalvsis  in  another  laboratory  gave  like  results.    The  absence  of  oxygen  shows  that  the  gas  was  not  contaminated  with  air. 

84.  In  rolling  puddled  plate  iron  about  three-eighths  of  an  inch  thick  (10  mm.)  in  the  finishing  rolls,  a  blister  arose,  nearly  equal  on  both  sides  of  the  plate.    It  was  bored  nnder  water,  and  100  cc. 
gas  extracted,  while  the  volume  of  the  blister  itself  was  180  cc. 

a  =  Muller,  Iron,  1883,  p.  61. 

b  =  Idem,  p.  115. 

c  =  Muller,  Stahl  und  Eisen  18R3,  p.  446  ;  Iron.  1888.  p.  244. 

d  =  A.  Friedman.  Stahl  und  Kisen,  1885,  p.  529,  .Tonrn,  Iron  and  St.  lost.,  1885,  II.,  p.  646. 

e  =  Muller,  Stah)  und  Kisen,  II.,  p.  79, 1886, 


IRON    AND    NITROGEN.       §  172. 


107 


TABLE  55.— GAS  ESVAI-INK  KKIIM  HOT  IK.IN.  ]!KFI>I:K,  IH'i-.iNci  AND  SHOBTLY  AFTER  SOLIDIFICATION. 


Number. 

Drscription  of  metal. 

When  collected. 

Authority. 

Kecarbur- 
ized  or  not. 

Composition  of  im-Ud. 

Degree  of 

Composition  of  gases. 

Collected 
from 

C. 

81. 

Mn. 

P. 

Scattering. 

Rising. 

Solidity. 

CO. 

H. 

N. 

00* 

0. 

61. 
62. 
63 
64 
65. 
66. 

67 
68. 

69. 
70. 
71. 

72. 
73. 
74. 

75. 
76. 

77. 
78. 
79. 
80 
81. 

82 
83. 

84. 
65. 

86. 
87. 

88. 
89 

90. 
91. 

92. 
98. 

94. 

95. 
96. 

97. 
98 
99. 

100. 
101. 

Bessemer  rail  steel 
spring  st 

"        rail  steel, 
later 

From  mould  

M 

Yes 

•28Q-88 
•48®  -88 
do. 
do. 

do. 
do. 

do! 

•illlfu-lls 

do. 
do. 

Quiet  

No  rising 

Risesslightly 
Rises  exces- 

Perfectly  solid 
u 

4-0 

T7± 
59 
88-7 

(3-4 
8-9 

42-5 

IV  4 

73 
'.>  r, 
9  1± 
1-4 
1-3 

46-9 
44  5 

6-5 
I'O 

7-9 
8  6 
7  9± 
9  9 

7-2 

6  6 
2-5 

7-1 
2'2 

7-r. 

7  9 

!J'4± 

•]'- 

8-1 
4-B 

8-7 

Above 
Below 

eel  

•  • 

.« 

u 

u 

14      ' 

From  tirst  mould.. 

"     last       "    .. 

"     first       "    .. 

(( 

Above 
Below 

~:mir    cast.  17    min. 

"  :':..  ::: 

Bessemer  spring  si 
later 

eel,  first  mould  

'  same  cast,  21  min. 

"     last        "    ; 

u 

„ 

Bessemer  stet-1  i-isi 

S 
M 

M 

H 

No 
Yes 

No 
Yes 

excessively,  ingots 

\ 

31-5 

70-7 
12-5 

8-6 
18-1 

61-8 

57-5. 
76-6 
57'7± 
50-9 
77-8 

9  2 

0-7 
2'5 

54  2 

>2  9 

2  8 

47 

C'l 
4-8± 
51 
6  4 

21-6 

6-5 
50 

24-9 
26-8 

ill  4 
88-0 
17  3 
80  5± 
48-8 
16  0 

7  7 

2-1 
0 

2  8 
2-2 

0 
0 
0 

0  8 
0'4 

Bessemer  steel  risi 

11            "     Da 

j.     "           "    oxj 

1  Basic  steel,  soft, 
f     of  95f  ferro-m 
do        ... 

..   1 

Rises  exces- 

lington.a  

1 

Scatters  

Rises  

A   zone     of  ( 
blowholes,  j 

recarburized  with  2# 

•«5®  -1 
do. 
do. 
do. 
do. 
do. 

•25 

tr. 
do. 
do. 
do. 
do. 
do. 

do. 

•45©  '55 
do. 
do. 
do. 
do. 
do. 

do. 

05®'l 
do. 
do. 
do. 
do. 
do. 

do. 

Below 

Above 

ielow 

ibove 
rlelow 

Above 

j 

do  . 

do  .. 

do 

Basic  rail  steel  recarburized  with  B%  of 

68- 
56-5 

62- 
77-9 

62-6 
81  -T 

54-1 

8-8 
27-3 
85-0 
64-6 

16-2 
88-0 

84  2 
57 

12-6 

8-2 

38-6 

71-9 

43-5 
38-4 
18  9 

11-0 
8-6 

1-0 
14-7 

23  2 
9-5 

35 

18-1 

26-2 
22-5 
14-4 

4-8 
1  9 

2-8 
1-7 

1  6 
0-6 

8-8 

2- 

3- 
4-1 
2-1 

ItasU-  rail  steel  recarburized  with  18^  ol 

Restless  

Rose  quickly 

Basic  steel,  same  cast  as  the  pri-ft-ding.. 

Last  mould  9  mins. 
later  

During1  tt'emiiijr.  .. 
During     solidifica- 
tion   
During  teeming... 
During    solidifica- 
tion   

Same  cast  as  the  p 

Samr  cast  as  the  p 

I'.asic  steel  nnrecar 
blowing)  ... 

burized  (interrupted 

Basic  steel  unrecarbnrized,  two  samples 

i 

t  Basic  steel  recar 
<      ferro-silicon  of 
I      ferro-iiia[ii.'am- 
Basic  steel  recarbu 
preceding  in  the 

U-'ssciiHT  steel,  ga, 
ga 
verter  during  vu 
Bessemer  su-rl.  i,':i 
verter  (Stead)... 

burized  with  5#   of) 
14^  and  2-5^  of  70^  V 
,e  | 

First  ingot  
At  end  of  teeming. 

•Oil 
do 

•618 
do. 

•097 

Quiet  

Rose  

t 

Rose  slowly. 

Zone  of  blow 
holes  

•   -i 

44-1 

84-7 

Ill-s 
12  69 
12-90 
82  6 
78-55 

47-8 

88-4 
46-8 

48-0 
46-1 

87-8 

48-7 

39  6 
57-9 
49  2 

41-6 

58  0 
65-8 
27-21 
20-47 
2  8 
2  52 

18-6 

50-2 
50-1 

85-1 
48-6 

58-8 
49-5 

46-8 
88-7 
88-6 

10-6 

4  1 
1-9 
59  91 
M-68 
14-8 
16  38 
81-4 

9-2 
1-2 

15  4 
6'9 

0  5 

0-5 

10-0 

8-4 
12-2 

3  7 

32 

1-5 

•115 

•162 

•944 

Perfectly  quiet 

•i/ed  nearly  like  the 
ladle  

i  from  soaking  pit.a  . 
s  escaping  from  con- 
tent spicL'cl  reaction, 
under  slag  in  con- 

1 

M 

" 

I 

o-oo 

0-86 
2'5 

2'2 
19 

1  5 
8-4 

3-9 
18 
3-6 

0 

1  32 

Half  blown  Bessemer  metal  (beginning 
ofboil)  

•• 

No 

it 

Frothed  much 

Active  gas  pro- 
duction... . 

Evolves  much 

Rising  

Solid  | 

A    zone     oft 
blowholes.  ( 

Solid  

Open-hearth  steel, 
short  

unrecarburized,  red- 

Bessemer  pig-iron 

Melted  in  a  common 
cupola  :     gases 

„ 

3-688 
4-180 
3-099 

1-68 
•258 

•203 

1-93 
7-37 
•786 



ADOT9 

Above 

M 

Evolves  much 

Rasic  pig-iron  

3ray  pig-iron,  Brit 
Charcoal  pig-iron,  , 

mon  cast-iron  in- 
got moulds. 

sh  

:::::::  

»  025 

Less  gas  than 
98 

(t 

C 

ti 

a  The  context  strongly  suggests,  but  I  do  not  find  that  it  positively  states,  that  the  metal  which  evolved  this  gas  was  Bessemer  steel. 

In  Muller's  experiments,  excepting  93  and  perhaps  95,  gas  was  collected  either  on  filling  the  mould  with  molten  metal  from  BELOW  (bottom  easting),  by  employing  a  mould  closed  at  the  ton  with  a 
small  aperture,  in  which  a  thin  iron  pipe  appears  to  have  been  inserted  :  or  else  on  teeming  from  ABOVE,  quickly  filling  the  mould  above  the  metal  with  clean  quartz,  and  closing  it  with  a  luted  plate  con- 
taining n  cork  with  the  collecting  tube.  The  mode  of  collecting  is  indicated  in  the  last  column. 

84  and  86.    The  gas  was  collected  while  the  mould  was  being  Hlled  from  below,  and  the  collecting  tube  was  removed  as  soon  as  the  mould  was  full. 

85  and  87  •    Here  he  did  not  begin  to  collect  the  gas  till  the  steel  became  stiff,  when  he  filled  a  tube  from  above  by  means  of  sand. 

92.  This  is  the  corrected  composition,  allowance  being  made  for  a  considerable  quantity  of  air  initially  present  in  the  soaking  pit.  The  quantity  of  air  is  arrived  at  by  assuming  that  the  carbonic 
acid  of  the  unconnected  analysis  escaped  from  the  steel  as  carbonic  oxide,  and  was  subsequently  oxidized  to  carbonic  oxide  by  atmospheric  oxygen.  A  further  correction  is  needed,  for  part  of  the 
atmospheric  oxygen  was  doubtless  consumed  in  burning  hydrogen,  and  its  accompanying  atmospheric  nitrogen  exaggerates  the  apparent  proportion  of  nitrogen  escaping  from  the  steel :  but  Messrs. 
Pattinson  and  Stead  found  no  way  of  estimating  the  quantity  of  nitrogen  which  should  be  thus  deducted  for  this  correction.  It  is  furthermore  possible  that  part  of  the  carbonic  acid  and  oxide  present 
may  have  arisen  from  the  oxidation  of  particles  of  fuel  dust  falling  into  the  soaking  pit. 

94.     '-Mr.  Stead  analyzed  in  1880  the  gas  liberated  in  the  converter  under  the  slag  crust  of  Bessemer  steel."    Muller. 

J  OO,  J  O  I .  A  hollow  east-iron  cone,  open  below,  connecting  at  its  apex  with  a  copper  tube,  and  previously  brought  to  a  red  heat,  is  plunged  into  molten  cast-iron  in  a  large  ladle.  The  cast-iron 
which  penetrates  into  the  interior  of  the  cone  solidities,  and  gives  off  gas  copiously,  which  is  collected  through  the  copper  tube  under  water  or  mercury. 

AUTHORITIES.— M.  =  Muller,  Stahl  und  Eiscn.  1883,  p.  444 :  Iron,  1883,  pp.  116,  245 :   1SS4,  p,  188. 

S  =  Stead.  Journal  Iron  and  Steel  Institute,  18S2,  II.,  p.  572. 

C  =  Cailletet,  Comptes  Bendus,  LXI.,  1865,  p.  850. 


cally  held  nitrogen  into  ammonia."  These  two  classes 
probably  overlap :  indeed,  from  the  fact  that  what  we 
may  consider  the  total  nitrogen  in  some  specimens  (Nos. 

a  That  nitrogen  present  in  iron,  but  not  chemically  combined,  should  form  am- 
monia when  the  metal  is  dissolved  by  acid  implies  that  under  these  conditions  nas- 
cent hydrogen  would  unite  with  non-nascent  nitrogen.  A  possibly  similar  case 
may  be  presented  by  the  ammonia  present  in  iron  rust  formed  in  damp  air,  which 
may  be  conceived  to  be  formed  by  the  union  of  the  non-nascent  atmospheric  nitro 
gen  with  the  nascent  hydrogen  set  free  by  the  decomposition  of  the  water  which 
rusts  the  iron.  But  this  is  not  conclusive,  for  the  ammonia  may  be  acquired 
already  from  the  atmosphere,  which  always  contains  this  alkali.  The  same  view 
is  supported  by  the  fact  that  Boussingault  obtained  apparently  from  the  same 
steel  nearly  as  much  nitrogen  ('043£i  by  dissolving  in  acid  as  by  heating  with  cin- 
nabar (-057$),  since  the  latter  treatment  should  expel  both  the  chemically  and  the 
mechanically  retained  nitrogen.  (Comptes  Rendus,  LIU  ,  p.  10,  1861.)  His  obser 
vation  (idem,  p.  7)  that  ammonia  was  not  formed  when  nitrogen  was  pissed 
through  a  cold  solution,  in  which  zinc  was  being  dissolved  by  sulphuric  acid,  in 
such  a  manner  that  the  gas  was  in  continual  contact  with  the  metallic  surfaces 


6  and  7)  does  not  greatly  exceed  either  that  which  is 
apparently  chiefly  physically  (12)  or  that  which  is  prob- 
ably chemically  combined  in  others  (3,  4,  5,)  we  may  con- 
jecture that  nearly  all  the  nitrogen  is  held  in  part  by 
chemical  in  part  by  physical  force,  and  that  these  forces 
are  so  weak  that  if  either  be  paralyzed  (as  the  physical 
force  is  by  attrition  in  No.  12)  the  other  is  unable  to  retain 
the  nitrogen  which  their  allied  strength  had  held 
captive. 


from  which  hydrogen  was  escaping  :  and  that,  when  iron  was  substituted  for  zinc, 
the  total  quantity  of  ammonia  formed  was  no  more  than  when  iron  was  thus  dis- 
solved in  the  absence  of  nitrogen,  oppose  this  view.  Non-nascent  nitrogen  and 
hydrogen  do  not  unite  to  form  ammonia,  even  when  heated  together  with  spongy 
platinum  But  if  either  or  both  of  these  gases  be  nascent  they  form  ammonia 
very  readily. 


108 


THE    METALLURGY     OF     STEEL. 


Table  58  does  not  include  almost  incredible  results 
such  as  Schafhautl's,  (he  found  from  '18  to  1'20$  nitrogen 
in  iron)  which  are  readily  explained  by  the  great  difficul- 
ties in  the  determination  of  this  element.  The  analytical 
results  in  lines  2  to  7,  obtained  by  four  distinguished 
observers,  by  five  different  methods,  nrost  of  them  with 
elaborate  and  effective  precautions,  agree  as  closely  as  do 
the  quantities  of  other  elements  (e.  g.  phosphorus,  man- 
ganese, etc.)  found  by  unquestionable  methods  in  differ- 
ent specimens  of  iron.  Confirmed  as  they  are  by  the 
discovery  of  similar  quantities  of  nitrogen  by  the  wholly 
independent  methods  of  heating  in  vacuo  and  of  boring 
under  water,  they  leave  little  or  no  doubt  that  commercial 
irons  ordinarily  contain  minute  quantities  of  nitrogen, 
rarely  exceeding  say  0-04$. 

Stuart  and  Baker*  thought  they  had  proved  that  nitro- 
gen was  rarely  present  in  iron.  Seeking  it  in  many  speci- 
mens by  attempting  to  convert  it  into  ammonia  through 
heating  them  to  full  redness  in  hydrogen,  they  found  in 
the  great  majority  of  cases  absolutely  no  nitrogen,  in 
only  two  cases  over  0'0051%  and  in  only  one  as  much  as 
0'015$.  (I  here  exclude  their  preliminary  and  distrusted 
results.)  The  evidence  of  its  existence  is,  however,  .so 


powerful  that  the  results  obtained  by  these  experimenters 
tend  rather  to  disprove  the  value  of  their  method  than 
the  presence  of  nitrogen,  for  it  is  by  no  means  certain 
that,  at  so  high  a  temperature  as  they  employed,  hydro- 
gen would  convert  the  minute  quantity  of  nitrogen  present 
into  ammonia.  Bor.is'  observation  that  this  method  acts 
only  superficially,  and  cannot  be  employed  quantitatively 
unless  the  metal  be  very  finely  divided  or  the  process  very 
long  continued,  accords  with  this  view. 

§173.  NITROGENIZ ED  IRON.— Berth ollet  and  after  him 
several  others,  notably  Depretz  and  Fremy,  observed 
that  iron  was  altered  in  appearance  by  being  heated 
in  a  stream  of  ammonia.  It  absorbs  nitrogen,  but  not 
hydrogen  as  proved  by  Fremy,  becomes  white,  brittle 
to  friable,  much  lighter  (its  specific  gravity  occasionally 
falls  to  5),  less  readily  attacked  by  air  or  moisture, 
easily  and  permanently  magnetizable,  and  acquires  a 
brilliant  fracture  ;  the  nitride  of  iron  thus  formed,  which 
is  reported  to  be  of  definite  composition,  is  not  decomposed 
by  a  red  heat,  nor  attacked  by  oxygen  except  at  high 
temperatures,  but  is  readily  decomposed  at  a  gentle  heat 
by  dry  hydrogen  with  formation  of  ammonia  and  pure 
iron." 


a  Journ.  Chem.  Soc.,  XVII.,  p.  390,  1864. 


b  Fremy,  Comptes  Rendus,  LII.,  p.  323,  1861  :  Percy,  Iron  and  Steel,  p.  53. 


TABLE  56. — GASES  EVOLVED  FROM  IRON  WHILE  HEATED  IN  VACUO. 


o 

Description  of  metal. 

Treatment  previous  to  heating 
in  vacuo. 

Evolution  of  gases  in  vacuo. 

Conditions  of  heating  in 
vacuo. 

Composition  of  gas  evolved. 

Volume  of  gas  evolved  per  volume  of  metal. 

Heated. 

So.  oflln  atmosphere 
Hours             of 

At  tem- 
per'ture  of 

Hours 

Temperature. 

CO. 

H. 

N. 

COj. 

O. 

CO. 

H. 

N. 

C08 

O. 

Tota 

T.AlI. 

P. 

K 

T.*H. 
P. 

T.AlI. 

P. 
Z. 

P. 
G. 

C. 
T.*H. 

P. 
G. 

P. 

T.AH. 

E. 

Not  previously  tr 
it            « 

eated. 

it 

White. 
Bright  red 

Mill"   C. 

800°  C. 
.  ated. 
800°. 
800°. 
eated. 

Mm-  C. 

Bed. 

it 

"3- 
65 
2- 
24- 
76 
52-5 
36' 
59- 
165- 
190- 
24- 

300° 
Low  red. 

•o 

17-87 
2  82 
6-20 
7-70 
42-97 
62-78 
17-56 
24-44 
89-70 
16-76 
9  09 
2 
2-36 
36  98 
68-65 
11-53 
62-50 
24-85 
52  8 
7  9 
44-07 
34  26 
67-  ± 

91-5 
81-10 
84- 
89-7 
91  2 
57-02 
47-21 
82-54 
75  55 
60-29 
74-07 
90-90 
89- 
94  42 
8-87 
22-72 
82-05 
25-00 
52-61 
45-6 
57-8 
2i'5 
54  1 

8-5 

•o± 

6  88 
3  25 

•o± 

•o 

•94 
6-80 
1-60 
1- 

•":$••• 

•o 

•85 
•04 
1-09 
1-46 
64-84 
65-19 
15-95 
47-50 
185' 
•04 
2' 
•80 
•016 
•21 
•02 
•013 
•029 
8-16 
37-22 
•43 
2-18 
•68 
6  29 

0-88 
1-62 
1.68 
18-8 
17-38 
72-76 
58  31 
74-95 
146-30 
205- 
•18 
20- 
18-4 
•68 
•02 
•007 
•092 
•012 
6-83 
32-15 
*-12 
1-21 
1-08 

•035 

•o± 

•18 

0-68 

•o± 

•o 

•018 
•186 
0-84 
0  19 

.0-42 
2  00 
2- 
21- 
19- 
127-6 
128  5 
90  80 
194  3 
340- 
•24 
22- 
15- 
•07 
•24 
•031 
•112 
•047 
13- 
70-5 
5-45 
4-95 
2 
7-94 
7-27 
12-55 
2-66 
2-85 

-214 
10-5 
0-50 
4-59 
8-2 
22 
10- 

White  cast-iron  
Gray           **        

Good  red. 
Red  to  white. 
White. 
Rising  to  high. 
Rising  to  full  heat. 

ti 

II 

"      )  wrapped  in  j 
11      f     platinum  \ 

800° 

5-58 

3  59 

014 

•009 

24"                  " 

48-                  " 
48'      Carbonic  oxide 
Not  previously  tr 
49'         Hydrogen. 
48"     ,  Carbonic  oxide 
Not  previously  tr 

11                          1 

it            *i 
48'         Hydrogen. 
84-5 

Carbonic  oxide 
68- 
48-                  " 

Charcoal     "      1  Same  piece) 
••     f     as  No.  11) 
Cast  steel 

8-22 
4-15 
11-86 
6  42 
12-4 
6  49 

S4:7  " 
31-42 
1-72 

•02 
•01 

•008 
007 
•006 

•84 

•o 

"'•ooi 
•o 

190' 

800° 

2-27 

"         1  Same  piece  as  No. 
"         \     16  

"2;" 
60' 

16:55 
1-6 

2-15 
1-12 

1000°  ±  C. 

1-89 
1  55 

•Of 

Puddled  Iron               ...   . 

2- 
2' 
1- 

7' 
45 
2-5 

9'92 

•19 

Red.      . 

(•               it 

14'  8 

1-08 

<•               (i 

Bed. 
Red. 

Redness 

52-7 
4'46± 

•0 

58-88 
4  81 
•0 
8- 
89-9 
100 
97-85 

80-4 

85'68± 

100- 
23-78 
71-94 
100- 
92- 

11  5 
9-86± 

•o 

5  95 
18-75 

5-2 

i-39 
0  12 

•80 
2-44 

•80 

0-28 

•13 

Electrolytic  iron  (0-262!  hydro- 

•o 

11-89 

190' 

800°  C. 

•167 
•009 

•068 
•154 
10-5 
0-46 

-017 
•051 

•084 

•o 



*'           same  os  No.  30. 

•]"• 

2- 

Ked. 
Low  red 

•0 

"    I  Wire,  same  piece  1 
"    j     asNo.  26  1 

0-04 
4-15 
8  2 
•21 

"            same  as  No.  81. 

800°  C. 

1-48 
100- 

0-72 

•008 

10- 

•002 

The  iron  from  which  gas  was  extracted  was  sometimes  in  its  natural  state,  and  had  sometimes  been  previously  heated  in  hydrogen  or  carbonic  oxide.  In  no  case  is  there  evidence  that,  even  after 
being  heated  in  vacuo  for  many  days,  the  escape  of  gas  had  wholly  ceased:  further  heating  would  probably  have  extracted  still  more  gas. 

Troost  and  Hautcfeuille  thrice  heated  in  vacuo  cylinders  of  c-.ast-iron,  cast-steel  and  wrought-iron,  each  weighing  500  grammes,  during  190  hours  at  800°  C..  first  in  their  natural  state,  next  after 
heating  during  48  hours  in  hydrogen  at  800°  C  ,  and  then  after  similar  heating  in  carbonic  oxide,  examining  the  gas  evolved  at  each  heating.  A  similar  cylinder  of  spiegeleisen  was  similarly  heated 
in  vacuo,  but  only  in  its  natural  state. 

Graham  similarly  heated  meteoric  iron,  horse-shoe  nails  and  fine  wrought-iron  wire.  21  to  23  gauge,  in  vacuo  in  its  natural  state.  Wire  number  26,  83 and  34,  which  all  refer  to  the  same  specimen, 
was  heated  in  vacuo  thrice,  as  in  the  experiments  of  Troost  and  Hautefeuille,  i  e.  first  in  its  natural  state  till  it  seemed  "  nearly  exhausted,"  then  after  heating  and  gradual  cooling  in  hydrogen  and 
free  exposure  to  air  '  to  get  rid  of  any  loosely  attached  hydrogen,"  and  then  after  similar  heating  in  carbonic  oxide. 

Parry  performed  similar  experiments  on  iron  sometimes  in  clean  lumps,  sometimes  in  borings. 

1 .  Troost  and  Hautefeuille,  Comptes  Rendus,  LXXX.,  1875,  p.  909.  it  3  and  4.  Parry,  Journal  Iron  and  St.  Inst,  1872,  II.,  p.  240.  6.  Idem,  1873,  I  .  p.  430.  6.  Idem,  1874, 1.,  p.  93. 
Temperature  rose  from  red  to  white:  iron  unchanged  in  appearance.  7.  Idem.  8.  Idem,  wrapped  in  platinum  :  temperature  rose  from  dull  red  to  "  high  heat."  9.  Idem,  wrapped  in  platinum. 
Tern  peraturc  rose  from  red  through  full  red  to  •  full  heat  of  furnace."  1  O.  Idem.  1881. 1  ,  p  189:  during  first  128  hoursratio  carbonic  oxide:  hydrogen  =  0'9.  during  last  86hours  =  0-213.  11.  Troost 
and  H.,  op.  clt,  LXXVI..  1S78,  p.  563.  Most  of  the  carbonic  oxide  comes  off  in  the  first  few  hours:  the  hydrogen  is  retained  more  tenaciously.  12.  Parry,  op.  cit.,  1873,  I.,  p.  430  I  3.  Idem,  1874, 
I  .  p.  93.  1  4.  Troost  and  II ,  op.  cit.,  p.  564.  This  specimen  before  saturation  with  hydrogen  had  been  exhausted,  with  results  as  described  in  No  11  15.  Idem:  this  specimen,  before 
saturation  with  carbonic  oxide  had  been  exhausted  with  results  as  described  in  No.  11.  iti,  17,  and  18.  Idem.  These  results  obtained  with  one  specimen  which,  before  saturation  for  Nos.  17 
and  18  had  been  exhausted  with  results  as  described  in  No  16.  19  Parry,  op.  cit.,  1871,  IT.,  p.  240.  20.  Idem,  1881  I.,  p  189.  Contains  -OS*  silicon.  -35  carbon.  -72  manganese.  1  -02  mag- 
netic oxide  (?)  =  0'281jf  oxygen.  21.  Zyromski,  Stahl  und  Eisen,  1884.  p  536.  Journ.  Iron  and  St  Inst..  1884  II..  p.  625.  Contains  -05£  carbon,  trace  silicon,  trace  sulphur.  -024g  phosphorus, 
•288£  msn"anese.  91.  Idem  Puddled  iron  from  same  materials  as  No.  20  Contains '03  carbon,  '(H6  silicon,  trace  sulphur.  078  phosphorus,  -20  manganese.  23.  I'arrv,  op.  cit .  1872,  II  ,  p. 
24(1.  24,  25,  96.  Graham,  Journ.  Chem.  Soc..  1867,  XX.,  p.  285.  27  and  28.  Graham,  Chem.  News.  XV.,  1867.  p.  278.  29.  Iron  deposited  by  electrolysis  from  ferrous  chloride. 
Oailletet,  fomptes  Rendus.  LXXX.,  1875.  p.  319.  8Oand.11  Troost  and  IT.,  loc.  cit.  Before  saturation  with  hydrogen  for  No.  81  it  had  been  exhausted  with  results  given  in  No  30.  32. 
Parry,  op.  cit.,  1873.  I.,  p  .430.  Before  being  saturated  with  hydrogen  it  had  been  exhausted  in  vacuo  for  7  days.  33.  Graham,  Journ.  Chem  Soc  ,  loc.  cit.  Before  being  saturated  with  hydrogen 
the  wire  had  been  exhausted  in  vacuo  with  results  given  ia  No.  26.  After  saturation  with  hydrogen  the  wire  became  white,  like  galvanized  iron.  A  repeat  experiment  gave  similar  results.  34* 
Idem  Before  exposure  to  carbonic  oxide  it  had  been  saturated  with  hydrogen,  and  subsequently  exhausted  with  results  given  in  No.  83.  35.  Parry,  op.  cit ,  1873, 1.,  p,  430,  36.  Traost  and 
H.,  loc.  cit.  Before  exposure  to  carbonic  oxide  it  had  been  exhausted  with  results  given  in  No.  31.  3T.  W.  Chandler  Roberts. 


IRON    AND    NITROGEN.       §  174. 


109 


TABLE  57. — ABSORPTION  or  (!ASKS  BY  IRON. 


Number. 

Observer. 

No.  in  Table  56. 

Description  of  metal. 

Treatment  before  exposure  to  the 
gas  absorbed  . 

Absorption  of  gases. 

Heated. 

Conditions  during  absorption. 

Gas  absorbed  . 

Hours. 

In. 

Temperature. 

Hours. 

In. 

Temperature. 

Vol.  gas  per  vol.  iron. 

llrasnrrd  ilirectly  or  inft-rrcd 
from  volume  subsequently 
'•vi'lvod  in  vacuo. 

H. 

00. 

41.. 
42.. 
43.. 
44.. 
45.. 
46.. 
41.. 
50.. 
51.. 
52.. 
58.. 
54.. 
60.. 
61.. 
63 
65.. 
66. 
67.. 

P 

T  and  II 
P 

T  and  II 
G 
P 
T  and  II 

P 
G 

'ia' 
'is' 

10 

14 
17 
•_'ii 
;i'2 
31 
S3 
10 
11 
16 
30 
35 
26 

Gra\  cast-iron  1 

Apparently     prcviou 

ly,  heated  in  j 

Hydrogen 
Carbonic  oxide 

«'4 

Direct 

Indirect. 
Direct. 

Indin  ct. 

Direct. 
Indirect. 

Direct. 
Indirect. 

13-2 
20- 
22- 
18-1 

20- 
0-63 
0  09 
10  54 
18- 
0  15 
•46 

"        "    "     i 

Vacuo 
<i 

1400°C  + 
1400°C  -f 

"is 

24 

White 
Bright  red 

tl                ((         U 

tl                (t         (i 

165 
190 

190 

800°« 
800°  <J 

43 
4S 
24 
84-5 
48 

800"  C 
800°  C 

'Red  '+'" 
800°C 
Ked 

0  Oil', 

o-oia 

168 
190 
T 
165 
190 
190 
190 

• 

800°C 

Bed 

0  009 

o- 

0  21 
ftf 
•21 
4-50 
4  15 

800°C 
800°C 
800-C 

Low  red 

48 

48 
48 
68 

800°C 
800°C 
800°C 

0-02 
0  01 

0-003 

Oast-steel  (see  No   f>0)            

Wro  light-iron  (see  No   58) 

"           '•  wire  {sec  No.  54)  

1 

Bed 

a  closed  tube 
It  is  assumed  in 


Parry  measured  the  absorption  of  hydrogen  and  carbonic  oxide  by  iron,  by  heating  the  metal,  which  at  least  in  certain  cases  had  been  previously  heated  or  even  fused  in  vacuo  in 
in  contact  with  n  known  volume  of  gus.  The  diminution  of  volume  could  then  be  read.  In  case  of  hydrogen  this  is  supposed  lo  be  due  to  absorption.  Incase  of  carbonic  oxide  it 
this  table  that  this  pis  was  absorbed  as  such  :  but,  as  will  be  shown  later,  its  disappearance  may  be  due  to  its  decomposition,  with  the  absorption  of  its  oxygen  an;l  carbon  separately 

The  indirect  determinations  were  made  by  first  heating  the  metal  In   vacuo,  in  some  cases  till  it  appeared  to  be  nearly  exhausted,  then  heating  it  in  an  atmosphere  of  hydrogen  or  carbonic  oxide 
and  then  Inter  again  heating  it  in  a  vacuo.    The  gas  DOW  evolved  is  analyzed,  and  is  supposed  to  have  been  absorbed  from  the  atmosphere  of  gaa  in  which  the  metal  had  just  been  heated.     Its 

mposition  in  general  supports  this  view. 


lively.     66)  I'arry,   op.  cit.,  1S73,  I.,  431.     67$  Graham,  loc.  cit.     This  wire  had  previously  been  saturated  with  hydrogen  and  then  exhausted,  as  per  No.  54. 

TABLE  58.— NITROGEN  IN  COMMERCIAL  IRON. 


(.. 

2 
8.. 

4.. 
6.. 
6.. 
7.. 
8.. 
9.. 
10 

Observer. 

Mode  ot  extracting  nitrogen. 

Cast-iron. 

Steel. 

Wrought-iron. 

f. 

Vols. 

f. 

Vol». 

%• 

Vols. 

Stuart  and  Baker  

Expulsion  and  Conversion 
measurement  into 

f  Heating  in  hydrogen  

0@-015 

o<a  ooi 

•004®  -0093 

0@'98 
•005 
•26@'64 

0@'01 

•0063®  -01  72 
•022  ©'042 
•014 
•0189 
•057 

0®   '65 
•013  @ir654 
•41     @1  12 
1-44    @2'74 

1-24 
8  72 

[            •'      '•          "        

•0009 
•OOi)4@-014S 
•0075 

Allen     

1  1  Solution  with  acid                                   

•61@-97 
•49 

Boussingault  

"         "      "    

5     Heating  with  soda-lime  

•009 
•0189 

•69 
1  24 

Bouesingault  

'         "    cinnabar  

•00459 
•00026 
•000459 
•024 

•80 
•017 
•08 
1-55 

•00021©-00061 
0@-010 

•014®  04 
0®'68 

•000046 
•0129 
•029 
•0178 
•0019? 
•0002®  -0016 

•003 
•84 
1-89 
1-18 
•126? 
•01@1-18 

Parry    

t      K      <t 

11 

4             II             It 

1* 

Stead  

Boring  cold  metal  

042 

2  73 

13.. 
14 

Muller  

Escape  during  solidification  

•0002®  0007 

•01@'05 

]  ,  1'ure  hydrogen  passed  over  the  metal  at  full  redness  :  the  ammonia  formed  was  absorbed  in  sulphuric  acid.  Their  results  average  0'0033#  nitrogen.  Journ.  Chem.  Soc.,  XVII.,  1864,  p.  390. 
3,  Comptes  Kendus,  L.II.,  p.  1,195, 1861.  Percy,  Iron  and  Steel,  p.  55.  Two  streams  of  the  same  perfectly  dried  hydrogen  are  passed  independently  through  two  red-hot  porcelain  tubes  in  the 
i»aine  furnace,  one  containing  the  iron,  the  other  empty  and  serving  as  a  check.  The  removal  of  nitrogen  appears  to  be  only  superficial :  on  filing  the  iron  after  exposure  to  hydrogen  the  fresh  sur- 


nitrogen  recovered  must  have  come  from  the  iron,  for  analyses  of  zinc  and  of  iron  freshly  reduced  by  hydrogen  gave  absolutely  no  ammonia  whether  in  presence  or  absence  of  air:  blank  analyses 
gave  minute  quantities  of  ammonia,  which  were  deducted.  49  Coinptes  Rendus,  1831.  LXIIL.  p.  77.  Percy,  Iron  and  Steel,  p.  56.  Method  same  us  the  last,  except  that  the  ammonia  is  deter- 
mined by  sulphuric  acid.  This  method  gave  2 '655  nitrogen  in  nitrogenized  iron,  in  which  the  cinnabar  method  found  2'(M»U.  5  and  6,  Percy,  Iron  and  Steel,  p.  52.  7,  Idem,  p.  56.  8,  9.  I  *>• 
See  Table  56.  11,  Stahl  und  Eisen,  IV.,  p.  584.  18S4.  1  2,  Iron.  1683,  p.  115.  1  3,  Idem.  1884,  p.  138.  Muller  iound  from  1  to  1-5  volumes  of  gas  escaping  from  Bessemer  steel  during  solids 
fication,  whose  composition  was  not  determined.  The  percentage  of  nitrogen  in  gas  escaping  under  similar  conditions  varied  from  2*2  to  43#  (see  Table  55 ):  assuming  it  at  10#  merely  to  get  a  rough 
Idea  of  the  quantity  of  nitrogen  thus  escaping,  we  have  0  125  volumes  per  volume  of  steel.  1 4j  See  Table  54 


The  percentages  of  nitrogen  found  by  several  investiga- 
tors in  iron  thus  nitrogenized  are  here  given. 

TAULE  59. — NITROGENIZED  IRON  OBTAINED  BY  HEATING  IN  AMMONIACAL  GAS. 


No. 

1... 
2... 

8... 

i::: 

6... 

Observer. 

Substance  heated. 

Nitrogen  absorbed. 

Vol. 

*. 

How  determined. 

Despretz  
Fremy  

Iron  
Ferrous  chloride  at  bright  red- 

754-585 

6«8-22 
640-92 
173  964 
28  776 
00-  -2616 
82-70 

11-538 

9-8 
9'8 
2  66 
0  44 
0  004 
to  5 

By  gain  of  weight. 
By  loss  en  heating  in  hydrogen. 

As  ammonia. 
By  gain  of  weight. 

>  By  Nessler's  test. 

Iron  at  redness,  20  hrs  
Thin  iron  wire,  90  niins  .  .  . 

Boussingault.. 
Percy  

II.  N.  Warren. 

1.  Percy,  Iron  and  Steel,  p.  51.     2.  Idem,  p.  53.     2  and  B.  Comptes  Kendus,  LII.,  1861,  p. 
825  :  Percy,  op.   cit.   p.  54.    4.  Comptes  Kendus.  LIII.,  p.  10,  1861,  Percy,  op.  cit,  p.  57.     6. 
Percy,  op.  cit..  p.  55.    6.   Chem  News,  LV.,  p.  165,  1887. 

Percy's  wire,  number  5,  though  it  apparently  had 
taken  up  but  0'44$  of  nitrogen,  had  turned  white,  was 
remarkably  brittle,  and  had  a  very  brilliant  fracture. 
Bars  of  the  finest  puddled  iron  nitrogenized  by  Warren 
(included  in  number  6,  Table  59),  after  taking  up  Q-5% 
nitrogen  became  so  brittle  that  they  broke  transversely 
on  falling  from  a  height  of  6  feet.  A  bar  of  the  same 
iron  which  had  absorbed  but  04004$  nitrogen  is  reported 
as  breaking  with  a  decidedly  crystalline  structure :  one 


with  0-01%  nitrogen  is  reported  as  still  more  crystalline 
and  apparently  somewhat  more  brittle.  Unfortunately 
Warren  reports  no  numerically  comparable  tests  of 
strength  and  ductility. 

§  174.  INFLUENCE  OF  NITUOGEN  iff  COMMERCIAL  IRON.— 
As  0%  of  nitrogen  suffices  to  render  iron  friable,  and  as  even 
0'44$  appears  to  render  it  "remarkably  brittle,"  it  is  by 
no  means  unlikely  that  the  0'04$  occasionally  found  in 
commercial  iron  may  materially  affect  it.  Metcalf  as- 
cribes the  lustrous  fracture  of  Bessemer  steel  and  its 
reported  relatively  low  ductility  compared  with  crucible 
steel  of  otherwise  identical  composition,  to -the  presence 
of  nitrogen  absorbed  from  the  enormous  volumes  of  air 
blown  through  the  metal  at  high  pressure  during  manu- 
facture. If  merely  a  coincidence,  it  is  a  striking  one 
that  Allen  (Table  58)  finds  twice  as  much  nitrogen  in 
pneumatic  as  in  crucible  steeP:  but  his  results  are  too  few 
to  decide  the  question.  The  nascent  iron  which  alone  ab- 

»  Trans.  Am.  Inst.  Miuing  Ensrs.,  IX  ,  p.  548,  1881. 

b  Journ.  Iron  and  St.  Inst.,  1880,  I.,  p.  188.  He  obtained  the  following  per- 
centages of  nitrogen  in  several  specimens  of  steel:  acid  Bessemer,  -0164;  basic 
I  Bessemer,  '0115 ;  open  hearth,  '0107,  '0098  ;  blister,  '0148,  '0156  ;  double  shear, 
J  -0139  ;  crucible,  '0083. 


110 


THE    METALLURGY    OF    STEEL. 


sorbs  nitrogen  from  the  atmosphere,  may  be  furnished  by 
the  reduction  of  iron-oxide  by  carbon,  etc.,  in  the  Bes- 
semer process. 

IRON  AND  HYDROGEN." 

§  175.  SUMMARY.— Hydrogen  is  usually  present  in 
both  solid  and  molten  iron,  abundantly  if  measured  by 
volume,  sparingly  if  measured  by  weight :  commercial 
iron  probably  does  not  usually  contain  much  more 
than  0-01$.  Parry  has  indeed  found  0'22 '%  of  hydrogen 
in  commercial  iron :  but  numerical  relations  in  his  results 
and  the  wide  discrepancy  between  them  and  those  of  other 
observers  indicate  that  they  are  erroneous.  Certain  facts 
suggest  that  iron  cannot  retain  permanently  more  than 
about  OM7$  or  154  volumes  of  this  gas,  but  it  can  tempo- 
rarily acquire  at  least  '26%. 

The  hydrogen  in  iron  usually  and  perhaps  always  exists 
in  part  at  least  as  gas,  and  sometimes  as  ammonia  gas  : 
but  a  part  at  least  in  certain  cases  probably  exists  in  some 
non-gaseous  state.  It  appears  to  be  always  easily  ex- 
pelled, and  hence  is  probably  not  in  strong  chemical  union 
with  the  metal. 

Heated  in  hydrogen  or  exposed  when  cold  to  nascent 
hydrogen  iron  absorbs  a  minute  quantity  of  this  gas,  ex- 
posure to  the  nascent  gas  reducing  the  metal' s  flexibility 
surprisingly,  in  view  of  the  minute  quantity  of  gas  ab- 
sorbed, probably  not  over  'Q\%.  The  flexibility  is  re- 
stored and  at  least  part  of  the  hydrogen  is  expelled  rapid- 
ly by  heating,  and  slowly  by  simple  rest.  It  is  uncertain 
whether  the  hydrogen  usually  present  in  commercial  iron 
affects  it  sensibly. 

Hydrogen  escapes  from  iron  when  heated  in  vacuo, 
when  bored  under  water,  oil  or  mercury,  and  during 
solidification,  in  the  latter  case  producing  blowholes.  It 
is  usually  accompanied  by  nitrogen  and,  except  when  the 
metal  is  bored  under  water,  etc.,  by  carbonic  oxide. 
From  fresh  fractures  of  ingots  and  other  castings,  and 
sometimes  even  from  rails,  a  strong  smell  of  ammonia 
sometimes  escapes,  which  unquestionably  proceeds  from 
the  metal  itself  :  and  occasionally  the  escape  of  ammonia 
and  hydrogen  from  the  fracture  is  so  rapid  as  to  be 
distinctly  audible. 

§  176.     T7ie  presence  of  hydrogen  in  iron. 

A.  Its  Absorption. — Melting  cast-iron  in  vacuo,  in  order 
to  remove  the  gas  initially  present,  and  then  without 
removing  it  from  his  apparatus  and  while  it  was  still  hot 
exposing  it  to  a  known  volume  of  hydrogen,  Parry  found 
by  direct  measurement  that  it  absorbed  from  13'2  to  22-4 
volumes*1  of  this  gas. 

In  a  similar  way  he  found  that  malleable  iron,  after 
more  or  less  complete  exhaustion  in  vacuo,  reabsorbed 
from  10-5  to  13  volumes  of  hydrogen  (see  Table  57). 

No  other  observer,  so  far  as  I  know,  has  directly  meas- 
sured  the  volume  of  gas  absorbed  by  iron,  though  Troost 
and  Hautefeuille  and  Graham  have  estimated  it  by  first 
exhausting  the  iron  by  heating  in  vacuo,  then  heating 
and  cooling  it  in  hydrogen,  and  noting  the  quantity 
emitted  on  again  heating  in  vacuo:  this  varied  from  -09  to 
•63  volumes  per  volume  of  iron.  The  gas  now  evolved 
contained  a  larger  and  usually  a  much  larger  proportion 
of  hydrogen  than  that  originally  extracted.  Graham 


'ound  a  low,  Parry  a  relatively  high  temperature  most 
'avorable  to  the  absorption  of  hydrogen." 

B.  Hydrogen  a  usual  constituent  of  commercial  iron. 
So  far  as  my  inquiries  have  gone  hydrogen  has  always 
jeen  found  when  properly  sought  in  commercial  iron, d 
3ut,  neglecting  Parry's  results  for  the  moment,  in  very 
small  quantities.  The  largest  quantities  found  by  each  of 
several  observers  in  previously  untreated  commercial  iron 
are  given  in  Table  60. 

TABLK  (ill. — MAXIMUM  HYDROGEN  FOUND  BY  SEVERAL  OBSERVERS  IN  SOLID  IRON  PREVIOUSLY 

UNTREATED. 


1. 

2 
V 
4. 
5 
6 
7. 
B. 

Cast-Iron. 

Wrought-iron. 

Steel. 

Vols.  per 
vol.  iron. 

% 

Yols.  per 
vol.  iron. 

% 

Vols.  per 
vol.  iron. 

* 

Troost  and  Hautefeuille  1 
Graham                   ..       .  (Heated  in  I 

O'lTT 

•00019 

068 
0-8 
1-21 
1-08 

•00007 
•0009 
•0013 
•0012 

•007 

•000008 

8-12 
32-15 
5'Ola 
1-6 
9-76 
•53 

•0084 
•085 
•0055 

•oon 

0106 
•0006 

Parry                                 J                    [ 

205- 

•223 

F  Fox                        1     Com-    1 

Ledebur  (bustlon.  | 
Stead  (dull  drill)  ..    1  Boring  under  i 
M  filler                          (         water        1 

2-6 
8-8 

•29 

•0028 
•0086 
•0003 

a  Tables  54  to  57  and  Chapter  XI.  contain  additional  facts  and  further  discus- 
sion concerning  hydrogen  and  iron. 

b  Throughout  this  work  thj  volume  of  gas  is  supposed  to  be  measured  at  0°  C. 
and  76  cc.  barometric  pressure,  unless  otherwise  stated. 


a  Other  experiments  with  this  same  bteel  gave  O'l  volume  of  hydrogen.  I  have  deducted  for 
probable  error  as  inferred  from  blank  analyses. 

The  results  obtained  bv  Troost  and  Hautefeuille,  Graham,  Zyromski,  Parry,  Stead  and  Miiller 
are  further  described  in  Tables  54  and  56. 

Ledebur  (Wagner's  Jahresbericht,  IsfvX  XXIX.,  p.  4G,  Stahl  und  Eisen,  1882.  p.  .r»91)  oxidized 
ferro-silicon  and  ingot  iron  with  dry  air  in  a  porcelain  tube,  first  thoroughly  drying  the  tube 
while  the  iron  was  in  it  by  heating  to  800°  or  400°  0.  in  a  stream  of  dry  nitrogen.  The  water 
formed  by  the  oxidation  of  the  hydrogen  of  the  iron  was  caught  and  weighed.  Fox  ('Hiei-is  lor 
the  degree  of  Master  of  Science,  Mass.  Inst  Technology,  1886)  in  a  long  and  careful  investigation 
in  Drown's  laboratory,  made  some  twenty  determinations  of  the  hydrogen  in  cast-iron  and  steel,  by 
oxidizing  the,  metal,  mixed  with  copper  oxide  or  chromate  of  lead  in  porcelain  tubes,  bv  means  of 
dry  oxygen,  catching  and  weighing  the  water  formed.  When  employing  chromate  of  lead  ho  ob- 
tained 14  volumes  of  hydrogen  from  cast-iron  :  but  he  suspected  that  the  result  was  exaggerated 
by  hydrogen  evolved  by  this  reagent,  though  precautions  apparently  sufficient  were  employed. 
That  the  iron  was  completely  oxidized  is  inferred  from  the  fact  that  the  carbonic  acid  escaping  dur- 
ing combustion  corresponded  closely  to  the  total  carbon  independently  determined  by  trustworthy 
methods. 

The  results  obtained  by  these  observers  by  the  combustion  method  must  be  accepted  reserved- 
ly. In  the  first  place,  wo  do  not  know  that  this  method  \vill  remove  the  hydrogen  from  iron.  It 
is  possible,  though  Indeed  extremely  improbable,  that  the  hydrogen  initially  occluded  by  the  iron 
may  not  become  oxidized  by  the  oxygen  employed,  but  may  remain  occluded  in  the  resulting  iron 
oxide  :  for  we  do  not  know  that  iron  oxide  has  not  as  great  or  even  greater  power  for  occluding 
hydrogen  than  metallic  iron  has.  Indeed,  some  of  Fox's  results  suggest  that  it  has  greater  occlud- 
ing power.  Thus,  a  steel  which  in  one  combustion  yielded  5  volumes  of  hydrogen,  in  another 
?ave  but  (VI  volume,  or  very  much  less  than  Parry,  Zyromski,  Graham  and  Stead  extract  in  vacuo 


,  , 

i>r  by  boring.  We  have  in  the  second  place  the  danger  of  leakage  at  the  many  joints  or  through 
the  cracks  or  pores  of  the  porcelain  tubes,  and  of  the  introduction  of  unoxidized  hydrogen  or 
some  of  its  volatile  compounds  along  with  the  air  :  they  might  well  pass  the  apparatus  employed 


for  drying  the  air,  become  oxidized  with  the  iron  and  swell  the  results.  Hence  the  air  or  oxygen 
employed  should,  before  admission  to  the  combustion  tube,  be  heated  witli  copper  oxide  and 
dried.  As  the  weight  of  hydrogen  found  was  generally  and  that  of  the  water  caught  occasionally 
less  than  one  milligramme,  trifling  errors  would  seriously  vitiate  the  results.  A  M:nilar  source  oi 
error  is  the  hydrogen  initially  occluded  by  the  porcelain  tubes  and  other  portions  of  the  apparatus 
and  slowly  evolved  ;  Low  tenaciously  this  adheres  may  be  inferred  from  the  fact  that  when,  as  in 
Bunsen  and  lioscoe's  photometer,  it  is  necessary  to  obtain  even  in  so  non-absorptive  a  body  as  a 
glass  vessel,  an  atmosphere  absolutely  free  from  oxygen  and  nitrogen,  the  vessel  must  be  swept 
for  several  days  with  other  gases  (in  this  case  chlorine  and  hydrogen.  lioscoe,  in  Watt's  Diction- 
ary, II  ,  p.  805). 

"Fox  found  that  thoroughly  dried  oxygen,  when  swept  through  an  otherwise  empty  redhot  por- 
celain tube,  persistently  yielded  small  quantities  of  water,  8'5  mmgms.  during  the  first  hour,  0'7 
mmgms.  per  hour  from  the  12th  to  the  14th  hour. 

While  the  results  obtained  by  these  combustions  might  well  be  too  high,  it  seems  decidedly  im- 
probable that  they  should  be  too  low. 


In  the  combustion  methods  employed  by  Ledebur  and 
Fox  the  slight  changes  in  the  weight  of  their  phos- 
phoric anhydride  tubes,  following  the  protracted  passage 
of  gas,  might  be  attributed  to  experimental  error  rather 
than  to  the  absorption  of  water  actually  formed  by  the 
oxidation  of  hydrogen  escaping  from  the  metal  under 
treatment.  Indeed,  with  elaborate  precautions,  Fox  found 
that  these  tubes  always  gained  weight,  even  when  the 
combustion  tubes  contained  no  iron,  though  the  increase 
of  weight  was  invariably  greater  when  iron  was  under 
treatment.  In  heating  in  vacuo,  too,  there  is  a  chance  that 
hydrogen  should  enter  the  apparatus  through  faulty 
joints  or  through  the  pores  of  the  apparatus,  rendered 
permeable  by  the  high  temperature.  Had  we  to  rely  on 
these  methods  alone  the  usual  existence  of  hydrogen  in 
iron  might  well  be  questioned. 

But  wholly  independent  methods  corroborate  its  pres- 


c  Journ.  Iron  and  Steel  Inst.,  1874,  I.,  p.  95. 

dOn  beating  iron  wire  in  dry  nitrogen  for  30  minutes  at  a  "  bright  glow," 
Ledebur  found  no  weighable  quantity  of  hydrogen:  but  it  is  doubtful  if  so 
brief  a  heating  in  nitrogen  should  be  expected  to  extract  a  weighable  quantity  of 
his  gas.  (Stahl  und  Eisen,  VII.,  p.  693,  1887.) 


THE    PRESENCE    OF    HYDROGEN    IN    IRON. 


176. 


Ill 


ence.  Troost  and  Hautefeuille  observed  that,  when  iron 
after  tranquil  fusion  in  hydrogen  was  suddenly  solidified 
with  fall  of  pressure,  gas  was  visibly  evolved.  Miiller 
finds  that  the  gas  evolved  by  iron  on  solidifying  in  the  aii 
is  chiefly  hydrogen.  This  is  the  chief  constituent  of  the 
gaseous  contents  of  the  blowholes  found  after  solidification. 

By  increasing  the  pressure  during  solidification  and  by 
the  addition  of  silicon,  manganese  or  aluminium  before 
solidification,  the  escape  of  this  hydrogen  can  be  pre- 
vented, and  it  is  probable  that  it  remains  after  solidifica- 
tion in  the  cold  iron.  The  indirectly  and  more  especially 
the  directly  measured  absorption  of  hydrogen  by  solid 
iron  and  the  frequent  evolution  of  ammonia  from  common 
cold  steel,  so  abundant  as  to  force  itself  on  the  attention 
of  numerous  unexpectant  observers,  prove  that  solid  iron 
can  contain  hydrogen  :  and  the  hydrogen  almost  always 
found  on  boring  cold  iron  under  water,  oil  or  mercury, 
leaves  no  doubt  that  iron  usually  contains  this  gas. 

AVhile  part  of  the  hydrogen  found  on  boring  cold  steel 
doubtless  exists  as  gas  in  visible  cavities,  which  indeed 
sometimes  contain  it  in  such  quantities  that,  when  bored 
from  below  under  water,  gas  bubbles  out  from  the  bore 
hole  when  the  point  of  the  drill  pierces  the  first  blow- 
holes, yet  in  some  cases  hydrogen  is  released  on  boring 
solid  steel  quite  free  from  visible  cavities.  Moreover,  by 
triturating  the  metal  with  a  dull  drill  over  69  times  as 
much  hydrogen  has  been  obtained  as  when  the  same  metal 
was  cut  in  tbe  ordinary  way  with  a  sharp  drill.  (16-17, 
Table  54.) 

While  the  trituration  may  increase  the  evolution  of 
hydrogen  simply  by  laying  bare  innumerable  microscopic 
but  not  intermolecular  cavities,  it  seems  probable  that  a 
considerable  part  of  the  hydrogen  extracted  by  trituration 
exists  in  the  iron  in  some  non-gaseous  state ;  and  in  such 
a  state  the  gas  which  escapes  from  molten  iron  certainly 
exists  before  its  escape. 

Now  the  quantity  of  hydrogen  which  is  found  on  boring 
under  water  and  which  unquestionably  comes  from  the 
iron,  does  not  differ  more  from  that  found  in  other  speci- 
mens of  iron  by  combustion  and  heating  in  vacno  (except 
Parry's  results)  than  do  the  proportions  of  manganese  or 
of  carbon  in  different  specimens  of  iron.  This  is  no  proof 
that  the  results  obtained  by  these  latter  methods  are  cor- 
rect, but  it  shows  that  they  are  not  in  themselves  improb- 
able. 

The  combustion  method  should  give  the  total  hydrogen: 
indeed  the  errors  to  which  it  is  liable  should  exaggerate 
the  proportion  of  this  gas.  But,  if  part  of  the  hydrogen 
were  united  with  the  iron  by  some  strong  chemical  tie, 
heating  in  vacuo  and  boring  might  not  release  it,  and  we 
might  expect  that  the  results  thus  obtained  would  be 
below  those  of  the  combustion  method.  The  fact  that 
they  are  not  suggests  that  most  and  perhaps  all  the  hydro- 
gen is  but  feebly  held  by  the  metal.  The  fact  that  the 
marked  effects  apparently  produced  by  the  absorption  of 
nascent  hydrogen  are  removed  by  heating  and  rest,  which 
simultaneously  expel  hydrogen,  points  in  the  same  direc- 
tion. (§  178.) 

C.  Parry's  Results. — In  eight  out  of  the  twelve  cases  in 
which  he  extracts  hydrogen  from  previously  untreated 
iron,  he  recovers  more,  usually  much  more  and  in  one  case 
21  times  as  much  hydrogen  as  has  been  recovered  by  any 
other  observer  by  any  method  whatsoever  within  my 


knowledge."  In  the  remaining  four  cases  the  length  of  ex- 
posure, if  stated,  was  comparatively  short :  so  that  the 
inference  might  be  justified  that,  had  he  employed  his 
usual  prolonged  exposures,  he  would  probably  in  every 
case  have  extracted  much  more  hydrogen  than  any  one 
else. 

He  found  that,  while  the  flow  of  gas  from  iron  heated 
in  vacuo  gradually  slackened  at  constant  temperature, 
and  could  be  completely  checked  by  lowering  the  tem- 
perature say  from  whiteness  to  redness,  yet  it  always 
started  up  afresh  on  raising  the  temperature,  "and  this 
continued  up  to  the  highest  heat  attainable."  In  no  case 
was  there  satisfactory  evidence  that  the  metal  was  com- 
pletely freed  from  hydrogen,  even  after  seven  days  heat- 
ing in  vacuo. b 

There  is  little  reason  to  doubt  that  he,  like  others,  actu- 
ally extracted  some  hydrogen  from  the  iron  itself :  but 
the  great  difference  between  his  results  and  those  of 
others  suggests  that  a  large  portion  of  his  gas  may  have 
come  from  some  source  other  than  his  iron.  Shall  we 
accept  or  reject  his  results  ?  Shall  we  believe  that  a  com- 
paratively short  heating  in  vacuo  suffices  to  extract  near- 
ly all  the  hydrogen  present,  or  that  it  extracts  but  a 
small  fraction  of  the  hydrogen,  and  that  this  gas  is  actu- 
ally evolved  by  the  iron  at  a  rapid  rate  even  after  days  of 
heating  ? 

Against  his  results  we  have  his  own  candid  admission0 
that  it  appears  to  the  last  degree  improbable  that  cast- 
iron  contains  the  large  quantity  of  hydrogen  shown  :  the 
fact  that  the  iron  from  which  he  extracted  these  large 
volumes  of  hydrogen  would  reabsorb  but  a  relatively 
small  proportion0 :  the  fact  that  there  appears  to  be  a 
chance  for  hydrogen  to  enter  his  apparatus,  which  might 
be  suspected  of  permeability  at  the  high  temperatures 
employed  :  and  that,  as  just  stated,  when  he  employed 
a  long  exposure  he  obtained  much  higher  results  than 
other  observers,  even  when  they  employed  methods  which, 
unlike  his,  would  naturally  be  expected  to  extract  the 
whole  of  the  hydrogen  present.  I  see  but  two  ways  of 
reconciling  his  results  with  theirs.  These  are  to  suppose 
either  that  he  usually  happened  on  irons  very  exception- 
ally rich  in  hydrogen :  or  that  the  methods  employed  by 
Fox  and  Ledebur  recover  but  a  fraction  of  the  hydrogen 
present :  and  neither  of  these  suppositions  is  probable. 
A  further  difficulty,  that  of  supposing  that  the  large 
quantity  of  carbonic  oxide  and  hydrogen  which  he  finds, 
sometimes  amounting  together  to  nearly  one  per  cent, 
should  be  overlooked  in  ordinary  analyses,  the  sum  of 
whose  results  still  usually  very  nearly  equals  100$,  cannot 
be  passed  over  lightly. 

In  favor  of  his  results  we  have  the  following  facts. 

1.  The  nearly  and  often  quite  complete  absence  of  nitro- 
gen from  his  gases  indicates  that  they  are  not  of  atmos- 
pheric origin:  and  the  absence  of  carbonic  acid  argues  that 
they  do  not  arise  from  the  flame  used  for  heating  the  tubes, 
which  should  yield  carbonic  acid  and  nitrogen,  and  this 
carbonic  acid  would  probably  only  be  partially  reduced 
by  the  iron  under  treatment.  To  this  it  may  be  objected 
that  hydrogen  is  so  diffusive  that  it  might  enter  rapidly 
where  nitrogen  and  carbonic  acid  could  enter  but  slowly, 


a  Cf.  Tables  56  and  60. 

b  Journ.  Iron  and  St.  Inst.,  1881,  I.,  p.  189, 

cldem,  1874,  I.,  p.  100. 


112 


THE    METALLURGY    OF    STEEL. 


and  that  the  carbonic  oxide  which  Parry  finds  with  his 
hydrogen  may  arise  from  reaction  within  the  tube."  More- 
over, the  hydrogen  might  arise  from  the  tubes  themselves. 

2.  There  is  a  rough  accord  between  the  quantity  of  gas 
extracted  on  the  one  hand,  and  the  temperature  and 
length  of  exposure  on  the  other.     But  to  this  it  may  be 
objected  justly  that,  if  the  gas  arose  from  leakage  or  diffu- 
sion or  any  source  other  than  the  iron,  its  quantity  would 
still  increase  with  the  temperature  and  duration  of  the 
experiment. 

3.  On  exhausting  platinum  by  this  same  method  Parry' s 
results  agreed  with  Graham's. 

4.  Parry  is  a  very  intelligent  chemist,  of  prolonged  ex- 
perience in  the  analysis  of  iron,  and,  according  to  such 
information  as  I  can  obtain,  exceptionally  conscientious 
and  trustworthy. 

5.  With  his  longer  exposures  and  higher  temperatures 
we  should  expect  him  to  extract  whatever  hydrogen  was 
present  more  completely  than  others  who  heat  iron  in 
vacuo.     This  latter  consideration  does  not  explain  why 
he  gets  more  hydrogen  than  Ledebur  and  Fox,   who 
appear  to  have  completely  oxidized  their  specimens.     Its 
force  is  also  much  weakened  by  the  fact  that  the  very 
prolonged  exposures  to  a  vacuum  employed  by  Troost 
and  Hautefeuille  extracted  but  a  minute  fraction  of  the 
quantity  of  hydrogen  that  Parry  found.     That  at  about 
the  melting  point  of  copper,  say  1000°  C.,  and  in  60  hours 
(Number  20,  Table  56)  he  should  extract  nearly   5000 
times  as  much  hydrogen  per  volume  of  steel  as  they  did 
in  190  hours  at  800°  C.  (Number  16,  idem)  is  surprising, 
and  perhaps  more  than  surprising. 

6.  Parry  states  that  the  gas  is  certainly  not  due  to  leak- 
age :  that  experiments  with  empty  tubes  do  not  indicate 
that  it  can  enter  by  diffusion  :  and  that  his  rubber  connec- 
tions do  not  evolve  gas  at  70,°  (probably  C.). 

This  is  a  vital  point.  Were  his  tubes  impermeable  or 
not  «b 

It  seems  to  me  quite  clear  that  Parry  satisfied  himself 
that  there  was  no  leakage  through  the  joints,  but  did  not 
satisfy  himself  that  the  portions  of  his  apparatus  other 
than  the  joints  were  also  impermeable.  His  language 
implies  that  experiments  with  empty  tubes  were  not  de- 
cisive. 

Looking  beneath  the  surface,  let  us  see  whether  the 

a  See  §  188  B. 

b  This  is  so  important  a  matter  that  I  quote  at  length  several  of  Parry's  remarks 
bearing  on  it.  "A  good  heat  could  be  applied  without  danger  from  leakage  or 
fusion  of  tubes."  (Journ.  Iron  and  St.  Inst.,  1872,  II.,  p.  241.)  "  At  a  full  red 
heat  a  vacuum  could  always  be  obtained,  but,  on  raising  the  heat,  gas  again  came 
off.  The  cause  of  this  continuous  evolution  of  gas  has  not  yet  been  ascertained. 
It  has  been  proved  that  it  is  not  due  to  leakage."  (Idem,  1873, 1.,  p.  430.)  "  On 
fusing  gray  pig  iron  in  vacuo  it  was  found  impossible  to  maintain  a  good  vacuum 
for  any  length  of  time,  gas  in  small  quantity  being  continually  evolved  :  that  this 
continuous  evolution  of  gas  did  not  appear  to  be  due  to  leakage,  for  the  quantity 
of  gas  evolved  increased  in  proportion  to  the  weight  of  iron  used."  The  italics 
are  mine.  (Idem,  1874,  I.,  p.  92.)  It  will  be  shown  shortly  that  the  relation 
between  the  quantity  of  gas  and  that  of  iron  gives  good  reason  to  suspect  thai 
much  of  the  gas  obtained  came  from  some  source  other  than  the  iron.  "  It  is  cer- 
tain that  the  gas  is  not  due  to  leakage,  and  must  be  derived  either  from  the  iron  or 
tubes,  or  by  diffusion  from  the  gas  flame  through  the  substance  of  the  tube, 
this  latter,  considering  the  precautions  taken,  being  very  improbable,  and  is  no1 
confirmed  by  experiments  with  empty  tubes."  (Idem,  p.  100.)  "  It  is,  moreover, 
very  possible  that  no  exhausted  vessel  heated  from  the  exterior  rema'nr;  perfectly 
gas-tight  at  the  high  temperature  which  appears  necessary,  although  actual  results 
with  empty  tubes  so  far  disprove  this.  To  remove  all  uncertainty  arising  from 
possible  leakage,  the  author  proposes  heating  the  metal  (inclosed  in  an  exhauster 
glass  globe)  by  means  of  the  electric  current."  (Idem,  p.  1881,  I.,  p.  192.)  Thi: 
would  indeed  be  a  crucial  as  well  as  an  extremely  easy  test.  I  commend  it  to 
metallurgical  investigators. 


numerical  relations  between  his  various  results  support  or 
oppose  the  belief  that  all  or  nearly  all  his  gas  came  from  his 
iron.  Leaving  out  of  consideration  his  exposures  of  6-5 
tiours  and  less,  because  at  the  beginning  of  an  exposure  a 
very  large  quantity  of  gas  would  be  expected  to  be  given  off 
by  the  metal,  we  have  six  experiments  in  which  the 
quantity  of  gas  and  of  metal  are  given,  and  in  which  the 
exposures  lasted  24  hours  or  longer.  If  now  the  whole  of 
the  gas  came  from  the  metal,  we  might  expect  that  the 
volume  of  gas  per  gramme  of  metal  would  gradually 
diminish  with  the  progress  of  the  exhaustion,  so  that  the 
longer  the  exposure  the  less  gas  would  be  given  off  per 
dour  per  gramme  of  metal,  and  so  that,  were  we  to  num- 
ber the  experiments  by  the  length  of  exposure,  1  having 
the  longest,  and  place  them  in  the  order  of  the  volume 
of  gas  emitted  per  hour  per  gramme  of  metal,  the  most 
rapid  emission  first,  they  should  stand  thus  ;  6,  5,  4,  3, 
2,  1.  Now  they  actually  stand  in  a  very  different  order, 
viz.:  3,  5,  4,  1,  2,  6,  the  shortest  exposure  yielding  the 
least  gas  per  hour.  (Lines  9  and  10,  Table  60  A.)  Heie 
the  sum  of  the  first  half  of  the  digits  is  but  little  larger 
than  that  of  the  last. 

TABLE  60  A.— ANALYSIS  OF  PARRY'S  RESULTS,  SPECIMENS  HEATED  24  nonns  OK  MOKE. 


Number. 

I.  Relation  between  weight  of  metal  and  volume  of  gas  per  volume  of  metal. 

Number  in  Tablo  86 

9. 

6. 

7. 

8. 

20. 

5. 

I.. 

2.. 
3.. 

4.. 
!>.. 

6.. 
7.. 
8.. 

9 
10.. 

Volume  of  pas  per  volume  of  metal.  .  . 
Weight  of  metal,  grammes  
No.  by  weight  of  metal.    1.  Heaviest 

194 
3-33 
5 

127-6 
10 
2 

123-5 
4-5 
4 

90-8 
5-1 
3 

70-5 
10 
2 

19 

41- 
1 

II.   Relation  between  volume  of  gas  per  hour  and  weight  of  metal. 

Number  in  Tablo  56  

9. 
1-64 
493 
5 
59 

8. 
1-J8 

•382 
3 
36 

7. 
1  f>9 
•358 
4 
52  5 

6. 
2-4) 
•241 
2 
76 

20. 
1-51 
•151 

2 
60 

5. 
4-79 
•117 
1 
24 

Volume  of  gas  per  hour,  cc.        ..   .. 
Vol.  of  gas  per  hour  per  gr.  metal,  cc. 
No.  by  weight  of  metal.    1.  Heaviest. 

Relation  between  volume  of  gas  per  gramme  of  metal  per  hour  and  length  of  exposure. 

Vol.  of  gas  per  hour  per  gr.  metal  .  .  . 
No.  by  length  of  exposure.  1.  Longest 

•493 
3 

•882 
5 

•353 
4 

•241 
1 

•151 
2 

•117 
6 

The  actual  differs  so  much  from  the  expected  sequence 
that  it  certainly  does  not  argue  for  the  belief  that  the 
whole  of  the  gas  came  from  the  metal :  nor,  on  the  other 
hand  does  it  differ  enough  to  argue  strongly  against  this 
belief. 

Whether  the  gas  came  wholly  from  the  metal  or  partly 
from  metal  and  partly  from  other  sources,  the  total  vol- 
ume of  gas  per  hour  should  increase  with  the  weight  of 
metal ;  and,  numbering  the  experiments  according  to  the 
weight  of  metal,  1  having  the  most,  and  placing  them  in 
order  of  the  total  volume  of  gas  per  hour,  the  largest  vol- 
ume first,  they  should  stand  1,  2,  2,  3,  4,  5 :  actually  the 
order  in  which  they  stand,  viz. :  1,  2,  3,  5,  4,  2,  while  it 
differs  from  the  expected  sequence,  hardly  differs  enough 
to  suggest  that  no  important  part  comes  from  the  metal. 
But  this  sequence  of  course  throws  no  light  on  the  ques- 
tion whether  an  important  part  also  comes  from  some 
other  source. 

If,  however,  the  gas  came  wholly  from  the  metal,  then, 
numbering  the  experiments  according  to  the  weight  of 
metal  as  before  and  placing  the  numbers  in  the  order  of  the 
volume  of  gas  per  hour  per  gramme  of  metal,  no  especial 
order  should  be  looked  for.  But,  if  the  gas  came  in  large 
part  from  some  other  source,  then  the  less  metal  the  more 
gas  per  hour  per  gramme  of  metal  should  be  found  :  and, 
if  numbered  and  placed  as  just  stated,  the  largest  volume 
first,  they  should  stand  5,  4,  3,  2,  2,  1 :  and  this  is  almost 


HYDROGEN     IN     IRON.       AMMONIA     FROM     STEEL.       §  176  E. 


113 


exactly  their  order,  which  is  5,  3,  4,  2,  2,  1  (line  7,  Table 
60  A).  Here  the  sequence  would  be  perfect  but  for  the 
transposition  of  4  and  3,  which  is  far  from  surprising : 
for  number  4  had  a  longer  exposure  than  number  3,  which 
might  well  diminish  its  volume  of  gas  per  hour  by  a 
greater  amount  than  the  very  slight  difference,  less  than 
8%,  in  the  volume  of  gas  per  hour  per  gramme  of  metal  of 
these  two  experiments. 

If  we  go  a  step  farther  and,  ignoring  the  quantity  of 
gas  evolved  during  the  first  part  of  the  exhaustion,  con- 
sider only  that  evolved  later,  we  obtain  a  similar  sequence, 
viz.  :  4,  5,  3,  2,  2,  1.  Here,  too,  transposing  two  adjoining 
numbers  gives  us  the  perfect  sequence. 

Again,  even  if  much  gas  came  from  some  source  other 
than  the  metal,  the  quantity  of  gas  obtained  during  the 
first  part  of  the  exhaustion  should  increase  with  the  weight 
of  metal  treated,  for  doubtless  some  gas  comes  from  the 
metal  itself.  But  if,  as  we  suspect,  the  metal  itself  is 
soon  exhausted,  and  the  gas  obtained  later  comes  from 
some  other  source,  then  the  total  volume  of  gas  per  hour 
obtained  during  the  latter  part  of  the  exhaustion  should 
bear  no  relation  to  the  weight  of  the  metal :  and  it  bears 
none.  Still  confining  ourselves  to  these  six  cases,  and 
ignoring  the  volume  of  gas  evolved  during  the  first  re- 
corded division  of  each  experiment,  we  find  that  in  three 
experiments  (5,  6  and  20,  Table  56),  in  which  from  10  to 
41  grammes  of  metal  were  treated,  from  0'42  to  2-15  cc.  of 
gas  were  obtained  per  hour,  or  on  an  average  1  '28  cc.  : 
while  in  the  other  three  (7,  8  and  9)  only  from  3'33  to  5'16 
grammes  of  metal  were  treated,  yet  more  gas  than  before 
was  obtained,  viz.:  from  1-3  to  2'16  cc.,  or,  on  an  average, 
1'59  cc  This  probably  cannot  be  explained  away  by  dif- 
ferences in  the  temperature  of  the  experiments,  for  compar- 
ing those  portions  of  the  experiments  in  which  a  given 
temperature  prevailed  I  find  no  indication  that  after  the 
first  hours  the  greater  weight  of  metal  evolved  more  gas 
than  the  lesser.  Thus  at  redness  the  greater  weights  of 
iron  evolve  from  '42  to  3'1  cc.  per  hour,  the  lighter  weights 
from  1'2  to  5 '2  cc.  At  whiteness  the  heavy  weights 
evolve  in  the  only  recorded  case  2*1  cc.  per  hour, 
while  the  light  weights  evolve  from  1'79  to  2 -59  cc.  per 
hour. 

In  regard  to  the  sequences  just  discussed  we  have  this 
dilemma :  either  these  numbers  stand  so  close  to  the  ex- 
pected sequences  by  a  chance  conspiracy  of  the  other 
conditions  :  or  a  considerable  proportion  of  the  gas  which 
Parry  found  came  from  some  source  other  than  the  metal, 
and  the  latter  seems  in  itself  rather  the  more  probable 
supposition.  Add  the  weight  of  the  fact  that  the  quan- 
tity of  gas  evolved  after  the  first  hours  seems  quite  inde- 
pendent of  the  weight  of  metal  treated,  of  the  intrinsic 
improbability  of  Parry's  results,  and  of  the  fact  that  no 
other  observer  has  been  able  to  obtain  by  any  method  any- 
thing beginning  to  approach  these  quantities  of  gas,  and 
the  balance  of  probabilities  inclines  very  strongly  to  this 
latter  supposition.  The  balance  may  of  course  be  reversed 
by  additional  facts  which  Mr.  Parry  may  now  have  or 
may  discover  later. 

D.  Saturation  Point  for  Hydrogen  in  Iron. — Several 
facts  indicate  that  the  proportion  of  hydrogen  which  iron 
can  retain  permanently  is  small  measured  by  weight. 

a.  From  glass-hard  electrolytic  iron  Cailletet  extracted 
from  238 -5  to  250  volumes  of  hydrogen  by  heating  in 


vacuo.a  During  15  days  exposure  in  an  open  tube, 
apparently  at  the  ordinary  temperature,  it  appeared  to 
lose  about  94  volumes  of  this  gas.  In  water  at  60°  to  70° 
C.  (140°  to  158°  F.)  it  gave  off  gas  tumultuously.  If, 
ignoring  Parry' s  results,  we  consider  that  on  heating  in 
vacuo  Cailletet  extracted  all  or  nearly  all  the  hydrogen 
present,  it  appears  that  under  these  conditions  iron  is 
unable  to  retain  more  than  250  —  94  =  15tf  volumes  of 
hydrogen,  =  0*17$.  If  we  accept  Parry's  results,  we 
must  admit  that  even  his  prolonged  heating  may  not  have 
extracted  all  the  hydrogen.  But  it  would  be  generous,  I 
think,  to  admit  that,  in  his  seven-day  heating,  Parry 
extracted  only  half  the  hydrogen  :  but  let  us  admit  it.  Let 
us  go  farther,  and  admit  that  after  Cailletet  had  heated 
his  iron  in  vacuo  it  still  retained  twice  as  much  hydrogen 
as  Parry  extracted  from  his  iron  in  seven  days.  With 
this  extreme  admission,  Cailletet' s  iron  appears  able  to 
retain  on  exposure  to  the  air  for  15  days  only  250  -f-  2  X 
205  —  94  =  566  volumes  or  0'615$  of  hydrogen. 

b.  It  is  probable,  however,  that  common  commercial 
steel  is  actually  nearly  saturated  with  hydrogen,  and  that, 
if  Cailletet' s  iron  had  been  long  enough  exposed  to  the  air 
a  far  greater  proportion  of  its  hydrogen  would  have 
escaped  than  left  it  in  his  fifteen-day  exposure.  The 
small  quantity  of  hydrogen,  1P9  to  4'8  volumes  (-0021  to 
•0052$)  which  Ledebur  found  in  iron  after  exposure  to 
nascent  hydrogen  probably  escapes  on  simple  exposure  to 
the  air :  at  least,  its  effects  disappear,  and  they  are  made 
to  disappear  by  the  very  treatment  (gentle  heating)  by 
which  Ledebur  extracts  this  hydrogen  from  the  iron.  This 
is  of  course  simply  suggestive,  not  conclusive. 

Again,  on  solidiiying,  most  classes  of  iron  evolve  more 
or  less  hydrogen,  which  indicates  that  they  are  then  satu- 
rated. That  this  expulsion  continues  after  solidification 
has  well  advanced  is  shown  by  the  presence  of  hydrogen 
in  the  blowholes  of  iron.  Unless  the  iron  were  saturated 
it  would  not  expel  this  hydrogen  ;  nay,  it  would  rather 
reabsorb  that  present  in  the  blowholes. 

If  this  view  that  common  commercial  irons  contain 
nearly  or  quite  as  much  hydrogen  as  they  are  capable  of 
holding  permanently  be  true,  and  if  the  results  in  Table  60 
give  the  whole  or  nearly  the  whole  of  the  hydrogen  in  iron, 
it  would  follow  that,  while  their  capacity  for  hydrogen 
varied  greatly,  none  of  those  tested  are  able  to  hold  much 
over  say  10  volumes  (0-01$)  of  this  gas  if  we  reject  Parry's 
results.  If  we  accept  them,  and  admit  as  above  that  his 
seven-day  heatings  extract  but  half  the  hydrogen,  it  would 
follow  that  none  of  the  irons  tested  can  contain  much 
over  410  volumes  (0'446$). 

E.  Ammonia  from  Steel. — Regnardb  observed  that  the 
fresh  fractures  of  all  or  nearly  all  the  3'1  inch  square  in- 
gots from  certain  heats  of  open-hearth  steel  emitted  a 
sound  of  escaping  gas,  and  an  ammoniacal  smell  whose 
intensity  seemed  proportionate  to  the  quantity  of  gas 
escaping.  Soap  water  placed  on  the  fresh  fracture  was 
thrown  into  thousands  of  microscopic  bubbles,  whose 
total  volume  sometimes  exceeded  1  cc.  (0'06  cubic 
inches),  and  which  formed  chiefly  in  the  center  of  the 
fracture.  The  gas  from  more  than  a  hundred  fractures 
when  collected  in  test  tubes  burned  with  a  hardly  visible 
flame,  detonated  if  mixed  with  air,  and  was  almost  pure 


aComptes  Rendus,  LXXX.,  1875,  p.  319. 
b  Idem,  LXXXIV.,  p.  260,  1877. 


114 


THE    METALLURGY    OP    STEEL. 


hydrogen.  If,  as  is  probable,  the  gas  was  collected  over 
water,  it  may  be  inferred  that  the  steel  emitted  a  mixture 
of  hydrogen  and  ammonia,  the  latter  being  absorbed  by  the 
water.  These  phenomena  did  not  occur  with  porous  and 
soft  steel,  and  were  prevented  by  annealing,  which  prob- 
ably permitted  the  imprisoned  hydrogen  to  escape  by 
diffusion. 

Barre,8  by  smell  and  litmus  paper,  recognized  ammonia 
escaping  from  the  fracture  of  both  open-hearth  and  Bes- 
semer steel ;  and,  without  knowledge  of  these  facts,  For- 
sythb  at  Chicago  and  Emmertonb  at  Joliet  independently 
observed  the  unmistakable  evolution  of  ammonia  on 
breaking  certain  Bessemer  steel  rails  under  the  hammer. 
Here  we  may  suppose  that  the  greater  thickness  of  the 
ingots  prevented  the  hydrogen  from  escaping  during  heat- 
ing so  completely  as  it  appears  to  have  from  Regnard's 
thin  ingots. 

Finally,  Goetz  reports  that  the  fresh  fractures  of  large 
steel  castings,  especially  those  of  large  risers  which  have 
a  shrinkage  hole  at  the  fracture,  nearly  always  evolve  a 
smell  of  ammonia,  which  has  been  so  strong  as  to  draw 
the  attention  of  the  workmen.  The  presence  of  ammonia 
is  proved  by  the  white  fumes  formed  on  the  approach  of 
hydrochloric  acid,  and  by  the  formation  of  chloride  of 
ammonium  when  the  air  in  the  neighborhood  of  the  frac- 
ture is  drawn  through  hydrochloric  acid.  On  evaporat- 
ing this  to  dryness  chloride  of  ammonium  is  found.  In 
the  shrinkage  hole  itself  he  reports  "  a  regular  pocket" 
of  ammonia.  The  smell  is  noticed  even  when  the  frac- 
ture is  perfectly  solid,  "not  a  pin-hole  in  it":  and  the 
fumes,  though  less  noticeable,  appear  when  the  steel  is  cut 
in  a  lathe.  Like  Regnard,  he  has  not  noticed  the  escape 
of  ammonia  from  soft  castings,  and  he  finds  it  most  pro- 
nounced when  the  steel  contains  from  '3  to  '38$  of  carbon, 
•9  to  \'%  of  manganese,  and  -3$  of  silicon.  When  but 
little  silicon  is  present  little  and  sometimes  no  odor  can 
be  detected."  The  low  silicon  suggests  porosity,  and  re- 
calls Regnard's  observation  that  porous  steel  evolved  no 
ammonia.  The  close  agreement  between  the  observations 
of  Regnard  and  Goetz  is  the  more  striking  as  the  latter 
was  unacquainted  with  the  former's  work. 

From  these  observations  and  especially  from  the  ' '  pock- 
ets of  ammonia"  in  large  cavities  described  by  Goetz,  it 
is  probable  that  ammonia  is  formed  in  the  cooling  steel, 
the  hydrogen  in  its  pores  acting  on  nitrogen  combined 
with  the  metal  or  escaping  from  it.  (See  §  172,  p.  106.) 

§  178.  INFLUENCE  OF  HYDROGEN. 

A.  Non-nascent  Hydrogen. — So  far  as  I  know,  nomarked 
change  in  the  properties  of  iron  has  been  observed  to  fol- 
low the  removal  of  hydrogen  by  heating  in  vacuo.     Gra- 
ham observed  that  iron  wire  Number  04,  Table  57,  after 
taking  up  apparently  but  0'46  volumes  or  '0005%  of  hydro- 
gen, became  white  like  galvanized  iron.      Bouis  observed 
that  after  being  heated  for  some  hoars  in  hydrogen  iron 
became  very  crystalline,  brittle,  and  of  a  steel-like  appear- 
ance."1   Further  observations  are  needed. 

B.  Exposure  to  nascent  hydrogen"  greatly  diminishes 


a  Wagner's  Jahresbericht,  XXIII.,  p.  95,  1877. 

*>  Private  communications,  1886. 

c  G.  W.  Goetz,  of  the  Otis  Works,  Cleveland,  Ohio,  private  communications, 
Nov.  18th  and  Dec.  17th,  1887:  also  quoted  by  Wedding,  Btahl  und  Eisen,  VII., 
p.  513,  1887. 

d  Comptes  Rendus,  LIL,  p.  1195,  1861. 

«  For  our  information  on  this  subject  we  are  chiefly  indebted  to  W.  H.  Johnson 


the  flexibility'  of  wrought-iron  and  steel,  and  to  a  much 
smaller  degree  that  of  cast-iron,1  and  the  transverse 
strength  of  steel'  and  probably  of  the  other  varieties  of 
iron.  The  elongation  of  the  metal  is  of  ten  simultaneously 
diminished,  though  usually  to  a  very  much  smaller  de- 
gree, and  it  is  in  general  affected  in  a  way  which  is  much 
less  clearly  understood  ;  while  the  tensile  strength  and 
modulus  of  elasticity  are  affected  but  slightly,  if  at  all. 

The  fracture  of  metal  which  has  been  thus  exposed,  if 
moistened  while  siill  warm  from  the  effort  of  breaking, 
froths  and  gives  off  copious  gas  bubbles  for  30  or  40  sec- 
onds, and  even  the  unbroken  metal  evolves  gas  bubbles 
when  first  immersed  in  water,  especially  if  the  latter  be 
warm.8  The  frothing  power  is  destroyed,g  and  the  flexi- 
bility nearly,  and  perhaps  quite  completely  restored,  very 
rapidly  by  heating  the  metal,  slowly  by  simple  exposure 
to  the  atmosphere  at  ordinary  temperatures. 

Some  or  all  of  these  effects  are  produced  when  iron  is 
immersed  A  in  hydrochloric,  sulphuric,ghl  or  acetic8  acid, 
in  the  two  former  even  if  extremely  dilute :  B  in  mine 
water1 :  C  if  employed  as  the  hydrogen  pole  (cathode)  in 
electrolyzing  common  water, gh  caustic  soda,8  hydro- 
chloric,8 sulphuric,11  or  indeed  any  acid,h  or  neutral  salts,h 
the  iron  becoming  very  brittle  though  wholly  uncorroded ; 
while  if  employed  as  the  oxygen  pole  (anode)  it  is  greatly 
corroded  but  does  not  become  brittle.8 h  Moreover,  the 
m3tal  exhibits  the  characteristic  frothing  after  employ- 
ment as  cathode,  but  not  after  acting  as  anode.8  D  If 
exposed  to  the  weather.1  E  In  electrolytically  deposited 
iron  some  at  least  of  these  effects  are  greatly  exaggerated. 

That  these  effects  are  due  to  exposure  to  nascent  hydro- 
gen and  not  to  corrosion,  is  shown  by  several  facts,  e.  g., 
A  That,  as  just  stated,  in  iron  electrodes  they  are  directly 
as  the  exposure  to  hydrogen  but  inversely  as  the  corrosion. 
B  That  they  are  hastened  and  intensified  by  means  which 
increase  the  evolution  of  nascent  hydrogen  :  among  these 
we  have  the  passage  of  an  electric  current,  and  the  con- 
tact of  the  iron  with  metallic  zinc.hl  The  latter  intensi- 
fies the  brittleness,  both  in  case  of  immersion  in  acidu- 
lated water  and  of  exposure  to  the  weather,1  though  it 
simultaneously  diminishes  the  corrosion  of  the  metal. 
Indeed,  acidulated  water  renders  iron  brittle  much  faster 
if  scraps  of  zinc  be  dropped  into  it,  even  if  the  two 
metals  do  not  touch,  and  evidently  because  of  the  hydro- 
gen rapidly  evolved  by  the  zinc.h  CThat  heating  and 
rest  which  expel  hydrogen  also  remove  these  effects.8 hl 
D  That  on  filing  away  the  exterior  of  the  metal  the 
interior  is  found  brittle.'1  E  That  immersion  in  nitric  acid, 
which  does  not  under  ordinary  conditions  liberate  hydro 
gen  by  its  action  on  iron,  does  not  render  the  metal  brittle, 
though  it  rapidly  corrodes  it.8 

That  the  nascent  state  is  essential  to  these  phenomena 
is  indicated  by  the  fact  that  when  a  violent  stream  of 


(Proc.  Royal  Society,  XXIII.,  p.  168, 1875),  D.  E.  Hughes  (Journ.  Soc.  Telegraph 
Engineers,  1880,  IX.,  p.  163),  and  A.  Ledebur  (Stahl  und  Eisen,  VII.,  p.  681, 
1887).  Johnson's  results  have  been  strangely  overlooked,  though  they  appear  to  me 
much  more  important  than  those  of  Hughes,  which  have  attracted  wide  attention. 
Indeed,  I  do  not  find  that  Ledabur  even  refers  to  Johnson's  work  in  his  own 
admirable  paper,  though  he  gives  a  r&ume'  of  all  the  literature  of  the  subject  that 
he  has  found. 

Johnson  anticipated  most  of  the  results  and  deductions  of  Ledebur  and  Hughes. 

1 1.  e..  the  power  of  being  bent  back  and  forth  without  breaking. 

g  Johnson,  loc.  cit. 

h  Hughes,  loc.  cit. 

l  Ledebur,  loc.  cit. 

i  Strob,  Journ.  Teleg.  Engrs.,  ante,  cit 


INFLUENCE     OF    EXPOSURE    TO    NASCENT    HYDROGEN.      §  178,   B. 


115 


TABLE  61. — INFLUENCE  OF  EXPOSURE  TO  NASCENT  HYDROGEN. 


k 

1 

1 
1. 

2. 
3. 
4.. 
5. 

6.. 

7.. 
8.. 

9.. 
10.. 
11.. 

12.. 
13.. 

14.. 

15.. 
16.. 

lit. 

17b. 
17o. 

ISa. 

ISb. 
18c. 

19a. 
ISb. 
19o. 

20a. 

20b. 

21a. 
21b. 
21-5 

Observer. 

•a 

1 

*•"•  2. 

0   « 
_q 

| 
z 

8. 

S. 
8.. 
8.. 
8.. 

8.. 

8.. 
8. 

8 

Description  of  iron 
experimented  on. 

Exposure  to  nascent  hydrogen. 

Subsequent  treating  before 
testing. 

Effect  of  exposure. 
Tensile  strength,  etc.,  of  the  bar  after  treatment  per  100  of  initial  tensile  strength,  etc. 

Immersed  or  ex- 
posed to 

Days 

In  contacl 
with  zinc. 

Heated  —  yes 
or  no. 

E 

H 
0 

Temperature. 

Allowed  to 
rest,  days. 

Tensile 
strength. 

Modulus 
of 
elasticity. 

Elongation. 

80-0 

79-4 
i   (86-7)  |a 

'  "£*  } 
94-4 

87  3 

92-1 

794 

54-0 
65-1 
69-8 

55-6 
91-9 

Flexibility. 

Transverse 
strength. 

Break- 
ing 
loat. 

79-0 

64-9 
52  4 
85-4 

Maxi- 
mum 
bend- 
Ing. 

100-9 
82-7 

81-2 

L. 

{Iron    wire    from  ] 
•065  to  -14  inch  I 
diameter  

ti                          14 

I  Iron  wires    from 
1-08  to  -14  inch  f- 

In     dilute    sulphuric 
acid,  strength,  1:100 

"                   1:40 
"                  1:40 
"                   1:40 
1:40 

In    very    dilute    sul- 

i- 

0-96 
0-12 
OM2 
0-17 

0-42 
4- 

No.  

No 

8 

0 
0 
4 

0 

99-51 

102  1 
989 

102  9 

j  (100-7)  la 
i   103-9  \ 

99  4 

93-6 
96  0 

)       64  9 
f       84-6 
82  5 

94  9 
98  8 

100-2 

108-5 
98  9 
106  3 
104  7 

99  3 

94-8 
97  6 

54  9 

83  0 
82-4 

96  0 
99   5 

73-4 

45-9 
39  0 
71-3 
90  1 

23  7 

26-8 
82-5 

68  5 

65-8 
86-8 

56-1 
86  9 

70-8 
60-5 

No  

No 

Yes  .... 

No 

Yes  

fin 

Yes 

Yes 
No 

0  25 

Cherry  red 

Yes    

In    dilute     sulphuric 
acid,  1-200 

No.. 

[n    very    dilute   sul- 
phuric acid  

0'42 
3- 

Yes  

28 

8 
8.. 

8.. 
6.. 

2.. 
2.. 

tt               u 

(  Oil-hardened  bars  j 
K     of  spring  steel,  > 
(      '87  inchsqr  \ 
Spiral     springs,     oil- 
hardened  

0'96 
!• 

1  Exposed    to    the  j 
f     weather  | 

j  In      dilute      sul-  1 
|     phuric  acid  f 

62- 
14- 

1- 
1- 

No  
Yes  

No  





Yes  

J  springs  hardened.. 

In    dilute     sulphuric 
acid  

1- 

J... 
H.'.' 

8. 

10 

10.. 

6.. 
6.. 

6  . 

6.. 

6.. 

2.. 
2.. 
7. 

5. 
6. 

j  Cast-iron  bars,  '2  I 
|     inch  square  f 

J-shaped       cast-iron 
bars  

'.n    dilute     sulphuric 
acid,                  1:50 
"                    4:f>0 

4:50 
f 

1- 

J- 

9- 

9- 

0-21 
0-21 
0-21 

0  5 
0-5 

Yei 

100-2 
89-0 

f  Bright,  i.e.,  hard! 
j    drawn  mild  steel  [ 
1    wire,  0227*  car-  f 
[   bon  J 

No 

96-1 
104-5 
109-9 

80-8 

98-9 

99-7 
105-2 

168-7 
180-1 
206  0 

88-7 

128-1 

100-0 
78-8 

16-9 

17-4 
24  3 

In   very  dilute  hy-  j 
drochloric  acid.  .  .  j 

In  sulphuric  acid  

Yes 

Yes 

No 

• 
12- 

168- 

100«C 
100»C 

f  Hardn'd  and  ternO 
/     pered  hard  cast-  , 
|     steel  wire,  about  f 
1     '  68  carbon  j 

Soft   iron  wire,   0"06 
inch  diameter  
The  same  galvanized  . 

Yes 

No 

240- 

100@200°C 

«           d 

0-04 

1                             '"( 

fin  sulphuric  acid,  J 
about  1:50.    ..A 

0-04 

1- 
1- 

r 

Yes 
No. 

24. 

o- 
o- 
o- 

100@200'C 

No  ... 

No  

•'    same  Barffed  .   . 

Ho  

Effect  of  heating. 
Tensile  strength,  etc.,  of  the  iron  after  exposure  to  hydrogen  and  reheating,  per  100  of 
the  tensile  strength  of  similarly  exposed  iron  not  reheated. 

22.. 
23 
24.. 

25.. 
26.. 

I... 

12.. 
S.. 
9.. 

6.. 
6.. 

Vnnealed  iron  wire... 
bright  iron  wire  .  ... 
Annealed   mild    steel 
wire  

n  hydrochloric  acid, 
very  dilute  

0-04 
0'04 

0  21 
0-5 
0-5 

Yes 

12-O48- 

100-49 
100-27 

104-77 
106-62 
105-85 

103-9 
141-5 

76  6 

807-7 
826-2 

Yes 

Yes 

Yes 
Yes 

12-S48- 

12- 
120- 
120- 

100-  ± 

j  Bright      charcoal  I 
|     iron  wire  j 

.n  sulphuric  acid  .  .  . 
.n  hydrochloric  acid  .  . 

Heavy-faced  figures  indicate  that  the  iron  was  in  contact  with  zinc. 

The  numbers  in  this  table  represent  not  the  absolute  tensile  strength,  etc  ,  but  the  tensile  strength,  etc.,  of  the  iron  after  exposure  to  hydrogen  per  100  of  the  tensile  strength,  etc.,  of  similar 
but  unexposed  pieces. 

The  eight  wires  for  Numbers  1  to  5  inclusive  appear  to  have  been  cut  from  the  same  eight  mine  ropes,  which  had  already  been  in  use:  and  though  in  each  individual  test  the  same  wire  wa! 
tested  I  before  and  after  exposure  to  nascent  hydrogen,  yet  it  does  not  appear  that  the  same  eight  wires  were  used  for  the  different  experiments.  The  eight  wires  employed  for  each  of  experiments 
6  to  18  were  cut  from  the  «ame  eight  coils  of  previously  unused  wire.  These  experiments  are  thus  more  closely  comparable. 

ZINCING.—  In  certain  experiments  the  wires  were  in  contact  with  metallic  zinc.  In  Ledebur's  experiments  contact  was  effected  by  castin^  a  zinc  block  weighing  about  one  pound  around  one 
end  of  the  wire  :  in  every  case  this  prevented  the  corrosion  of  the  wire  completely  or  nearly  so 

.  =  the  author. 


pieces,  before  fracture. 

.  s  we  obtain  the  numbers  given  in  parenthesis. 

.  .  previously  cleaned  with  ether. 

3   A  violent  evolution  of  gas  over  the  whole  surface  of  the  wire,  which  remained  completely  white,  and  was  not  in  the  least  eaten  with  acid. 

n    in   ,"il'es  wcre  considerably  but  not  very  seriously  (deutlich,  doch  nicht  sehr  erheblich)  corroded. 

9,  10,  1  1    9  and  10  immersed  in  acid1  water  from  one  mine,  11  in  that  from  another  mine.      The  wire  became   coated  with  salts  in  each  case.      In  9  and  11  the  wire  was  much  corroded  by  the 
water,  in  10  less  corroded  than  in  9. 

IS    The  wires  were  not  previously  freed  from  grease.    They  became  much  covered  with  rust. 

13.  The  wires  rusted  considerably,  but  much  less  than  in  Number  12. 

14  and  15    Spring  steel,  with  0  $5  carbon,  oil-hardened  and  spring-tempered.    Loaded  to  breaking  in  the  middle,  between  supports  17-7  inches  apart. 

ID    Spiral  springs,  made  from  steel  of  0-9  carbon,  0-81  inch  in  diameter,  were  oil-hardened  and  tempered.     Those  which  had  not  been  exposea  to  acid  broke  into  2  or  3  pieces  :  those  which 
had  lieen  so  exposed  broke  into  from  10  to  12  pieces. 

17.   U  springs  were  hardened  in  water,  tempered  to  spring  hardness  and  loaded  to  breaking.      One  was  not  treated  with  acid,  the  remaining  three  were  treated  for  24  hours  with  sulphuric 
acid,     A  was  loaded  to  breaking  without  further  treatment,  B  after  being  hammered,  C  after  being  heated,  again  hardened,  and  tempered. 

18    Hars  0-197  inch  square,  were  fixed  at  one  end  and  loaded  at  the  other  to  breaking,  at  a  distance  of  9-76  inches  from  the  fixed  end. 

21-5.  A  single  coil  of  wire  was  cut  into  many  pieces.      Some  of  these  were  galvanized,  others  were  Bower-Barffed,  and  the  remainder  were  not  coated.      They  were  then  simultaneously 
immersed  in  dilute  sulphuric  acid  for  24  hours.    The  flexibility  was  determined  by  bending  the  wire  back  and  forth  till  fracture  occurred.    The  wire  was  held  in  iron  laws  with  rounded  edges. 


hydrogen  was  bubbled  for  an  hour  through  water  con- 
taining wire,  and  when  the  latter  was  exposed  to  hydrogen 
for  hours  in  a  glass  tube  at  the  ordinary  temperature,  no 
brittleness  arose. a 

The  great  loss  of  flexibility  and  elongation  which  simple 
exposure  to  the  weather  produces,  even  when  the  almost 

»  Jotason,  loc.  oit. 


undiminished  tensile  strength  indicates  that  but  little 
rusting  has  occurred,  may  seriously  affect  iron  engineer- 
ing structures  :  and  it  is  surmised  that  coating  with  zinc 
to  prevent  the  action  of  the  weather  will  merely  aggra- 
vate the  evil.'0  That  iron  should  lose  nearly  half  its 
elongation  and  flexibility  on  simple  exposure  for  62  days, 


*>  Ledebur,  loc.  cit. 


116 


THE    METALLURGY     OF     STEEL. 


though  but  little  corroded,  is  certainly  disquieting.  The 
fact  that  pieces  nearly  an  inch  thick  are  rapidly  rendered 
brittle  in  acid,  and  are  probably  affected  by  the  weather 
much  as  thinner  ones  are,  is  not  reassuring.  (Experiments 
14  and  15  )  Further  investigations  to  learn  the  extent  of 
injury  to  large  pieces  by  the  weather,  and  to  discover 
whether  certain  classes  of  iron  may  not.  resist  this  action 
better  than  others,  seems  desirable.  It  is  not  improbable 
that  the  tendency  of  the  absorbed  hydrogen  to  escape 
ultimately  balances  its  absorption, a  and  so  prevents  the 
effects  of  the  weather  from  being  cumulative  beyond  a 
certain  point. 

We  may  now  consider  in  more  detail  the  specific  effects 
of  exposure  to  hydrogen,  as  given  in  Table  61. 

The  tensile  strength  and,  modulus  of  elasticity  are  not 
in  general  seriously  affected,  unless  the  cross  section  of 
the  piece  is  diminished  by  actual  corrosion,  as  in  numbers 
9,  10  and  11.  The  only  exception  to  this  is  number  20  A, 
and  here  the  conditions  are  complicated  by  the  fact  that 
the  wire  before  immersion  was  hardened  and  tempered. 
On  exposure  its  tensile  strength  falls  to  80'8$  of  the  origi- 
nal, but  rises  again  to  98  -9%  on  reheating,  which  suggests 
that  the  iron  had  not  become  corroded. 

In  the  six  experiments,  numbers  3,  4,  6,  6,  8  and  13 
(comprising  92  individual  tests  for  each  property)  in  which 
unexposed  iron  is  compared  with  that  which  had  been 
exposed  to  hydrogen  but  which  had  been  at  least  partially 
protected  from  corrosion  by  contact  with  zinc,  the  average 
loss  of  tensile  strength  is  but  0'017$  of  the  original,  while 
there  is  a  gain  of  1'05$  in  modulus  elasticity. 

The  elongation  is,  on  the  whole,  affected  somewhat 
more  than  the  tensile  strength,  the  average  loss  in  these 
six  experiments  being  10 -62$  (14'5$  if  we  omit  one  abnor- 
mal result).  The  elongation  ratios  are  very  high  in  num- 
bers 19  B,  19  C,  20  B,  25  and  26,  perhaps  because  here  the 
elongation  of  the  wire  unexposed  to  hydrogen  had  been 
depressed  by  the  stresses  induced  by  previous  hard-draw- 
ing or  hardening.  It  may  be  that  these  stresses  are 
released  by  the  subsequent  heating  which  expels  the 
hydrogen,  and  that  their  release  brings  the  elongation  of 
the  wire  exposed  to  hydrogen  and  reheated,  above  that  of 
the  wire  before  exposure  to  hydrogen.  (Cf.  §  51,  C,  §  53,  2, 
A,  pp.  29-31).  Indeed,  the  high  elongation  ratio  of  number 
19  A,  which  is  hard-drawn  wire  exposed  to  hydrogen 
without  subsequent  heating,  suggests  that  the  hydrogen 
has  in  some  way  released  these  stresses.  But  the  effects 
of  exposure  to  hydrogen  and  of  subsequent  rest  and  heat- 
ing on  the  elongation  are  so  often  extremely  anomalous, 
that  it  is  not  improbable  that  this  property  is  influenced 
by  some  important  factor  which  has  escaped  detection. 

The  flexibility,  however,  is  the  property  which  appears 
to  be  most  affected,  usually  falling  more,  and  often 
very  much  more  than  the  other  properties  tested.  In 
average  of  the  six  cases  in  which  the  iron  was  in  contact 
with  zinc  the  flexibility  falls  by  34'42$. 

The  transverse  strength  of  spring  steel  and  the  carrying 
power  of  steel  springs  are  also  greatly  diminished  by  ex- 
posure to  hydrogen,  falling  by  from  14'6  to  47'6$. 

The  hardness  is  affected  if  at  all  to  a  degree  which 
usually  escapes  observation.  According  to  Stroh  it  is  not 
affected  in  the  least."  But,  by  sufficient  exposure  to  hy- 

a  Johnson,  loc.  c  it. 

b  Journ.  Teleg.  Engrs.,  IX.,  p.  173,  1880. 


drogen,  as  when  iron  is  electrolytically  deposited,  glass- 
hardness  is  acquired. 

In  numbers  2,  3,  6  and  7  the  effects  of  exposure  to  hy- 
drogen, unobscured  by  heating,  rest,  or  visible  corrosion, 
are  especially  striking,  the  tensile  strength  and  modulus 
being  practically  unaffected,  on  an  average  falling  by  only 
1-5$  and  0-87$  respectively,  while  the  elongation  falls  by 
7'8$  (13-62^  omitting  one  abnormal  result)  and  the  flexi- 
bility by  66-27^. 

Contact  with  Zinc. — In  experiments  2  and  3  the  con- 
ditions are  alike,  except  that  in  the  latter  the  iron  was  in 
contact  with  zinc,  and  was  exposed  to  hydrogen  for  a 
much  shorter  time :  the  same  is  true  of  experiments  12 
and  13.  In  the  first  pair  the  loss  of  elongation  is  greater 
(if  we  except  one  abnormal  result),  and  that  of  flexibility 
very  much  greater  per  day  of  exposure  when  zinc  is  pres- 
ent. Indeed,  the  total  loss  of  flexibility  is  greater  in  the 
short  exposure  with  zinc  than  in  the  long  one  without  it. 
In  the  second  pair  also  the  presence  of  zinc  increases  the 
loss  of  flexibility  per  diem. 

In  the  former  pair  of  experiments  the  zinc  appears  to 
have  slightly  diminished,  in  the  latter  pair  to  have  slight- 
ly protected  the  tensile  strength  and  modulus  of  elasticity. 
But  an  examination  of  the  details  of  the  experiments 
leaves  little  doubt  that  the  changes  in  the  tensile  strength 
and  modulus  of  elasticity  are  apparent  only,  and  are  due 
to  those  slight  differences  in  the  properties  of  different 
portions  of  the  same  piece  which  are  to  be  expected. 

It  might  be  inferred  that  the  contact  of  electro-negative 
substances,  such  as  iron  scale,  would  lessen  just  as  that  of 
zinc  intensifies  the  effect  of  exposure  to  nascent  hydrogen. 
To  test  this  as  well  as  Ledebur's  inference  that  coating 
with  zinc  like  other  contact  with  that  metal  should  inten- 
sify these  effects,  I  have  cut  a  single  coil  of  wire  into  many 
pieces,  some  of  which  were  galvanized,  some  Bower- 
Barffed,  and  some  employed  without  protective  coating. 
As  the  important  question  is  whether  these  coatings  in- 
fluence the  degree  of  brittleness  caused  by  exposure  to 
the  weather,  several  of  each  set  are  now  under  exposure  : 
the  results  will  appear  in  an  appendix.  In  order  to  ob- 
tain immediate  indications  others  were  immersed  in 
dilute  acid  (number  21 '5,  Table  61):  the  results  do  not 
support  Ledebur's  inference,  but  they  tend  to  show  that 
Barffing  does  lessen  the  effects  of  exposure  to  nascent 
hydrogen. 

Heating,  even  if  brief,  removes  the  effects  of  exposure 
to  hydrogen  (the  loss  of  elongation  sometimes  excepted), 
nearly  and  sometimes  quite  completely.  Johnson  states 
that  the  metal  regains  its  original  toughness  in  twelve 
hours  at  200°  C.,  and  that  no  bubbles  can  then  be  seen  on 
moistening  its  fracture :  Hughes  that  its  flexibility  is 
completely  restored  by  heating  to  cherry  redness  for  a 
few  seconds  in  a  spirit  lamp :  while  Lebebur  (3  and  5, 
Table  61)  finds  that  in  15  minutes  at  cherry  redness  in  a 
stream  of  producer  gas  made  from  charcoal,  the  elongation 
usually  rises,  while  the  flexibility,  which  exposure  to  hy- 
drogen had  depressed  to  39^  of  the  original,  rises  on 
heating  to  90  -\%  of  the  original.  In  17  b  and  c  heat- 
ing restores  to  a  spring  much  of  the  carrying  power  which 
it  had  lost  by  exposure  to  hydrogen. 

In  six  out  of  Johnson' s  nine  experiments  heating  raises, 
and  twice  it  more  than  triples  the  elongation  which  had 
been  diminished  by  hydrogen  :  yet  in  the  remaining  three 


NASCENT    HYDROGEN.— DEOXIDATION.      §  180. 


117 


cases,  collectively  representing  the  results  of  fifteen  pairs 
of  comparative  tests,  heating  the  wire  after  exposure  to 
hydrogen  lowers  the  elongation. 

These  surprising  results  may  be  regarded  as  additional 
illustrations  of  the  wide  difference  between  the  effects  of 
hydrogen  on  elongation  and  on  flexibility :  for  Johnson 
states  unreservedly  that  heating  restores  the  original 
toughness :  and  his  remarks  leave  little  doubt  that  he 
uses  toughness  as  nearly  identical  with  flexibility,  as 
something  to  be  gauged  by  the  bending  power,  and  as 
having  little  connection  with  ductility  as  measured  by 
elongation." 

Influence  of  Rest. — The  flexibility  and  possibly  the 
elongation  are  restored  more  or  less  completely  by  simple 
rest.  In  experiments  3  and  4  the  conditions  are  alike, 
except  that  in  4  the  wire  is  allowed  to  rest  before  testing 
it :  so  with  experiments  6  and  8.  In  both  cases  there  is  a 
surprising  restoration  of  flexibility  :  the  elongation,  how- 
ever, falls.  In  experiments  6  and  8,  which  are  closely 
comparable,  the  elongation  is  less  after  than  before  the 
four  weeks  rest  in  five  out  of  the  eight  cases.  Johnson 
found  that  wire  "regained  its  original  toughness "  (L  e. 
flexibility «)  after  resting  three  days  at  about  1 6°  C.  (61°  F.), 
and  Dittmar  states  that  the  brittleness  due  to  pickling  is 
so  far  removed  by  simple  rest  that  the  wire  can  be  drawn 
with  complete  satisf action. b  Yet  Hughes  states  that  the 
effects  of  exposure  to  hydrogen  do  not  disappear  at  ordi- 
nary temperatures.  Ledebur' s  results  are  so  harmonious 
that  it  is  probable  that  Hughes  did  not  thoroughly  ex- 
amine the  effect  of  rest  on  flexibility.  In  all  of  the  eight 
cases  in  which  similar  wires  were  tested  after  and  before 
rest,  and  in  five  out  of  the  eight  in  which  dissimilar  wires 
were  tested,  Ledebur  found  a  very  marked,  and  in  a  sixth 
a  decided  restoration  of  flexibility. 

Cold  working,   according  to  Brustlein,  expels  the  hy- 
drogen from  wire  rendered  brittle  by  immersion  in  acid' 
but  Ledebur  found  that  the  carrying  power  of  steel  U 
springs  thus  immersed  was  not  restored  by  hammering. 
(17  b,  Table  61). 

Proportion  of  Hydrogen  Absorbed. — If   these   effect; 
are  really  due  to  the  absorption  of  hydrogen  it  might  be 
anticipated  that  heating  and  rest,  which  remove  the  effects, 
would    also    expel    the    hydrogen,    though  they  might 


Observer. 


W.  C.  llobertsa  , 
F.  Fox,  Jr.  b  .... 
Ledebur  c 


Method. 


Heating  in  vaeuo 

Combustion  in  dry  oxygen . . . 
Heating  in  steam  of  nitrogen. 


Hydrogen, 
volumes. 


10-0 

9-5 

l-93@4  78 


Hydrogen  %. 


0-0109 

0-0103 

0-0021@0-005: 


simply  transfer  it  from  a  noxious  to  a  relatively  harmless 
state  without  expelling  it.  Johnson  found  indications 
;hat  the  gas  whose  gradual  escape  from  iron  was  shown 
:>y  the  protracted  frothing  accelerated  by  heating,  was 
hydrogen  ;  and  Eoberts,  Ledebur,  and  Fox  have  extracted 
from  iron  which  had  been  immersed  in  acid  the  quantities 
of  hydrogen  given  in  the  accompanying  table. 

The  quantity  of  hydrogen  thus  extracted  is  so  minute 
as  to  suggest*  that  its  absorption  has  merely  accompanied 
not  caused  the  intense  effects  described.  If,  however,  the 
influence  of  an  element  on  iron  depends  not  on  the  weight 
but  number  of  equivalents  present,"  our  0'002$  of  hydro- 
gen might  indeed  affect  iron  as  intensely  as  0'002  X  31  -f-  1 
—  •Q62?0  of  phosphorus.  Indeed,  that  one  part  of  hydro- 
gen should  so  greatly  affect  the  properties  of  fifty  thou- 
sand of  iron  would  hardly  surprise  him  who  already  knew 
how  greatly  one  of  phosphorus  affects  five  thousand  of 
iron,  as  much  as  this  latter  fact  would  surprise  one  who 
was  ignorant  of  the  influence  of  small  quantities  of  im- 
purities on  the  metals  in  general. 

If  the  hydrogen  absorbed  be  the  direct  cause  of  these 
effects,  its  influence  is  clearly  far  out  of  proportion  to  that 
of  the  much  larger  quantities  of  this  gas  in  the  irons  of 
Table  60,  which  suggests  that  hydrogen  may  exist  in  two 
or  more  conditions  in  iron.  It  is  conceivable  that  the 
hydrogen  absorbed  when  nascent  exists  in  iron  in  a  state 
resembling  that  of  adhesion,  whose  possible  effects  have 
been  conjectured  in  §  170. 

§180.  DEOXIDATION  BY  HYDROGEN. — Bell's  experiments 
indicate  that  hydrogen  and  carbonic  oxide  begin  to  reduce 
iron  oxide  at  about  the  same  temperature,  the  reduction 
of  Cleveland  ore  by  hydrogen  beginning  at  between  199° 
and  227°  C. f  (390°  and  440°  F.),  and  by  carbonic  oxide  at 
199°  C.,  the  latter  gas  reducing  precipated  ferric  oxide  at 
141°  C.K  (285°  F.).  But,  as  might  be  inferred  from  its 
power  to  reduce  not  only  carbonic  acid  but  carbonic  oxide, 
hydrogen  reduces  iron  oxide  far  more  energetically  than 
carbonic  oxide  does,  as  is  indicated  by  the  following 

RESULTS  OF  BELL'S  EXPERIMENTS  ON  CALCINED  CLEVELAND  QBE.    TABLE  62. 


Wo 

Composition  of   reducing 
gas  by  volume. 

Hours     e  x- 

Oxygen  removed  per  100 
of  initial  oxygen. 

H. 

CO. 

CO,. 

Per  hour. 

Total. 

1f 

10-7 

o- 

89-8 

427°@525°  C. 

1-5 

45" 

68- 

2f.   . 

o- 

100- 

0 

427°  C.=  800°  F. 

7-0 

1-84 

9-4 

3f 

7-8 

62  6 

29'6a 

450°  C.  ±  =  842'  F.  ±. 

.0  » 

I'll 

11  1 

4f 

o- 

76  4 

23'6 

427°  C 

10-5 

0-65 

6-8 

of.   . 

10-7 

89-3 

o- 

Very  bright  red. 

1- 

70- 

70- 

6h.  . 

o- 

100- 

o- 

Bright  red. 

8-7S 

24' 

90- 

a  Excluding  46-4#  nitrogen. 


a  "  By  experiment  I  found  that,  on  heating  the  steel  wires"  (after  exposure  to  nascent  hydro 
gen )  '•  in  vacuo,  it  is  possible  to  remove  from  them  at  least  ten  times  their  volume  of  hydrogen 
the  latter  being  quite  pure  and  not  contaminated  with  hydrocarbon,  provided  care  is  taken  tc 
extract  any  natural  gas  occluded  by  the  wire  during  the  metallurgical  process  involved  in  the  manu 
facture."  "The  amount  of  natural  gas  varies  from  three  to  ten  volumes."  Kobcrts,  Journ.  Teleg 
Ecjrs.,  IX.,  pp.  168-9,  1S80.  It  is  not  absolutely  clear  whether  ten  volumes  is  the  total  quantity 
of  gas  which  he  extracts  from  hydrogenized  wire,  or  whether  he  extracted  ft  larger  quantity,  an< 
after  making  allowance  for  natural  gas  regards  ten  vo.umes  as  the  quantity  due  to  exposure  tc 
hydrogen. 

b  Loc.  cit. 

c  Loc.  cit.  He  reasonably  objects  to  the  method  of  heating  in  vacuo  that,  as  we  cannot  firs 
warm  the  iron  for  fear  of  expelling  the  absorbed  hydrogen,  we  cannot  be  sure  that  it  is  free  froir 
moisture :  that  this  moisture  on  heating  in  vacuo  is  liable  to  bo  decomposed  by  the  iron  with  th 
liberation  of  hvdrogen,  thus  exaggerating  the  apparent  proportion  of  this  gas  evolved  by  th 
metal.  Employing  a  rapid  stream  of  nitrogen  we  remove  the  moisture  rapidly,  and  thus  diminish 
its  opportunity  of  being  decomposed  by  the  metal.  This  method,  applied  to  wire  which  had  no 
been  exposed  to  nascent  hydrogen,  extracted  no  trace  of  this  gas. 


a  "  No  exact  and  easily  applied  test  has  yet  been  devised  by  which  we  can  obtain 
with  precision  a  numerical  result  expressing  the  relative  toughness  of  any  of  two 
samples — this  difficulty  is  fortunately  not  met  with  in  the  examination  of  the 
change  in  elasticity  and  tensile  strength  ;  for  the  breaking  weight  and  maximum 
elongation — can  be  pretty  easily  ascertained."  Op.  cit.,  p.  175. 

b  Ledebur,  loc.  cit.,  from  Zeit.  Vereins  Deutsch.  Ingen.,  1887,  p.  331. 

cgtahl  und  Eisen,  III.,  p.  252,  1883. 


In  No.  1  the  rapidity  of  reduction  by  the  mixture  of 
hydrogen  and  carbonic  oxide  exceeds  that  of  reduction  by 
pure  carbonic  oxide  in  No.  2  far  more  than  can  be  ac- 
counted for  by  the  difference  in  temperature.  In  No.  3, 
even  in  presence  of  a  larger  proportion  of  an  oxidizing  gas, 
carbonic  acid,  the  addition  of  hydrogen  to  carbonic  oxide 
accelerates  deoxidatiop.. 

The  same  holds  true  at  higher  temperatures  :  thus  in  5 
and  6  the  addition  of  10  •!%  of  hydrogen  to  carbonic  oxide 
at  a  red  heat  hastens  reduction. 


d  Abel,  Jeurn.  Teleg.  Eng.,  ante  cit. 

o  Ledebur,  loc.  cit. 

t  Principles  of  the  Manufacture  of  Iron  and  Steel,  pp.  310  to  314. 

B  Jour.  Iron  and  St.  Inst.,  1871,  I.,  p.  98. 

n  Idem,  p.  103. 


118 


THE    METALLURGY    OF    STEEL. 


IRON  AND  CAKBONIC  OXIDE. 

§  181.  SUMMARY. — Carbonic  oxide  reduces  iron  oxide, 
but  never  quite  completely  :  indeed  at  high  temperatures 
it  oxidizes  metallic  iron  slightly,  especially  spongy  iron. 
Carbonic  acid  oxidizes  hot  metallic  iron  energetically. 
Mixtures  of  these  gases  occupy  an  intermediate  position, 
their  reducing  power  rising  with  the  proportion  of  car- 
bonic oxide  and  within  limits  with  falling  temperature. 

While  oxidizing  iron  nickel  and  cobalt,  and  while  re- 
ducing their  oxides,  carbonic  oxide  impregnates  them  with 
carbon,  probably  at  all  temperatures  above  200°  C.,  but 
most  rapidly  between  400°  and  500°  C.  This  action  al- 
most ceases  at  bright  redness.  Compact  metallic  iron 
absorbs  but  little  carbon  from  pure  carbonic  oxide,  but 
receives  it  more  readily  if  a  little  carbonic  acid  be  present. 
Spongy  iron  acquires  much  more  and  partially  reduced 
oxide  still  more  carbon,  the  former  acquiring  as  much  as 
158,  the  latter  as  much  as  808  parts  per  100  of  iron.  Car- 
bonic acid  opposes,  and  if  as  much  as  50$  of  it  be  present, 
completely  prevents  carbon  deposition. 

Iron  evolves  and  sometimes  absorbs  carbonic  oxide,  both 
when  solid  and  when  molten  :  but  trifling  quantities  are 
usually  found  on  boring  cold  metal  under  water,  yet  suffi- 
cient to  prove  that  it  can  exist  undecomposed  for  a  consider- 
able length  of  time,  in  the  cavities  of  the  iron  while  still 
hot ;  indeed,  in  distinct  blisters  it  is  found  in  considerable 
quantity.  In  some  cases  its  apparent  absorption  by  iron 
is  due  to  its  decomposition,  the  iron  absorbing  its  carbon 
and  oxygen  separately.  There  is  evidence  which  strongly 
indicates,'  or  at  least  very  strongly  suggests,  that  in  other 
cases  carbonic  oxide  as  such  dissolves  in  iron  :  but,  with 
perhaps  one  exception,  there  seems  to  be  room  for  a  differ- 
ence of  opinion  as  to  whether  any  or  all  of  this  collective- 
ly is  quite  conclusive.  It  may  be  later  shown  that  car- 
bonic oxide  influences  the  properties  of  iron  :  I  know  of 
no  present  evidence  that  it  does. 

TABLE  GS.—  TEMPERATURES  WHICH  LIMIT  THE  ACTION  or  CARBONIC  OXIDE  AND  CAEBONIO  ACID. 

F.xpt.  No.  Cent.         >'ahr. 

Carbonic  oxide  begins  to  reduce  precipitated  ferric  oxido  at  about.  141°  285° 

"  "  Cleveland  ore  at  about 199  890 

"      deposit  carbon,  reactions  (1)  and  (5) 200@221    892@430 

"         removes  49#  of  the  oxygen  of  precipitated  ferric 

oxide  in  six  hours  at 282 

Deposited  carbon  begins  to  react  on  iron  oxide  at  or  below 249i 

Carbonic  acid  begins  to  oxidize  metallic  iron  between 299( 

**  oxidizes  soft  but  not  hard  coke  at 417 

Carbonic  oxide  begins  to  oxidize  spongy  iron  at  or  below 417 

Carbon  deposition  is  most  rapid  between ' 400©450    752@842 

Hard  coke  is  oxidized  by  carbonic  acid  at  bright  redness. 

Carbon  deposition  almost  ceases  at. very  bright  redness. 

,      NOTE.— These  are  the  temperatures  found  by  Bell.    The  numbers  in  the  first  column  are  those 
of  his  experiments  as  given  In  the  Journal  of  the  Iron  and  Steel  Institute,  1871,  1872. 

§  182.  REDUCTION  AND  OXIDATION  BY  CARBONIC  OXIDE 
AND  ACID. — Carbonic  oxide  reduces  iron  oxide  at  all  tem- 
peratures above  141  °C.  as  far  as  observed  (Table  63),  at  a 
rate  which  increases  with  the  temperature  at  least  up  to 
bright  redness,*  and  with  the  rapidity  of  the  current  of  gas, 
and  is  greatly  influenced  by  the  structure  of  the  oxide. 
It  is  however  unable  to  completely  deoxidize  it,  but 
slightly  oxidizes  metallic  iron,  slowly  if  compact,6  com- 
paratively rapidly  if  spongy,  perhaps  thus  : 

(1) ;  Fe  +  xCO  =  FeOx  +  xC. 


18 

IT 

200 

20 

241 
72 

708-9 

886 

201@22S 

706 

229 


,254 

,265    480@509 

417    570®788 

783 

783 


a  Bell,  Jour.  Iron  and  St.  lost.,  1871, 1.,  p.  183,  states  that  deoxidation  is  at  a 
maximum  at  about  417°C.  If  "at  a  maximum"  means  most  rapid  or  most 
thorough,  I  am  at  a  loss  to  reconcile  this  statement  with  his  experimental  results. 

*>  That  iron  wire  is  oxidized  by  carbonic  oxide  and  simultaneously  absorbs  car- 
bon was  shown  by  its  turning  blue  and  straw-colored  after  heating  in  this  gas, 
and  by  its  yielding  black  flakes  (carbon)  when  dissolved  in  hydrochloric  acid  :  the 
same  wire  when  not  previously  exposed  to  carbonic  oxide  yielded  no  such  flakes. 
In  another  case,  after  exposure  to  carbonic  oxide,  the  solution  obtained  by  brief 
contact  of  strong  hydrochloric  acid  gave  an  intense  blue  with  ferrocyauide  of 
potassium,  indicating  the  formation  of  an  oxide  higher  than  ferrous  oxide.  (Bell 
Journ.  Iron  and  St.  Inst.,  1871,  I.,  pp.  16a-4). 


210@254°  C. 
18-65 
0-28®  0-66 
49-3 
8'2 

410°  C   ± 
9'4  @50'6 
1-84®  8-4 
49  2  @80- 
8'2  @13'8 

Low  red. 
63' 
7-9 

liripht  red. 
90  a 
24' 
99- 
19-8 

Cleveland  ore                       j  Totol  

ore"--  \  Per  hour  .. 

Precipitated  ferric  oxide,  j  pJJ^J^J'  ;  ; 

a  Nearly  90  %. 

The  influence  of  temperature  is  illustrated  by  Table  64, 
and  by  numbers  11,  12  and  13,  and  19  and  21  in  Table  65, 
in  which  gases  of  given  composition  deoxidize  ferric  oxide 
more  fully  at  a  higher  temperature  than  in  the  same  or  a 
longer  period  at  a  lower  one. 

The  influence  of  rapidity  of  current  is  shown  by  Table 
67,  in  which  the  swift  current  removes  on  an  average  1  -76, 
and  in  one  case  4  times  as  much  oxygen  as  the  slow  one. 

The  influence  of  structure  also  is  exemplified  in  Table 
67.  Of  two  specimens  of  the  same  ore  but  of  different 
structure  exposed  together,  one  lost  six  times  as  much 
oxygen  as  the  other  ;  ferric  oxide  obtained  by  calcining 
ferrous  sulphate  lost  4'7  times  as  much  as  spathic  ore  ex- 
posed beside  it.  The  influence  of  structure  is  also  shown 
in  Table  64,  but  less  clearly,  as  it  is  here  sometimes 
masked  by  the  effects  of  other  variables. 

TABLE  64.— REMOVAL  OF  OXYGEN  PEE  100  op  ORIGINAL  BY  CAEBONIC  OXIDE. 


Pure  carbonic  acid  oxidizes  metallic  iron  and  its  low 
oxides  energetically,  if  in  sufficient  excess  probably 
eventually  producing  ferric  oxide. 

(2) ;   Fe  +  xC08  =  FeOx  +  xCO, 

(3) ;  FeO,  +  yC02  =  FeOx+y +  yCO. 

It  thus  appears  that  when  iron,  oxygen  and  carbon, 
however  initially  combined,  are  together  exposed  to  a  high 
temperature,  the  oxygen  tends  to  distribute  itself  between 
the  carbon  and  iron  in  proportions  corresponding  to  equi- 
librium for  the  existing  conditions,  such  as  temperature, 
proportion  of  iron  to  carbon  present,  etc.  This  is  true 
whether  the  mixture  consists  initially  of  metallic  iron, 
carbonic  acid  and  oxide,  or  of  iron  oxide  and  carbon,  or 
whatever  it  be.  For  instance,  if  a  mixture  of  equal  vol- 
umes of  carbonic  acid  and  oxide  be  exposed  at  full  redness 
to  ferrous  oxide,  which  contains  28-57  of  oxygen  per  100 
of  iron,  no  action  occurs  ;  neither  takes  nor  yields  oxygen  ; 
;hey  are  in  equilibrium.  If  however  the  gases  contain  6(  >% 
of  carbonic  acid  they  yield  oxygen  to  ferrous  oxide,  if 
only  40$  they  take  oxygen  from  it :  if  the  iron  oxide  has 
more  oxygen  than  ferrous  oxide  it  gives  up,  if  less  it 
absorbs  oxygen  from  this  mixture  of  equal  volumes  of 
carbonic  acid  and  oxide.  In  each  case  the  transfer  of 
oxygen  proceeds  till  a  new  equilibrium  is  reached. 

In  Table  65  the  full-faced  figures  indicate  approximately 
certain  of  these  sets  of  conditions  of  equilibrium  :  that  is, 
the  proportion  of  oxygen  retainel  by  100  of  iron  when 
exposed  to  certain  mixtures  of  carbonic  oxide  and  acid 
till  they  have  ceased  or  nearly  ceased  to  react.  Unfortu- 
nately in  but  a  few  cases  has  the  composition  both  of  the 
gas  and  of  the  iron  oxide  which  are  in  mutual  equilibrium 
been  directly  determined  :  but  in  several  others  where 
one  is  given  the  other  can  be  more  or  less  closely  esti- 
mated. 

In  figure  10  the  five  points  p  to  p*  indicate  by  their  dis- 
tance from  the  horizontal  axis  the  percentage  of  oxygen 
which  iron  oxide  must  hold  in  order  to  stand  in  equilib- 
rium with  jthe  five  corresponding  mixtures  of  carbonic 
acid  and  oxide  at  bright  redness.  Of  these  p,  p8  and  p* 
command  confidence,  for  in  these  cases  the  fact  that  the 
gases  gave  to  spongy  iron  the  same  percentage  of  oxygen 


REACTIONS  BETWEEN  THE  OXIDES  OF  IEON  AND  THOSE  OF  CARBON;      §  183. 


119 


TABLE  65. — REDUCTION,  OXIDATION  AND  CARBON  DEPOSITION  BY  CARBONIO  OXIDE  AND  ACID. 


Number. 

No.  of  Bell'i  ex- 
periment. 

Conditions  of  exposure. 

After  exposure  to  the  gas  the  metal  held 
per  100  of  iron. 

Composition  of  gas  by  vol- 
ume. 

Kemarkfi 

Material 

Hours. 

Temperature. 

At    low 
t'mp'ra- 
tures. 

At  m  odi- 
um tem- 
peratures. 

At    high 
tempera- 
tures. 

Before  expos- 
ure. 

After  expos- 
ure. 

%  carbon. 

H  Oxygen. 

CO. 

CO8. 

CO. 

CO,. 

1  ... 
2.   .. 
3  ... 

849 
90 
91 

0-75 
0-5 
0  75 

417. 
lied. 
Bright  red. 

o- 

18-46 

14- 
14- 
14- 

86- 
86- 
86- 

14-— 

14-  + 

86-+ 
86'- 

(Equilibrium     «early 
f    reached. 

40  3 
37  3 

"       6 

4.... 
5.... 
6.... 
7... 

8  .  . 
9.... 
10.... 

73-8 
74-350 
258 
248 
89 
85 
57 

Low  red. 
417. 
Fairly  red. 
Bright  " 

o- 

50-5 

so- 
so 
so- 
so- 
so- 

100 
49-5 
BO' 

so- 
so- 
so- 

50- 

40- 
50- 

so- 
so- 

60- 

so- 
so- 
so- 

Equilibrium  reached 
h     with  FeO. 

0  5 
6-0 
55 
18-0 
5-5 

o- 
o- 
o- 

0' 

29  06 

28  59 
28  5 
28 
28  59 

11... 
12... 
18..  . 
14  ... 

15.... 

16  .. 
17.... 
18  ... 

261 
101 
263-103 
79 
853 

V  Dumas 

10-5 
11  S 
6- 
11  5 

7- 

410. 
417. 
Very  dull  red. 
Bright  red. 

Cherry  red. 
Almost  white. 

6-4 

26-7 
26-6 

67- 
67" 
67' 
59-7 
68-7 

0- 

o- 

o- 

fiS- 
SS- 
88- 
86-9 
86-8 

100- 
100- 
100- 

j-Equilibriui 

COj  max. 
41-86 
86-66 
85  82 

n  reached. 

COS  mtn. 
81-81 
25-56 
16  39 

1-5 

28  2 

'  35 

5  14 

65-8 

64-29 

68-74 
71-71 

30-9 

84-84 
81-04 
27-94 

o- 

19  ... 
20  ... 
21  .. 
22... 

105-266 
854 

108-434 

77 

5- 
0-5 

5- 

0-5 

410- 
417- 
Low  red. 
Full  red. 

9-8 

o- 

09 

16-2 
1  81 

76' 
72-5 
76-4 
78- 

23-6 
27-5 
28  6 
27- 

Precipitated  ferric  oxide  

4-2 

'  Ysi" 

28... 
24.... 

338 
80 

2-5 

7 

•86 

9-02 
61 

91'8 
68  2 

8  2 
36-5 

i  Equilibrinm  reached. 

Nearly  white. 

89-2 

10- 

25... 
26.... 

27... 
28  ... 
29.... 
30  ... 
32  .. 
S8  ... 
84 

72 
345 

342 

831-6 
382 
835 
848 
837 
°S4-370 

0-66 
5'5 

9 
4-5 
1 
2-5 
3' 
4- 
5' 
4- 
1- 
4' 
8  IT 
4" 

417- 
288@248- 

417- 
417- 
Very  dull  red. 
Low  red. 
Red 
Bright  red. 

18®282 
Bright  red. 

"•—  > 

2 
0 

1587 
20  3 
28  8 
12  75 
2-48 
•80 
•24 
•36 
•82 

6 
8 

o- 
too- 

100- 
100- 
100- 
100- 
100- 
100- 
100- 
100- 

loo- 

100- 
100- 
100- 

100- 

o- 

o- 
o- 
o- 
o- 
o- 
o- 
o- 
o- 
fl- 
it- 
o- 
o- 

96- 

4' 

Carbon  deposited. 

>  Equilibrium  reached 

!•  Equilibrium  reached. 
I  Equilibrium  reached. 

„ 

14 

22 

II 

H 

0  84 

•40 
•36 
43 
30 

•48 
34 

85  .. 
86  .. 
87  . 

286-372 
285-371 
93-4 

100- 

o- 

88  .. 
39.... 

843 
844 

tr. 

0'17±a 

b-i8±a 

The  horizontal  rule  lines  divide  these  experiments  into  six  groups,  in  each  of  which  the  final  composition  of  the  gases  is  nearly  constant.  Comparing  one  greup  with  another  gives  at  a  glance 
the  influence  of  the  proportion  of  carbonic  acid  to  carbonic  oxide. 

The  column  head  "  %  of  oxygen  "  is  split  into  three,  in  each  of  which  the  temperature  of  exposure  is  approximately  constant.  The  temperature  is  more  accurately  givpn  in  the  column  headed 
"  temperature  :"  but  this  grouping,  combined  with  the  grouping  by  the  horizontal  lines,  shows  at  a  glance  the  Influence  of  temperature.  In  any  one  of  the  horizontal  groups,  e.  g.  lines  11  to  18,  on 
passing  from  left  to  right  the  proportion  of  oxygen  acquired  declines :  and  as  the  carbonic  acid  is  approximately  constant  in  each  group,  this  decline  is  readily  attributed  to  the  rise  of  temperature. 

"Precip.  sponge"  =  precipitated  ferric  oxide  reduced  by  hydrogen. 

**  Cleveland  sponge  "  =  Cleveland  ore  thus  reduced. 

Full-faced  figures  indicate  that  the  exposure  had  been  so  long  that  equilibrium  had  probably  been  nearly  reached.  , 

'•  Equilibrium  reached  "  in  the  last  column  indicates  that  successive  analyses  or  other  data  prove  that  action  had  ceased. 

aThese  numbers  are  doubtful. 

I  give  these  results  at  greater  length  than  would  otherwise  be  expedient,  because  no  digested  statement  of  them  exists  elsewhere  so  far  as  I  am  aware,  and  the  labor  of  mining  the  raw  but 
precious  material  from  its  labyrinthine  deposit  is  usually  prohibitory. 

I  am  at  a  loss  to  reconcile  certain  of  these  results.  Thus,  in  No.  5,  equal  parts  of  carbonic  acid  and  oxide  are  inert  on  Cleveland  sponge  :  yet  other  mixtures  with  less  carbonic  acid,  and  even  as  In 
No.  32  pure  carbonic  oxide  Itself,  oxidize  this  same  substance. 


that  they  left  in  iron  oxide,  proves  that  their  action  was 
complete  on  both,  p1  and  pa,  however,  were  obtained 
simply  by  treating  spongy  iron,  and  not  checked  by  re- 
ducing iron  oxide  with  the  same  gases  :  hence  the  suspi- 

Figure  10 


CONJECTURED  CU 
INTENSITY  OF  TE 


LEGEND. 
RVES  OP  EQUILIBR 
DENCYTOWARDSC 


UM  BETWEEN  CO, 
ARBON  DEPOSITIO 


TEMPERATURE    200°  C. 


400-°  C. 


***]( 

C0e  AND  Fe  OjC 


(TO 


1000°  C. 


cion  that  .while  the  outside  of  the  sponge  doubtless  ac- 
quired all  the  oxygen  required  for  equilibrium,  its  interior 
may  not  have  been  thus  saturated.  This  suspicion  is 
strengthened  by  the  fact  that  p1  and  p2  are  much  lower 
than  the  position  of  p3  would  lead  us  to  expect. 


§  183.  INFLUENCE  OF  TEMPEBATTTEE  ON  THE  CONDI- 
TIONS OF  EQUILIBRIUM  BETWEEN  THE  OXIDES  OF  IRON 
AND  OF  CARBON. — Bell's  experiments  indicate  that,  under 
the  conditions  we  are  studying,  /.  e.,  when  carbonic  acid 
or  oxide  or  both  are  exposed  to  iron  or  its  oxide,  the  rela- 
tive affinity  of  iron  for  oxygen  as  compared  with  that  of 
carbonic  oxide  rises  with  rising  temperature.*  I  do  not 
consider  the  evidence  either  harmonious  or  abundant 
enough  to  prove  this,  but  it  points  strongly  toward  it.  For 
instance,  a  mixture  of  these  gases  which  at  one  tempera- 
ture is  inert  toward  a  given  iron  oxide,  or  which  even  takes 
oxygen  from  it,  at  a  higher  temperature  yields  oxygen  to 
it.  Thus  in  numbers  14  and  24,  Table  65,  mixtures  of 
carbonic  acid  and  oxide  of  initially  almost  identical  com- 
position were  exposed  to  spongy  iron  (1)  at  bright  redness 
and  (2)  just  below  whiteness.  At  redness  equilibrium  was 
reached  when  enough  oxygen  had  passed  from  carbonic 
acid  to  iron  to  lower  the  proportion  of  this  gas  to  30'9$ 
and  to  give  the  iron  3'5^b  of  oxygen  (p1,  figure  10) :  at 
just  below  whiteness  (p6),  however,  this  transfer  of 


a  This  supposition  that  the  relative  affinity  of  carbon  for  its  second  equivalent  of 
oxygen  as  compared  with  that  of  iron  for  oxygen,  decreases  with  rising  tempera- 
ture, does  not  exclude  the  belief  that  its  affinity  for  its  flrst  equivalent  as  compared 
with  that  of  iron  rises  with  rising  temperature  :  in  other  words,  while  a  given 
low  oxide  of  jron  may  deoxidize  carbonic  acid  the  more  readily,  and  be  deoxidized 
by  carbonic  oxide  the  less  readily  the  higher  the  temperature,  yet  with  rising  tem- 
perature it  may  be  deoxidized  by  carbon  itself  tho  more  readily. 

b  These  numbers  refer  to  the  proportion  of  orygen  per  IOC>  of  iron. 


120 


THE    METALLURGY    OF    STEEL. 


oxygen  went  much  farther,  ceasing  only  when  the  propor- 
tion of  carbonic  acid  had  fallen  to  10$  and  when  the  iron 
had  taken  up  5'lffi  of  oxygen,  the  carbonic  acid  thus  hav- 
ing lost  and  the  iron  having  gained  more  oxygen  than  at 
the  lower  temperature.  On  slightly  lowering  the  tempera- 
ture in  the  latter  experiment  part  of  the  oxygen  which  at 
the  higher  temperature  had  just  left  carbonic  acid  for 
iron  immediately  returned  to  the  carbonic  oxide,  and  the 
proportion  of  carbonic  acid  rose  again  to  13 '4$,  again  to 
fall  when  the  temperature  again  rose.  In  both  these  ex- 
periments it  is  known  that  equilibrium  was  reached,  for 
further  exposure  of  from  one  to  two  hours  caused  no  fur- 
ther transfer  of  oxygen. 

Returning  now  to  figure  10,  in  which  we  have  already 
plotted  at  p1  the  equilibrium  which  the  last  paragraph 
states  was  obtained  at  bright  redness  with  '30  -9$  of  car- 
bonic acid,  we  may  plot  in  it  as  p6  the  equilibrium 
obtained  just  below  whiteness  between  iron  oxide  with 
5-1%  of  oxygen  and  a  mixture  of  89'2$  of  carbonic  oxide 
with  10  of  carbonic  acid  (No.  24,  Table  65),  interpreting 
"just  below  whiteness"  as  about  1160°  C. 

If  now  we  were  to  determine  the  different  percentages 
of  oxygen  which  iron  oxide  must  hold  at  each  of  several 
temperatures  in  order  to  remain  in  equilibrium  with  a 
mixture  of  say  equal  volumes  of  carbonic  acid  and  oxide, 
and  plot  corresponding  points,  a  curve  would  be  formed 
which  we  may  term  the  50$  carbonic  acid  equilibrium 
curve :  similar  curves  might  be  plotted  for  equilibrium 
with  other  proportions  of  carbonic  acid.  As  the  tempera- 
ture rises  above  bright  redness  the  tendency  of  oxygen  to 
leave  carbonic  acid  for  iron  increases ;  hence  the  propor- 
tion of  oxygen  which  iron  oxide  must  contain  in  order  to 
resist  this  tendency  in  presence  of  a  given  mixture  of 
gases,  and  to  stand  in  equilibrium  with  it,  must  also 
rise.  Hence  these  equilibrium  curves  rise  as  we  pass  to 
the  right  from  redness,  somewhat  as  sketched.  Indeed, 
it  is  clear  that  the  30 '9$  curve  must  rise  somewhat  rapidly 
from  p1  to  clear  the  10$  curve  at  p6,  though  perhaps  less 
abruptly  than  in  the  sketch,  for  we  have  seen  that  p1  may 
have  been  plotted  too  low. 

Searching  carefully  I  find  little  to  locate  these  curves 
to  the  left  of  bright  redness :  that  little,  however,  indi- 
cates that,  while  the  curves  do  not  reverse  and  rise  as  we 
pass  to  the  left,  they  probably  fall  much  less  suddenly 
than  between  1,200°  and  900°  C.  No.  25,  Table  65,  shows 
that  at  417°  C.  the  4$  carbonic  acid  curve  is  at  least 
as  high  as  p5,  which  implies  that  the  30 '%%  curve  must 
flatten  in  passing  from  900°  to  417°  C.  No.  7,  Table  65, 
proves  that  the  50°  curve  does  not  pass  higher  than  p7  at 
417°  C.,  hence  that  it  does  not  rise,  but  probably  falls  as 
the  temperature  descends  from  900°  to  417°  C.  No.  28, 
in  which  pure  carbonic  oxide  confers  about  five  times  as 
much  oxygen  on  spongy  iron  at  417°  as  in  any  of  the  ex- 
periments at  redness,  at  first  suggests  that  between  these 
points  the  tendency  of  oxygen  to  leave  carbon  for  iron 
or  the  relative  affiinity  of  iron  for  oxygen,  falls  with  ris- 
ing temperature,  i.  e.  that  a  given  percentage  of  carbonic 
acid  stands  in  equilibrium  with  a  higher  oxide  of  iron  at 
the  low  than  at  the  higher  temperature,  and  thus  that  our 
equilibrium  curves  rise  as  the  temperature  falls  from  900° 
to  417°,  instead  of  descending  as  sketched.  But  this  is 
fallacious :  at  these  low  temperatures  carbonic  acid  is 
rapidly  generated,  as  will  be  shortly  shown  :  the  large 


deposition  of  carbon  recorded  in  No.  28  shows  how  much 
carbonic  acid  must  have  been  formed :  this,  not  the  low 
temperature,  is  probably  the  direct  cause  of  the  greater 
absorption  of  oxygen  by  the  iron. 

§  184.  INFLUENCE  OF  THE  PROPORTION  OP  IRON  TO 
CARBON  ON  THE  CONDITIONS  OF  EQUILIBRIUM. — Clearly  a 
small  quantity  of  carbonic  oxide  or  acid  or  both  can  but 
slightly  alter  the  degree  of  oxidation  of  iron,  for,  when 
but  a  little  oxygen  has  been  transferred  a  mixture  of  these 
gases  is  reached  which  is  enert  towards  the  existing  com- 
pound of  iron  and  oxygen.  Nor,  conversely,  can  a  small 
surface  of  iron  or  of  its  oxide  greatly  affect  the  proportion 
of  carbonic  oxide  to  acid.  Thus  Dumas  found  (No.  16, 
Table  65)  that  carbonic  acid  was  so  imperfectly  reduced  in 
passing  over  iron  turnings  that  the  issuing  gas  held  at 
least  31  '8$  by  volume  of  carbonic  acid  and  sometimes  as 
much  as  41'86$a  :  for  the  iron  became  so  oxidized,  at  least 
superficially,  that  it  was  inert  on  this  mixture  of  gases. 
On  increasing  the  exposed  surface  by  filling  the  inter- 
stices with  iron  filings,  the  proportion  of  carbonic  acid  fell 
to  from  16-39  to  36'66$  (No.  17 and  18,  idem) ;  while  when 
Bell  passed  this  gas  at  snail-pace  over  spongy  iron,  which 
offers  still  more  surface,  the  first  issuing  portions  were 
almost  completely  reduced,  holding  but  4$  of  carbonic 
acid.b  (No.  25,  Table  65.) 

A  sufficient  excess  of  surface  of  iron,  such  as  is  offered 
when  a  minute  quantity  of  gas  is  evolved  in  a  solidifying 
ingot,  would  probably  not  only  completely  reduce  car- 
bonic acid  to  carbonic  oxide,  but  might  even  completely 
deoxidize  the  latter  gas  by  reaction  (1),  absorbing  both 
its  carbon  and  oxygen. 

§  185.  CARBON  IMPREGNATION. — While  oxidizing  iron 
and  reducing  its  oxides,  carbonic  oxide  simultaneously 
impregnates  them  with  carbon,  probably  at  all  tempera- 
tures above  200°  C.,  but  most  rapidly  between  400°  and 
450°  :  at  and  above  bright  redness  permanent  deposi- 
tion almost  ceases.  Carbon  is  deposited  on  metallic  iron 
containing  at  most  a  trace  of  oxygen,  on  ferric  oxide 
which  has  lost  but  l-36$  of  its  initial  oxygen,  and  which 
contains  no  iron  in  the  metallic  state,  and  on  all  interme- 
diate compounds  :  the  deposition  usually  progresses  with 
deoxidation,  but  in  no  fixed  'ratio.  It  is  far  more  rapid 
with  a  swift  than  with  a  slow  current  of  gas.  The  carbon 
deposits  now  in  blotches,  now  uniformly;  here  bursting  the 
iron  oxide  into  powder,  there  without  changing  its  form.0 
On  iron  oxide  808  parts  of  carbon,  and  on  metallic  iron  158 
parts,  per  100  of  metal,  have  been  deposited.4  The  re- 
actions may  be : 

(1)  Fe  +  xCO  =  FeOx  +  xC, 

(4)  FeOx+  yCO  =  FeOx_y  +  yC02, 

(5)  FeO*  +  yCO  =  FeOx+y  +  yC, 

(6)  2CO  =  C  +  C0«. 

Under  altered  conditions,  and  especially  at  higher 
temperatures,  deposited  carbon  is  oxidized  by  carbonic 
acid  and  iron  oxide,  thus : — 

(7)  C02  +  C  =  2CO, 

(8)  FeO,  +  y  +  yC  =  FeO,  +  yCO. 

The  action  of  carbonic  acid  probably  begins  at  about 
417°  C.e:  that  of  iron  oxide  certainly  begins  at  or  perhaps 


aComptes  Rendus,  LXXV.,  p.  511  :  Watt's  Diet.  Chem.,  3d  Supp.,  p.  360. 
b  Journ.  Iron  and  St.  Inst.,  1871, 1.,  p.  108. 
c  Bell,  idem,  p.  135. 
d  Idem,  p.  163. 
e  Idem,  p.  193. 


CARBON    IMPREGNATION.      §  185. 


121 


even  below  265°  C.a  (Table  63).  A  mixture  of  60$  by  vol- 
ume of  carbonic  oxide  with  40  of  carbonic  acid  still  deposits 
a  little  carbon,  but  the  presence  of  50$  of  carbonic  acid  com- 
pletely arrests  the  deposition,  or  at  least  the  permanent 
deposition  of  carbon. b  This,  coupled  with  the  fact  that  car- 
bon is  permanently  deposited  on  almost  pure  ferric  oxide, 
suggests  that  the  oxygen  of  this  substance  attacks  deposited 
carbon  less  energetically  than  carbonic  acid  does. 

The  tendencies  to  deposit  carbon  and  to  reoxidize  the 
carbon  thus  deposited  exist  simultaneously,  and  one  or 
the  other  action  takes  place  till  equilibrium  between  them 
is  reached.0  But,  in  general,  the  higher  the  temperature 
and  the  larger  the  proportion  of  oxygen  (free  or  combined) 
present,  the  stronger,  relatively  speaking,  is  the  tendency 
to  oxidize  the  deposited  carbon. 

To  the  deposition  of  carbon  in  the  blast  furnace  we 
probably  owe  not  only  much  of  the  carbon  of  the  cast- 
iron11  but  also  the  removal  of  the  last  1$  of  the  initial 
oxygen,  which  carbonic  oxide  alone  is  powerless  to  expel. 

Carbon  is  also  deposited  by  carbonic  oxide  on  nickel 
and  cobalt  and  their  oxides  at  all  temperatures  between 
417°  C.  and  low  redness,  with  simultaneous  partial  oxida- 
tion of  the  metals  and  reduction  of  their  oxides,  but  not  on 
spongy  platinum,  copper,  or  lead,  nor  on  the  oxides  of  zinc, 
tin,  manganese  or  chromium,  nor  on  asbestos,  pumice- 
stone'  or  other  inert  substance.  It  is  true  that  carbonic 
oxide  is  also  decomposed  by  heat  alone  at  a  very  high  tem- 
perature," its  constituents  combining  when  the  temperature 
again  declines  :  but  in  the  presence  of  iron,  nickel,  cobalt 
and  their  oxides  it  is  decomposed  at  a  relatively  low  tem- 
perature, and  its  elements  do  not  recombine  during  slow 
cooling. 

I  will  now  indicate  a  little  more  fully  the  evidence  on 
which  some  of  these  statements  are  based :  it  is  derived 
almost  wholly  from  Bell' s  famous  researches. 

That  carbon  deposition  is  the  rule,  not  the  exception, 
between  200°  C.  and  dull  redness  is  indicated  by  the  ex- 
periments of  Table  65. 

The  influence  of  temperature  is  illustrated  by  Table  65, 
Nos.  11,  13  and  15  ;  19  and  21  ;  and  27  to  36  ;  and  better 
by  Table  66,  and  is  indicated  graphically  in  figure  10. 
Mark  in  Table  66  how  Cleveland  ore  received  but  1  -85$  of 

TABLE  66. — INFLUENCE  OF  TEMPERATURE  AND  STRUCTURE  ON  CABBON  IMPREGNATION. a 


Temperature  C. 

Carbon  deposited  by  carbonic  oxide  per  100  of  metallic  iron. 

On  Cleveland 
ore. 

1  o 

V 

jls 

On  Lanca- 
shire or*. 

gs 

e« 

On  Fe0O,, 

a  o 

on  pumice. 

is 

IB 

£"S 
S3 

o 

o   - 
fa  bf, 

"1 

<r 

I- 

So 

£'2 

a 

213to221  

%  0. 
1-85 
4-iM'. 
0-3 
86-13 
2-3 
0  3 

20.5 

£'} 

12 
21 
4-5 

*C. 

%  C. 

*c. 

«5  ±  .  .  .                                       .  \ 

65-3@531 

T-5 

770<aS08 

•i 

15S 
20-3 

9 
4'5 

1 
Higher  but  not  red  

Uril  to  bright  red  

0-30 

4 

Very  bright  red  

a  Condensed  from  Bell,  idem,  pp.  130  to  162. 

carbon    in  20"5  hours  at  213°  C.,  and  no  less  than  86*13$ 
in  a  shorter  time  at  a  higher  temperature  :  and  how  at 

a  Idem,  pp.  137-8. 

b  Hem,  pp.  140,  et  seq. 

c  It  is  probably  more  accurate  to  say  that  both  reactions  occur  simultaneously, 
one  outstripping  the  other  till  equilibrium  is  attained,  after  which  they  just  bal- 
ance each  other. 

d  Idem,  p.  189. 

e  Idem,  p.  182. 

'Idem,  pp.  173  to  183. 

g  Peville,  Lesons  sur  la  Dissociation. 


bright  redness  carbon  deposition  was  so  nearly  arrested 
that  but  0-3$  was  deposited  in  4-.")  hours.  Note  how 
spongy  iron,  which  took  up  20-3$  and  158$  of  carbon  at 
about  417°,  acquired  but  0-3$  at  bright  redness.  Gruner, 
too,  found  that  carbon  deposition  ceased  if  the  tempera- 
ture rose  to  redness.'1 

Though  carbon  deposits  much  more  slowly  at  213°  than 
at  417°  C.,  it  is  quite  possible  that  as  much  might  eventu- 
ally deposit  at  the  former  as  at  the  latter  temperature, 
granted  time  and  carbonic  oxide  enough.  This,  however, 
would  imply  that  there  was  a  limit  to  the  amount  of  car- 
bon which  can  be  absorbed,  and  it  is  not  clear  that  there 
is  any  such  limit :  deposition  may  go  on  indefinitely. 

A.  The  Deposition  of  Carbon  on  Metallic  Iron  is  illus- 
trated by  Nos.  27  to  39  in  Table  65.      That  the  presence  of 
metallic  iron  is  not  necessary  to  this  deposition  is  shown 
by  the  fact  that  Cleveland  ore  absorbed  O'il$  of  carbon 
when  it  had  lost  but  2-84  of  oxygen  per  100  of  ferric 
oxide  (9-48$  of  its  total  oxygen).  Here,  and  in  another  case 
in  which  T69$  of  carbon  was  absorbed,  the  absence  of 
metallic  iron  was  directly  proved  by  attacking  the  ore 
with  iodine  and  cold  water,  which  dissolved  no  iron, 
though  it  readily  dissolves  any  which  is  in  the  metallic 
state.1 

Though  carbon  deposits  rapidly  oii  iron  sponge  (Nos. 
27  and  29,  Table  65),  it  deposits  very  slowly  on  compact 
iron  (Nos.  38-9,  idem).  In  §  .88,  B,  instances  are  given  in 
which  at  most  but  little  decomposition  of  carbonic  oxide 
can  have  occurred  when  this  gas  was  exposed  to  hot  com- 
pact iron.  Gruner  found  that  perfectly  pure  dry  carbonic 
oxide  deposited  carbon  on  ferrous  oxide,  but  hardly  at  all 
on  metallic  iron :  if  mixed  with  a  little  carbonic  acid 
however,  it  deposited  carbon  on  metallic  iron  as  well.h 
Bell's  carbonic  oxide  too  should  have  been  pure,  for  it 
was  prepared  from  f errocyanide  of  potassium,  was  passed 
through  potash  and  nitrate  of  silver,  and  produced  no 
turbidity  in  lime  water  (op.  cit.  p.  97). 

B.  The   Influence  of  Carbonic  Acid    on  carbon   im- 
pregnation is  readily  traced  in  Table  65.     Here  when  less 
than  25$  of  carbonic  acid  is  present  the  deposition  of  car- 
bon is  usually  recorded,  its  absence  never :  when  more 
than  33$  of  this  gas  is  present  the  absence  of  deposited 

arbon  is  frequently  recorded,  its  presence  never.  In 
various  other  experiments  Bell  never  observed  carbon  de- 
position from  gas  containing  as  much  as  50$  of  carbonic 
acid  :  when  2i>-6  and  83$  of  this  gas  with  76  and  67$  of  car- 
Donic  oxide  respectively  was  present,  some  forms  of  oxide 
of  iron  received  carbon,  others  did  not.  While  blast  fur- 
nace gases  which,  excluding  their  nitrogen,  consisted  of 
29'6$of  carbonic  acid  with  70 '4$  of  carbonic  oxide,  de- 
posited on  Cleveland  ore  from  trace  to  1  '28  parts  of  car- 
x>n  per  100  of  iron,  those  with  16$  of  carbonic  acid  de- 
posited from  1'96  to  3 '11$  of  carbon  in  from  one  hour  to 
'our  days.1 

C.  That  deposited  carbon  is  attacked  by  iron  oxide  at 
249°  to  265°  C.  was  proved  by  Bell.    Iron  oxide,  previously 
partly  reduced  and  richly  impregnatad  with  carbon  by 
gnition  in  carbonic  oxide,  was  heated  to  this  temperature 

in  a  sealed  tube  filled  with  nitrogen,  when  carbonic  acid 
and  oxide  were  evolved. k 


i>  Watts,  Diet.  Chem.,  2d  Supp.,  p.  259,  from  Comptes  Rend.,  LXXIII.,  281. 
1  Bell,  op.  cit.,  pp.  105, 167,  expts.  358-9. 
J  Op.  cit.,  pp.  140  to  143  and  154. 
k  Idem.,  pp.  137-8,  expts,  341-2, 


122 


THE    METALLURGY    OF     STEEL. 


D.  That  it  is  attacked  by  carbonic  acid  at  about  417°  is 
probable,  for  at  this  temperature  this  gas  rapidly  attacks 
soft  and  sometimes  slightly  affects  hard  coke.a    But  de- 
posited carbon  in  Cleveland  iron  ore,  whose  iron  had  been 
removed  by  digestion  in  acid  and  which  therefore  held 
only  carbon  and  gangue,  was~not  acted  on  by  carbonic  acid 
at  260°  C.b 

That  deposited  carbon  is  competent  to  account  for  the 
carbon  which  cast-iron  acquires  in  the  blast-furnace  Bell 
proved  by  melting,  in  a  '.veil  closed  crucible,  iron  oxide 
which  previous  exposure  to  carbonic  oxide  had  impreg- 
nated with  8$  of  carbon,  and  had  reduced  till  it  held  but 
6  74$  of  oxygen  :  a  button  holding  \%  of  carbon  resulted. 
Moreover,  in  the  interior  and  at  50  feet  below  the  throat 
of  a  furnace  in  blast,  and  also  in  cavities  due  to  excessive 
wear  in  the  lower  part  of  extinguished  furnaces,  he  found 
lumps  of  fuel  and  flux,  but  none  of  ore,  which  was  re- 
placed by  "a  powdery  substance  consisting  of  partially 
reduced  ore"  and  of  carbon.0  Ure  exposed  to  the  fur- 
nace gases  absorbs  carbon  till  it  bursts.  Now  the  carbon 
thus  intimately  mixed  with  the  ore  seems  a  more  probable 
source  of  the  carbon  of  the  cast-iron,  and  more  competent 
to  remove  the  last  traces  of  oxygen  from  the  iron  than 
the  comparatively  scattered  lumps  of  fuel,  though  these 
doubtless  contribute.  That  the  iron  is  finally  completely 
deoxidized  is  shown  by  the  usual  absence  of  ferrous  oxide 
from  the  slag. 

The  fact  that,  at  given  temperature,  the  most  readily 
reducible  oxides  absorb  the  most  carbon,  and  that  carbon 
deposition  progresses  with  deoxidation,  though  in  no  fixed 
ratio  and  indeed  not  invariably,  is  illustrated  by  Table  67. 
Numbering  its  cases  in  order  of  the  quantity  of  carbon 
deposited,  1  having  the  most,  and  placing  them  in  the 
order  of  deoxidation,  the  most  thoroughly  reduced  first, 
they  stand  thus :— 3,  1,  4,  8,  2,  6,  16,  jO,  7,  21,  19,  12,  5, 
13,  14,  9,  11,  18,  20,  15,  22,  17,  23,  24.  The  sum  of  the 
digits  of  the  first  eight  cases  in  this  list  is  50,  that  of  the 
second  eight  100,  that  of  the  last  eight  150.  This  law 
does  not,  however,  hold  good  with  varying  temperature. 
As  we  rise  from  200°  to  about  500°  C.  both  reduction  and 
carbon  impregnation  accelerate  :  with  further  rise  of  the 
temperature  reduction  is  further  hastened,  but  carbon 
deposition  is  checked. 

E.  The    exact  nature    of  the   reactions  in    the   de- 
position of  carbon  is  not  known.     Metals  which  like  iron 
are  reduced  by  carbonic  oxide,  but  which  unlike  it  are 
not  oxidized  by  this  gas  or  by  carbonic  acid,  do  not  induce 
carbon  deposition  as  far  as  is  known  :  this  suggests  that 
it  is  connected  with  the  oxidation  of  iron  by  one  or  both 
of  these  gases  by  reactions  like  (1)  and  (5),  rather  than 
that  it  is  due  to  mere  dissociation  of  carbonic  oxide  by 
(6),  which  indeed  may  be  regarded  as  the  resultant  of  (4) 
and  (5).     Gruner's  observation  that  with  a  minute  quan- 
tity of  oxygen  or  carbonic  acid  carbon  was  deposited  on 
metallic  iron,  but  that  hardly  any  was  deposited  by  pure 
carbonic  oxide,  favors  the  belief  that  this  action  is  con- 
nected with  oxidation.*1 

F.  The  influence  of  structure  is    prominent  in  Tables 
(50    and    67.     In    the    latter,   one    of  two  specimens  of 
Cleveland  ore,  differing  only  in  structure,  and  exposed 


EFFECT. 

0.  removed     ( 
%  of  initial  .  .  "i 
C  .  deposited     j 
per  100  Fe.  .  ) 

1 

O 

1 

Slow 
Fast 
Slow 
Fnst 

Exposed  together  for  C  hours  at  410° 
C. 

Simultaneously  exposed  at  410° 

Cle 

140 
20-6 
20-0 

7  1  -f, 

veland 

81-7 
48-2 
44-8 
1256 

ore  in 
condll 

80-4 
85-fi 
40  '7 
195-8 

differ.) 
Ions. 

18-0 
58-8 
26-4 
S5b-5 

it  phys 

184 
586 
16-4 
HOC 

leal 

7-4 
80-8 
0-7 

82-4 

OEJ 

«! 

fc  h 

1<5 
f-S 

fcfe 

|f 

jl 

|3| 

1 

ll 
O 

37-8 
50-7 
12-6 
22-8 

1 

ej 

js 

H 

1C-9 
18-2 
8-8 
4-9 

11 
Z.2 

">3 

18-0 
42-0 
2-3 
8-9 

60-9 

72-6 
90-9 
476-5 

49-8 
80-6 
78-7 
835-4 

86'0 

71-0 
«M 

270-s- 

aCondensed  from  Bell,  Journ.  Iron  and  St.  Inst.,  1S7 

1,  I.,  pp.  144,150. 

a  Idem,  p.  193,  expt,  446,  1871,  II.,  p.  331,  expte.  708-9, 
i>I(lein,  1871,  H.,  pp.  330-1,  expts.  706-7. 
eldem,  1871,  I.,  pp.  186-9. 
.  cit. 


side  by  side,  absorbed  63  times  as  much  carbon  as  the 
other  :  artificial  ferric  oxide  absorbed  122  times  as  much 
as  spathic  ore  exposed  beside  it.  The  results  in  Table  66 
are  still  more  striking,  though  not  so  exactly  comparable, 
for  the  exposures  were  not  simultaneous.  Observe  how 
at  about  the  same  temperature  and  in  about  the  same  time 
Lancashire  ore  absorbed  more  than  100  times,  and  arti- 
ficial oxide  nearly  200  times  as  much  carbon  as  Cleveland 
ore.  In  another  case6  artificial  ferric  oxide  absorbed  at 
420°  C.  480  times  as  much  carbon  as  Cleveland  ore  exposed 
beside  it  in  the  same  vessel,  to  wit  111  vs.  0-J  per  100  of 
iron. 

G.  The  influence  of  speed  of  current  is  illustrated 
by  Table  67.  Here  on  an  average  the  fast  current  deposits 
5.26  times  as  much  and  in  one  case  actually  118  times  as 
much  carbon  as  the  slow  current,  under  otherwise  like 
conditions,  be  it  because  it  offers  more  carbonic  oxide,  be 
it  because  it  more  thoroughly  sweeps  away  the  heavy  car- 
bonic acid  which  tends  to  linger  and  obstruct,  be  it  be- 
cause the  accelerated  action,  by  raising  the  temperature, 
still  further  accelerates  itself. 

TABLE   67.— INFLUENCE  OF  STRUCTURE  AND  OF  SPEED  OF  CURRENT  ON  REDUCTION  AND  CAR 
BON  IMPREGNATION  BY  PURE  CARBONIC  OXIDE. a 


§  188.  DOES  CARBONIC  OXIDE  EXIST  AS  SUCH  IN  IKON  ? 
— (1)  That  it  should  is  perhaps  not  improbable,  cer- 
tainly not  impossible  on  a  priori  grounds  :  (2)  that  it  does 
occasionally  in  the  blisters  of  solid  iron  is  certain  :  that  it 
exists  in  combination,  solution  or  adhesion,  i.  e.  in  a  non- 
gaseous  state,  in  both  (3)  molten  and  (4)  solid  iron  is  on  the 
whole  probable.  I  will  now  substantiate  these  statements, 
admitting  first  that  we  may  not  now  and  may  never  have 
positive  evidence  that  carbonic  oxide  or  indeed  any  other 
compound  exists  as  such  dissolved  or  chemically  combined 
with  another  body,  or  as  to  the  grouping  in  which  the 
separate  elements  of  a  single  ternary  or  more  complex 
substance  are  chemically  combined  inter  se.  We  can, 
however,  pile  up  cumulative  evidence  pointing  one  way 
or  the  other. 

(1)  The  difficulty  which  some  have  had  in  understanding 
how  a  metal  can  unite  chemically  with  an  oxidized  sub- 
stance like  carbonic  oxide,  or  at  least  dissolve  it,  seems 
to  evaporate  when  we  recall  the  presence  of  iron  oxide  in 
molten  iron,  of  copper  oxide  in  molten  copper,  of  many 
sulphides  in  molten  slags,  and  the  stubborn  retention  of 
small  quantities  of  nitrogen  and  hydrogen  in  charcoal 
after  intense  and  prolonged  heating.  Moreover  Graham 
has  shown  that  gold  and  silver  absorb  and  evolve  carbonic 
oxide  and  acid.'  We  have  seen  that  the  dissociation  of  car- 
bonic oxide  at  a  red  heat  by  iron,  etc. ,  is  probably  connected 


e  Idem,  p.  132,  Expts.  201,  205. 

*  E.  g.  he  found  that  4 '83  cc.  of  previously  untreated  gold  cornets  gave  out 
when  heated  to  redness  in  vacuo  3'1  volumes  of  gas,  or  10-35  cc.,  consisting  of  6'7 
co.  carbonic  oxide,  1'5  cc.  carbonic  acid,  1'58  cc.  hydrogen  and  0'44  cc.  nitrogen, 
The  same  cornets  after  soaking  in  carbonic  oxide  gave  out  1'6  cc.  of  occluded  gas, 
composed  of  1-4  cc.  of  carbonic  oxide  and  0'2  of  carbonic  acid.  Silver  was  found 
to  occlude  '486  volumes  of  carbonic  oxide  and  '156  of  carbonic  acid.  (Jouru, 
Chem.  Soc.,  1867,  pp.  381, 383.) 


DOES    CARBONIC    OXIDE    EXIST    AS    SUCH    IN    IRON  ?      §  188. 


123 


with  the  oxidizing  action  of  this  gas  or  of  carbonic  acid, 
and  that  spongy  platinum,  copper  and  lead  do  not  disso- 
ciate it :  hence  it  is  probable  that  it  is  carbonic  oxide  itself 
and  not  merely  its  dissociated  elements  that  the  gold  and 
silver  absorb. 

But  can  carbonic  oxide  exist  in  hot  iron  without  being 
decomposed  ?  Will  not  the  iron  rob  it  of  its  oxygen  '* 
Not  necessarily  completely.  The  larger  the  proportion 
of  surface  of  iron  to  carbonic  oxide  the  more  completely, 
probably,  is  the  gas  decomposed  by  iron.  Thus  we  have 
seen  that  compact  iron  (No.  39,  Table  615)  took  up  but 
0'17$  of  carbon  and  not  over  0-13$  of  oxygen,  when  heated 
during  four  hours  to  bright  redness  in  this  gas,  while 
spongy  iron  absorbed  at  this  temperature  from  0'30  to 
(V48$  of  oxygen  (the  latter  in  one  hour,  No.  36)  and  at 
417 "  C.  2  -2%  of  oxygen  and  20  -3%  of  carbon  in  4-5  hours 
(No.  ifS).  and  in  another  case  158$  of  carbon.  That  the 
decomposition  of  carbonic  oxide  by  metallic  iron  may  be 
a  comparatively  slow  matter  is  shown  by  the  fact  that  in 
four  out  of  five  experiments  in  which  Parry  heated  iron 
in  a  measured  volume  of  this  gas  no  diminution  of  volume 
could  be  detected.  It  is  certain  that  no  considerable  de- 
composition of  carbonic  oxide  can  have  occurred  here,  for 
its  decomposition  is  accompanied  by  contraction  of  volume 
whether  it  take  place  according  to  reaction  (1),  (5),  or 
(6).a  I  have  already  alluded  to  Gruner's  observation  that 
carbonic  oxide  deposits  hardly  any  carbon  on  metallic 
iron,  which  implies  that  it  yields  it  almost  no  oxygen,  for  at 
least  an  equivalent  of  carbon  must  be  deposited  for  each 
equivalent  of  oxygen  taken  by  iron  from  carbonic  oxide." 

(2)  But  apart  from  these  reasons  we  know  that  car- 
bonic oxide  does  exist  undecomposed  in  the  pores  of  solid 
iron,  for  it  has  been  obtained  in  small  quantities  from 
compact  cast-iron,  and  in  considerable  amount  from  blisters 
of  puddled  and  ingot  iron,  on  boring  these  metals  under 
water  (Nos.  33  to  39,  Table  54,  p.  106).  Clearly  it  cannot 
have  been  generated  by  boring,  nor  after  the  metal  had  be- 
come cold  :  hence  we  cannot  escape  the  conclusion  that  it 
must  have  existed  as  such  in  the  cavities  of  the  iron  while 
still  hot. 

At  the  Bethlehem  Iron  Works  ifc  was  thought  that  car- 
bonic oxide  was  recognized  escaping  from  a  fourteen-inch 
crank  pin,  made  of  steel  containing  0-09$  of  carbon,  which 
w::s  being  cut  in  a  lathe.  The  indication  (smell)  was  not 
conclusive  :  I  mention  this  to  suggest  farther  observation.0 

(M)  While  the  fact  that  carbonic  oxide  can  exist  un- 
decomposed  for  a  considerable  length  of  time  in  the  cavi- 
ties of  iron  does  not  prove  that  it  can  exist  undecomposed 
in  solution  (in  which  the  intimacy  of  contact  is  immeas- 
urably greater,  with  probably  correspondingly  better  op- 
portunity to  decompose  the  carbonic  oxide),  yet  it  makes 
it  easier  to  believe.  The  mere  escape  of  carbonic  oxide 
frc.m  molten  iron  does  not  in  itself  prove  that  this  gas 
h;:d  existed  as  such  in  the  metal,  for  it  may  have  been 
formed  by  reaction  between  carbon  and  oxygen  or  by  the 
decomposition  of  some  oxycarbide  at  the  instant  of  its 
escape.  It  is  necessary,  then,  in  each  case  to  consider 
whether  the  carbonic  oxide  could  be  thus  formed. 


'••  That  reaction  (1)  Fe+xCO  =  FeOx+xC  would  cause  loss  of  volume  is  self  evi- 
dent. Reaction  (5)  FeOx  +  y  CO  =  FeOi  +  y  +  y C  can  only  occur  after  the  iron  has 
bcca  oxidized  by  (1).  Reaction  (6)  SCO  =  C  +  CO2  yields  but  one  volume  of  car- 
1  or.ic  acid  for  two  initial  volumes  of  carbonic  oxide. 

l>  \Vatts.  Diet.  Chem.,  2d  supp.,  p.  259,  Fr.  Comptes  Rendus,  LXXIII.,  p.  881. 

c  M.  White,  Private  Communications,  Oct.  1  and  Nov.  29,  1887. 


A.  Troost  and  IlautefeuiUe  observed  that  when  iron, 
long  held  in  tranquil  fusion  in  an  atmosphere  of  carbonic 
oxide  (which,  a  vacuum  to  other  gases,  might  be  expected 
to  cause  the  expulsion  of  all  but  itself),  was  suddenly 
solidified  with  simultaneous  fall  of  pressure,  scattering 
occurred,  "un  faible  rochage.""    This  certainly  strongly 
suggests  that  carbonic  oxide  had  been  dissolved,  but.  un- 
fortunately, we  do  not  know  that  this  was  the  gas  which 
was  evolved  on  solidification. 

B.  Parry''  s    Experiment. — On    heating    cast-iron    in 
vacuo  he  extracted  from  it  0'72$  or  47 "5  times  its  own 
volume  of  carbonic  oxide,  together  with  0'16$  or  146'8 
times  its  own  volume  of  hydrogen  when  the  metal  was 
wrapped  in  platinum,   and  2  04$  "or  135  times  its  own 
volume  of  carbonic  oxide  when  this  precaution  was  neg- 
lected.8 

Serious  reasons  for  doubting  that  all  the  hydro- 
gen which  Parry  found  came  from  the  iron,  have  been 
offered  in  §  176,  C.  In  the  case  of  carbonic  oxide  these 
same  reasons  are  reinforced  by  others.  In  all  but  two  of 
his  experiments  the  iron  appears  to  have  been  in  direct 
contact  with  the  porcelain  tube,  whose  silica  could  easily 
generate  carbonic  oxide  by  reacting  on  the  carbon  of  the 
metal.  When  this  source  of  error  was  eliminated  by 
wrapping  the  metal  in  platinum,  another  possibly  serious 
one  suggests  itself.  Could  the  cast-iron  have  contained 
some  0 '80$  of  slag?  If  so,  this  slag  could  generate  the 
0-72  of  carbonic  oxide  which  is  found,  by  reaction  on  the 
metal's  carbon. 

It  is  uncertain  whether  cast-iron  often  contains  slag  or 
not.  On  the  one  hand,  while  the  conditions  under  which 
pig-iron  runs  into  its  moulds  might  permit  the  occasional 
admixture  of  metal  and  slag,  yet,  owing  to  the  fluidity  of 
the  former  and  the  difference  of  specific  gravity,  one 
would  hardly  anticipate  that  slag  would  be  a  common 
constituent  of  pig-iron.  E.  Riley,  a  chemist  of  most  ex- 
tended experience  in  this  branch  of  analysis,  has  never 
found  evidence  of  the  existence  of  slag  in  clean  solid  pig- 
iron.'  Their  experiments  with  chlorine  left  Drown  and 
Shinier  in  doubt  whether  the  silicon  which  is  not  volatil- 
ized by  chlorine  results  from  the  presence  of  slag  or  not,  * 
and  Drown,  himself  a  distinguished  authority  on  the 
analysis  of  iron,  informs  me  that  he  knows  of  no  satis- 
factory evidence  of  the  presence  of  slag  in  cast-iron. 

On  the  other  hand,  slag  is  frequently  reported  in  cast- 
iron.  Fresenius  found '665^  in  spiegeleisen.h  Percy  quotes 
cast-iron  with  aluminium,  calcium  and  magnesium  which, 
if  they  existed  as  silicates,  would  imply  the  presence  of 
about  9$  of  slag  ;  but  he  properly  questions  these  num- 
bers.1 Taking  at  random  the  first  twenty  analyses  of 
cast-iron  in  my  own  notes,  in  which  slag  is  recorded,  the 
proportion  of  this  substance  varies  from  0-13  to  2.65$,  its 
average  proportion  being  0'74$.  Of  these  analyses  fifteen 


d  Comptes  Rendus,  LXXVL,  p.  563,  1873. 

e  9  and  10,  Table  56,  p.  108. 

'E.  Riley,  Journ.  Chem.  Soc.,  XXV.,  p.  543,1872.  "In  dissolving  pig-iron 
in  neutral  chloride  of  copper  and  using  a  little  dilute  hydrochloric  acid  to  dissolve 
any  basic  iron  salt,  I  have  never  been  able  to  get  any  indications  of  the  presence  of 
slag  in  pig-iron,  or  have  never  been  able  to  find  satisfactorily  aluminium  in  pig- 
ircn  :  if  the  pig  contained  slag  it  certainly  oujht  to  be  present."  Idem,  p.  543. 

I  cannot  say  that,  in  all  my  experience,  I  ever  found  any  evidences  of  slag  in 
pig-iron  when  it  was  perfectly  solid,  and  the  pig  carefully  bored  after  removing 
all  the  outer  skin." 

g  Trans.  Am.  Inst.  Mining  Engrs.,  VIII.,  p.  514. 

h  Kerl,  Grundriss  der  Eisenhiittenkuude,  p.  42. 

J  Percy,  Iron  and  Steel,  p.  542. 


124 


THE    METALLURGY    OF    STEEL. 


are  by  Wuth,  a  trustworthy  analyst,  and  give  from  '31 
to  1'43  %  of  slag,  or  on  an  average  0-74$. 

C.  Bessemer1  s  Experiment. — Twelve  pounds  of  tran- 
quil molten  ingot  iron,  when  exposed  by  Bessemer  in  a 
crucible  suitable  for  holding  forty  pounds  of  unmelted 
iron,  to  a  vacuum  of  perhaps  twelve  or  thirteen  pounds 
per  square  inch,  boiled  so  furiously  that  all  but  a  pound 
or  two  overflowed.*  He  found  that  boiling  could  always 
be  induced  or  completely  stopped  at  will  by  simply  lower- 
ing or  raising  the  pressure.  The  gas  evolved  was  some- 
times analyzed,  and  in  each  case  found  to  be  carbonic 
oxide,  by  Henry's  determination. 

This  evidence  points  so  strongly6  to  solution  that  it 
is  well  to  scmtinize  it  very  carefully.  Henry  was  a 
most  careful  analyst:  Bessemer' s  reputation,  or  better 
renown,  is  known  to  all.  It  is  to  be  observed,  how- 
ever, that  his  statements  are  made  in  the  discussion  of 
another  gentleman's  paper :  that  they  refer  to  experi- 
ments made  some  twenty-five  years  earlier ;  that  it  is  not 
clear  that  they  are  not  made  in  considerable  part  or  even 
wholly  from  memory ;  that  the  gas,  consisting  apparently 
of  carbonic  oxide  unaccompanied  by  hydrogen  and  nitro- 
gen, differs  materially  from  that  recovered  by  Cailletet 
and  Muller  from  molten  iron,  and  by  fetead  from  iron  in 
the  soaking  pits,  which  always  contained  a  considerable 
proportion  of  hydrogen  and  nitrogen. 

Still  worse,  that  which  Muller  obtained  from  unrecar- 
burized  ingot  iron  (and  this  appears  to  be  what  Bessemer 
experimented  on)  contained  only  from  8'8  to  48%  of  car- 
bonic oxide,  and  probably  less  on  an  average  than  that 
from  any  other  class  of  molten  iron.  I  think  it  just  to 
call  attention  to  these  points,  which  certainly  detract  from 
the  weight  of  Bessemer' s  testimony. 

Now,  if  the  gas  which  he  obtained  were  of  the  composi- 
tion which  Muller  found  in  similar  cases,  containing  per- 
haps 25%  of  carbonic  oxide  and  15%  of  hydrogen  and 
nitrogen,  it  is  altogether  possible  that  the  fall  of  pressure 
caused  the  latter  gases  to  escape  from  solution,  and  that 
the  stirring  caused  by  their  escape  gave  carbon  and  oxygen 
previously  present  in  the  iron,  but  not  united,  an  oppor- 
tunity to  unite  and  escape  as  carbonic  oxide,  and  that  the 
quantity  of  this  gas  thus  set  free  might  form  one  quarter 
of  the  total  escaping  gas.  I  do  not  say  that  this  would 
be  a  probable,  but  a  conceivable  explanation. 

Were  we  to  reject  Bessemer5  s  experiment,  then  the  evi- 
dence which  has  been  adduced,  together  with  further  evi- 
dence to  be  detailed  chiefly  in  §§  213,  214  and  218,  and 
consisting  chiefly  of  the  resemblance  of  the  behavior  of 
carbonic  oxide  to  that  of  hydrogen  and  nitrogen  in  escap- 
ing in  iron  ;  of  the  protracted  and  deferred  escape  of 


a  Journ.  Iron  and  St.  Inst,  1881,  p.  197. 

b  It  is  quite  possible  that,  accepting  Bessemer's  statement,  these  may  be  merely 
dissociation  phenomena.  If  carbonate  of  lime  is  highly  heated  in  a  closed  vessel  it 
dissociates  and  evolves  carbonic  anhydride  :  the  escape  of  gas  may  be  completely 
arrested  and  started  again  by  raising  or  lowering  the  pressure  of  this  gas,  its 
gaseous  tension.  Now  in  Bessemer's  experiments  the  molted  metal  may  not  have 
cintained  carbonic  oxide  as  such  but  some  oxycarbide  of  iron.  Lowering  the 
pressure  might  cause  the  non-volatile  iron-carbon  or  iron-oxygen  compounds  to 
dissociate,  and  their  dissociation  would  lead  to  the  formation  and  escape  of  car- 
bonic oxide  :  increase  of  pressure  would  again  check  their  dissociation  and  stop 
the  evolution  of  gas.  But  by  parity  of  reasoning  every  case  of  evolution  of  gas 
by  a  liquid  may  be  regarded  as  an  instance  ot  dissociation  by  those  who  regard 
solution  as  a  form  of  chemical  combination.  Indeed,  even  some  of  those  who 
class  these  as  radically  different  processes  regard  some  apparently  typical  cases  of 
gas  solution  as  chemical  unions,  believing  for  instance  that  carbonic  anhydride, 
COj,  when  dissolved  in  water  forms  a  true  acid  H2CO3,  which  is  broken  up  when 
carbonic  anhydride  escapes  from  the  liquid.  (Watts,  Diet.  Cfaem.  I.,  p.  772.) 


0 

K 

Observer. 

Model  of  extraction, 
etc. 

Cast-iron. 

Wrought-iron. 

Steel. 

% 

Vol. 

% 

Vol. 

* 

Vol. 

1. 
•>. 

3 

4 

5. 

6 

7. 

S. 

Graham  
Troostand  H... 
Parry 

Heating  in  vacuo. 

1C                  it 

::   ::    « 

Evolved  from  molten  j 
or  solidifying  metal.   | 

Boring  cold  metal.    -< 

t-021® 
\  -080 
•0025 

^  -0103 
•083 
t 

1-39© 
S-29 
•167 

•68 
2-18 

•0003 
•56 
•OOffi 
•015 
•0023 

•000075 
•00006 

•02 
37-22 
•43 
l'24(f) 
•19  (?) 

0-@'006 
0'@'004 

•0007 

•oooc® 

2-04 

•04 

•MO® 

135-00 

Zvromski  
Mliller  (see  note) 

Stead  (see  note) 
Muller  
Stead  

•0069 
•0091 

•46® 
•60 

)  " 

•000015 

a 

•ooon 

•001® 

•on 

t 

1 

carbonic  oxide  when  no  reaction  forming  it  is  to  be  ex- 
pected ;  of  the  arrest  of  the  escape  of  carbonic  oxide  by 
chemical  additions  which  would  be  expected  to  stimulate 
it ;  and  of  the  remarkably  close  similarity  of  the  blow- 
holes which  are  probably  partly  formed  by  carbonic  oxide 
to  those  formed  by  air  in  ice,  as  regards  their  shape  and 
position ;  these  still  seem  to  create  a  strong  probability 
that  carbonic  oxide  does  dissolve,  but  not  to  prove  it 

§  189.  OTHER  INSTANCES  OF  THE  EVOLUTION  OF  CAK- 
BONIC  OXIDE  are  condensed  in  Table  68.  In  cases  1  to  4 
the  gas  was  extracted  by  heating  in  vacuo  :  in  5  and  6  it 
was  collected  from  molten  or  solidifying  metal:  in  7,  8 
and  9  it  was  recovered  by  boring  under  water. 

The  greatest  quantity  is  that  obtained  by  heating  in 
vacuo,  5'29  volumes  being  found  by  Graham  and  135  by 
Parry  :  next  comes  that  evolved  from  molten  and  solidi- 
fying metal,  reaching  perhaps  about  1  vorume  :  while 
that  obtained  by  boring  cold  metal  does  not  exceed  O'Oll 
volumes,  expect  perhaps  in  those  cases  where  gas  is  found 
in  distinct  blisters. 

TABLE  68. — CARBONIC  OXIDE  IN  COMMERCIAL  IRON  PREVIOUSLY  UNTREATED. 


1.  Jonrn.  Chem.  Soc.,  XX.,  p.  2S5,  1867,  and  Chom.  News,  XV.,  p.  273,  18C7.  Wrougbt- 
iron  wire  and  horse  nails,  Nos  24  and  27,  Table  56  2  Cnmptcs  Itcndus,  LXX  ,  p.  562,  1S73. 
Iron  cylinders  weighing  500  grammes  were  heated  at  800°  C.  in  vacuo  for  190  hours.  Nos.  11,16 
and  80,  Table  56.  3.  Journ.  Iron  and  St.  Inst.,  1872,  If.,  p.  240;  1873,  I.,  p.  430;  1874,  I.,  p  98; 
and  1881,  I.,  p.  189  :  these  cases  are  given  In  detail  in  Table  56.  4.  Stahl  und  Kisen,  1884,  p.  586: 
Jonrn.  Iron  and  St.  Inst.,  18S4,  II.,  p.  625.  Nos  21  and  22,  Table  56.  5.  Iron,  1884,  p.  1«8. 
Muller  found  from  1  to  1'5  volumes  of  gas  of  undetermined  composition  escaping  from  Bessemer 
steel  during  solidification  :  and  in  gas  escaping  under  similar  conditions  tie  found  in  general  from  8-8 
to  82'6^  of  carbonic  oxide:  the  figures  in  this  line  are  only  very  roughly  approximate  See  Table 
55.  6.  Stead  found  12-5£  of  carbonic  oxide  in  the  gas  escaping  from  solidifying  steel.  Assum- 
ing that,  as  found  by  M  tiller,  the  steel  evolved  about  1'5  volumes  of  gas.  we  have  0-19  volumes  of 
carbonic  oxide  thus  evolved.  This,  like  the  preceding,  is  simply  to  give  a  rough  idea  of  the  evol- 
ution of  this  gas.  7.  and  8.  The  solidified  metal  is  bored  under  water,  and  the  pas  thus  released 
caught  and  measured.  See  Table  54.  Also  Iron,  1883,  pp.  51,  115  :  Stahl  und  Eisea  1883,  p. 
466. 


§  190.  THE  APPARENT  ABSORPTION  OF  CARBONIC  OXIDE 
by  iron  has  been  observed  by  Graham,  Troost  and  Haute- 
feuille  and  Parry.  Troost  and  Hautefeuille  found  that 
much  less  carbonic  oxide  could  be  extracted  from  iron  on 
heating  in  vacuo  when  in  its  natural  state  or  after  soaking 
in  hydrogen,  than  when  the  samples  previously  exhausted 
after  soaking  in  hydrogen  were  later  exhausted  after  heat- 
ing in  carbonic  oxide.  Clearly  if  the  carbonic  oxide 
evolved  arose  from  oxygen  and  carbon  derived  in  process 
of  manufacture  and  initially  present,  the  iron  would  evolve 
less  of  it  at  each  heating  in  vacuo  than  at  the  preceding  : 
therefore  when  heated  in  carbonic  oxide  it  must  have 
absorbed  either  that  gas  as  such,  or  its  dissociated 
elements :  but  which  we  cannot  tell,  for  if  the  oxygen 
and  carbon  had  been  absorbed  separately  they  might  re- 
combine  and  escape  as  carbonic  oxide  when  the  iron  was 
again  heated  in  vacuo. 

Their  results  are  condensed  in  Table  69  and  detailed  in 
Table  57. 

Parry,  too,  in  one  out  of  five  experiments,  No.  66, 
Table  57,  found  that  wrought-iron,  previously  heated  in 
vacuo  till  only  traces  of  gas  escaped,  when  heated  in  car- 
bonic oxide  during  28  hours  absorbed  by  direct  measure- 
ment 4*6  times  its  own  volume  of  this  gas,  of  which  it 


GENERAL  PHENOMENA  OF  THE  ABSOKPTION  AND  ESCAPE  OF  GAS.      §  200. 


125 


TABI.K  Oil.—  I.NFM-KM  K  w  1'unvKirn    Kxi-osriiK   T.>   CAKIK.M.:   OXIIIK    ox  THE  EVOLUTION  OF 
THAT  GAB  IN  VACUO. 

Description. 

O 
g  gggg  Weight  taken. 

In  natural  state. 

Alter  heating  in  hy- 
drogen. 

After  heating  in  car- 
bonic oxide. 

Vol.   CO    evolved  In 
vacuo. 

Vol.  CO  evolved    in 
vacuo. 

Vol.  CO  evolved   in 
vacuo. 

I>er  100  of 

K;ts 
evolved. 

16-76 
H-ffi 
K-K 

C7- 

Per  vol. 
iron. 

0-040 
0-080 

II  K.7 

5-29 

Per  100  of 

IMS 

evolved. 

2  -TO 
11-68 
4-81 

8" 

Per  vol. 
iron. 

Per  100  of 
gas 
evolved. 

Per  vol. 
iron. 

Cast-iron,  T.  &  II  
Cut-steel,  T.  &  II  

Wrought-iron,         " 
Wrought  -  iron     w  i  r  e, 

0  016 
0-018 

0-009 

0-040 

86-98 
OS-DO 

97-85 

S9-9 

0-211 
0-OM 

(1  211 

4-150 

NOTK.  —  The  larger  volumes  obtained  by  Graliam  than  by  Troost  und  llautefeuille  are  explicable 
by  the  fact  that  ho  treated  small  wire,  they  thick  cylinders. 

evolved  3-2  volumes  when  again  heated  in  vacuo  without 
removal  from  the  apparatus.*  Here  too  it  is  uncertain 
whether  any  carbonic  oxide  was  taken  up  as  such,  or 
whether  the  total  apparent  absorption  was  due  to  the 
dissociation  of  carbonic  oxide :  but  that  carbonic  oxide 
was  dissociated  to  a  certain  extent  is  indicated  by  the  fact 
that  the  residual  gas  contained  from  4  to  6$  of  carbonic 
acid,b  doubtless  arising  from  reactions  (6)  or  (1)  and  (4)  of 
§  185. 

If  it  were  positively  proved  that  iron  does  not  absorb 
carbonic  oxide  when  heated  in  this  gas,  this  would  not 
prove  that  it  could  not  dissolve  it  as  such  under  other 
conditions.  We  have  seen  (§§  172-3)  that  iron  absorbs 
nitrogen  when  heated  in  this  gas  or  in  air  only  with  great 
difficulty,  but  readily  absorbs  it  when  heated  in  ammonia. 

Hydrogen  appears  to  escape  from  iron  on  heating  in 
vacuo  at  a  lower  temperature  than  carbonic  oxide.  Thus 
Parryc  found  that  at  and  below  full  redness,  say  1,000°  C., 
both  cast  and  wrought-iron  evolved  nearly  and  sometimes 
quite  pure  hydrogen,  while  with  further  rise  of  tempera- 
ture the  proportion  of  carbonic  oxide  increased.  This  ac- 
cords with  Graham's  statement*1  that  the  proportion  of 
carbonic  oxide  to  hydrogen  evolved  when  horse-nails  were 
heated  in  vacuo  increased  as  the  exposure  was  prolonged : 
Troost  and  Hautefeuille"  observed  that  wrought-iron 


evolved  its  hydrogen  more  readily  than  its  carbonic  oxide. 
On  the  other  hand  they  found  that  most  of  the  carbonic 
oxide  evolved  from  cast-iron  and  steel  in  vacuo  came  off 
in  the  first  few  hours,  the  hydrogen  being  retained  more 
tenaciously  :  here  their  results  seem  at  a  variance  with 
those  of  Graham  and  Parry. 

We  may  explain  in  two  ways  the  fact  that  the  expul- 
sion of  carbonic  oxide  requires  a  higher  temperature  than 
that  of  hydrogen.  Regarding  the  former  gas  as  dissolved 
in  the  metal,  we  may  suppose  that  its  solubility  dimin- 
ishes with  rising  temperature  less  rapidly  than  that  of 
hydrogen  :  or,  regarding  it  as  formed  at  the  instant  of 
escape  by  the  oxidation  of  carbon  by  oxygen  present  in 
the  iron,  we  may  believe  that  the  relative  affinity  of  car- 
bon as  compared  with  that  of  iron  for  oxygen  increases 
with  rising  temperature,  so  that  the  carbon  is  only  able 
to  remove  the  oxygen  from  the  iron  at  a  temperature 
above  that  which  renders  the  iron  porous  enough  to 
permit  the  escape  of  hydrogen.  This  accords  with  the  fact 
that,  while  carbonic  oxide  is  comparatively  rapidly  split 
up  by  iron  and  its  oxides  at  about  500°  C.,  this  action 
almost  ceases  at  bright  redness.  The  greater  diffusive- 
ness of  hydrogen  than  of  carbonic  oxide  might  explain 
why  but  little  of  the  latter  accompanied  the  first  escap- 
ing portions  of  hydrogen,  but  hardly  the  complete  ab- 
sence of  carbonic  oxide. 

§  191.  INFLUENCE  OP  CARIJONIC  OXIDE  ON  THE  PHYSI- 
CAL PROPERTIES  OF  IRON. — A  n  eminent  aiithority' believes 
that  carbonic  oxide  acts  like  phosphorus,  and  renders  iron 
cold-short.  I  have  vainly  applied  to  him  for  evidence. 
Only  one  consideration  which  throws  light  in  on  this  ques- 
tion suggests  itself.  Whitworth's  liquid  compression 
should  increase  the  quantity  of  gas  dissolved  by  steel,  and 
if  carbonic  oxide  is  soluble  Whitworth's  steel  should 
contain  more  than  others.  Its  excellent  quality  certainly 
opposes  the  belief  that  carbonic  oxide  is  injurious.  (See 
§  230.) 


CHAPTER      XI. 

GENERAL  PHENOMENA  OF  THE  ABSORPTION  AND  ESCAPE  OF  GAS  FROM  IRON. 


§  200.  A  classification  of  the  gases  present  in  molten 
iron  according  to  the  time  and  condition  of  their  escape, 
already  sketched  in  §  170,  is  given  in  Table  70.  Figure 

Fig,  II,  VOLUME  OF  GASES  ESCAPING  FROM  IRON. 


ESCAPE  DURING  80LIDIFICATION- 
"      ON  BORIN 


(PARTLY  CONJECTURAL.) 
0.6 2.4  8. 


OXYGENATED  BESSEMER  METAL 


CO. 


ESCAPE  DURING  SOLIDIFICATION,  gfl  H.fj1' 
"      ON  enaiNn 
11       ON  HEATING  IN  VACUO 


0.8        N. 


1  VOLUME  OF  METAL 


RECARBURIZEO  ACID  BESSEMER  8VEEL 


8.6  11 


CO. 


11  illustrates  what  now  appears  to  be  the  typical  composi- 
tion and  volume  of  certain  of  these  classes.    The  numbers 


« Journ.  Iron  and  St.  lust,  1873,  II.,  p.  431. 

bldem,  1874,  I.,  p.  93. 

«  Journ.  Iron  and  Steel  Inst..  1874,  I.,  p.  93  :  1873,  II.,  pp.  429-431. 

dChem.  News,  XV.,  p.  873,  1867. 

"Comptes  Readits,  LXXVi.,  p.  562,  1873. 


here  offered  must  be  received  cautiously  as  rough  crude 
generalizations,  necessarily  partly  conjectural,  thanks  to 
the  scantiness  of  our  data.  For  instance,  I  have  assumed 
in  Figure  11  that  oxygenated  Bessemer  metal  evolves 
eleven  times  its  own  volume  of  gas  when  bored.  This  is  a 
pure  guess. 

When  bored  with  a  sharp  drill  iron  evolves  much 
less  gas  than  this :  boring  with  a  dull  drill  in  one 
case  sets  free  eleven  volumes  of  gas,  and  possibly  still 
finer  comminution  might  release  still  more.  Again,  the 
gases  obtained  on  heating  in  vacuo  doubtless  include  at 
least  a  part  of  the  gas  which  would  have  been  set  free 
had  the  metal  being  bored  before  heating  in  vacuo. 
Again,  the  gases  escaping  during  solidification  from  the 
already  pasty  metal  are  doubtless  contaminated  with  those 
which  escape  before  solidification  from  the  central  portions 
of  the  metal,  which  remain  molten  longest. 

Of  two  of  these  classes,  A  2  which  redissolves  in  the  metal, 


f  Journ.  Iron  and  St.  Inst.,  1881,  I.,  p.  196. 


126 


THE    METALLURGY    OF    STEEL. 


TABLE  70.— GASES  or  STEEL  CLASSIFIED  ACCOEDING  TO  TIME  OF  ESCAPE. 


Mode  of  escape,  etc. 

Effect. 

Percentage  composition  by  volume. 

Volume  of  gas  per  volume  of  iron. 

CO. 

H. 

N. 

CO2 

CO. 

H. 

N. 

COj 

Total. 

I.  E. 
I 

P. 

8 

•SB 
Si- 

"3 

H 

»-I 

cape  while  the  metal  is  so  liquid  that  the 

Scattering  .... 

Rising,    blow- 
holes, etc... 

May       affect 

physical  pro- 
perties,     as 
suggested  in 
§  170 

8-8®82-6 
12  9 

L        0©  2  2 
J    7-9@C3-65 

2-3  @82-5 
20-47@27'21 

f.2'2  ©92-4 
22-72@57-3 

1-0  ©43-8 
59'91@66-C3 

5'9  @48-l 

ll-36@34-7 
[6'49]a 

0®8'4 

0®  1-23 

0©  0-OOC 

02®     -43 
[87'22]a 

0  @  1-61 

•03  ©  9-76 

•007®  3-12 
[82-15];. 

0  ®  0'78 

0-01  ©  1-13 
•008@  1-89 

0®  *18 

0®  8--J 

0  06  ©11' 

•031©  5'4t 

L70-5]a 

f 

A.  Held  as  gas  me- 
chanically, or 
by  capilarity, 
or        gasified' 
during     plas- 
ticity 

1.  Escapes  grad-  1 
ually     from 
blow  holes 
etc.,  through 
the  walls  of 
the  ingot  ..  1 

2.  K  ed  i  ssolves 
in  the  metal. 
3.  Heinains      in 
[pores      and 
blowholes.  .  .  I 
1.  Maybeextrac-  | 
ted  by  heat- 
ing in  vacuo. 
i2.  Cannot  be  ex-  }• 
tracted      by 
heating      in 
vacuo  J 

B.  Remains     dis- 
solved   after 
plasticity  has 
ceased  ;   or  is 
formed  by  re- 
actions there- 
after    ( 

2-27 

[16-55]a 

•001 

[2-15]a 

a  The  numbers  in  brackets  were  obtained  in  Parry's  experiments  (see  §  176,  C). 

The  numbers  in  this  table  are  derived  from  those  in  Tables  54,  55  and  5(i.  pp.  106  to  108. 

Those  in  columns  7  to  10  of  line  1  are  very  rough  approximations,  inserted  merely  to  give  a  rough  idea  of  the  quantity  of  car'i  cas  escaping  They  are  arrived  at  in  the  follow-in?  way.  Muller 
ftmnd  1  to  T5  volumes  of  gas  escaping  from  recarburized  steel,  and  3  or  more  volumes  from  oxygenated  metal,  during  solidification.  The  minimum  for  each  gas  is  0,  since  in  some  c:i>es  no  gas 
escapes.  The  maximum  for  hydrogen  is  obtained  by  assuming  th:it  in  each  of  the  cases  in  Table  55  in  which  the  composition  of  the  gas  from  recarburized  steel  is  given.  1-5  volumes  escapes  :  :md 
thatiu  thacase  of  oxygenated  metal  (74.  Table  56)  3  volumes  escapes.  The  maxima  for  the  other  gases  is  found  in  the  same  way.  Thus  the  maximum  for  carbonic  oxide  is  derived  from 
Number  86,  the  maxima  for  nitrogen  and  hydrogen  from  Number  73.  and  the  maximum  for  carbonic  acid  from  Number  69.  The  assumption  is  of  course  not  strictly  warranted.  We  can  only  say 


that  our  present  slight  knowledge  of  the  subject  suggests  that  these  numbers  may  not  be  exceeded  :  they  cannot  be  considered  as  limits  wliie.li  have  actually  been  reached. 
The  numbers  for  Class  II.,  A..  1.  give  merely  the  composition  of  tho  gas  escaping  from  the  ingots  in  the,  s  raking  pits,  as  determined  by  Stead.  Number  92.  Table  55. 


Tbn 


and  B2  which  remains  in  the  solid  metal  and  cannot  be 
extracted  even  by  heating  in  vacuo,  we  have  little  knowl- 
edge. §§  172  and  176  give  certain  facts  which  suggest 
that  most  and  perhaps  all  of  the  nitrogen  and  hydrogen 
of  solid  iron  can  be  removed  either  by  healing  in  vacuo 
or  very  fine  grinding. 

The  gases  which  directly  interest  the  steel-maker  are 
the  "mould"  gases,"  those  which  are  evolved  during 
solidification  and  which  cause  blowholes.  It  is  the 
formation  of  cavities  that  gives  the  gas  question  moment: 
it  is  not  clear  that  their  sides  can  ever  be  so  completely 
welded  together,  even  in  small  forgings,  as  to  wholly 
efface  their  effects.  In  large  forgings  it  is  still  more  diffi- 
cult to  close  them,  while  in  castings  their  effects  may  be 
disastrous.  Were  we,  however  to  confine  our  attention 
solely  to  the  phenomena  of  this  class  of  gases,  we  could 
obtain  but  a  very  incomplete  notion  of  the  causes  of  their 
generation  and  of  the  means  likely  to  prevent  it :  a 
general  study  such  as  we  will  now  attempt  may  give  us  a 
better  insight. 

I  will  now  detail  certain  phenomena  touching  this  ques- 
tion, and  later  seek  their  explanation  and  the  means  of 
preventing  and  obliterating  gas-formed  cavities.  The 
shape  and  position  of  the  blowholes  and  pipes  is  discussed 
in  Chapter  XII. 

§  201.  CONDITION'S  OF  THE  ESCAPE  OF  GAS  FROM 
MOLTEN  AND  SOLIDIFYING  METAL. 

A.  Scattering  and  Rising. — Gas  may  escape  from 
molten  iron  so  rapidly  as  to  cause  violent  boiling.  In  this 
way  the  contents  of  a  five-ton  ladle  may  be  nearly  com- 
pletely ejected.  Commonly  a  gentle  bubbling  occurs  till 
the  top  of  the  ingot  crusts  over :  after  this  the  gas  escap- 
ing from  the  still  liquid  interior  may  keep  minute  passages 
open,  as  at  J,  figure  12,  through  which  it  escapes,  "scat- 
tering" particles  of  molten  metal. 

Scattering  then  is  caused  by  gas  which  is  able  to  swim 
to  the  top  of  the  ingot.  Such  gas  might  be  evolved  either 
from  the  still  molten  interior,  or  from  the  already  pasty 
metal,  or  at  their  contact,  being  gasified  at  the  instant  of 
solidification.  But  when  the  pasty  metal  evolves  bubbles 

a  For  brevity  I  frequently  refer  to  the  gases  evolved  from  molten  and  solidifying 
iron  at  the  atmospheric  pressure  as  "  mould  gases,"  to  those  found  on  boring  the 
cold  solidified  metal  under  water,  etc.,  as  "  boring  gases,"  and  to  those  extracted 
on  heating  it  in  vacuo  as  "  vacuum  gases." 


of  gas,  whether  they  form  wholly  within  the  already  pasty 
portions  as  at  M,  figure  13,  or  whether  they  form  at  the 


Fig.  12 


Fig.  13 


contact  of  the  liquid  and  pasty  portions,  their  spherical 
ends  projecting  into  the  liquid  mass  as  at  L,  unless 
they  free  themselves  and  swim  to  the  top  of  the  ingot  and 
thus  escape,  they  must  occupy  room  which  had  been  oc- 
cupied by  the  metal,  and  must  thus  tend  to  force  the  still 
liquid  interior  upwards,  pressing  against  the  ingot  top,  or 
even  piercing  it  as  at  K.  This  pressure  against  the  top  of 
the  ingot  causes  it  to  rise.  This  rising  is  often  gradual, 
the  top  of  the  ingot  being  gradually  forced  upwards,  till, 
even  if  the  mould  was  originally  but  half  filled,  the 
top  of  the  ingot  may  eventually  protrude  above  that  of 
the  mould. 

The  blowholes  in  ice  appear  to  form  like  those  at  L, 
their  ends  projecting  into  the  still  liquid  water.  Water 
passes  so  suddenly  from  the  liquid  to  the  solid  state  that, 
once  the  blowhole  is  formed,  it  does  not  appear  to  be  sub- 
sequently enlarged  by  fresh  secretions  of  gas  from  the 
surrounding  ice.  Just  how  the  blowholes  form  in  steel  is 
not  certain.  On  the  one  hand,  when  the  molten  interior 
of  partly  solidified  ingots  of  rising  steel  is  poured  out,b 
the  perforations  found  in  the  inner  side  of  the  shell  indi- 
cate that  the  blowholes  initially  form  as  at  L,  figure  13 : 
on  the  other  hand,  the  gradual  rising  of  the  whole  top  of 
the  ingot  suggests  that,  even  after  the  blowhole  is  formed 
and  completely  inclosed,  fresh  gas  enters  it  from  the  ad- 
joining metal,  increasing  the  pressure  till  it  becomes  strong 
enough  to  elongate  the  already  partly  solidified  walls  of 
the  ingot. 

Thus  gas  which  forms  within  the  ingot  during  solidifi- 
cation will  cause  frothing,  boiling,  or  "scattering"  if  it  is 
able  to  swim  to  the  upper  portion  of  the  mass  and  escape, 
and  "rising"  if  it  is  unable  to  escape. 

Thus  scattering,  when  unaccompanied  by  rising,  ap- 


b  See  figure  32,  §228. 


WHAT    CLASSES    OP    IRON    SCATTER     AND     RISE  ?      §  202. 


127 


pears  to  be  due  to  the  early  escape  of  gas  :  while  rising  is 
rather  connected  with  its  later  escape.  Clearly  the  bub- 
bles which  cause  rising  must  form  blowholes  :  hence  the 
blowholes  are  referable  to  the  late  escape  of  gas." 

It  would  not  be  anticipated  that  the  escape  of  gas  at  the 
instant  of  solidification  would  necessarily  cause  rising  and 
blowholes.  If  the  gas  then  evolved  remains  attached  by 
capillarity  to  the  growing  walls  as  at  L,  or  if  it  be  mechan- 
ically enclosed  by  the  metal,  it  will  cause  blowholes.  But 
it  is  altogether  conceivable  that  it  may  not  be  detained  in 
either  of  these  ways,  but  that  all  of  it  may  swim  to  the 
surface.  '  As  the  solid  portion  gradually  encroaches  on 
the  liquid  interior,  the  condition  and  texture  of  its  sur- 
face may  vary  according  to  the  rate  of  solidification,  the 
composition  of  the  metal,  etc.:  and  some  kinds  of  sur- 
faces may  be  expected  to  have  a  greater  tendency  to  retain 
gas  bubbles  by  capillarity  than  others.  Again,  if  the  metal 
passes  directly  from  a  highly  liquid  to  a  distinctly  solid 
condition,  gas  set  free  at  the  instant  of  solidification  should 
have  a  better  chance  of  escaping  from  the  solidifying  metal 
and  of  swimming  upward  to  the  surface,  than  if  the  metal 
passed  through  an  intermediate  pasty  or  gummy  state. 

So,  too,  if  the  metal  on  solidifying  becomes  porous,  gas 
which  forms  will  be  more  likely  to  work  its  way  out 
through  tlie  ingot' s  walls  and  less  likely  to  collect  and 
push  the  metal  aside  so  as  to  form  blowholes,  than  if  the 
metal  becomes  pasty  or  gummy  on  solidifying. 

According  to  M filler  both  grey  und  white  cast-iron 
evolve  gas  copiously  in  setting.  White  iron  often  con- 
tains blowholes,  grey  iron  rarely  does.  It  is  natural  to 
refer  this  difference  to  the  fact  that  white  iron  passes 
through  a  pasty  condition  in  solidifying,  while  grey  iron 
is  said  to  pass  more  instantaneously  from  the  liquid  to 
the  solid  state.  Indeed,  from  its  behavior  in  the  foundry 
one  would  hardly  suspect  that  it  evolved  gas  at  all,  so 
tranquil  is  it,  save  for  the  beautiful,  kaleidoscopic,  shift- 
ing play  of  its  surface. 

It  is  probable  that  the  same  water  may,  under  different 
conditions  of  cooling,  yield  either  very  porous,  or  compar. 
atively  compact,  or  even  perfectly  solid  ice,  though  it 
may  evolve  the  same  quantity  of  air  in  each  case.  In  the 
first  case  much  of  the  air  is  mechanically  entangled  or  re- 
tained by  capillarity  ;  in  the  last  the  conditions  of  freez- 
ing enable  it  to  escape  completely.  How  much  more  may 
we  expect  differences  when  not  only  the  rate  of  freezing 
and  the  other  external  conditions  differ,  but  when  dif- 
ferent varieties  of  metal  differ  widely  in  the  order  and 
kind  of  changes  in  their  physical  condition  which  they 
themselves  undergo  in  solidifying  ?  With  our  present 
imperfect  knowledge  and  with  such  complex  conditions 
it  were  idle  to  seek  a  full  explanation  of  all  the  variations 
in  the  effects  of  our  escaping  gases. 


»  Mailer's  calculation,  implying  that  if  the  gas  found  in  the  cold  blowholes  had  ex- 
isted in  them  when  the  metal  was  at  1,400°  C.  its  pressure  would  have  been  between 
about  191  and  about  346  pounds  per  square  inch,  harmonizes  with  the  view  that  the 
blowholes  are  formed  by  a  late  rather  than  an  early  escape  of  gas  during  solidifi- 
cation, and  that  much  gas  enters  them  after  they  have  been  completely  enclosed 
by  pasty  metal.  For,  unless  the  metal  were  decidedly  stiff  and  hence  comparatively 
cool,  we  should  expect  that  gas  at  such  a  pressure  and  in  the  considerable  quantity 
in  which  it  exists  in  the  larger  blowholes,  would  push  the  surrounding  metal  aside 
and  enlarge  its  own  cavity  till  its  pressure  became  much  diminished,  unless  in- 
deed the  ingot's  outer  crust  had  become  so  strong  and  rigid  as  to  completely  resist 
the  expansive  tendency.  In  arriving  at  these  numbers  Miiller  deducts  for  the 
gas  which,  from  boring  solid  blowhole-less  iron,  he  infers  exists  in  the  solid  metal 
between  the  blowholes.  Cf.  §  S05,  B.  The  pressure  which  he  arrives  at  appears 
to  me  somewhat  conjectural  Iron,  Jan,  19,  1883,  p.  53  ;  Sept.  U,  1883,  p.  844. 


The  top  of  a  scattering  ingot  will  evidently  be  porous, 
but,  if  solidification  progresses  regularly  from  without  in- 
wards and  from  below  upwards,  all  the  gas  evolved  from 
the  still  molten  metal  and  all  that  is  evolved  at  the  in- 
stant of  solidification  may  escape  through  the  top  crust, 
or  collect  beneath  it,  and  the  rest  of  the  ingot  may  be  free 
from  blowholes  :  but  it  may  still  contain  the  central  pipe. 

J  f  the  still  molten  metal  evolves  gas  so  rapidly  that  it 
boils  violently,  and  if,  as  solidification  progresses,  the  es- 
cape of  gas  decreases  somewhat,  the  metal  will  now  sink 
back.  Very  soft  and  especially  basic  ingot  iron  may 
behave  in  this  way  to  such  an  extent  that  it  is  not  prac- 
ticable to  fill  the  mould  at  one  teeming.  With  soft  basic 
ingot  iron  it  is  often  necessary  to  pour  but  a  little  metal 
at  a  time,  returning  perhaps  as  many  as  nine  times  at  in- 
tervals, and  adding  a  little  metal  each  time  as  the  frothing 
slackens.  This  metal  often  pipes  slightly :  yet  it  some- 
times develops  a  sufficient  number  of  blowholes  to  rise, 
when,  in  spite  of  its  previous  sinking  back,  it  is  strictly 
speaking  a  "rising  metal."  To  the  superficial  observer 
its  rising  is  masked  by  the  more  violent  and  conspicuous 
frothing  which  precedes  it.  In  this  case  our  nomenclature 
is  rather  misleading,  and  calls  for  a  change.  Confusion 
may  be  lessened  by  calling  such  metal  "blowhole-form- 
ing" rather  than  "rising." 

B.  Piping  is  due  to  the  contraction  of  the  interior  of 
the  ingot  after  the  exterior  has  grown  cool  and  rigid.  The 
volume  and  position  of  the  pipe  will  be  considered  in 
§  §  224-5.  Suffice  it  here  to  point  out  that  the  blowholes, 
displacing  the  molten  or  pasty  metal  and  forcing  it  in- 
wards and  upwards,  must  diminish  and  may  obliterate 
the  pipe.  And  in  fact,  other  things  being  equal,  the 
fewer  and  smaller  the  blowholes,  the  larger  is  the  pipe. 
But  that  portion  of  the  blowholes  which  forms  before 
the  ingot-top  has  frozen  across  merely  raises  the  level  of 
the  ingot-top,  and  does  not  lessen  the  volume  of  the  pipe. 

Piping  proper  is  not  to  be  confounded  with  the  sinking 
back  which  occurs  when  metal  which  has  been  boiling  be- 
comes relatively  tranquil,  or  at  least  boils  less  violently: 
this  occurs  because  the  evolution  of  gas  slackens,  and  it 
has  but  little  and  remote  connection  with  contraction. 

§  202.  WHAT  CLASSES  SCATTER  AND  KISE? — Irons 
may  be  classified  into  those  which 

1.  Neither  scatter  nor  acquire  blowholes.  )  They  usually 

2.  Scatter  without  acquiring  blowholes.    )         pipe. 

3.  Acquire  blowholes  (rise)  without  scat-  •> 

tering.  I  They  do  not 

4.  Both  scatter  and  acquire  blowholes  f  usually  pipe. 
(rise).  J 

Classes  of  iron  which  scatter  much  usually  acquire 
blowholes,  and  those  which  acquire  blowholes  abundantly 
usually  scatter." 

A.  Influence  of  Temperature. — An  excessively  high 
casting  temperature  renders  the  metal  wild,0  and  favors 
the  formation  of  blowholes,  but,  according  to  Walrand,c; 
only  when  the  metal  is  cast  in  metallic  moulds  whose  walls 


b  The  statements  in  this  chapter  concerning  the  behavior  of  the  different  classes 
of  iron,  are  in  large  measure  based  on  Miiller's  authority,  in  part  on  personal  ob- 
servation. My  own  observations  are  not  sufficiently  extended  to  enable  me  to 
-peak  with  perfect  confidence  on  certain  points  ;  nor  do  I  feel  certain  that  the 
published  statements  of  others  on  these  same  points  are  based  on  sufficiently 
systematic  observation. 

c  Stead,  Journ.  Iron  and  St.  Inst,  1882,  II.,  p.  5S6. 

dTroilius,  Van  Nostrand's  Eng.  Mag.,  XXXIII.,  p.  364,  1885,  from  Jernkont. 

Annr 


J28 


THE    METALLURGY    OF     STEEL. 


have  become  oxidized.     In  this  case  an  external  zone  of  I     A  bath  of  oxygenated  metal  which,  if  recarburized  with 
innumerable  small,  narrow,  very  elongated,  closely  packed  large  additions  reacts  violently  and  yields  solid  ingots, 


blowholes  forms,  causing  the  ingot  to  crack  in  forging. 
In  soft  basic  ingot  iron  an  excessively  hi^h  temperature 
produces  numerous  pear-shaped,  subcutaneous  blowholes, 
together  with  many  central  ones." 

An  unduly  low  casting  temperature  likewise  causes 
rising  and  blowholes  under  many  conditions,  whose 
limits  are  not  well  known. 

B.  Influence  of  Composition  and  of  Additions. — In 
general,  the  freer  the  iron  from  carbon,  silicon  and  man- 
ganese, the  more  does  it  form  blowholes.  1  hus  oxygenated 
metal  scatters  violently  and  forms  blowholes.b  Ingot  iron 
comes  next :  it  occasionally  rises  so  violently  as  to  burst 
the  firmly  wedged  cover  from  its  mould,  causing  a  violent 
explosion.  If  at  the  same  time  it  be  unduly  cool  it  boils  all 
the  more  violently.  Highly  carburized  steel  is  normally 
comparatively  tranquil,  is  nearly  or  quite  free  from  blow- 
holes, and  pipes  deeply:  the  harder  i.  e.  more  highly  carbur- 
etted  crucible  steels  pipe  more  deeply  than  the  softer  ones. 

There  may  be  exceptions  to  this  rule.  Thus  in  the  basic 
Bessemer  process  it  is  found  that  steel  which  has  not 
been  thoroughly  after-blown,  and  hence  has  say  0'15$  of 
phosphorus  or  more,  is  much  wilder  than  that  which  is 
thoroughly  dephosphorized  :  it  boils  like  porridge,  with 
large  bubbles  and  violent  spirting." 


a  J.  Hartshorne,  private  communication,  March  1st,  1888. 

b  As  pointed  out  at  the  end  of  §  201,  A,  oxygenated  metal  and  soft  ingot  iron 
often  sink  back  in  the  mould,  so  that  fresh  metal  has  to  be  added  after  teeming: 
but  nevertheless  oxygenated  metal  is  strictly  speaking  a  "  rising,"  i.  e.  blowhole- 
forming  metal,  and  soft  ingot  iron  often  is. 


with  smaller  additions  of  spiegeleisen  or  ferromanganese 
may  give  porous  ingots,0  apparently  because  it  then  has 
so  much  less  carbon  and  manganese. 

But,  while  the  addition  of  silicon  usually  completely 
stops  both  rising  and  scattering,  its  mere  presence  is  no 
guarantee  of  soundness.  Not  only  does  siliciferous  grey 
cast-iron  occasionally  rise,  but  even  Bessemer  steel  re- 
taining 0'3,  O'C  or  even  \%  of  the  silicon  initially  in  the 
cast-iron,  and  obtained  by  interrupted  blowing  and  hence 
unrecarburized,  often  rises  so  suddenly  as  to  hardly  leave 
time  for  closing  the  mould.d  It  appears  therefore  that  it 
is  not  the  mere  presence  of  silicon  but  the  fact  that  it  has 
been  added  shortly  before  casting  that  prevents  blowholes 
and  rising. 

Table  70  A  gives  the  results  of  several  experiments  on 
the  influence  of  recarburizing  additions  on  the  evolution 
of  gas,  with  other  matter  elsewhere  referred  to  in  connec- 
tion writh  these  experiments. 

Here  the  degree  of  tranquillity  which  the  recarburizing 
addition  produces  is  roughly  proportional  to  the  quantity 
of  silicon  and  manganese  which  the  recarburized  steel 
holds,  and  bears  no  traceable  relation  to  the  quantity  of 
these  elements  which  is  oxidized.  Thus  1  and  5,  which 
retain  about  '66$  of  manganese  but  almost  no  silicon, 
scatter  and  rise,  and  become  pcrous  :  2,  6  and  7,  retaining 
more  silicon,  do  not  scatter,  rise  very  little  and  contain 


c  Miiller,  Iron,  Feb.  22,  1884,  p.  161. 

d  Idem,  Jan.  5th,  1883,  p.  18.  Even  16%  ferro-silicon  may  be  full  of  blowholes. 


TABLE  70  A. — KRCARBCTRIZINC  REACTIONS  IN  TNI:  I>I:SSKMI:K  PROCESS, 
These  cases  are  numbered  to  correspond  with  those  in  Tables  42,  43,  and  76,  pp.  92-!) 


Number  and  observer. 


3  »  f 


_  c 

II 

3.3 


Acid  or  basic. 


H  £ 
•5(2 


Previously      recar- 
burized a 


?•(  \  With. 


L  Containing 

Description  of  metal.. 

w      I 

f  Recarburized  in 

I  Slag  present  or  no 

f  |  Recarburized  with 

I 

•£  |  Containing 


Oxygenated. 

Iron  moulds. 
No. 

Spiegelcisen. 

C.    Si.   Mn. 
4-22  0-41  8-12 


-{  Present  before  recarbur- 
izing b 

Added  


Total     

After  recarburizing 


Removed 

Oxygen  corresponding.. 

fusing 

I  Scattering 

I  Solidity 


'CO 

Composition  of  J  TI . . . . 

gas.          IN 

[CO  ... 

Time  after  casting  when  col- 
lected  


1M. 


Basic. 
No. 


II  1C, 


•lll-J 

-1117 


Oxygenated. 

Iron  moulds. 
No. 

Ferro-silicon. 

C.  I  8i.    Mn. 

l-64'9-S6  2-05 


•160 
•516 


055   025  -017 
078  -048  -005 

Moderate. 

Scatters. 
Porous. 

58  8 
80-9 

6'8 

4-0 

7  mins.   after 
casting. 


2M. 
Basic. 

No. 


mi:! 


•35S 


144 
•217 


992 

062 

030  '120    -031 
040  '205?  -1X19 
Rises  a  little. 
No  scattering. 
A  few  blow- 
holes. 
82-6 
51-0 
7'5 
5  9 

7  mins.  after 
casting. 


3M. 
Basic. 
Yes. 


Rail  steel.O  25 

;:  carbon. 

Iron  moulds. 

No. 

Spfcgeleisen. 
C.     81.    Mn. 


Slight. 
Slight. 
A  few  blow- 
holes. 
55  2 
87-9 
8-2 


4  M. 

Basic. 
No. 


Oxygenated. 

Iron  moulds. 
No. 

Silicide  of  man- 
ganese. 

C.      Si.      Mn. 
18    6'10    28 


162 


•021 


•346 


55  4 


•181 
1  4S7 


1  66S 


020  -  007 

027— -012 

None. 

None. 

Complete 


•IIIVI 
•019 


5  M.  i  6  M. 

Basic.  Basic. 


Yes. 
2  %  ferro-man- 

ganese. 
70*Mn.  (?). 

Non-redshort. 

Iron  moulds. 
No. 

Spiegeleisen. 


C.     Si. 
•26  -35 


•cttli 


224 


•014 
•015 


Mn. 
7  94 


•811 
•845 


•656 
•6B7 


019  -Oil  —  Oil 

16  I -IB        "40 

Moderate.  ' 

Scatters. 

Porous. 

66-4  42-1 

29-6  42-8 

10'6  in 

8'4  4-0 

7  mins.  12  mins. 


Yes. 

2  %  ferro-man- 

ganese. 
70  %  Mn.  (»). 

Scattering. 

Iron  moulds. 
No. 

Ferro-silicon. 

C.      Si.      Mn. 
1-627  10-05    2-05: 


075 

•1154 


•12' 


•007 


•346 
•314 


•480 
•069 


•585 


•002      032- -036 
•18      -05       '40 

None. 

None. 
Nearly  complete 


36-6 

48-9 

7-8 

6'7 


36-6 

44-5 

11-0 

7-9 


7M. 

Basic. 
Probably  not. 


Ladle. 
Yes. 

j  Ferro-silicon  and 
I  ferro-manganesc. 

C.     81.    Mn.     P. 


•IHI2 


115 


•162 


1-250 


5321  333 


•944 


•07N 


097 


•027 

036  -633    -113 
Rose. 
None. 
A  zone  of  blowholes 


84-7 
58-0 
4-1 
3-2 


80  8 

65-8 

19 

1-5 


8M. 

Basic. 

Probably  not. 


Converter. 

Yes. 

(  Ferro-silicon 
<     and  ferro- 
(   manganese. 
C.      Si.      P. 


oil 


•70+... 


•IOC 


•515 


lose. 

Contained 
blowholes. 
64-6  44-1 
18-9  41-6 
14-4  10-6 
2-1  8-7 

Early     Late 
mould,  mould. 


9M. 

Acid. 


C.       Si.      Mn. 


882 

387 

•2.V! 


113 

•047 


081  — -073    '354 
108- -125    -103 


•231) 
•886 


•1601-OC6 
•238 


11  K. 
Acid. 


C.      Si.      Mn 


l  ISO 
•513 


•548 

H70 


•077 


•060 


•173    '052    '948 
217    -089    -274 


2-029 


1122-118 


1   170 


inn! 


M  =  Mullcr,  K  =  King. 

all)  certain  cases  the  metal  had  been  partially  rccarburized  before  receiving  the  recarburizing  additions  whose  reaction  forms  the  basis  of  this  table. 

bThc  numbers  in  this  line  give  the  carbon,  etc.,  per  100  of  the  weight  of  the  metal  after  recarburizing. 

'•  Oxygen  corresponding  "  is  calculated  on  the  assumption  that  the  reactions  are  Mn  +  O  =  MnO ;  Si  -(-  3FeO  =  2Fe  -f  FeSiOs  ;  and  C  -f-  O  =  CO. 

1.  Spiegeleisen  added  in  the  mould  to  oxygenated  basic  metal  causes  very  violent  brief  ebullition,  with  a  flace  a  yard  high.    The  steel  scatters,   rises    slightly,  and  yields  porous  ingots.     Stall' 

Eisen,  IV.,  p.  72.     The  manganese  removed  appears  to  be  incorrectly  calculated  in  the  original  memoir. 

2.  Ferro-silicon   added  in  this  proportion  in  themoulds  to  oxygenated  basic  metal  immediately  arrests  every  visible  development  of  gas.    The  steel   becomes  perfectly  quiet,  does  not  scatter, 
always  rises  a  little,  contains  a  few  blowholes,  mostly  sporadic,  and  is  slightly  redshort.     Idem.  p. 73. 

3.  Tobasicrail  stee]  of  "25$  carbon,  which  itself  develops  much  gas  and  scatters  actively,  melted  spiegeleisen  is  added.    No   boiling  occurs,  the  development  of  gas  at  once   diminishes  and 
soon  ceases.    The  steel  rises  slightly  and  has  scattered  blowholes.     Idem,  p.  72. 

4.  The  addition  of  a  siliciferous  ferro-manganese  to  oxygenated  basic  metal  instantly  and  completely  quiets  the  metal.     Almost  no  gas  escapes  :  the  metal  is  free  from  pores.     Idem.  p.  73. 

5.  To  basic  ingot,  produced  by  adding  2  %  of  ferro-mangancsc  in  the  converter,  11  S3  kg.  ot  spiegeleiseii  are  added,  causing  rather  active    boiling  and  a  Spiegel  flame.     The  steel  scatters  «  ith 
moderate  rising,  forming  a  porous  ingot  of  272  kg.     Idem,  p.  72. 

6.  To  a  basic  ingot  iron  produced  with  2  %  of  ferro-manganese,  which  scattered,  rose  slowly,  and  gave  ingots   with  few  scattered  blowholes,  9  65  kg.  of  ferro-silicon  is  added.    This  BireftM  ;i  II 
movement  and  all  visible  escape  of  gas  :  the  ingot,  weighing  286  kg.,  had  a  zone  with  a  few  blow-holes.     Idem,  p.  73. 

7.  5  %  of  ferro 'Silicon  and!  2  %  of  ferro-manganese  of  70  %  manganes,  both  red  hot,  were  added  in  tile  ladle,  and  tin-  metal  poured  on   them  from   the  converter.     There   was  no  reaction  ;  the 
steel  was  perfectly  quiet  but  rose,  and  acquired  a  marginal  zone  of  blowholes.    Stahl  und  Eisen,  IV.,  p.  71,  1884 ;  Iron,  1S88.  p.  246.  1S84,  p.  187. 

8.  5  %  of  ferro-silicon  and  2  '5  %  of  ferro-manganese  were  added  in  a  molten  state  to  oxygenated  basic  metal  in  ^hc  converter.     The  steel  was  quiet  but  rose.      Idem,   III.,   pp.  446,  452  :  Iron, 
1883,  pp.  244-6. 

9.  To  a  charge  of  blown  steel  000  kg.  of  spiegeleisen  w.i.s  added,  probably  in  a  molten  state  in  the  converter.    The  weight  of  the   resulting  ingots  was  7793  kg.       There  appear  to  be  certain 
discrepancies  in  the  numbers  which  M  niter  gives  concerning  th's  case.    Zeit.  VereitiR.  IVutn-h.  Ing..  XXII,  p.  385. 

II.  To  a  charge  of  blown  acid  metal  2000  Ibs.  of  spiegeleisea  and  4u  Ibs,  of  Icn'O-iuaiigafleac  are  i.d  Jc4.   Uu;  former   presumably  in  a  molten  state  in  the  converter,  the  latter  probably  red  hot 
bat  iwi  muiuii,    Tram.  Am.  last.  Mii:in£  Engineers,  LX,,  i>,  '£>$, 


WHAT    CLASSES    OF    IKON     SCATTER    AND     RISE  ?      §  202. 


129 


TAHI.K  71. — BEHAVIOR  of  IRON  BEFORE  AND  DURING  SOLIDIFICATION. 


Description  of  iron. 


Casting 
temperature. 


Behavior  before 
teeming. 


Behavior  in  moulds. 


Karly. 


Late. 


Piping. 


Blowholes. 


Quantity. 


Position. 


CAST-IRON  AND  INTERMEDIATE  BESSEMER  PRODUCTS. 


1... 
0 

Grey  cast-iron   

Scintillates  very  little  n 
running. 

Evolves   much  gas,  (a)  but 
few  sparks. 

Very  rarely  rises  (a)    

Pipes  

Usually  none  (a). 

3 

White  cast-iron 

4 

sluggish 

Rarely  if  ever  rises  (a).  .  .  . 

Pipes    . 

holes  (m). 

Quiet  in  the  ladle  (b) 

lively  

Is  solid  (b) 

6 

Scatters  violently  (c)  (n)  t  

Rises  (c)  (11)  t  

Hnori  1*     hlowhnlps 

basic,  Bessemer     or   open 
iK'iirth. 

verier  (c,  n)  t 

and     a     zone    ot 
pores.t 

ACID  JiKssn.vr.iE  MKTAL. 


7... 
8... 
9... 

10... 
11... 

12... 
18... 

f 
Rail     and     other      INGOT-J 

STEEL  
I 

INGOT  IRON  

Boebnm,  usual  hot  blows.  .  . 

Excessively  HOT  .. 

Normal  

Excessively  COOL.. 

Excessively  HOT... 

Spiegel  reaction  violent: 
much  gas  evolved  in 
ladle  (n). 

Spiegel  reaction  usually 
moderate  (n). 
No     spiegfil     reaction  ; 
quiet  in  ladle  (n). 

Quiet     in       converter, 
evolves  gas  in  ladle  (11; 
Quietin  converter,  quiet 
in  ladle  (n). 

Very  wild(n)t  

Violent  Spiegel  reaction; 
blaze  in  ladle  (d). 

See  note  (p)  

Does  notlise(n)t  
Rises(n)  

See  note  (p)..  .  . 

Pipes  t  
No  pipe(n)t.  .  . 

"     "     (n)... 

Innumerable(f)  small, 
elongated.t 

Few  or  none  

Many  :    metal   Is 
spongy  (f)  (n) 

Few  (n) 

Extern'l  zonc(f)(n)t 

Sporadic  (n). 

External  zone  :  also 
many  large  sporadic 
ones(f)  (n)t. 
Sporadic  (n). 

External  zone  :  also 
sporadic  ones  (n). 

External  zone  :   also 
very  uiany  sporadic 
ones. 

Scatters  slightly  if  at  all  (n).  . 

"        (n)  

"     (n)  

"        fnl 

"    (n)  

"     "     («)..- 
"      "     (n)t.. 
Pipes  

A  moderate  n'mb'r  (n) 

Very  many  :     metal 
very  spongy  (f)  (n)  t 

None(d)  

Excessively  COOL.. 
HOT  

Boils  &  scatters  violently  (n)t 

"    (n)  

Does  not  riseCd)  ,  .  .  . 

BASIC  BESSEMER  METAL. 

"1 

15.  [ 
16. 

IT... 

18... 

19... 
20... 

BASIC  INflOT    IRON,  C.    O'OS,   ' 

Si.  trace,  Mn.  0'2()@0'25  :  1 
recarburlzed   with   ferro-  I 
manganese   in    converter  -{ 
and  spiagekriaen  in  ladle. 

I 

Basic  steel  made  by  interrupt! 
out  reoarbmiz'jig,  holdings 
carburized  it  becomes  wild 

Basic  metal  partially  recarbur 
ro  manganese,  so  as  to  ho 
0-58SC  Mn. 
Basic  metal  recarburized  wit 
so  as  to  hold  about  O'SjJ  ot  f 
Oxygenated  basic  metal  recj: 
silico-nmiitfanese,  so  as  to 
and  l-6£Mn. 

Excessively  HOT..  1 

Ferro    reaction    (in 
converter)      very  1 
quiet  (h)  (o)  Spei-  !  , 
gel     reaction    (in|   ( 
ladle)      generally     f 
moderate  (o)  ... 

Quiet     in     ladle     and 
mould  (]). 

Much  wilder  than  15  &  16  (o). 

Kises  but  little  if  at  all  (o) 

Eises  but  little  A  slowly  (j) 

Eises  slowly  (i)  
Rises  alittle(k)  

Usually  a  mod- 
erate    pipe  : 
sometimes 
none(o)  

A  moderate  number 
(h)  (o),  rather  large 
and  irregular  (o).  .  . 

Few  Q). 

Few(i)  

A  m'derate  n'mb'r  (k} 
None(l)  

f  External  /one.  also 
central       b  1  o  w- 

Normal  1 

(  Kises  rapidly  during  teem- 
<  ing  and  sinks  again    fo). 
|  Scatters  and  boils  uiuch(hj 

Scatters  but  little  if  at  all  (j). 

Scatters  much  (1)  

Perfectly    quiut  ;    does    nol 
scatter  ;k). 
Perfectly    quiet  ;    does    noi 
scatter  (1). 

j  A  zone  about  mid- 
4  way  between  shell 
!  and  centre  (o). 

Excessively  COOL. 

d  blowing  and  with- 
ly  '15^  P.  If  now  ro- 

ized  with  1%  of  fer- 
Id  -08^  C,  0-007;*  Si. 

i  ferrosilicon  alone, 
ilicon. 
rburized  with  ferro- 
hold  '11%  C,  -35;6  Si, 

Large     blowholes 
scattered  through 
ingot  (o). 

Radial  (|). 

Scattered  (i). 
Mostly  sporadic  (k). 

Quiet  (k)  

Quiet  (i)              ... 

D  oes  not  rise  (1)  



CRUCIBLE  STEEL. 


23. 


High-carbon  crucible  steel Quiet:    very  fow  bub-  Quiet ;    a   little   shower    off  Does  not  rise Pipes  deeply  ,.  Few  or  none 

bles.  sparks. 


(a)  MiilkT,  Stahl  unil  Kisen,  III.,  p.  44S.  18S3 :  Iron,  Sept.  14,  1S83,  p.  245. 

(b)  Idem,  Stahl  und  Kisen,  IV.,  p.  74:  Iron,  Feb.  15,  1834,  p.  133.    "  Zu  dichten  Blocken  erstarrte."     I  do  not  think  that  Muller's  statement  that  the  ingots  wero  solid  necessarily  implies  that  they 
were  absolutely  free  from  blowholes. 

(c)  Idem,  Stuhl  und  Kisen,  III.,  p.  450 :    IV.,  p.  T5 :  Iron,  Jan.  5,  p.  18,  Sept.  14,  p.  245, 1883:  Feb.  15,  p.  138,  1884. 

(d)  Idem,  Stalil  und  Eis.,  III.,  p.  4411 :  Iron,  Sept.  14,  1SS3,  p.  245. 

(e)  Walrand,  Troilius,  Van  Nnstrand's  Eug.  Mag.,  XXXIII.,  p.  363,  1885,  from  Jernkont.  Ann. 

(f)  Idem,  p.  304. 

(g)  Stead,  Journal.  Iron  and  St.  Inst.,  1882,  II.,  p.  526. 

(h)  M  filler.  Stahl  und  Kisen,  III.,  p.  451.  1883.     "  Ziomllch  dicke  Blocke." 

(i)  Idem,  IV.,  pp.  72-3,  1884.    This  appears  to  be  the  usual  behavior  of  such  metal. 

(j)  Idem,  III.,  pp.  446^452, 1SS3.  The1  behavior  of  tho  blown  metal  varies  greatly  ;  now  it  is  quiet,  yielding  rather  solid  ingots,  now  it  scatters  and  rises  much  :  but  according  to  Muller,  if  th«  after 
blow  in  limited  so  that  the  metal  retains  some  .\a%  phosphorus,  the  unrecarburized  metal  is  quiet  and  rises  little.  But  if  spiegcl  be  added  the  metal  becomes  wild  again. 

(k)  Idem,  IV.,  p.  72,  1884.  This  appears  to  be  the  result  ot  four  experiments.  The  steel  was  slightly  redshort,  though  it  contained  only  about  0-07*  of  sulphur.  Number  2,  Table  70  A,  gives  the 
ili-uils  of  the  reaction  of  one  of  these  from  experiments. 

(1)  Idem,  p  73.    The  details  of  tho  reaction  are  given  In  Number4,  Table  70  A.    It  is  not  clear  that  tho  statements  in  this  line  refer  to  more  than  a  single  experiment. 

(in)  Muller,  Iron,  Jan.  5th,  1SS3,  p.  17. 

(n)  It.  Forsyth,  Private  Communication,  March  8d.  18S3. 

(o).J.  Hartshorne,  Private  Communication,  March  1st,  1SS3.    Thoroughly  afterblown  metal  is  recarburized  with  0-5  to  0-S#  of  fcrromanganeso  containing  8(1%  of  manganese,  added  red  hot  in  the 


iv/tri  iiiti  toiiunic,  i  UVULU  vumiiiuiiidiuuii,  muniu  101.,  1000^       -        -       „     .,  —  . 

converter,  and  then  with  1#  to  1*5#  of  spiegek-isen  containing  10^  of  maLganese,  added  red  hot  in  the  ladle  after  half  of  the  dune  lias  been  poured  into  the  ladle.  The  ferromanganesc  usually  pro- 
duces but  little  tl;une,  but  sometimes  a  large  name,  with  no  traceable  difference  in  the  results.  The  spicgel  also  produces  a  reaction  which,  though  usually  quiet,  is  sometimes  violent.  The  steel 
is  poured  from  a  lirst  ladle  into  a  second  before  teeming  :  this  transfer  occasionally  causes  a  reaction .  The  metal  froths  so  much  that  tho  mould  is  filled  only  about  one  third  fill!  at  first,  then, 
after  filling  other  moulds,  successive  small  additions  of  steel  are  made,  till  the  mould  is  finally  filled  to  within  four  inches  of  the  top.  This  is  substantially  the  practice  at  Teplitz  and  Kladnc, 

(p)  Opinions  differ  as  to  the  effects  of  excessively  high  casting  temperature  on  acid  ingot  steel.    Some  find  that  it  causes  rising,  others  that  it  does  not. 

Thus  Stead  finds  that,  if  Kesseiner  steel  has  just  tho  right  temperature,  it  does  not  rise:  if  the  temperature  be  higher  the  steel  swells  up  and  fiows  over  the  tops  of  tho  moulds,  (Journ.  Iron 
and  St.  Inst.,  1882,  II.,  p.  f>26).  M  filler  describes  steel  made  by  the  direct  Bessemer  process,  which  contains  \%  of  silicon  and  rises  very  rapidly.  So  high  a  percentage  of  silicon  almost  necessarily 
implies  an  excessively  high  temperature.  (Iron,  Jan.  5th,  1SS3,  p.  18).  Walrand  states  (Van  Nostrand's  Eng.  Mag.,  XXXIII.,  p.  304),  that,  if  Bossemer  steel  be  cast  at  too  high  a  temperature,  it 
yields  honeycombed  ingots. 

On  the  other  hand,  a  most  experienced  Bessemer  steel-maker,  in  whose  powers  of  observation  I  place  great  confidence,  informs  me  that,  in  his  experience,  excessively  hot-cast  Bessemer  rail 
steel  docs  not  rise,  but  pipes.  It  is  probable  that  an  excessively  high  temperature  leads  to  rising  under  certain  conditions,  but  not  under  others.  What  those  conditions  are  I  do  not  know. 

t  The  testimony  concerning  this  point  is  quite  harmonious. 


very  few  blowholes :  4,  which  holds  after  recarburizing 
•346$  of  silicon  and  much  more  manganese  than  the  rest, 
neither  scatters  nor  rises,  and  contains  no  blowholes.  No 
such  connection  however  can  be  traced  between  the  pro- 
portion of  silicon  and  manganese  oxidized  or  the  propor- 
tion of  oxygen  removed  by  the  reaction,  and  the  behavior 
of  the  metal.  Thus,  to  take  those  which  were  under 
substantially  the  same  conditions  before  receiving  the 
addition,  2,  which  is  intermediate  in  behavior  between 
1  and  4,  more  tranquil  than  the  former  but  less  than  the 
latter,  yet  has  more  oxygen  removed  by  the  reaction  than 
either.  1,  which  becomes  less  tranquil  than  4,  yet  loses 


more  oxygen  :  but  5,  though  it  becomes  less  tranquil  than 
6,  loses  less  oxygen. 

C.  Influence  of  the  Process  of  Manufacture. — In  tlie 
acid  Bessemer  process,  according  to  Muller,  if  the  blow- 
ing be  cut  rather  short  so  that  the  metal  is  not  fully 
oxygenated,  a  weak  reaction  follows  the  addition  of 
spiegeleisen,  and  the  resulting  steel  rises  and  often  scat- 
ters (suggesting  that  acid  Bessemer  steel  is  a  rising  rather 
than  a  scattering  metal) :  while,  under  like  conditions, 
longer  blowing  wonld  cause  a  more  violent  reaction  and 
the  steel  would  neither  rise  nor  scatter.*  We  have  just 


aMiiller,  Iron,  March  30,  1883,  p,  367,  Feb,  22,  1884,  p.  161. 


180 


THE    METALLURGY    OF    STEEL. 


seen  that  a  weak  reaction  due  to  adding  but  little  spiegel- 
eisen  is  also  followed  by  rising. 

Oxygenated  basic  metal,  though  quiet  in  the  converter, 
boils  in  the  ladle,  and  evolves  gas  copiously  in  the  moulds 
both  before  and  during  setting,  and  yields  porous  ingots. 
According  to  Miiller  if  recarburized  with  spiegeleisen  it 
evolves  gas  violently  in  the  ladle,  and  boils  and  scatters 
in  the  moulds  :  yet  it  may  yield  comparatively  solid  in- 
gots: /.  e.  it  tends  to  scatter  rather  than  to  rise.  (No.  1, 
70A.)  But  if  a  moderate  amount  of  ferro-silicon  be  added 
instead  of  spiegeleisen,  the  escape  of  gas  at  once  ceases, 
the  steel  does  not  scatter,  but  may  rise  somewhat 8  (No. 
2,  idem.)  With  larger  additions  of  silicon  and  manganese 
all  escape  of  gas  instantly  and  permanently  ceases,  and 
the  metal  neither  scatters  nor  rises.  (No.  4,  idem.) 

It  is  generally  stated  that  the  tendency  to  rise  is  greatest 
in  Bessemer  steel,  intermediate  in  open-hearth  steel,  and 
least  in  crucible  steel.  But  basic  Bessemer  steel,  though 
it  is  excessively  wild  before  solidification,  is  thought  by 
some  experienced  steel  makers  to  rise  less  and  acquire 
blowholes  less  than  metal  of  like  composition  made  by 
the  open  hearth  or  acid  Bessemer  process 

Crucible  steel  is  extremely  tranquil  in  the  crucible  dur- 
ing teeming,  a  few  small  bubbles  lazily  escaping  from  its 
surface,  apparently  of  combustible  gas,  as  the  crucible  is 
partly  filled  with  a  slowly-curling  transparent  blue  flame. 
A  beautiful  shower  of  sparks  escapes  from  the  surface  of 
the  steel  in  the  mould :  it  solidifies  tranquilly,  piping 
deeply. 

Table  71  indicates  the  behavior  of  some  of  the  more 
important  varieties  of  iron  before  and  during  solidifica- 
tion. 

Some  believe  that,  if  the  proportion  of  carbon, 
manganese  and  silicon  be  allowed  to  fall  so  low  in  the 
gradual  decarburization  of  the  bath  in  the  open-hearth 
process  that  the  metal  becomes  oxygenated,  a  tendency  to 
form  blowholes  is  established  which,  while  it  may  be 
greatly  lessened  by  subsequent  deoxygenating  additions 
of  silicon,  etc.,  can  be  fully  eradicated  only  with  great 
difliculty,  if  at  all.  Others  deny  this,  admitting  how- 
ever that  it  is  important  to  prevent  oxygenation,  since,  if 
oxygen  be  absorbed,  it  is  hard  to  ascertain  how  much  is 
present,  and  how  much  silicon,  etc.,  must  be  added  to 
remove  it.b 

D.  Influence  of  Pressure. — Bessemer  proved  that  the 
escape  of  gas  from  molten  steel  was  governed  by  the 
existing  pressure.  The  gentle  ebullition  of  molten  steel 
was  rendered  furious  by  lowering  the  pressure,  and  wholly 
stopped  by  raising  it.0  Troost  and  Hautefeuille  observed 
that,  after  cast-iron  had  been  long  held  fused  in  an  at- 
mosphere of  hydrogen,  bubbles  of  gas  escaped  if  the  pres- 
sure suddenly  fell,  though  the  metal  remained  perfectly 
tranquil  as  long  as  the  pressure  was  constant. d 

But  falling  pressure  does  not  always  induce  a  rapid  es- 
cape of  gas.  These  observers  found  that  phosphoric  cast- 
iron  would  not  boil  on  fall  of  pressure  unless  the  previous 
exposure  to  hydrogen  were  greatly  prolonged,  and  after 
highly  silicious  cast-iron  had  been  fused  in  hydrogen  they 

a  Iron,  Feb.  15,  1884,  pp.  138-9. 

i>Cf.  Holley,  Metallurgical  Review,  II.,  p.  211,  1878. 

<•  Jour.  Iron  and  St.  Inst,  1881,  I.,  p.  196:  cf.  §  188,  C. 

dComptes  Rendus,  LXXVI..  p.  568,  1873.  Before  the  fall  of  pressure  the 
metal  was  not  simply  comparatively  but  absolutely  tranquil.  "  On  n'observe 
aucune  projection,  aucuue  d^gagement  gazeux." 


could  only  induce  a  visible  escape  of  gas  by  cooling  and 
solidifying  the  metal  in  a  complete  vacmim  :  even  then  it 
scattered  but  feebly.  They  had  to  resort  to  the  same 
manoeuvre  to  induce  a  visible  escape  of  gas  from  iron  long 
held  in  fusion  in  an  atmosphere  of  carbonic  oxide. d  That 
pressure  raises  the  solubility  of  gases  in  hot  solid  iron 
also  has  been  abundantly  proved  by  the  absorption  of  hy- 
drogen (and  carbonic  oxide  ?)  when  exposed  to  the  hot 
metal,  and  their  subsequent  expxilsion  when  it  was  heated 
in  vacuo,  observed  by  these  chemists  as  well  as  by  Graham 
and  Parry.  (See  §§  176,  188,  189,  190,  pp.  110,  123,  124.) 

E.  Influence  of  Agitation  and  Solidification. — Agitation 
expels  gas  from  molten  steel.   Thus  half-blown  acid  metal, 
oxygenated  acid  metal,   and    spiegel-recarburized  basic 
ingot  iron  are  comparatively  quiet  while  lying  undisturbed 
in  the  converter,  but  boil  when  poured  from  converter  to 
ladle  or  from  ladle  to  mould.  In  no  case,  so  far  as  I  know, 
does  the  opposite  hold  true.     This  may  be  attributed  to 
the  agitation  due  to  pouring  and  enhanced  by  the  rapid 
circulation  of  the  metal,  due  to  its  contact  with  walls  of 
the  freshly  entered  vessel,  necessarily  much  cooler  than 
the  metal :  they  cool  it,  locally  change  its  density,  and  so 
induce  circulation.     As  the  walls  grow  hotter  this  effect 
diminishes.      So,  too,  the  bath  in  the  open-hearth  fur- 
nace is  often  made  to  boil  by  stirring,  much  as  cham- 
pagne is.     Solidification  also  evidently  expels  gas  from 
steel.     Thus  in  certain  cases  acid  Bessemer  steel  is  per- 
fectly quiet  in  the  converter  and  for  a  few  moments  after 
pouring  into  the  moulds  :  then,  as  solidification  sets  in,  it 
begins  to  rise."    It  is  possible  that  the  boiling  which  some- 
times follows  transferring  into  the  ladle  is  enhanced  by 
temporary  solidification  of  the  metal  against  its  cool  walls. 
More  conclusive  is  the  fact  that  while  slow  solidification,  by 
affording  the  gases  which  it  expels  time  to  escape,  yields 
comparatively  solid  ingots,  sudden  freezing  may  under 
otherwise  like  conditions  yield  extreme  spongy    ones. 
Thus  Brustlein  found  that  steel,  which  when  cast  in  the 
usual  way  gave  pretty  solid  ingots, 'rose  very  much  and 
formed  a  veritable  sponge*  when  cast  in  a  water-cooled 
copper  mold  six  inches  in  diameter.     In  harmony  with  this 
result  are  the  explosions  which  often  occur  when  a  piece  of 
cold  iron  is  dropped  into  molten  steel,  a  thin  coating  of  steel 
momentarily  solidifying  on  the  surface  of  the  cold  lump," 
and  the  fact  that  the  less  carbon  steel  contains  the  more 
does  it  tend  to  boil  in  the  moulds,  for  the  lower  the  carbon 
the  higher  the  melting  point  and  the  more  suddenly  does 
the  steel  set,  cceterisparibus.  (§202B,  p.  128.)  But,  though 
in  harmony  with  Brustlein's  result,  I  will  not  insist  that 
these  phenomena  are  due  to  the  same  cause. 

That  solidification  does  not  always  cause  an  important  es- 
cape of  gas  is  suggested  by  the  fact  that  some  varieties  of 
iron  neither  scatter  nor  rise,  and  proved  by  the  observations 
of  Troost  and  Hautefeuille,  mentioned  in  §  202  D,  and  by 
the  following  experiment  by  Parry.  Grey  cast-iron  was 
fused  in  an  atmosphere  of  hydrogen  :  on  solidifying  it  in 
vacuo  without  removal  from  the  apparatus,  only  a  few 
bubbles  of  gas  were  obtained,  though  on  reheating  (in 
vacuo?)  it  was  found  to  have  absorbed  much  hydrogen.' 

F.  Protracted  Escape. — Gases,  consisting  as  usual  of 


e  Miiller,  Iron,  Sept.  14,  1883,  p.  244. 

'  Stahl  und  Eisen,  HI.,  p.  251,  1883,  No.  5.   "Einen  ziemlich  gesundeu  Block." 

g  "  Glich  der  so  erhaltene  Block  buchstablich  einem  Schwamm." 

b  Ledebur,  Handbuch,  p.  268. 

i  Journ,  Iron  and  Steel  Inst,  1874,  I.,  p.  94. 


THE  QUANTITY  OF  GAS  EXTRACTED  FROM  IRON.   §  205. 


131 


hydrogen,  nitrogen  and  carbonic  oxide,  escape  from  steel 
cast  in  the  ordinary  way,  long  after  solidification  is  com- 
plete. Muller  states  that  combustible  gas  may  be  obtained 
from  ingots  of  compact  Bessemer  or  even  crucible  steel  '55 
minutes  after  teeming,  when  they  are  probably  completely 
solidified,  if,  as  I  understand,  he  refers  to  ingots  of  usual 
size  cast  in  iron  moulds.  For,  even  within  eleven  minutes 
after  teeming,  Bessemer  ingots  fourteen  inches  square  are 
so  far  solidified  that  they  may  safely  be  stripped,  and 
after  four  minutes  more,  or  altogether  fifteen  minutes, 
they  may  be  lifted  with  tongs.  Even  later,  after  the  steel 
has  been  withdrawn  and  placed  in  soaking  pits,  it  con- 
tinues to  evolve  a  large  quantity  of  gas.  (92,  Table  55, 
p.  107.) 

H.  W.  Lash,"  casting  a  large  ingot  with  a  thick  high 
sinking  head,  in  a  mould  sunounded  with  non-conduct- 
ing material,  enabled  gas  to  escape  from  it  for  hours  by 
opening  a  narrow  hole  lengthwise  through  the  sinking 
head  while  it  was  soft.  This  hole  of  course  remained 
open,  permitting  the  escape  of  gas,  but  by  its  length  and 
narrowness  preventing  rapid  radiation  of  heat.  It  enabled 
him  to  watch  the  internal  ebullition  which  continued  for 
2£  hours,  and  to  remove  with  a  rod  any  incipient  scum 
which  froze  on  the  surface  of  the  liquid  mass.  This  device 
greatly  increased  the  solidity  of  the  ingot.  It  is  not 
probable  that  the  gas  which  thus  persistently  escaped  was 
formed  by  the  oxidation  of  the  metal's  carbon  by  the 
small  quantity  of  air  which,  by  diffusion  and  owing  to  its 
greater  density,  would  gradually  pass  down  through  such 
a  long  narrow  hole :  for  its  oxygen  was  probably  wholly 
absorbed  by  the  incandescent  metal  through  which  its 
path  lay.  Being  rapidly  heated  and  lightened  as  it 
entered  the  hole,  the  action  of  gravity  probably  soon  be- 
came unimportant,  and  the  descent  of  the  atmospheric 
oxygen  then  became  dependent  on  diffusion  alone,  a  slow 
process. 

The  protracted  escape  of  gas  is  discussed  in  §  214  B. 
§203.  TJIK  EXTRACTION  OF  GAS  IN  VACUO.— Graham 
found  that  the  rate  at  which  iron  evolved  gas  when  heatec 
in  vacuo  steadily  diminished,  iron  wire  becoming  appar 
ently  nearly  exhausted  after  seven  hours  heating.  Parry, 
however,  found  that  iron  continued  to  evolve  gas  even  for 
seven  days,  and  that  though  the  escape  of  gas  gradually 
ceased  when  iron  was  exposed  to  a  red  heat,  it  started  up 
again  when  the  temperature  was  raised,  and  this  continued 
up  to  the  highest  temperature  attainable."  A  vacuum 
could  be  formed  and  maintained  for  hours  by  lowering  the 
temperature  to  a  point  below  that  at  which  gas  was  being 
evolved.0  §  176,  C,  p.  Ill,  presents  certain  reasons  for 
doubting  whether  the  gas  which  escaped  so  persistently 
actually  proceeded  from  the  iron. 

The.  absorption  of  hydrogen  and  of  either  carbonic 
oxide  as  such  or  of  its  dissociated  elements  has  been  meas 
ured  directly  and  indirectly  by  several    observers,   as 
described  in  §§  176  A  and  190,  pp.  1JO  and  124. 
§  205.  QUANTITY  OF  GAS  EVOLVED. 
A.  From  Spiegel  Reaction. — In  the  reactions  of  the 
acid  Bessemer  process  described  by  Muller    and  King 
(Table  70  A,  p.  128),  from  '08  to  -173$  of  carbon  are  re- 
moved.    Assuming  that  this  escapes  as  carbonic  oxide 
accompanied,  as  in  93,  Table  55,  p.  107,  by  20%  of  other 


"  Private  communication. 

*>  Jmir.-i.  Iron  and  Steel  Inst.,  1881, 1.,  p.  189. 

c  Idem,  1873,  II.,  p,  45J9. 


'.i.  — I.NFLUKNCE  OF  TEMI'EKATL'KE  AND  LENGTH  OP  EXPOSURE  ON  TUB  VOLUMK  AND 
COMPOSITION  OF  GAB  EXTRACTED  IN  VACUO. 


Temper  a- 
ture  . .  . . 

lours 

Vol.  gasp.hr 
CO... 


Cose  1.  Grey  cast-iron. 


Ued. 

0@7 

»"t 

30-4 


lied. 

3&17 

2-G6 


64  1 


Bed. 


14 

18-8 
BB  '.> 


Reel. 


1-37 
40-2 
M  8 


Red.      Red. 

87@S1 
1-08 

88  2  I    88  2 
61-3  I    61-8 


1-37 


Whit.'. 


68-1 
31-9 


aS.    <;n-y  Clht-iron. 


Bad. 


11-87 

go- 

M'S 


White. 


r,7  •  i 
48-9 


2-80 
52- 


White. 

46@r>2 
3-39 
64- 
36-5 


Temperature 

Hours 

Vol.  gas  per  hour. . . 

<COin  gas 


8   Grey  cast-iron. 


Red. 

0@12 

5-9 

19- 
78- 


Full  red. 

13©17 

10-4 


Full. 

sfi. 
1   (-,(-, 


33'3 
66- 


4.  Grey  cast-iron. 


Dull  red. 
0@9 
4  96 

16- 
i    74- 


Red. 

KW-M 
1-57 


25-8 

74- 


High. 

•>!>«!•:.;( 
1-88 


13- 

86- 


5.  Grey  cast-iron. 


0<a3|  4®19|  20®24 
8-4  I  0-1H  I     0  17 


91-2 


Temperature 

Houra 

Vol.  k'as  per  hour. 
*  CO  in  gas  


6.  Cast-iron. 


47- 


129©105 


7.  Bessemer  >t<-rl. 


Bright  red. 


1  4 
67-7 
29-7 


1-3 
41  8 
57-5 


0  ."2 
8  4 
90-1 


Wrought-iron. 


Red. 

4(a»     6       T 
22   0-C     0-2   O'l 


Cases  1  to  4,  grey  cast-iron,  Pnrry,  Jour.  Iron  and  St;  Inst.,  1874,  I.,  p.  99.  3d  and  4th 
wrapped  in  platinum.  6th  case,  grey  cast-iron,  Idem,  p.  93.  6th  case,  grey  cast-iron,  Idem. 
1881,  I.,  p.  190.  7th  case,  Bessemer  steel,  Idem.  8th  case,  wrought-iron,  Graham,  Jour. 
Chein.  8oc.,  1867,  XX.,  p.  285.  These  cases  are  given  also  in  Table  56,  Nos.  5  to  10,  20,  and  26 
In  every  case  the  volume  of  gas  per  volume  of  metal  is  referred  to. 


gases,  from  15  to  38  volumes,  measured  at  the  ordinary 
temperature,  would  escape.  I  give  these  numbers  for  com- 
parison with  the  quantity  observed  to  escape  from  the 
moulds. 

In  a  spiegel  reaction  at  Joliet,  in  which  molten  Spiegel 
was  added  in  the  usual  manner  to  blown  acid  Bessemer 
steel,  only  0-025$  of  carbon  was  oxidized,  which  with  the 
same  assumptions  implies  the  escape  of  about  5  volumes 
of  gas.d 

B.  In  Solidifying.— An  ingot  of  non-rising  acid  Bes- 
semer steel  gave  off  between  1  and  1*5  volumes  of  gas 
during  the  first  twenty  minutes  after  casting,  as  measured 
by  Muller  with  a  crude  meter  at  the  ordinary  temperature. 
Oxygenated  metal  evolved  gas  so  rapidly  that  he  was 
unable  to  measure  it,  but  he  was  convinced  that  it  gave 
off  at  least  thrice  its  own  volume.6    At  1800°  C.  these 
quantities  became  7 '6,  11 '4  and  22 '8  volumes. 

In  five  cases  Muller  calculated  that  the  gas  which  he 
extracted  on  boring  existed  in  the  blowholes  at  a  pressure 
of  from  38  to  69  pounds  per  square  inch  (2 '6  to  5  atmos- 
pheres). Hence,  if  this  same  quantity  had  been  present 
as  gas  when  the  metal  was  somewhat  below  its  freezing 
point,  say  1400°  C.,  its  pressure  would  have  been  from 
about  19]  to  about  346  pounds  per  square  inch.  That  the 
gas  actually  existed  under  considerable  pressure  in  the 
cold  metal  is  further  indicated  by  his  statement  that,  in 
some  cases,  gas  escaped  from  the  boring  hollow  as  soon 
as  the  point  of  the  drill  penetrated  the  first  blowholes. '  The 
high  pressure  which  exists  within  the  ingot  shortly  after 
teeming  occasionally  manifests  itself  by  bursting  the 
strongly  fastened  cover  from  the  mould,  and  spurting  the 
metal  high  in  the  air. 

C.  On  boring  under  water,  etc.,  the  more  porous  the 
metal  and  the  more  finely  it  is  comminuted  by  the  drill, 
the  more  gas  does  it  evolve  in  general.     Thus  Table  73 
shows  that  the  greatest  quantity  of  gas  per  volume  of 
metal  which  any  specimen  of  only  slightly  porous  steel 
evolves  is  smaller  than  the  least  quantity  which  is  evolved 
by  any  very  porous  steel. 


d  F.  A.  Emmerton,  private  communication,  Feb.  4,  1888. 
elron.  Feb.  15,  1884,  p.  138. 
*  Iron,  January  19,  1883,  p,  5<l 


132 


THE    METALLURGY    OF     STEEL. 


TABLE  78.— GASES  OBTAINED  BT  BORING  TVITII  SHARP  DRILL. 


Material. 


Steel 

Very  porous  steel. . 
Slightly  porousstee] 

Solid  steel 

Cast-iron 


Composition. 


Hydrogen. 


52-292  4 
-l  (in-:! 
54-186-4 
52  292-4 
52-1  8C-5 


Nitrogen. 


6-9  48-1 
85-96  9-8208 
68'60l2  745-3 
72  94  6-9  48  ] 

9  245  5 


13  42 
30  97 
26  64 


Carbonic 
Oxide. 


1-65 
0-4 


4  3 


Volume  of  gas 

per 
vol.  metal. 


50 
16 

•11. 


a  Omitting  the  result  (11  volumes)  obtained  by  boring  with  a  dull  drill. 


0-75  volumes  of  gas  is  the  largest  quantity  obtained  by 
boring  with  a  sharp  drill ;  this  is  decidedly  less  than 
escapes  during  the  solidification  of  molten  metal,  and  very 
much  less  than  may  be  extracted  by  heating  in  vacuo. 
With  finer  comminution  six  and  even  eleven  volumes  of 
gas  per  volume  of  metal  have  been  extracted.  The  latter 
is  probably  far  more  than  escapes  during  the  solidification 
of  most  varieties  of  iron,  and  is  abort  as  much  as  any 
observer  save  Parry  has  extracted  from  commercial  iron 
in  vacuo. 

From  one  and  the  same  ingot  Stead  obtained  52  times  as 
much  gas  on  finely  comminuting  it  with  a  dull  drill  as  when 
it  was  cut  into  comparatively  coarse  chips  with  a  sharp  one : 
and  from  cast-iron  a  dull  drill  extracted  eight  times  as 
much  as  a  sharp  one.  (Nos.  16-17,  40-41,  Table  54,  p.  106.) 
Still  finer  comminution,  exposing  still  more  of  the  minute 
pores,  might  set  free  a  still  larger  volume  of  gas.  It  is 
not  clear  that  the  whole  of  the  gas  extracted  by  triturat- 
ing with  a  dull  drill  was  released  thereby  from  simple 
mechanical  retention,  for  this  action  might  well  liberate 
gas  held  in  adhesion.  (See  §  170,  p.  105.) 

D.  On  heating  in  vacuo  Troost  and  Hautefeuille  ex- 
tracted in  no  case  more  than  0'42  volumes  of  gas,  while 
G-raham  extracted  in  one  case  12-55  volumes,  and  Parry 
340  volumes :  but  we  have  seen  reason  for  doubting  his 
results. 

It  is  not  clear  why  Troost  and  Hautefeuille  obtained  so 
little  gas,  for  they  employed  a  temperature  (800°  C.)  ap- 
proaching that  of  Graham's  experiments,  and  they  ex- 
hausted their  specimens  during  very  nearly  eight  days, 
while  his  exposures  were  but  from  one  to  seven  hours. 
Possibly  the  shape  of  the  pieces  treated  may  have  had 
some  influence  :  Graham  employed  fine  wires,  number  23 
gauge  or  about  '025  inch  (0'64mm.)  in  diameter :  Troost 
and  Hautefeuille  treated  cylinders  weighing  500  grammes 
each,  while  Parry  employed  sometimes  "clean  lumps," 
sometimes  drillings.  Possibly,  too,  part  of  the  gas  ob- 
tained by  Graham  came  from  some  source  other  than  the 
iron. 

Clearly  the  gases  which  the  iron  would  have  released  if 
previously  comminuted  form  a  part  of  those  which  it  gives 
off  when  heated  in  vacuo,  and  how  large  a  part  we  can- 
not now  tell. 

§206.  QUANTITY  OF  GAS  ABSORBED.— Graham  and 
Parry  both  found  that  previously  untreated  iron  evolved 
much  more  hydrogen  and  carbonic  oxide  when  heated  in 
vacuo  than  it  reabsorbed  when  heated  in  these  gases. 

Thus,  Parry  extracted  as  much  as  205  volumes  of  hydro- 
gen and  135  of  carbonic  oxide  from  a  specimen  of  cast- 
iron  which  only  reabsorbed  20  volumes  of  hydrogen  and 
which  absorbed  no  carbonic  oxide  :a  and  in  no  case  did  he 


a  10,  46,  60,  Tables  56-7,  pp.  108-9. 


induce  iron  to  absorb  more  than  22 '4  volumes  of  hydro- 
gen and  4-5  of  carbonic  oxide.  Graham  extracted  nearly 
thrice  as  much  gas  on  exhausting  previously  untreated 
iron  as  he  could  later  obtain  from  it  on  twice  exhausting 
it,  first  after  soaking  in  hydrogen  and  then  after  soaking 
in  carbonic  oxide." 

But,  at  least  in  case  of  hydrogen,  it  is  not  certain  that 
in  their  absorption  experiments  the  metal  became  satur- 
ated with  gas  :  possibly  if  soaked  long  enough  in  hydro- 
gen it  might  have  absorbed  as  much  gas  as  it  previously 
emitted. 

Troost  and  Hautefeuille  obtained  results  diametrically 
opposed  to  these.  They  extracted  from  2-3  to  12-8  times 
as  much  hydrogen  and  from  1-3  to  5 '3C  times  as  much 
carbonic  oxide  from  iron  which  had  been  soaked  in  these 
gases  as  from  the  same  specimens  in  their  natural  state. d 

The  hydrogen  which  previously  exhausted  iron  absorbs 
when  soaked  in  this  gas,  is  again  and  usually  fully  ex- 
pelled on  heating  in  vacuo :  specimens  which  absorbed 
20  and  14*1  volumes  by  direct  measurement,  subsequently 
emitted  20  and  13  4  volumes  of  hydrogen.6  A  third  speci- 
men absorbed  13  volumes,  but  when  reheated  in  vacuo 
evolved  only  10'5,  and  further  heating  extracted  no  more 
gas,  perhaps  because  the  temperature  at  which  the  iron 
was  exhausted  was  lower  than  that  at  which  it  soaked 
in  hydrogen.6  In  the  sole  case  in  which  Parry  directly 
observed  the  absorption  of  carbonic  oxide  by  iron,  only 
71$  of  the  absorbed  gas  could  later  be  extracted  in  vacuo  : 
but  part  or  indeed  all  of  the  apparent  absorption  of  car- 
bonic oxide  may  have  been  due  to  the  absorption  of  its 
dissociated  elements. 

§  207.  THE  COMPOSITION  OF  THE  GASES  EVOLVED  BY 
IRON  is  detailed  in  Tables  54  to  57  and  70  A,  and  is  con- 
densed in  Table  70,  pp.  106-9,  129. 

A.  In  general  we  may  divide  the  gases  into  two  groups, 

I.  The  carbonic  oxide  group,  comprising  carbonic  oxide 
and  acid,  and 

II.  The  hydrogen  group,    comprising   hydrogen  and 
nitrogen. 

Carbonic  acid  is  not  found  in  the  boring  gases,  and  it 
occurs  but  sparingly  in  those  from  the  moulds  and  from 
heating  in  vacuo.  It  may  arise  from  the  oxidation  of  part 
of  the  carbonic  oxide  evolved,  and,  as  the  volume  of  car- 
bonic acid  is  the  same  as  that  of  the  carbonic  oxide  from 
which  it  is  derived,  we  may  consider  these  gases  jointly. 

B.  The  carbonic  oxide  group  usually  constitutes  some- 
what more  than  half  of  the  mould  gas  from  basic  Bes- 
semer steel  which  has  been  recarburized  with  spiegeleisen 
or  f  erro-manganese  or  both,  but  less  than  half  of  the  mould 
gases  from  all  other  varieties  of  iron  and  of  the  vacuum- 
extracted  gases  from  all  varieties  of  iron,  and  is  invariably 
almost  completely  absent  from  the  boring  gases,  which  con- 
sist essentially  of  the  hydrogen  group.*    Spiegel-recarbur- 
ized  basic  steel,  be  it  remembered,  is  distinctly  a  scattering 
rather  than  a  rising  steel.     (§  202  C,  Table  71,  p.  129.)    For 
brevity  I  shall  call  "  spiegel-recarburized  "  steel  both  that 
recarburized  with  spiegeleisen  and  that  recarburized  with 


b  Numbers  26,  33,  34,  54  and  67,  Idem. 

c  Or  from  1'05  to  4'3  times  as  much,  if  we  include  the  carbonic  acid  with  tho 
carbonic  oxide. 

<J  See  numbers  11,  15,  16,  17,  18,  30,  31,  36,  47,  50,  53, 61,  63,65,  Tables  56-7. 

e  Numbers  12-43,  13-45,  32-53  and  35-66,  Tables  56-7. 

*  It  has  been  attempted  to  prove  that  the  hydrogen  found  on  boring  proceeds 
not  from  the  pores  thus  laid  bare  but  from  the  decomposition  of  water:  this  will 
be  discussed  in  §  218. 


THE    COMPOSITION    OF    THE    GASES    EVOLVED    BY    IRON.      §  207,  C. 


133 


ferro-manganese,  to  distinguish  them  from  that  recarbur- 
ized  with  ferro-silicon. 

C.  In  iJie  hydrogen  group  hydrogen  almost  invariably 
preponderates,  and  in  the  great  majority  of  cases  greatly 
preponderates  over  nitrogen,  whether  in  mould,  boring  or 
vacuum  extracted  cases,  with  the  single  exception  of  the 
mould-gases  from    spiegel-reoarburized    basic  Bessemer 
steel,  which  usually  contain  far  more  nitrogen  than  hydro- 
gen.    In  most  of  tne  other  classes  the  ratio  of  hydrogen 
to  nitrogen  usually  lies  between  1  '5 : 1  and  6:1.  But,  in  the 
vacuum  extracted  gases  from  all  classes  of  cast-iron  tested, 
and  in  the  mould  gases  from  certain  classes  of  cast-iron 
this  ratio  is  much  higher,  rising  often  to  25 : 1  and  some- 
times to  100  : 1.    Indeed  nitrogen  is  sometimes  reported  as 
wholly  absent. 

D.  Two  varieties  of  iron,  then,  differ  from  the  rest  in  the 
composition  of  the  gases  which  they  yield,  spiegel-recar- 
burized  basic  Bessemer  steel,  whose  mould  gases  are  usu- 
ally exceptionally  free  from  hydrogen,  and  cast-iron,  whose 
vacuum-extracted  and  mould  gases  are  exceptionally  free 
from  nitrogen.   All  the  other  classes  of  iron  tested  evolve 
on  solidifying  and  in  vacuo  gases  of  .one  common  type  of 
composition,  and  on  boring  gases  of  a  second  type,  differ- 
ing from  the  first  in  lacking  carbonic  oxide.     These  nor- 
mal types  and  the  exceptional  ones  just  described  are 
summed  up  in  Table  75.    It  is  to  be  understood  that  these 
numbers  represent  not  the  extreme  but  the  usual  limits  of 
composition. 

TABLE  75. — DOMINANT  TYPES  or  COMPOSITION  OF  GASES  EVOLVED  BY  IEON. 


Metal. 

Time  of  escape. 

Composition  of 
gases. 

Composition  of 
H  group. 

CO 
group. 

H 

group. 

II. 

N. 

Spiegel-recarburized  basic  Besse- 
mer steel. 
Cast-iron  

Normal  compositions,  all  classes 

55@75i 

87@58 
0@53 

18®60 

0®4  3 

25®45* 

42®63* 
47@100 
flft®^ 
95'7@100 

10®  60 

75(899 
92*3100 

^60    90 

40®90 

1@25 
0©  8 

10@40 

In  moulds  
In  vacuo  
\  Moulds  and  vacuo... 
|  Boring  

But  withal  the  compositions  thus  referred  to  a  common 
type  differ  considerably  among  themselves,  and  the  rela- 
tions of  their  variations  to  those  of  the  source,  history, 
composition  and  structure  of  the  mother  metal  are  in 
general  little  understood.  In  many  cases  the  gases  emit- 
ted under  like  conditions  by  similar  specimens  of  the 
same  variety  of  iron  differ  as  much  among  themselves  as 
those  from  different  varieties  of  iron. 

E.  There  are,  however,  certain  strongly  marked  features 
in  the  composition  of  the  gases  evolved  by  cast-iron  and 
by  the  intermediate  and  finished  products  of  the  Besse- 
mer and  open-hearth  processes,  which  characterize  the 
different  stages  of  these  processes.  I  attempt  to  explain 
certain  of  these  in  §  217.  They  are  illustrated  in  figure 
14.  In  sketching  them  I  have  comparatively  few  analyses 
to  guide  me  :  further  light  may  wholly  change  the  aspect, 
and  my  present  sketch  is  merely  provisional. 

Considering  first,  not  the  gas  evolved  in  the  converting 
operation  itself  but  that  which  escapes  when  a  given  pro- 
duct is  removed  from  the  converter  and  allowed  to  solidify 
undisturbed  in  moulds,  we  note  that  the  proportion  of  car- 
bonic oxide  diminishes  with  progressing  decarburization, 
from  about  50$  in  case  of  cast-iron  to  about  44$  in  case  of 
half -blown  Bessemer  metal ;  thence  to  about  27$  in 
case  of  ingot  iron  obtained  by  interrupting  the  blow 
and  without  recarburizing,a  and  thence  to  about  20$  in 


case  of  oxygenated  Bessemer  metal.  It  is  somewhat 
higher  in  case  of  oxygenated  open-hearth  metal,  viz.:— 
about  47$.  (Be  it  remembered  that  Snelusb  and  Tammc 
independently  found  that  the  proportion  of  nitrogen  to 

INFLUENCE  op  STAGE  OF  MANUFACTURE  ON  THE  PROPORTION  OF  CARBONIC: 
OXIDE  IN  THJS  MOULD  AND  OTHER  GASES.    PROVISIONAL  SKETCH. 

Fig.  14 


MOULD  OASES  BESSEMER  STEEL 

LEGEND. 

O  Acid  Bessemer  Process.        0  Basic  Bessemer  Process. 

hydrogen  in  the  gases  escaping  from  the  Bessemer  con- 
verter diminished  greatly  during  the  blow,  in  Snelus'  case 
from  98 '4  :  1  to  30 -7  :  1  and  in  Tamm'sfrom  oo  :  1  to  48 : 1, 
teaching  that,  at  least  in  Tamm's  case,  the  metal  rapidly 
absorbed  hydrogen  from  the  blast  during  the  early  part  of 
the  blow,  perhaps  again  emitting  towards  the  end  of  the 
operation  a  portion  of  that  absorbed  at  its  beginning). 

To  our  oxygenated  metal,  which  of  itself  evolves  gases 
containing  about  20$  of  carbonic  oxide,  we  add  spiegel- 
eisen,  when  of  course  a  violent  evolution  of  gas,  contain- 
ing about  80$  of  carbonic  oxide,  occurs.  As  the  resulting 
steel  gradually  cools,  the  proportion  of  carbonic  oxide  in 
the  escaping  gases  steadily  diminishes  from  80$  during 
the  spiegel  reaction  to  72$  during  early  teeming  and  60$ 
during  solidification  in  case  of  spiegel-recarburized  basic 
Bessemer  steel ;  to  46$  in  the  mould  gases  of  acid  Bessemer 
steel  (in  acid  steel  the  proportion  of  carbonic  oxide  re- 
mains nearly  constant  during  teeming  and  solidification), 
and  32$  in  those  of  silicon-recarburized  basic  steel,  .(No. 
91,  Table  55,  p.  107  ;  No.  7,  Table  70  A,  p.  128).d  Thence  it 
declines  to  13$  in  the  soaking-pit  gases  of  the  solidified 
ingot,  and  finally  thence  to  about  1$  in  the  gases  released 
by  boring  the  completely  cooled  steel.  But  when  this  is 
again  heated  in  vacuo  the  proportion  of  carbonic  oxide 
rises  to  25  or  even  50$,  and  the  gas  found  on  boring  blisters 
in  the  cold  metal  also  contains  a  large  proportion  of  car- 
bonic oxide. 

To  sum  this  up,  the  proportion  of  carbonic  oxide  in  the 
mould  gases  from  products  taken  at  different  stages  of  the 
Bessemer  process  gradually  diminishes,  reaching  a  mini- 
mum in  oxygenated  metal :  turning  from  the  mould  gases 
to  those  of  the  spiegel  reaction  we  find  that  carbonic 
oxide  here  leaps  to  a  maximum,  to  again  decrease  as  the 
recarburized  molten  metal  cools  and  sets,  becoming  nil  in 
the  boring  gases,  but  again  rising  when  the  cold  metal  is 
reheated. 


a  Nos.  88-89,  Table  55,  p.  107.     Carbonic  acid  is  here  included. 


b  Journal  of  the  Iron  and  Steel  Institute,  1871,  II.,  p.  S57. 

c  Ledebur,  Handbuch  der  Eisen-Hiittenkunde,  p.  927. 

d  In  No.  90,  Table  55  =  No.  8,  Table  70A,  the  metal  was  reearburized  with 
ferro-silicon  and  ferro-manganesc,  yet  its  mould  gases  held  from  44  to  64 '6^  of 
carbonic  oxide  :  in  this  case,  however,  the  recarburizing  additions  were  made  in 
the  converter,  and  the  silicon  was  oxidized  by  the  phosphoric  acid  of  the  slag,  so 
that  the  oxygen  of  the  metal  was  chiefly  removed  by  carbon.  In  No.  91,  how- 
ever, the  action  of  the  slag  wag  diminished  by  adding  the  recarbunzers  in  the 
ladle,  and  in  this  case,  as  shown  in  Table  70A,  the  oxygen  of  the  metal  was  taken 
up  by  silicon  and  manganese. 


134 


THE    METALLURGY    OF    STEEL. 


F.  The  influence  of  the  composition  of  the  metal  on 
that  of  its  mould  gases  is  not  in  general  easy  to  trace. 
We  have  indeed  just  noted  that  those  of  cast-iron,  with 
its  high  proportion  of  carbon,  contain  comparatively  little 
nitrogen :   and  the  preceding  paragraph  shows  striking 
changes  in  the  proportion  of  carbonic  oxide,  due  however 
rather  to  the  history  and  treatment  of  the  metal  than  to 
its  composition.    The  gases  of  steel  of  different  composi- 
tions,  but  produced  under  substantially  like  conditions, 
might  be  expected  to  exhibit  corresponding  differences, 
those  of  spring  differing  from  those  of  rail  steel,  and  both 
from  those  of  ingot  iron  :  but  I  have  not  succeeded  in  trac- 
ing such  relations  confidently,  perhaps  because  we  have 
BO  few  analyses  that  the  influence  of  the  composition  of 
the  mother  metal  is  masked  by  that  of  other  variables. 

G.  The  influence  of  the  recarburizing  additions  on 
these  gases  is  more  conspicuous.  We  have  just  noted  that 
if  basic  Bessemer  steel  is  recarburized  with  spiegeleisen, 
its  mould  gases  are  rich  in  carbonic  oxide,  but  not  if  it 
is  recarburized  with  ferro-silicon.   The  influence  of  silicon 
is  farther  illustrated  by  the  fact  that  if  we  add  ferro-sili- 
con to  molten  basic  ingot  iron  which,  though  already 
partially  recarburized  with  2%  of  f  erro-manganese,  scatters 
actively  and  doubtless  gives  off  chiefly  carbonic  oxide  (at 
least  this  has  always  been  the  chief  gas  from  other  speci- 
mens under  like  conditions)  the  scattering  now  completely 
stops,  and  the  mould  gases  hold  only  44.%  of  carbonic  oxide 
plus  acid.     A  few  blowholes  may  still  form  however.* 

§  208.  THE  COMPOSITION  OF  THE  BOKING  AND  VACUUM- 
EXTRACTED  GASES. — I  have  succeeded  poorly  in  tracing 
the  relations  between  the  composition  of  these  gases  and 
the  source,  structure  and  composition  of  the  mother  metal. 

A.  Tfie  boring  gases  from  cast-iron  contain  slightly  more 
carbonic  oxide  than  those  from  steel,  viz.:  from  2'5  to  4'3% 
against  0  to  2'2$.  Those  from  forged  steel  (9, 10, 12  Table 
54,  p.  106)  contain  much  less  hydrogen  and  consequently 
much  more  nitrogen  than  those  from  most  of  the  unf orged 
steels,  and,  in  the  sole  case  in  which  the  blowholes  gases 
have  been  collected  from  the  same  steel  both  before  and 
after  forging,  those  from  the  forged  piece  contained  but 
73*4$  of  hydrogen  against  92  '4$  in  those  before  forging. 
(11  and  12  id.)  This  may  be  accidental,  or  it  may  mean 
that  the  more  diffusive  hydrogen  has  more  fully  escaped 
during  heating  and  forging. 

When  the  same  steel  was  attacked  with  both  dull  and 
sharp  drills,  (16, 17,  id.)  the  dull  drill  released  gas  con- 
siderably richer  in  hydrogen  than  the  other,  viz.:  88'7  vs. 
67-1%.  This,  however,  was  probably  accidental,  perhaps 
due  to  boring  different  portions  of  the  ingot :  for,  a  piece 
of  cast-iron  evolved  gas  of  almost  exactly  the  same  com- 
position when  attacked  by  a  dull  as  when  bored  by  a 
sharp  drill  (40,  41,  id). 

The  composition  of  the  gases  obtained  by  boring  the 
blisters  which  occasionally  form  on  both  weld  and  ingot 
iron,  differs  very  strikingly  from  that  of  the  other  boring 
gases,  containing  27'2  and  70'42$  of  carbonic  oxide  (33 
and  34,  Table  54). 

The  vacuum  extracted  gases  from  cast-iron  have  already 
been  shown  (Table  75,  §  207,  D)  to  hold  less  nitrogen 
than  those  from  other  classes  of  metal :  but  beyond  this 
all  is  uncertain.  Parry  indeed  repeatedly  stated  that  the 
higher  the  temperature  the  larger  the  ratio  of  carbonic 


a  No.  6,  Table  70  A,  S  203,  p.  138. 


oxide  to  hydrogen  in  those  gases.  He  states  that  at  dull 
redness,  and  in  one  place  that  even  at  full  redness  pure 
hydrogen  is  evolved,  and  that  with  further  rise  of  tem- 
perature a  continually  increasing  proportion  of  carbonic 
oxide  escapes  from  both  cast  and  wrought-iron.b  In 
a  careful  study  of  his  published  results,  however,  I 
h'nd  little  support  for  these  assertions.  Thus,  in  Table  72, 
we  note  that  even  at  dull  redness  a  large  proportion  of 
carbonic  oxide  escapes,  and  that  in  two  out  of  the  six 
cases  in  which  the  same  piece  of  iron  is  successively  ex- 
posed different  temperatures  (the  higher  always  following 
the  lower)  the  proportion  of  carbonic  oxide  is  lower  at 
the  higher  temperature.  Nor  can  a  more  constant  relation 
be  traced  between  the  proportion  of  carbonic  oxide  and 
the  progress  of  exhaustion.  There  are  ten  sets  of  cases  in 
this  table,  each  giving  the  composition  of  the  gas  evolved 
during  two  successive  periods  at  constant  temperature. 
In  four  the  ratio  of  carbonic  oxide  to  hydrogen  is  higher, 
in  five  lower  and  in  one  the  same  in  the  later  as  in  the 
earlier  period.  Troost  and  Hautefeuille  moreover  found 
this  ratio  higher  in  case  of  cylinders  of  cast-iron  and  steel. 
and  lower  in  case  of  a  cylinder  of  wrought-iron,  in  the 
early  than  in  the  later  portion  of  their  exposures  to  a 
vacuum :  or,  as  they  put  it,  wrought-iron  retains  carbonic 
oxide  more  tenaciously  than  hydrogen,  while  with  cast- 
iron  and  steel  the  reverse  is  true.0  To  generalize  from  such 
scanty  data  would  be  extremely  rash. 

§  210.  WHAT  CAUSES  BLOWHOLES  ?  We  have  seen  that 
they  are  gas  bubbles  mechanically  retained  by  the  pasty 
metal,  or  held  by  capillarity  to  the  surface  of  the  solidify- 
ing metal.  Their  formation  requires  first  a  metal  of  the 
proper  consistency  to  retain  them  mechanically,  or  one 
whose  surface  in  solidifying  retains  them  by  capillarity : 
and  second  the  evolution  of  gas  within  it.  Why  certain 
classes  of  metal  which  evolve  gas  during  or  at  least  just 
before  solidification  do  not  acquire  blowholes  while  others 
do,  we  cannot  now  and  perhaps  never  can  tell.  Little  is 
recorded  even  of  the  changes  in  consistency  which  dif- 
ferent classes  of  metal  undergo  :  as  to  the  capillary  reten- 
tion of  gas  by  different  classes  of  iron  we  are  completely 
in  the  dark. 

Three  sources  of  gas  bubbles  have  been  suggested  :  1st, 
the  mechanical  retention  of  air  drawn  down  with  the 
stream  of  metal  while  teeming :  2d,  the  formation  of  car- 
bonic oxide  at  the  instant  of  its  escape  by  chemical  .reac- 
tions :  3d,  the  gasification  of  substances  which  had  existed 
in  some  non-gaseous  state  (solution,  chemical  union)  and 
which  had  earlier  been  formed  by  reaction  or  acquired 
from  the  atmosphere  or  the  furnace  gases.  Pourcel 
would  explain  all  the  phenomena  by  the  second  cause, 
while  Muller  victoriously  champions  the  importance  of 
the  third.  Indeed,  we  are  indebted  to  his  zeal  and  elo- 
quence for  most  of  the  evidence  and  reasoning  which  now 
render  the  solution  theory  well-nigh  impregnable  if  taken 
in  its  modified  form,  as  holding  solution  as  an  important 
cause  of  blowholes.  He  has  really  built  it  up,  maintain- 
ing it  almost  single-handed,  with  vigorous  defense  and 
brilliant  attack,  against  his  numerous  and  well  equipped 
opponents. 

The  discussion  which  occupies  the  remainder  of  this 
chapter  leads  to  the  conclusion  that  blowholes  are  chiefly 


b  Jour.  Iron  and  St.  Inst.,  1873,  II.,  p.  429,  431:  Idem,  1874,  I.,  p.  ! 
c  Cofflptes  Rendus,  LXXVL,  p.  534,  1873. 


CAUSES    OF    BLOW-HOLES.      THE    MECHANICAL    THEORY.      §  211. 


135 


due  to  hydrogen  and  nitrogen  escaping  from  solution : 
that  carbonic  oxide  co-operates,  probably  also  escaping  at 
least  in  part  from  solution  but  perhaps  partly  and  pos- 
sibly wholly  from  immediately  preceding  reaction  :  and 
that  the  retention  of  air  mechanically  drawn  down  in  teem- 
ing contributes  but  slightly  in  those  cases  which  have  been 
thoroughly  studied  and  described.  Let  us  first  note  that, 
besides  the  gas  escaping  from  within,  the  metal,  carbonic 
oxide  may  be  formed  by  superficial  action  between  the 
metal's  carbon  and  the  oxygen  of  the  atmosphere  or  of 
the  containing  vessel. 

§  211.  THE  MECHANICAL  THEORY  holds  that  a  large 
quantity  of  air  is  drawn  down  by  the  falling  stream  of 
metal,  just  as  it  is  by  the  falling  water  in  the  trompe,  and 
that  the  metal  is  so  mucilaginous  that  the  air  bubbles  are 
imprisoned.*  Some  air  may  be  thus  drawn  down,  and  it 
may  under  certain  conditions  contribute,  and  perhaps 
largely,  to  the  porosity  of  the  metal. 

It  is,  however,  easy  to  exaggerate  "the  importance  of 
this  action.  It  is  the  liquidity  of  the  falling  stream  of 
water  in  the  trompe  that  enables  it  to  split  up  into  many 
fine  streams,  which  collectively  offer  great  surface,  and 
thus  by  their  friction  drag  down  great  volumes  of  air. 
If  the  steel  is  liquid  it  may  indeed  drag  down  much  air, 
but  should  quickly  release  it :  and  that  blowhole  forming 
steel  often  is  liquid  when  teemed  is  certain.  If  it  is  thick 
and  mucilaginous,  it  will  hold  in  teeming  to  a  single  con- 
tracting stream  with  but  little  surface,  and  hence  will 
drag  but  little  air  with  it.  There  may,  however,  be  inter- 
mediate cases  in  which  the  steel  is  highly  liquid  while 
falling  through  the  air,  and  so  drags  much  air  with  it, 
yet,  becoming  mucilaginous  shortly  after,  may  retain  the 
air  thus  dragged  down  before  it  has  time  to  escape ; 
or  having  become  mucilaginous  it  may  entangle  air 
bubbles  drawn  down  by  later  falling  portions  of  highly 
liquid  steel.  Under  such  special  conditions  it  is  not 
improbable  that  blowholes  may  be  in  large  part  due  to 
mechanical  action.  But  in  many  important  cases  this 
combination  of  circumstances  does  not  exist,  yet  blow- 
holes abound. 

Quite  independently  of  this,  however,  six  collectively 
sufficient  reasons,  which  I  now  detail,  demonstrate  that 
air  mechanically  drawn  down  is  not  a  chief  cause  of  blow- 
holes in  those  cases  which  have  been  most  carefully 
studied  and  most  fully  described. 

1.  The  gases  escaping  before  and  during  solidification 
and  those  found  in  the  blowholes  on  boring  the  cold 
metal  consist  chiefly  of  hydrogen :  their  composition  can- 
not be  readily  explained  by  mechanical  retention." 


»  Proc.  U.  S.  Naval  Inst. ,  XII. ,  3,  pp.  379-382 :  Trans.  Am.  Inst.  Mining  Engrs. , 
XIV.,  p.  133,  1886. 

b  To  reconcile  the  absence  of  oxygen  from  the  blowhole  gases  with  their  sup- 
posed atmospheric  origin,  it  has  been  supposed  that  the  atmospheric  oxygen  has 
been  consumed  in  oxidizing  the  iron :  while  the  atmospheric  moisture  has  been 
assumed  to  be  the  source  of  their  hydrogen.  But  the  ratio  of  hydrogen  to  nitro- 
gen in  these  gases  is  far  greater  than  in  air  saturated  with  moisture.  This 
ratio  can  only  be  accounted  for  by  supposing  that  part  of  the  atmospheric  nitrogen 
has  been  absorbed  by  the  metal:  but  the  moment  this  is  admitted  the  theory 
ceases  to  be  mechanical,  awl  nearly  coincides  with  that  of  solution,  which 
supposes  that  the  gases  evolved  during  solidification  were  originally  of  atmos- 
pheric origin. 

One  cubic  metre  of  air  saturated  with  moisture  at  10  C.  holds9'74grmsof 
aqueous  vapor,  containing  1'08  grms  of  hydrogen,  which  if  set  free  would  occupy 
13-09  litres.  The  air  would  hold  about  790  litres  of  nitrogen  or  about  65-3  vol- 
umes of  nitrogen  to  one  of  hydrogen.  The  gas  evolved  by  iron  during  solidifica- 
tion contains  in  exceptional  cases  as  much  as  58'3$  by  volume  of  hydrogen  with 


II.  Air  escaping  from  mechanical  entanglement  would 
form  spheroidal  cavities,   while   blowholes  are  usually 
lenticular  or  tubular,  with  horizontal  axes  perpendicular 
to  the  cooling  surfaces,  and  arranged  in  concentric  ver- 
tical layers  often  of  decided  regularity. 

III.  It  is  inconceivable  that  the  addition  of  silicon, 
which  often  instantly  and  totally  stops  the  escape  of  gas 
bubbles,  should  mechanically  prevent  the  escape  of  me- 
chanically held  air. 

IV.  Mechanically  held  air  would  escape  continuously, 
in  gradually  and  regularly  diminishing  quantity,  while 
in  many  cases  steel  lying  perfectly  tranquil  for  a  time, 
only  begins  to  evolve  gas  after  freezing  reaches  a  certain 
point  (§  202,  E.). 

V.  Increase  of  pressure  completely  arrests  the  evolu- 
tion of  gas  from  molten  metal :    it    might   retard  but 
it  certainly  could    not    completely  stop  the  escape  of 
gas  which  was  simply  mechanically  entangled  and  in- 
soluble.    Conversely,  a  fall  of  pressure  causes  a  lively 
escape  of  gas  from  previously  perfectly  tranquil  molten 
metal,   which  could  not  have  remained  tranquil  had  it 
held  mechanically  suspended  gas.    (§§  188,  C.,  p.  124; 
202,  D). 

VI.  It  is  inconceivable  that  molten  steel  should  hold 
purely  mechanically  anything  like  the  quantity  of  gas 
which  it  evolves  in  solidifying.     It  is  generous  to  admit 
that  the  highly  fluid  metal  could  hold  mechanically  one 
tenth  of  its  own  volume  of  gas  as  gas,  even  for  an  instant: 
yet  Muller  found  that  even  comparatively  quiet  steel 
evolved  in  the  moulds  between  7'6  and  11'4  times  its  own 
volume  of  gas,  measured  at  1,800°  C.,  while  oxygenated 
metal  evolved  about  23  times  its    own   volume.      (Cf. 
§  205,   B.)     The  mechanical  theory  then  breaks  down 
quantitatively  as  well  as  qualitatively,  and  we  must  call 
on  chemistry  or  physics  or  both.     Some  of  the  reasons 
which  support  the  reaction  and  solution  theories  further 
weigh  against  the  mechanical  hypothesis. 

The  fact  that  the  top  of  the  ingot  is  more  porous  than 
the  bottom  is  adduced  to  support  the  mechanical  theory. 
But  from  whatever  source  gas  is  evolved,  whether  from 
mechanical  retention,  solution  or  reaction,  that  which  is  not 
held  down  mechanically  or  by  capillarity  will  of  course 
rise  to  the  upper  part  of  the  ingot. 

Pasty  metal  would  also  flow  down  from  the  top  to  feed 
contraction  cavities.  In  a  freezing  ice  bottle,  though  the 
water  be  absolutely  free  from  bubbles,  the  ice  formed  from 
it  is  porous,  and  under  certain  conditions  the  pores  are 
much  more  abundant  above  than  below.  Moreover,  if  the 
gases  evolved  by  iron  escape  from  solution,  the  ferrostatic 
pressure  at  the  bottom  of  the  ingot  would  tend  to  retain 
them  in  solution. 

Let  us  now  turn  to  the  other  sources  of  gas. 


but  0'5<S  of  nitrogen,  or  116'6  :  1.  Hence  this  gas  holds  116'6  x  65'3  =  7,614 
times  as  much  hydrogen  per  unit  of  nitrogen  as  saturated  air  does. 

But  we  need  not  turn  to  exceptional  compositions.  The  ratio  of  hydrogen  to 
nitrogen  in  the  gases  evolved  from  iron  and  steel  is  usually  from  1'5  :  1  t.o  6  :  1, 
or  from  about  100  to  400  times  as  great  as  in  air  saturated  with  moisture  at  10' 
C.  (§  207,  C.)  At  higher  temperatures  air  can  hold  more  moisture  than  at  10°  C. 
At  35°  C.  (95°  P.)  it  can  hold  about  four  times  as  much :  but  even  then  its  ratio  of 
hydrogen  to  nitrogen  is  only  from  one  twenty-fifth  to  one  one-hundredth  of  that 
usual  in  the  gases  from  iron :  and,  moreover,  the  air  is  very  rarely  saturated 
with  moisture  except  in  the  most  moist  climates. 

It  is  hardly  supposable  that  the  hydrogen  arises  from  moisture  in  or  around  the 
moulds,  for  in  many  cases  these  were  of  iron,  and  water  if  present  would  have 
been  visible:  we  can  hardly  believe  that  Muller  would  be  so  grossly  careless  as  to 
allow  his  work  to  be  thus  completely  vitiated. 


136 


THE    METALLURGY    OF    STEEL. 


§  212.  THE  REACTION  AND  SOLUTION  THEORIES." 

Numerous  analyses  of  the  gases  escaping  from  iron 
under  a  great  variety  of  conditions  show  that  those  which 
form  blowholes  escape  in  large  part  from  previous  solution. 

But  quite  independently  of  this  a  mass  of  cogent 
cumulative  evidence  leads  to  the  same  conclusion.  Its 
chief  points  are  that  the  escape  of  gas  from  both  molten 
and  solid  iron  can  be  stimulated  and  arrested  by  purely 
physical  means,  and  in  case  of  molten  iron  by  independ- 
ent chemical  means,  both  of  which  almost  certainly  act 
through  the  metals  solvent  power :  that  gas  escapes  and 
blowholes  form  when  no  gas-forming  reaction  is  probable : 
and  that  the  phenomena  of  the  escape  and  absorption  of 
gas  in  general  by  iron  are  very  closely  analogous  to  those 
of  its  escape  and  absorption  by  other  substances  in  which 
it  is  undoubtedly  in  solution,  if  there  be  such  a  thing  as 
solution. 

From  the  fact  that  only  nitrogen  and  hydrogen  are 
found  on  boring  cold  blowhole-holding  iron,  and  from 
other  suggestive  facts,  it  has  been  inferred  that  these 
gases  alone  cause  blowholes :  but  this  inference  is  not 
justified.  There  is  good  reason  to  believe  that  carbonic 
oxide  co-operates  in  forming  blowholes  :  this  granted,  it 
it  is  uncertain  whether  it  escapes  from  solution,  or  re- 
action, or  both. 

§§  213  to  218  chiefly  present  the  evidence  and  reasoning 
which  show  that  a  part  at  least  of  these  gases  escapes 
from  solution,  §  219  the  reasons  for  regarding  reaction 
as  a  contributory  cause. 

a  Many  may  hold  that,  iu  the  ultimate  analysis  of  our  phenomena,  all  gases 
which  escape  from  molten  liquids,  save  the  trifling  quantity  held  by  capillary  attrac- 
tion, are  formed  at  the  instant  of  escape  by  chemical  reaction  of  one  kind  or 
another:  that  before  their  escape  they  had  been  held,  if  partly  or  even  chiefly  by 
physical  forces,  still  at  least  partly  by  chemical  ones;  that  in  escaping  the  gas 
breaks  its  chemical  bonds,  which  in  itself  implies  a  chemical  reaction.  Indeed, 
even  those  who  regard  chemical  union  and  solution  as  radically  different  are 
sometimes  puzzled  to  draw  the  line,  and  some  of  them  class  apparently  typical 
cases  of  solution  as  instances  of  chemical  union :  e.  g.  holding  that  carbonic  anhy- 
dride (C0.2)  is  not  absorbed  as  such  by  water,  but  enters  it  through  a  chemical 
reaction,  CO2  +  H20  =  H2C03,  and  that  it  is  generated  at  the  instant  of  its 
escape  from  soda  water  by  the  reverse  reaction.  In  this  view  all  the  gases  emitted 
by  molten  iron,  save  the  slight  proportion  mechanically  held,  are  generated  by 
reaction  at  the  instant  of  escape.  Others  again  may  consider  that  hydrogen  and 
nitrogen  are  held  by  purely  physical  bonds,  and  hence  that  no  chemical  reaction 
is  directly  connected  with  their  escape,  and  that  this  may  be  true  of  a  portion  of 
the  carbonic  oxide  evolved,  while  another  may  be  generated  by  reaction  at  the 
instant  of  escape.  Still  others  may  hold  that  nitrogen  and  hydrogen  are  in  typical 
chemical  uuiou  with  the  metal,  or  alloyed  with  it,  but  that  carbonic  oxide  cannot 
be,  and  that  it  may  either  exist  in  and  escape  from  a  state  of  purely  physical 
solution,  or  escape  while  being  formed  by  reactions. 

In  the  first  view  the  important  question  is  "  are  blowholes  due  to  hydrogen  and 
nitrogen,  or  to  carbonic  oxide  ?"  In  the  second  and  third  views  this  question 
remains,  and  a  second  one  arises,  "  If  by  carbonic  oxide,  does  this  gas  escape 
from  previous  solution,  or  is  it  generated  at  the  instant  of  escape  by  reaction  ?" 
The  Subject  admits  different  lines  of  treatment  corresponding  to  these  different 
standpoints;  but  space  forbids  this.  Practically  I  believe  that  the  convenience  of 
a  plurality  of  readers  will  be  complied  with  by  assuming  that  hydrogen  and 
nitrogen,  except  in  so  far  as  they  are  held  mechanically  or  by  capillarity,  exist  in 
iron  in  solution,  if  at  all,  and  hence  if  they  escape  it  must  be  from  solution,  em- 
ploying this  word  purposely  in  a  vague  generic  sense,  including  all  the  non-gaseous 
states,  whether  chemical  or  physical,  chemical  union,  alloying,  adhesion:  and  by 
admitting  that  it  is  quite  different  with  carbonic  oxide.  It  is  certain  that  this  gas 
may  escape  from  immediately  preceding  reaction:  but  we  must  for  the  present 
treat  it  as  an  open  question  whether  it  can  also  exist  in  solution.  This  plan  of 
treatment  has  its  manifest  drawbacks,  but,  with  the  existing  limitations  ot  space 
and  language  I  see  no  better. 

The  most  ardent  advocate  of  the  solution  theory  must  admit  that  it  is  conceiv- 
able that  carbonic  oxide  may  escape  from  solution.  For  if  this  gas  dissolves,  still 
if  its  formation  is  continued  the  metal  must  eventually  become  saturated  with  it, 
and  should  more  form  it  must  escape  as  fast  as  formed. 

These  questions  are  of  practical  importance,  for  the  means  of  preventing  the 
escape  of  a  previously  dissolved  gas  may  naturally  be  expected  to  differ  from 
those  appropriate  for  preventing  the  oxidation  of  carbon  and  the  new  formation 
of  carbonic  oxide;  and  the  means  for  preventing  the  absorption  and  evolution  of 
carbonic  oxide  on  the  one  hand  and  of  hydrogen  and  nitrogen  on  the  other  may  be 
expected  to  differ, 


I  must  again  point  out  that,  though  mechanical  reten- 
tion is  not  an  important  cause  of  the  presence  of  blowhole- 
forming  gases  in  the  cases  which  we  will  now  study,  it 
may  be  under  other  conditions. 

§  213.  EVIDENCE  FROM  THE  COMPOSITION  OF  THE 
GASES. — We  have  seen  in  §  207  B,  and  Tables  55-75,  that 
the  hydrogen  group  always  forms  a  large  and  usually  the 
chief  portion  of  the  mould  gases  from  rising,  i.  e.  blow- 
holes forming  as  well  as  from  most  of  the  classes  of  non- 
rising  steel,  of  the  soaking  pit  gases,  and  of  the  gases  ob- 
tained on  heating  in  vacuo  ;  and  that  it  is  always  practic- 
ally the  sole  constituent  of  the  gases  found  in  the  blow- 
holes themselves  on  boring :  in  brief  the  gases  exhaled 
before,  during,  and  after  the  period  when  blowholes  form 
are  largely  of  this  group.  The  chain  of  evidence  could 
hardly  be  more  complete.  It  is  next  to  certain  then  that 
hydrogen  and  nitrogen  are  an  important  cause  of  blow- 
holes ;  that  their  proportions  cannot  be  mechanically 
accounted  for  ;b  -that  they  come  from  no  reaction  in  the 
common  sense  of  the  word ;  and  hence  that  they  arise 
from  previous  solution  in  the  sense  here  employed. 

But,  if  more  closely  studied,  some  features  of  the  com- 
position of  the  mould  gases  suggest  that  hydrogen  and 
nitrogen  play  an  even  more  important  part  in  the  forma- 
tion of  blowholes  than  at  first  appears,  and  that  the  car- 
bonic oxide  which  is  often  abundantly  present  in  these 
mould  gases  is  connected  rather  with  the  early  escape  of 
gas,  which  causes  harmless  frothing  and  scattering,  than 
with  the  later  escape  during  solidification,  which  causes 
rising  and  blowholes.  (§§  201,  A  ;  207,  E.) 

I.  The  proportion  of  carbonic  oxide  is  very    much 
larger  in  the  early  than  in  the  late  escaping  mould  gases, 
constantly  decreasing  from  say  80%  in  the  spiegel  reaction 
gases  to  say  13$  in  those  of  the  soaking  pit. 

II.  Spiegel-recarburized  basic  Bessemer  steel,  the  only 
variety  of  iron  whose  mould  gases  are  known  to  be  usually 
rich  in  carbonic  oxide,  scatters  much  but  rises  little,  and 
is  relatively  free  from  blowholes. 

Moreover,  as  the  scattering  diminishes,  so  does  the  pro- 
portion of  carbonic  oxide  in  the  gases  evolved.  Thus,  in 
numbers  84-5  and  86-7,  Table  55,  page  107,  the  propor- 
tion of  carbonic  oxide  in  the  gases  evolved  by  basic  steel 
is  much  less  after  solidification  than  in  the  gases  from  the 
same  steel  during  teeming,  which  is  the  scattering  period, 
to  wit,  54'1  and  Q2'V>%  against  81 -7  and  77 '9$.  If  we  add 
ferro-silicon  to  the  scattering,  carbonic  oxide  evolving 
basic  steel,  the  scattering  and  the  proportion  of  carbonic 
oxide  per  100  of  gas  evolved  both  decrease,  while  the 
rising  may  continue.  (§  202  C.  :  §  207  E.,  G.) 

Further,  there  is  reason  to  believe  that  the  very  treatment 
which  causes  this  basic  steel  to  scatter  also  causes  it  to 
evolve  gas  rich  in  carbonic  oxide.  For  it  is  stated  that 
basic  ingot  iron  produced  by  interrupted  blowing  and 
without  recarburizing,  from  which  our  spiegel-recarburized 
basic  steel  may  be  made,  neither  scatters  nor  evolves  gas 
rich  in  carbonic  oxide  (Table  71,  p.  129).  If  recarburized 
with  spiegeleisen  it  does  both,  if  with  ferro-silicon  it  does 
neither.  (§  202  C,  p.  129.) 

We  will  now  consider  the  evidence  which,  independ- 
ently of  the  composition  of  the  gases,  shows  that  they 
arise  in  large  part  from  solution. 

§  214.  EVIDENCE  FROM  ANALOGY. — The  solubility  of 


b  Bee  foot  note  to  §  311,  J).  136. 


BLOWHOLES :      THE    REACTION    AND    SOLUTION    THEORIES.      §  213. 


137 


gases  in  solids  and  liquids  rises  with  the  pressure  :  in 
solids  and  most  liquids  it  falls  with  rising  temperature  : 
it  is  far  greater  in  liquids  than  in  solids :  hence  most 
liquids  in  solidifying  expel  much  of  their  dissolved  gases. 
Thus  water  in  freezing  expels  air ;  silver  spits,  expelling 
its  oxygen  ;  copper  and  nickel  expel  gas,  and  blowholes 

Fig.  15,  CONJECTURED  GENERAL  SHAPE  OF 
CURVE  OF  SOLUBILITY  OF  GASES  IN  IRON. 


TEMPERATURE. 


FREEZING  POINT  OF  IRON. 


Fig.  15. 

form  within  them.  Figure  15  sketches  the  influence  of 
temperature  on  solubility,  a  gentle  rise  as  the  tempera- 
ture falls  towards  the  freezing  point,  a  sudden  fall,  another 
gentle  rise  as  the  temperature  declines  still  farther.  The 
absorption  and  expulsion  of  gases  by  solids  and  liquids, 
at  first  rapid  then  gradiaally  slackening,  is  extremely  pro- 
tracted, probably  ceasing  asymtotically* :  agitation  hast- 
ens the  expulsion  of  gas  from  liquids.  The  gas  expelled 
by  freezing  water  forms  lenticular  blowholes,  their  longer 
axes  normal  to  the  cooling  surfaces,  and  the  blowholes 
themselves  lie  in  regular  layers  parallel  with  those  sur- 
faces. This  is  probably  true  of  other  freezing  liquids. 

Mark  now  how  accurately  these  phenomena  are  repro- 
duced by  iron.  That  the  solubility  of  gases  in  both 
molten  and  solid  iron  rises  with  the  pressure  has  already 
been  shown,  by  the  ebullition  and  tranquillity  produced 
by  lowering  and  raising  the  pressure  to  which  molten 
metal  is  exposed  (§  188  C,  p.  124,  §  202  D),  and  by  the  ex- 
traction of  hydrogen,  carbonic  oxide  and  nitrogen  from 
solid  iron  heated  in  vacuo.  and  their  reabsorption  when  the 
first  two  gases  and  ammonia  are  exposed  under  pressure 
to  the  hot  metal  (§§  172,  p.  106,  203).  We  have  seen  that 
agitation,  as  in  pouring  and  stirring,  expels  gas  from  molten 
iron  as  from  other  gas-charged  liquids  (§  202  E):  and  by  its 
blowholes,  and  better  by  the  violent  escape  of  gas  on  very 
sudden  cooling,  that  iron  like  other  liquids  expels  gas  in 
solidifying  (Id.).  We  have  noted  the  protracted  escape 
of  gas  from  hot  solid  iron  in  the  moulds,  in  the  soaking  pit, 
and  in  vacuo  (§§  202  F,  203).  Finally  the  shape  and  posi- 
ition  of  the  cavities  in  ingot  iron  and  steel,  normal  to  the 
cooling  surface,  resembles  those  of  the  bubbles  in  a  frozen 
ice  bottle  far  more  closely  than  we  could  expect,  in  view 
of  the  very  different  conditions  under  which  water  and 
iron  solidify,  and  of  the  differences  in  their  physical  prop- 
erties, thermal  conductivity,  specific  heat,  dilatation,  vis- 
cosity, etc.,  which  might  well  modify  the  shape  and  dis- 
tribution of  the  gas  bubbles  profoundly.  (§  216.) 

Three  of  these  phenomena,  the  expulsion  of  gas  by 
agitation,  the  shape  and  position  of  blowholes,  and  the 
protracted  escape,  may  be  harmonized  more  or  less  com- 
pletely with  the  reaction  theory,  though  to  my  mind  they 
harmonize  decidedly  better  with  that  of  solution.  I  will 
not  say  that  the  phenomena  of  the  expulsion  and  reten- 


»  Charcoal  continues  to  absorb  oxygen  from  the  air  for  at  least  a  month,  though 
most  of  it  is  absorbed  in  a  few  hours  or  even  seconds.  Though  gas  at  first  escapes 
violently  from  aerated  water  when  uncorked,  bubbles  long  continue  to  attach 
themselves  to  the  sides  of  the  vessel  which  contains  it, 


tion  of    gas  by  fall    and  rise    of    pressure,    of    its    ex- 

mlsion  on  solidification,    and  of    its  protracted  escape, 

cannot  be  harmonized  with  the  former  theory,  yet  their 

accord  with  it  must  be  forced,  harsh  and  strident,  while 

with  the  solution  theory  it  is  so  harmonious,  smooth  and 

lowing  that,  even  without  the  irresistible  argument  of  the 

omposition  of  the  gases,  this  theory  in  its  restricted 

sense  would  almost  compel  acceptance. 

Two  points  suggest  themselves  in  which  the  behavior  of 
iron  might  at  first  be  thought  to  differ  from  that  of  other 
solvents.  Half  blown  Bessemer  metal  evolves  gas  copi- 
ously :  it  therefore  seems  to  be  supersaturated :  if  its 
solvent  power  falls  on  solidification  it  should  still  evolve 
gas  and  rise :  but  it  is  stated  that  it  yields  solid  ingots.b 
Rising  however  requires  not  only  the  escape  of  gas  during 
solidification  but  that  the  metal  shall  be  of  a  certain  con- 
sistency" and  structure,  which  it  may  be  inferred  are  lack- 
ing in  this  case. 

Again,  the  escape  of  carbonic  before  and  during  solidi- 
fication implies  that  the  metal  is  supersaturated  with  this 
gas :  we  therefore  expect  to  find  it  in  the  blowholes  on 
boring  the  cold  metal.  Its  absence  is  referred  in  §  217 
to  its  reabsorption  or  decomposition. 

A.  Temperature  and  Solvent  Power. — While  freezing 
lowers  the  solvent  power  of  iron  as  of  other  solvents  for 
gases,  there  is  no  conclusive  evidence  that,  at  tempera- 
tures which  do  not  include  the  freezing  point,  its  solvent 
power  follows  the  usual  law  and  rises  with  fall  of  tem- 
perature :  nor  on  the  other  hand  is  there  good  reason  to 
doubt  that  it  does.  This  uncertainty  is  not  surprising  in 
view  of  the  complexity  of  our  conditions,  of  the  proximity 
of  molten  iron  to  its  freezing  point,  of  the  long  range  of 
temperature  through  which  freezing  may  extend,  and  of 
our  limited  experimental  data.  False  inferences  from 
our  available  evidence  may  be  prevented  by  pointing  out 
how  inconclusive  it  really  is.  This  I  now  attempt. 

Parry's  observation"  that  the  evolution  of  gas  from 
solid  iron  could  always  be  completely  stopped  by  lower- 
ing the  temperature  from  whitness  to  redness,  and  always 
started  afresh  when  the  temperature  again  rose,  seems  to 
indicate  that  the  solvent  power  rises  with  falling  tempera- 
ture :  for  the  loss  of  porosity  when  the  temperature  falls 
to  redness  is  not  complete  enough  to  arrest  the  escape  of 
gas  totally.  Unfortunately,  we  are  in  doubt  whether  the 
gas  obtained  at  high  temperatures  came  from  his  metal." 

If  it  be  true  that  the  tendency  to  rise  is  stronger  in  cool 
than  in  moderately  hot-blown  Bessemer  steel  (§  202  A, 
p.  127),  it  would  indicate  that  the  former  absorbs  or  retains 
more  gas  at  the  lower  temperature  of  its  manufacture  than 
the  latter,  and  hence  has  more  to  evolve  in  setting,  which 
again  would  support  the  contention  that  the  solubility 
falls  with  rising  temperature.  But  here  the  phenomena 
are  so  complicated  by  differences  of  composition  accom- 
panying if  not  causing  these  differences  in  temperature, 
and  by  the  proximity  to  the  freezing  point,  at  which  the 
solubility  curve  reverses,  that  we  cannot  attach  great 
weight  to  them. 

On  the  other  hand,  excessively  hot-blown  steel  is  said  to 
rise  excessively.  This  is  said  to  be  due  to  a,  wholly  dif- 
ferent cause,  a  reaction  between  the  carbon  of  the  metal 


b  Table  71,  §  202,  p.  1S9. 

c  §  201  A,  p.  126. 

d§  203. 

e|  176  C,  pp.  Ill,  114. 


138 


THE    METALLURGY    OF    STEEL. 


and  the  oxidized  surfaces  of  the  mould,  which  the  high 
temperature  causes  the  metal  to  wet.  Carbonic  oxide  is 
thus  generated,  causing  rising  and  external  blowholes. 

To  test  this  Walrand  polished  the  interior  of  one  cast- 
iron  mould,  removing  all  oxide,  and  left  a  second  in 
the  usual  oxidized  condition.  A  lot  of  superheated  Besse- 
mer metal  poured  into  both  yielded  a  "  perfectly  sound" 
ingot  in  the  former  but  externally  honeycombed  ones  in 
the  latter.*  We  may  reasonably  question  whether  Wal- 
rand has  here  hit  the  true  cause.  This  formation  of  ex- 
ternal blowholes  occurs  in  hot-blown  basic  ingot  iron,  even 
if  it  hold  but  0-07$  of  carbon,  and  it  is  not  clear  that  the 
little  carbon  present  would  be  attacked  by  the  oxide  of 
the  moulds  with  sufficient  energy  to  account  for  these 
blowholes.  It  is  highly  improbable,  to  say  the  least,  that 
the  oxide  of  the  mould  could  oxidize  enough  of  the  metal's 
carbon  to  produce  the  violent  frothing  which  occurs  be- 
fore solidification,  for  this  probably  calls  for  the  oxida- 
tion of  at  least  0'01$  of  carbon  from  the  whole  ingot :  as 
the  mould  can  only  attack  the  outside  of  the  ingot,  a 
much  larger  local  decarburization  seems  to  be  implied. 

Parry's  observation  that  iron  absorbs  hydrogen  most 
readily  at  high  temperatures  might  suggest  that  the  solu- 
bility of  this  gas  rises  with  the  temperature.  (§  176  A, 
p.  110. )  But  Graham  found  a  comparatively  low  tempera- 
ture most  favorable,  and  Parry's  observation,  even  if  un- 
contradicted,  would  be  more  reasonably  interpreted  as 
meaning  that  iron,  even  though  its  total  absorbing  power 
be  less,  at  first  absorbs  hydrogen  more  rapidly  at  a 
relatively  high  temperature  because  more  porous. 

The  fact  that  Graham  and  Parry  found  that  iron  evolves 
much  more  gas  in  vacuo  than  it  can  be  made  to  reabsorb 
(§  206)  might  suggest  that  at  the  exalted  temperature  of 
its  manufacture  its  power  of  dissolving  gas  is  greater  than 
at  the  relatively  low  temperature  of  their  absorption 
experiments,  i.  e.  that  its  solvent  power  rises  with  the 
temperature.  But  their  results  are  directly  opposed  by 
those  of  Troost  and  Hautef euille :  and,  indeed,  during 
manufacture  conditions  other  than  temperature  (e.  g.  the 
presence  of  nascent  gases,  §  172, 178  B,  p.  106,)  may  have 
favored  the  absorption  of  gas. 

The  fact  that  molten  iron  often  evolves  gas  in  the  ladle 
and  moulds  in  spite  of  its  constantly  growing  cooler,  at 
first  suggests  that  the  solubility  of  the  escaping  gas  is 
diminishing  instead  of  rising  with  the  falling  temperature. 
When  agitation,  due  to  pouring,  and  local  solidification 
do  not  suffice  to  explain  this  escape  of  gas  it  may,  I  think, 
be  reasonably  ascribed  to  the  slowness  with  which  super- 
saturated metal  expels  its  excess  of  gas,  and  occasionally 
to  a  slowly  terminating  reaction  between  the  carbon  of  the 
metal  and  the  oxygen  of  the  moulds,  of  the  atmosphere, 
or  of  the  metal  itself.  The  agitation  due  to  the  escape  of 
such  nascent  carbonic  oxide  might  well  liberate  the  nitro- 
gen and  hydrogen  which  accompany  it. 

B.  Protracted  and  Deferred  Escape  of  Gas. — Were  we 
ignorant  of  the  composition  of  the  gases,  we  might  refer 
the  protracted  escape  of  gas,  continuing  from  the  time  of 
the  spiegel  reaction  up  to  and  during  solidification,  either 
on  the  one  hand  to  gradually  diminishing  solubility,  or  pro- 
tracted escape  from  a  supersaturated  solution,  or  on  the 
other  to  a  persistent  and  slowly  perfected  reaction  be- 
tween carbon  and  oxygen.  Such  a  protracted  reaction 


Troilius,  Van  Nostrand's  Eng.  Mag.,  XXXIII.,  p.  365,  1885. 


may  be  due  either  to  imperfect  mixing,  or  to  the  inability 
of  the  carbon  and  oxygen  to  unite  immediately,  so  that, 
though  perfectly  mixed  and  brought  into  contact  mole- 
cule with  molecule,  their  union  is  not  perfected  for  hours. 
It  seems  very  improbable  that  the  phenomena  are  due  to 
imperfect  mixing.15  The  metal  is  twice  poured,  from  con- 
verter to  ladle,  from  ladle  to  moulds :  the  ebullition  which 
occurs  both  before  and  after  teeming  should  greatly  aid 
mixing.  But,  passing  Ihis  by  as  inconclusive,  we  have  the 
fact  that  if  a  charge  of  steel,  from  which  this  protracted 
escape  of  gas  would  naturally  occur,  be  thoroughly  mixed 
by  raising  the  converter  and  blowing  air  through  it  after  the 
spiegel  reaction,  the  same  protracted  escape  of  gas  occurs." 
There  must  be  a  cause  other  than  imperiect  mixing  to 
explain  protracted  escape  of  gas  when  mixing  is  perfect. 
Is  it  tardiness  in  reacting,  or  slow  escape  from  solution  ? 
It  may  be  the  former,  though  no  one  has  pointed  out  a 
chemical  phenomenon  which  is  known  to  be  strictly  anal- 
ogous. The  slow  parting  of  precipitates/  the  slow 
growth  of  crystals,  have  been  suggested :  but  in  both 
cases  purely  physical  and  mechanical  reasons  suffice  to 
explain  the  tardiness.  The  fine  precipitate,  if  instantane- 
ously formed,  may  be  held  to  part  slowly  because  fine, 
because  its  particles  are  of  such  form  and  texture  that 
they  adhere  to  and  hook  into  each  other,  slowly  coalesce, 
and  long  remain  too  small  to  settle  rapidly :  friction  op- 
poses gravitation.  Our  protracted  gas  escape  cannot  be 
of  this  nature,  a  gradual  rising  of  mechanically  suspended 
gas  bubbles,  too  minute  to  coalesce  and  rise  rapidly,  be- 
cause their  collective  volume  (from  7  to  23  times  that  of 
the  containing  metal,  §  211,  "VI.)  is  far  greater  than  could 
be  thus  suspended.  The  crystal  grows  slowly,  probably 
because  gravity  and  diffusion,  but  feebly  overcoming  fric- 
tion and  inertia,  can  but  slowly  move  the  molecules  from 
distant  regions  across  the  solution  to  the  crystal' s  grow- 
ing apex.  In  both  cases,  then,  force  has  to  impel  matter 
over  considerable  distances  :  in  neither  do  we  know  that 
the  reaction  is  not  instantaneous.  Eeaction  whose  im- 
mediate effects  are  of  a  nature  which  renders  them  visible 
as  soon  as  produced  and  without  waiting  for  subsequent 
motion  or  coalescing  of  their  products,  often  appear  to 
be  well-nigh  instantaneous.  Thus  when  a  drop  of 
sulphocyanide  is  added  to  a  dilute  ferric  solution,  the  full 
intensity  of  coloring  is  very  quickly  reached." 

b  The  beterogereousness  of  steel  ingots  is  often  adduced  as  evidence  of  imperfect 
mixing.  There  can  be  little  doubt  that  is  in  large  part  the  result  of  segregation 
during  cooling  and  solidification,  though  under  certain  conditions,  as  when  cold 
additions  are  made  to  molten  metal,  it  may  be  exaggerated  by  imperfect  mixing. 
Others  have  pointed  to  the  protracted  stirring  needed  to  uniformly  mix  black  and 
white  paint,  and  to  the  veins  and  striae  in  imperfect  glass  as  evidence  that  steel 
can  be  rendered  homogeneous  only  by  long  stirring.  But  it  is  manifestly-  unfair 
to  liken  the  mixing  of  seething  highly  fluid  steel,  whose  fluidity  is  attested  by  the 
sharp  outlines  of  its  stream,  by  the  tiny  gas  bubbles  which  are  able  to  part  it  and 
travel  up  through  it  when  it  effervesces,  by  the  minute  and  quickly  propagated 
waves  which  stirring  produces, — it  is  most  unfair  to  liken  it  to  the  mixing  of  dif- 
ferent colored  paints,  which  consist  of  finely  divided  solids  mechanically  suspended 
in  an  initially  viscous  liquid:  their  coloring  matter  is  solid.  Mark  rather  what 
brief  stirring  suffices  to  mix  a  drop  of  ink  with  a  tumbler  of  water  so  thoroughly 
that  the  eye  can  detect  no  sign  of  heterogeneousness.  Does  glass  on  the  punty 
seethe  and  splash  and  foam  ?  Does  the  blower's  breath  pass  through  in  fine  bub- 
bles ?  Shall  we  gauge  the  action  of  water  on  the  hurdy-gurdy,  of  ether  in  the 
atomizer,  by  that  of  cold  molasses  3  (Journ.  Iron  and  St.  Inst.,  1881,  II.,  p.  373.) 

cMiiller,  Stahl  und  Eisen,  IV.,  p.  77,  1884  :  Iron,  Feb.  22,  1884,  p.  161.  In 
treating  a  basic  charge  he  "  had  the  converter  raised  for  several  seconds  after  the 
spiegel  reaction,  when  the  steel  did  not  behave  differently  in  tto  least  in  the  ladle 
and  mould."  and  mould."  A  still  more  striking  case  is  given  in  §  331  Killing. 

d  Ledebur,  Iron,  Nov.  llth,  1883,  p.  462. 

e  This  is  an  elaboration  and  extension  of  Mailer's  argument,  Stahl  und  Eisen, 
IV.,  pp.  76  et  seq  :  Iron,  Feb.  33d,  1884,  p.  161. 


RATIONALE    OF    THE    QUIETING    EFFECT    OF    SILICON.      §  215. 


139 


Metal,  which  has  been  perfectly  quiet  after  the  end  of 
the  spiegel  reaction,  remains  still  for  a  time  in  the  mould, 
neither  froths  nor  scatters  ;  yet  it  is  said  that  after  solidifi- 
cation has  reached  a  certain  point  it  may  begin  to  rise, 
and,  if  unopposed,  may  double  its  length,8  owing  to  the 
formation  of  gas  within  it. 

It  seems  far  more  probable  that  the  renewed  escape  of 
gas  is  here  due  to  a  fall  of  solvent  power  owing  to  solidifi- 
cation, than  that  reaction,  having  once  totally  ceased, 
recommences  during  solidification,  especially  as  the  fall 
of  temperature  should  oppose  the  oxidation  of  carbon. 

C.  That  the  shape  and  position  of  the  blowJioles  in  ice 
and  in  iron  respectively  are  governed  by  similar  causes  we 
infer  from  their  remarkable  similarity.  As  the  ice  bubbles 
are  doubtless  due  to  the  escape  of  gas  (in  this  case  air) 
during  solidification,  and  as  they  owe  their  contour  and 
place  to  the  manner  in  which  the  ice  grows  during  the 
emission  of  this  air,  so  with  the  blowholes  in  iron.  The 
fact  that  the  air  in  ice  escapes  from  solution  does  not,  how- 
ever, prove  that  the  blowhole-forming  gas  in  iron  also  es- 
capes from  solution.  It  is  clearly  gasified  under  similar  out- 
ward conditions,  but  not  necessarily  from  the  same  previous 
state.  It  is  conceivable  that  the  very  act  of  solidification 
might  cause  previously  uncombined  carbon  and  oxygen  to 
unite  in  such  a  manner  that  their  escape  would  closely 
simulate  that  of  a  previously  dissolved  gas.  But  it  is 
certainly  far  more  natural  to  refer  the  phenomena  to  an 
escape  from  solution. 

§  215.  RATIONALE  OF  THE  ACTION  OF  SILICON. — 
Our  study  of  the  analogy  between  the  behavior  of  iron  and 
that  of  other  solvents  towards  gases  would  be  most  incom- 
plete if  it  did  not  embrace  the  action  of  silicon  on  the 
escape  of  gas  and  on  the  formation  of  blowholes. 

The  addition  of  O'lfo  of  lead  to  molten  copper  and  of 
0'12  of  magnesium  to  nickel  is  said  to  prevent  these 
metals  from  evolving  gas  and  from  acquiring  blowholes 
while  solidifying.  These  additions  appear  to  act  by  in- 
creasing the  metal's  solvent  power,  so  that  it  is  able  to 
retain  in  solution  while  setting  the  gas  which  it  holds 
while  molten,  and  which  it  would  have  evolved  but  for 
these  additions.  On  uncorking  a  bottle  of  soda  water  it 
evolves  gas  violently.  The  escape  of  gas  soon  diminishes, 
but  it  continues  at  a  much  reduced  rate  for  hours :  yet  the 
addition  of  freshly  boiled  cold  water  arrests  it  at  once  and 
completely.  Now  do  silicon  and  manganese,  as  Muller 
contends,  act  through  the  iron's  solvent  power ;  or  do  they, 
as  Pourcel  maintains,  simply  prevent  the  formation  of 
carbonic  oxide  by  being  preferentially  oxidized?  I  will 
endeavor  to  show  (I)  that  the  quieting  action  of  additions 
of  silicon  harmonizes  better  with  the  former  than  with  the 
latter  view:  (II).  that  the  effervescence  following  the  re- 
moval of  silicon  accords  with  either :  but  (III)  that,  while 
the  escape  of  gas  from  iron  rich  in  silicon  is  in  perfect 
harmony  with  the  former  view,  it  seems  directly  opposed 
to  the  latter. 

A.  In  many  cases  the  quieting  action  of  silicon  appears 
to  harmonize  with  either  view.  Doubtless  if  added  to 
metal  in  which  the  oxidation  of  carbon  was  actually  occur- 
ring it  might  check  that  action.  But  I  can  recall  no  case 
in  which  it  is  clear  that  silicon  checks  the  blowhole-form- 
ing escape  of  gas,  i.  e.  the  escape  during  solidification, 


Number  in  Table  70  A  *  

2. 

4. 

6. 

c. 

81. 

Mn. 

C. 

81. 

Mn. 

C. 

81. 

Mn. 

Present  in  the  metal  before  recorburiztng  
Added  in  the  recarburizer  

•038 
•flV) 

•008 
•866 

•144 

•073 

•038 
•Ifi? 

•021 
•818 

•181 
1'487 

•075 
•OM 

•007 
•389 

•480 
•069 

Total     

•092 

•358 

•?I7 

•191 

•889 

T66S 

•129 

•31fi 

•549 

•062 

'238 

'186 

'175 

'846 

1'604 

'127 

'814 

•585 

•oso 

•120 

•011 

•020 

•007 

•064 

002 

'032 

'036 

•"•  I  have  never  seen  such  a  case,  but  Muller  states  that  rising  steel  may  act 
thus.    Iron,  Jan.  5th,  1883,  p.  17. 


by  preventing  the  oxidation  of  carbon :  on  the  other 
hand  in  those  important  and  striking  cases  which  have 
actually  been  investigated,  silicon  certainly  seems  to  act 
through  the  solvent  power. 

Midler  found  in  three  cases  (numbers  2,  4  and  6,  Table 
70  A)  that,  on  adding  f erro-silicon  or  f erro-silico-manganese 
to  molten  basic  oxygenated  or  ingot  iron,  contained  in 
iron  moulds  and  with  the  action  of  the  slag  and  of  the 
containing  vessel  thus  nearly  eliminated,  the  protracted 
escape  of  gas  (carbonic  oxide,  hydrogen  and  nitrogen) 
which  had  been  occurring  either  immediately  diminished 
or  stopped,  though  part  of  the  carbon  present  simultane- 
ously disappeared.  In  number  2  the  volume  of  gas  was 
diminished  by  about  80^ :  in  number  4  gasification  stopped 
so  completely  that  Muller  was  unable  to  collect  enough 
gas  for  analysis,  though  the  0-02$  of  carbon  which  dis- 
appeared should  generate  carbonic  oxide  equal  in  volume 
to  twenty  times  that  of  the  metal.  These  results  are  sum- 
marized in  Table  76. 

TABLE  76.— BECABBUBIZING    ADDITIONS  WIIICH    IMMEDIATELY  CHECK  THE    ESCAPE  OF  GAS 
THOUGH  APPARENTLY  CAUSING  THE  OXIDATION  OF  CAKBON. 


Here  the  quieting  effect  of  silicon  and  manganese  cer- 
tainly does  not  seem  to  be  due  to  their  preventing  the 
formation  of  carbonic  oxide  by  being  oxidized  in  prefer- 
ence to  carbon,  1,  because  though  in  some  cases  part  of 
the  carbon  added  with  them  appears  to  be  immediately 
oxidized,  or  at  least  disappears,  so  that  more  carbonic  oxide 
appears  to  be  present  after  than  before  their  addition,  yet 
no  gas  escapes,  neither  the  carbonic  oxide  thus  formed, 
nor  that  carbonic  oxide,  hydrogen  and  nitrogen  which 
would  have  continued  to  escape  had  the  silicon  and  man- 
ganese not  been  added.  Unfortunately,  the  quantity  of 
carbon  which  disappears  is  so  small  that  it  is  possible  to 
attribute  its  disappearance  to  experimental  error.  2,  Be- 
cause the  escape  of  gas  was  wholly  arrested  when  no  silicon 
and  but  a  trifling  quantity  of  manganese  (-06$)  appeared 
to  be  oxidized,  and  only  by  being  oxidized  should  these 
elements  prevent  the  oxidation  of  carbon.  (No.  4.)  But  this 
little  manganese  may  suffice  to  arrest  the  oxidation  of  car- 
bon :  and,  moreover,  more  manganese  and  silicon  may  be 
oxidized  than  is  recorded :  for,  should  part  of  their  oxides 
remain  suspended  or  dissolved  in  the  metal,  they  would 
appear  on  analysis  as  if  unoxidized. 

3,  Because,  on  a  priori  grounds,  one  would  hardly  expect 
that  carbonic  oxide  would  be  formed  in  this  practically 
carbonless  metal,  even  before  the  silicon  and  manganese 
were  added  (§  216). 

4,  Because,  if  it  were  being  formed,  one  would  hardly 
expect,  on  a  priori  grounds,  that  silicon  and  manganese 
could  thus  totally  arrest  its  formation.  For  at  this  exalted 
temperature  the  affinity  of  carbon  for  oxygen  probably 
greatly  outweighs  that  of  silicon  and  manganese  :  hence, 
while  under  especially  favorable  conditions  (e.  g.  in  the 
presence  of  a  basic  slag,  or  when  a  very  large  proportion 
of  silicon  is  added  to  metal  containing  very  little  carbon), 
silicon  might  totally  arrest  the  oxidation  of  carbon,  yet  one 


bStahl  und  Eiseu,  IV,,  p,  75,  1884. 


140 


THE    METALLURGY    OF    STEEL. 


would  not  expect  it  to  when,  as  in  the  case  under  consider- 
ation, a  very  considerable  proportion  of  carbon  is  added 
along  with  it.  In  each  of  the  ten  cases  in  Table  70  A  in 
which  the  behavior  of  carbon  on  recarbiirizing  is  recorded, 
a  considerable  quantity  of  it  is  oxidized,  while  in  certain 
cases  no  silicon  and  but  little  manganese  is.  Indeed  in 
number  9,  Table  70  A,  no  less  than  0'073%  of  silicon  ap- 
pears to  be  reduced  from  the  slag  by  the  recarburizing 
additions.  This  reduction  of  silicon  from  the  slag  also 
occurs  in  another  spiegel  reaction,  which  will  appear  later. 

5th,  Because  when  oxygenated  metal  receives  a  recar- 
burizing addition  the  resulting  tranquillity  and  freedom 
from  blowholes  should,  on  the  reaction  theory,  be  propor- 
tional to  the  quantity  of  oxygen  removed  by  the  silicon 
and  manganese  (the  more  they  remove  the  less  remains  to 
react  on  carbon),  but,  on  the  solution  theory,  propor- 
tional to  the  quantity  of  these  elements  which  remain  in 
the  recarburized  steel.  Yet  in  the  examples  in  Table  70  A, 
the  latter  is  in  the  main  true,  while  the  most  solid  and  tran- 
quil steel  of  all,  4,  is  the  very  one  from  which  the  least 
oxygen  is  removed,  the  one  which  on  the  reaction  theory 
should  become  the  most  porous  because  retaining  the  most 
oxygen  to  react  on  carbon.  It  is  but  fair  to  say,  however, 
that  it  may  have  lost  less  oxygen  in  the  reaction  than  the 
others  because,  though  apparently  produced  under  like 
conditions,  it  may  have  held  less  initially. 

In  brief,  while  it  is  possible  that  silicon  and  manganese 
act  in  these  cases  by  arresting  the  oxidation  of  carbon, 
the  phenomena  harmonize  much  better  with  the  view  that 
these  additions  act  through  the  solvent  power. 

B.  Just  as  the  addition  of  silicon  stops  the  evolution  of 
gas,  so  there  are  reasons  for  believing  that  its  sudden  re- 
moval induces  violent  ebullition.     This  is  not  so  well  seen 
in  the  Bessemer  process,  for,  owing  to  the  violent  agitation 
caused  by  the  blast,  as  the  removal  of  silicon  lowers  the 
solvent  power  of  the  metal  a  large  portion  of  the  excess  of 
gas  is  expelled  almost  as  fast  as  it  becomes  an  excess,  and 
the  metal  does  not  become  greatly  supersaturated.     Still, 
both  half -blown  and  fully-blown  Bessemer  metal  froth, 
scatter  and  sparkle  much. 

Washed  pig,  i.  e.  cast-iron  whose  silicon  has  been  very 
rapidly  removed  by  iron  oxide  in  a  reverberatory  furnace, 
effervesces  very  energetically  as  it  runs  from  the  furnace. 
This  may  be  due  to  the  sudden  fall  of  solvent  power 
through  the  removal  of  silicon.  It  may,  however,  be  due 
to  the  retention  of  suspended  particles  of  iron  ore,  which 
would  energetically  attack  the  carbon  of  the  washed 
metal,  with  evolution  of  carbonic  oxide. 

C.  Though  the  addition  of  a  relatively  small  quantity 
of  silicon  and  manganese  to  boiling,  oxygenated,  blow- 
hole-forming metal  completely  arrests  the  escape  of  gas, 
yet  hot-blown,  unrecarburized,  oxygenated,  acid  Bessemer 
metal  may  evolve  an  abundance  of  gas,  chiefly  hydrogen 
and  nitrogen,  before  and  during  setting,  and  may  rise 
very  rapidly  in  spite  of  holding  \%  of  silicon  :  molten  grey 
cast-iron,  too,  may  evolve  hydrogen  and  carbonic  oxide 
copiously  and  sometimes  rises  in  setting,   in  spite  of  its 
high  proportion  of  silicon.     I  cannot  reconcile  these  facts 
with  the  belief  that  reaction  is  the  sole  cause  of  the  escape 
of  gas.    For  if  the  addition  of  0'318$  of  silicon  and  1'487$ 
of  manganese  can  completely  arrest  the  oxidation  of  car- 
bon in  oxygenated  iron,  and  if  that  of  '356$  of  silicon  and 

of  manganese  can  so  far  check  it  that  the  metal 


is  perfectly  quiet  and  rises  but  little  (2  and  4,  Table 
70  A);  then  surely  the  presence  of  \%  of  silicon  should 
restrain  it  enough  to  prevent  extremely  rapid  rising,  and 
far  more  should  the  1  to  Z%  of  silicon  in  grey  iron  prevent 
it  at  the  relatively  low  temperature  at  which  this  variety 
of  iron  sets  ;  for  the  ratio  of  the  affinity  of  silicon  for  oxy- 
gen to  that  of  carbon  appears  to  be  much  greater  at  low 
than  at  high  temperatures. 

But  the  phenomena  readily  agree  with  the  solution 
theory.  If  silicon  raises  the  solvent  power,  it  should  raise 
it  for  both  solid  and  molten  metal,  so  that  the  sudden  fall 
of  solvent  power  in  solidifying  should  remain.  Our  hot- 
blown  Bessemer  metal,8  retaining  l^of  the  silicon  initially 
in  the  cast-iron,  retains  with  it  its  high  solvent  power, 
and  retains  or  takes  up  during  the  blow  a  correspondingly 
high  proportion  of  gas.  In  setting,  its  solvent  power  like 
that  of  non-silicious  metal  suddenly  falls,  it  is  unable  to 
retain  the  large  quantity  of  gas  within  it,  it  evolves  a  por- 
tion, it  rises  violently. 

So  too  our  grey  cast-iron,  its  solvent  power  perhaps 
increased  a  considerable  while  before  its  escape  from  the 
blast  furnace  by  the  acquisition  of  silicon,  and  thereafter 
exposed  to  nascent  carbonic  oxide,  hydrogen,  and  perhaps 
nitrogen,  may  be  conceived  to  become  well  saturated  with 
these  gases,  a  portion  of  which  is  subsequently  evolved, 
their  escape  perhaps  facilitated  by  the  release  of  pressure, 
and  by  the  agitation  due  to  atmospheric  oxidation  of  car- 
bon. But  our  oxygenated  metal,  acid  or  basic,  Bessemer 
or  open-hearth,  holds  comparatively  little  gas,  that  ini- 
tially present  probably  escaping  during  the  converting  pro- 
cess as,  with  the  removal  of  silicon,  the  metal's  solvent 
power  diminishes.  On  solidifying,  its  solvent  power  fur- 
ther falls,  and  gas  is  evolved,  and  the  more  violently  be- 
cause, owing  to  its  high  freezing  point,  our  oxygenated 
metal  is  the  more  suddenly  solidified  by  the  cold  moulds. 
But  the  addition  of  even  as  little  as  0  '318$  of  silicon  might 
well  suffice  to  raise  its  solvent  power  enough  to  permit  it  to 
retain  while  setting  the  comparatively  small  quantity  of 
gas  which  it  contains  when  molten.  Be  it  remembered 
that  the  quantity  of  gas  evolved  in  setting,  which  accord- 
ing to  Muller  is  something  over  three  volumes  in  case  of 
wild  oxygenated  metal,  is  probably  but  a  small  propor- 
tion of  that  which  it  still  retains  in  solution.  11  volumes 
have  been  extracted  on  boring  and  22  volumes  of  hydro- 
gen have  been  absorbed  by  direct  measurement.  A 
comparatively  small  change  of  solvent  power,  then,  might 
well  determine  the  retention  or  expulsion  of  enough  gas 
to  convert  a  compact  into  a  spongy  metal. 

In  brief,  the  fact  which  appears  to  be  general,  that 
though  the  presence  of  silicon  does  not  necessarily  prevent 
the  escape  of  gas,  its  addition  temporarily  arrests  it,  har- 
monizes so  completely  with  the  solution  theory  that  it 
could  be  deduced  from  it,  but  is  diametrically  opposed 
to  the  belief  that  the  oxidation  of  carbon  is  the  exclusive 
cause  of  blowholes. 

Does  silicon  act  by  reducing  iron  oxide  ?  In  the 
Mitis  process  rising,  gas-generating,  oxygenated  metal  is 
rendered  perfectly  tranquil  by  tha  addition  of  ferro- 


a  If  as  Walrand  holds  the  escape  of  gas  from  hot-blown  Bessemer  steel  be  flue 
to  a  reaction  between  its  carbon  and  the  oxygen  of  the  coating  of  iron  oxide  on  the 
interior  of  the  mould,  the  bearing  of  the  phenomenon  on  the  rationale  of  sili- 
con's action  remains  unchanged.  It  still  opposes  the  view  that,  when  silicon  does 
prevent  the  escape  of  gas,  it  does  so  by  preventing  reaction,  for  here  this  reaction 
occurs  in  spite  of  the  abundant  silicon :  and  it  still  harmonizes  with  the  view  that 
silicon  acts  by  raising  the  solvent  power. 


RATIONALE  OF  CHANGES  IN  THE  COMPOSITION  OF  GASES  EVOLVED  BY  IRON.     §  217.     141 


aluminium  sufficient  to  introduce  0'06$  of  aluminium.  As 
the  aluminium  appears  to  be  wholly  oxidized,  so  that  none 
of  it  remains  in  the  metal,  it  can  hardly  directly  raise  the 
solvent  power :  its  direct  influence  can  hardly  survive  its 
departure.  Nor  is  it  probable  that  it  acts  by  preventing 
the  oxidation  of  carbon,  for  the  metal  itself  is  practically 
carbonless.  But  may  it  not  be  that  the  presence  of  oxygen 
diminishes  the  solubility  of  gas  in  iron,  and  that  the 
aluminium,  by  removing  this  oxygen,  indirectly  raises  the 
solvent  power  ?  Silicon  sometimes  produces  similar  effects 
under  like  conditions  :  may  it  not  act  in  this  same  indirect 
way? 

Of  course  in  many  cases  gas  is  evolved  when  iron  oxide 
can  hardly  be  present :  in  others  the  silicon  added  is  ap- 
parently not  oxidized :  so  that  this  mode  of  action  can 
hardly  be  regarded  as  the  prevalent  one.  It  is  striking, 
however,  that  several  important  classes  of  rising  metal  do 
contain  iron  oxide,  e.  g.  oxygenated  metal  and  much  of 
the  hot-blown  rising  Bessemer  steel,  in  which  the  presence 
of  oxygen  is  indicated  even  when  it  retains  as  much  as  0-6 
of  silicon.  (§  159,  p.  94.) 

§  216.  GASES  ESCAPE  AND  BLOWHOLES  FORM  WHEN  GAS 
FORMING  REACTIONS  ARE  IMPROBABLE. — At  the  beginning 
of  the  after-blow  of  the  basic  Bessemer  process  only  about 
0-04$  of  carbon  remains  in  the  metal.  The  enormous  quan- 
tity of  air  introduced  during  the  remaining  four  minutes  or 
so  oxidizes  this  carbon  but  slowly,  and  it  remains  nearly 
constant  at  about  '04$  :  it  has  nearly  reached  a  minimum. 
We  teem  without  recarburizing,  and  our  metal  evolves 
thrice  its  own  volume  of  gas,  and  becomes  more  porous 
than  any  other  variety  of  iron."  Even  if  ignorant  of  the 
composition  of  the  gas  now  evolved,  it  would  be  hard  to 
believe  that  this  was  wholly  an  escape  of  carbonic  oxide 
from  a  suddenly  invigorated  reaction:  for  the  escape  of 
three  volumes  of  carbonic  oxide  implies  the  removal  of 
'02%  of  carbon,  and  it  certainly  seems  most  improbable 
that  the  small  proportion  of  oxygen  which  molten  iron 
can  contain  could  rapidly  remove  half  of  that  persistent 
residuum  of  carbon  which  had  defied  the  great  excess 
of  air  and  the  basic  slags  of  the  afterblow,  especially  as 
the  falling  temperature  probably  constantly  lowers  the  rel- 
ative affinity  of  carbon  for  oxygen  as  compared  with  that 
of  iron. 

Turning  from  oxygenated  metal,  in  which  gas-form- 
ing reaction  is  improbable  from  lack  of  carbon,  to  cast- 
iron  in  which  it  is  improbable  from  lack  of  oxygen,  we 
have  seen  that  rising  and  blowholes  occasionally  occur, 
even  when  considerable  silicon  is  present,  as  in  grey  iron  : 
when  silicon  is  absent,  as  in  white  iron,  blowholes  are 
common  (Table  71).  That  during  solidification  a  reaction 
between  carbon  and  oxygen  should  generate  carbonic 
oxide  and  thus  liberate  gas,  would  imply  that  this  cast- 
iron,  rich  in  carbon  and  silicon,  contains  oxygen  which 
up  to  the  time  of  solidification  remains  uncombined  with 
these  elements:  (if  combined  with  silicon  the  resulting 
silica  should  rise  to  the  surface  by  gravity).  This  in  it- 
self is  improbable.  That  the  carbon  and  oxygen  which 
have  remained  uncombined  up  to  the  time  of  solidification 
should  then  combine  is  improbable,  because  the  falling 
temperature  should  constantly  diminish  the  relative 
affinity  of  carbon  for  oxygen. 

The  formation  of  blowholes  when  gas-forming  reaction 


aMiiller,  Stahl  und  Eisen,  IV.,  p.  75,  1884;  Iron,  Feb.  15,  1884,  p.  138. 


is  improbable  is  further  discussed  in  §  214,  B  and  §  215,  A. 

§  217.  RATIONALE  OF  CERTA«I  VARIATIONS  IN  THE 
COMPOSITION  OF  THE  GASES. 

The  variations  which  I  now  attempt  to  explain  are  de- 
tailed in  §  207  E,  and  illustrated  in  figure  1 4,  p.  133. 

A.  We  have  seen  that,  when  cast-iron  and  the  inter- 
mediate and  final  products  of  the  Bessemer  process  are 
isolated  and  allowed  to  solidify  in  iron  moulds,  the  propor- 
tion of  carbonic  oxide  in  the  gases  which  they  then  evolve 
is  greater  the  more  highly  carburetted  they  are.     For 
reasons  just  detailed  this  opposes  the  belief  that    this 
carbonic  oxide  is  generated  at  the  instant  of  solidification 
by  reaction  between  the  carbon  and  oxygen  contained 
within  the  metal :  for,  the  more  carbon  the  metal  holds 
the  more  rapidly  and  completely  should  any  oxygen  pres- 
ent be  eliminated,  and  the  less  should  remain  to  cause 
a  protracted  escape  of  carbonic  oxide  in  the  moulds.    But, 
on  the  solution  theory,  we  may  suppose  that  the  changing 
composition  of  the  metal  changes  the  relative  solubility  of 
the  different  gases,  and  thus  alters  the  proportion  of  car- 
bonic oxide  to  hydrogen  evolved  in  the  moulds.     The  rela- 
tively high  proportion  of  carbonic  oxide  in  the  mould 
gases  of  highly  carburetted  iron  may  be  partly  due  to  super- 
ficial oxidation  by  the  atmosphere,   the  surfaces  of  the 
moulds,  etc. 

The  high  proportion  of  carbonic  oxide  in  the  spiegel- 
reaction  gases  and  its  continuous  decrease  as  the  metal 
solidifies  and  cools  accord  well,  however,  with  the  reaction 
theory,  since  the  reaction  should  very  rapidly  decrease. 
But  it  accords  at  least  as  well  with  the  solution  theory. 
The  more  highly  supersaturated  a  solvent,  the  more 
violently  should  it  expel  the  dissolved  substance,  and  the 
more  marked  should  be  the  decline  in  the  rate  at  which  it 
evolves  it.  A  bottle  of  soda  water  when  first  uncorked 
evolves  gas  tumultuously :  the  retardation,  at  first  ex- 
tremely conspicuous,  can  later  be  detected  only  by  sys- 
tematic observation.  Now  at  the  time  of  the  spiegel  re- 
action our  metal  should  be  only  moderately  supersaturated 
with  hydrogen  and  nitrogen :  hence  the  rate  at  which 
these  gases  escape  should  decline  but  slowly.  The  spiegel 
reaction,  however,  evolving  nascent  carbonic  oxide  so 
copiously  within  the  metal,  should  greatly  supersaturate 
it  with  this  gas.  Hence  the  decline  in  the  rate  at  which  it 
escapes  should  be  more  marked  than  in  case  of  hydrogen 
and  nitrogen,  and  hence  the  proportion  of  carbonic  oxide 
to  these  gases  should  decline  ;  and  so  it  does. 

B.  The  gases  from  molten  metal,  from  solidifying  metal, 
from  the  solid  metal  in  the  soaking  pits,  all  contain  much 
carbonic  oxide :  but  when  the  metal  has  completely  cooled 
and  we  bore  it  we  find  little  or  no  carbonic  oxide,  nothing 
but  hydrogen  and  nitrogen."     If  we  reheat  it  in  vacuo 
carbonic  oxide  reappears.     If  we  reheat  it  in  a  common 
furnace,  and  if  by  accident  a  blister  forms  on  it,  this  blister 
contains  much  carbonic  oxide.     The  absence  of  carbonic 


b  Miiller  (Iron,  Sept.  14,  1883,  p.  344),  can  find  no  explanation  of  the  absence 
of  carbonic  oxide  from  the  boring  gases,  but  simply  likens  it  to  the  fact,  surpris- 
ing to  him,  that  silicon  does  not  crystallize  out  along  with  graphite  when  cast-iron 
solidifies.  But  these  two  cases  call  for  radically  different  explanations.  We  do 
not  expect  silicon  to  separate  during  solidification,  because  molten  commercial 
irons  are  never  saturated  with  it:  solid  iron  is  known  to  be  capable  of  retaining 
far  more  silicon  than  molten  commercial  irons  actually  contain.  (§63,  p.  37.) 
We  do  expect  carbon  to  separate  out.  because  we  know  that  molten  iron  often 
contains  more  carbon  than  solid  iron  is  capable  of  retaining:  and,  if  we  regard 
carbonic  oxide  as  dissolved  iu  iron,  we  expect  it  too  to  separate  on  solidification, 
because  its  escape  from  the  mol'en  iron  shows  that,the  metal  is  supersaturated 
with  it,  and  solidification  should  increase  the  supersaturation. 


142 


THE    METALLURGY    OF    STEEL. 


oxide  from  the  boring  gases  may,  however,  be  explained 
on  either  the  reaction  or  solution  theory. 

On  the  solution  theory  the  fact  that  the  molten  metal 
gives  off  carbonic  oxide  implies  that  it  is  supersaturated 
with  this  gas :  as  the  solvent  power  should  fall  on  solidifi- 
cation, carbonic  oxide  should  still  be  given  off :  and  that 
it  is  is  shown  by  its  presence  in  the  soaking-pit  gases. 
Why  then  is  it  not  found  in  the  blowholes  on  boring  '< 
We  have  seen,  figure  15,  that  after  solidification  is  com- 
plete the  solvent  power  should  rise  with  further  fall  of 
temperature.  Now  a  large  part  of  the  gases  set  free  during 
solidification  probably  works  its  way  out  at  a  somewhat 
lower  temperature,  through  the  hot  porous  metal.  It  is 
conceivable  that  the  remaining  carbonic  oxide  is  reab- 
sorbed  by  the  metal :  but  that  the  solvent  power  for  hy- 
drogen and  nitrogen  does  not  rise  enough  with  falling 
temperature  to  cause  their  complete  reabsorption,  so  that 
they  are  found  on  boring. 

On  the  reaction  theory  as  well  we  should  at  first  expect  car- 
bonic oxide  in  the  boring  gases,  since  this  theory  supposes 
that  this  gas  is  given  off  during  solidification  and  forms  the 
blowholes.  The  following  explanation  of  its  absence,  which 
is  here  offered  in  its  entirety  for  the  first  time  so  far  as  I 
know,  applies  to  both  the  reaction  and  the  solution  theories. 

We  have  seen  in  §  185  that  at  from  about  300°  to  about 
tOO°  C.  carbonic  oxide  is  split  up  by  iron  very  readily,  the 
iron  absorbing  carbon  and  oxygen.  At  higher  tempera- 
tures the  tendency  towards  this  reaction  is  very  slight,  and 
iron  oxide  then  reacts  readily  on  deposited  carbon,  regen- 
erating carbonic  oxide.  Now  the  carbonic  oxide  given  off 
by  our  white  hot  iron  may  be  present  in  the  soaking-pit 
gas  and  in  the  moulds  gases,  because  the  tendency  to  split 
it  up  is  relatively  slight  at  the  high  temperature  at  which 
these  gases  escape.  But,  as  our  iron  cools  our  liberated 
carbonic  oxide  splits  up  while  we  are  passing  through  the 
range  of  temperature,  say  300°  to  700°,  favorable  to  its 
decomposition,  and  so  none,  or  next  to  none,  is  found  in  our 
cold  metal. 

If,  however,  by  the  formation  of  a  large  blister  our 
carbonic  oxide  accumulates  and  has  but  a  relatively 
small  surface  of  iron  exposed  to  it  while  the  metal 
is  cooling,  it  is  easy  to  see  that  much  or  most  of  it  might 
escape  decomposition,  and  be  found  as  such  when  the  cold 
blister  is  bored  under  water.8  When  our  metal  is  again 
heated  in  vacuo  we  may  suppose  that  the  oxygen  and  car- 
bon which  had  previously  been  dissociated  recombine,  and 
we  find  carbonic  oxide  in  our  vacuum  gases.  This  view 
harmonizes  with  the  fact  stated  by  Wedding  in  this  con- 
nection,1" that  the  cavities  in  puddled  balls,  at  least  after 
long  exposure  to  the  air,  are  free  from  carbonic  oxide, 
though  doubtless  formed  in  large  part  by  that  gas.  In 
either  view  carbonic  oxide  is  gasified  during  solidification, 
along  with  hydrogen  and  nitrogen,  and  cooperates  with 
them  to  form  blowholes. 

§  218.  SOURCE  OF  THE  HYDROGEN  AND  NITROGEN  OF 
THE  BORING  GASES. 

Attempts  have  been  made,  by  two  different  lines  of 
argument,  to  show  that  the  hydrogen  and  nitrogen  of 
which  the  boring  gases  consist  are  not  the  causes  of  blow- 
holes. Neither  of  these  bear  scrutiny.  We  will  now 
consider  them  separately. 


a  See  reference  to  numbers  33,  34,  Table  54,  p.  106. 
bStahl  und  Eisen,  III.,  p.  200,  1883. 


1.  It  has  been  argued  that  the  boring  gases  do  not  pro- 
ceed from  the  blowholes,  b.ut  from  the  decomposition  of 
the  water  in  which  the  boring  occurs.  This  superficially 
attractive  theory  received  powerful  but  ephemeral  sup- 
port from  E.  W.  Richards'  statement"  that,  on  attacking 
a  steel  ingot  with  a  dull  drill,  enormous  quantities  of 
hydrogen  were  evolved,  "  although  no  steel  had  been  cut 
away,  showing  clearly  that  the  hydrogen  was  obtained  by 
the  decomposition  of  the  water."  But  he  appears  to  have 
been  misinformed,  for  Muller  flatly  contradicts  him,  and 
states  that  l-5  cubic  inches  of  steel  were  cut  away.d  This 
contradiction  remains  unchallenged  as  far  as  I  know,  and 
destroys  the  only  important  support  of  this  theory.6 

This  instance  (Number  17,  Table  54,  p.  106),  really  points 
to  the  metal,  not  the  water  as  the  source  of  the  boring  gases. 
For  it  shows  that  when  we  finely  triturate  our  metal  and 


Fig.  16.—  Muller's  Boring  Apparatus,  for  Obtaining  the  Oases  from 
the  Blowholes,  etc.,  of  Cold  Metal. 

thus  lay  bare  numberless  minute  pores,  we  release  vastly 
more  gas  than  when  we  simply  turn  comparatively  thick 
shavings,  here  more  than  fifty  times  as  much.  In 
this  case  the  dull  drill  released  gas  still  consisting  of 
hydrogen  and  nitrogen  in  normal  proportions,  though 


c  Journ.  Iron  and  St.  Inst.,  1882,  II.,  p.  530. 

dlron,  1883,  p.  115. 

e It  is  true  that  Walrand  (Van  Nostrand's  Eng.  Mag.,  XXXIII.,  p.  361,  1885, 
from  Jernkont.  Ann.)  states  that  on  boring  steel  under  oil  and  mercury  he  could 
not  obtain  a  trace  of  gas,  while  on  boring  under  water  he  always  obtained  gas, 
which  he  found  detonated  without  the  addition  of  air,  and  he  believes  that  the 
theory  which  considers  hydrogen  as  a  source  of  blowholes  has  no  more  foundation 
than  the  old  theory  that  nitrogen  was  the  essential  element  of  steel. 

Such  a  negative  result  as  his  failure  to  obtain  gas  on  boring  under  mercury  and 
oil  counts  for  little  against  the  positive  determinations  which  are  recorded:  it  is 
surprising,  but  incomparably  less  so  than  his  brushing  aside  the  great  mass  of 
evidence,  furnished  in  large  part  by  most  trustworthy  observers,  which  demon- 
strates the  presence  of  hydrogen  in  iron  and  its  escape  from  it,  and  of  which  the 
composition  of  the  boring  gases,  the  only  point  assailed  by  him,  forms  but  a  single 
unessential,  though  indeed  valuable,  portion. 

The  fact  that  the  gas  which  he  obtained  on  boring  under  water  would  detonate 
implies  that  it  contained  oxygen.  The  presence  of  oxygen  derived  from  some 
Eource  other  than  the  decomposition  of  the  water  is  readily  accounted  for.  The 
slightest  error  in  manipulation  would  admit  atmospheric  oxygen:  had  the  water 
in  which  the  boring  occurred  not  been  freshly  boiled,  it  might  well  yield  up  suffi- 
cient oxygen  previously  dissolved  in  it  to  cause  detonation.  But  the  complete 
absence  of  oxygen  from  the  boring  gases  of  such  competent  observers  as  Muller 
and  Stead  cannot  be  harmonized  easily  if  at  all  with  the  belief  that  the  hydrogen 
which  they  found  came  from  the  decomposition  of  water.  Walrand  supposes  that 
the  drill  rotated  so  rapidly  as  to  become  magnetized,  thus  causing  an  electric 
current,  which  decomposed  the  water.  Muller's  drills  were  actually  stationary, 
the  ingot  beiog  slowly  rotated.  Two  distinguished  physicists  inform  me  that  the 
decomposition  of  water  in  this  particular  way  under  these  conditions  is  not  only 
extremely  improbable  but  almost  inconceivable.  Indeed,  I  am  inclined  to  think 
that  Walrand  must  mean  something  quite  different  from  what  he  says,  which  is 
certainly  hard  to  understand, 


CARBONIC    OXIDE    FROM    REACTION    OR    SOLUTION?      §  219. 


143 


differing  somewhat  from  those  found  by  the  sharp  drill, 
which  might  easily  happen  were  different  portions  of  the 
ingot  attacked  by  the  two  drills.  But  in  another  instance 
a  specimen  of  cast-iron  was  drilled  A  with  a  sharp  and  B 
with  a  dull  drill :  though  the  latter  released  eight  times  as 
much  gas  per  volume  of  metal  as  the  former,  the  composi- 
tion of  the  gas  was  alike  in  the  two  cases.  This  would 
be  natural  if  the  gas  arose  from  the  metal,  but  if  it  arose 
from  the  decomposition  of  the  water,  the  proportion  of  ni- 
trogen should  be  less  with  the  dull  drill.  For,  as  the  nitro- 
gen found  must,  in  this  view,  have  been  previously  dissolved 
in  the  water,  and  as  only  a  limited  amount  could  be  so 
dissolved,  if  our  drill  released  it  from  solution  it  would  be 
almost  pumping  against  a  vacuum,  and  the  proportion  of 
nitrogen  should  rapidly  diminish ;  actually  it  increased.  It 
is  possible  that  a  little  previously  dissolved  nitrogen  might 
be  derived  from  the  water,  though  it  should  be  very  little, 
as  in  some  of  Muller's  experiments  the  water  had  been 
freshly  boiled.  But  it  is  extremely  improbable  that  the 
volume  of  nitrogen  thus  acquired  would  increase  propor- 
tionally to  the  hydrogen.  Nor  do  we  lack  further  evidence 
that  the  gas  did  not  come  from  the  water. 

A.  Steel  bored  under  oil  yielded  gas  similar  in  composi- 
tion and  quantity  to  that  obtained  in  boring  under  water. 
(No.  2,  Table  C4.)  An  ingot  bored  under  mercury  yielded 
gas  composed  as  usual  chiefly  of  hydrogen.  The  quantity 
obtained  was  indeed  small :  but  this  is  not  surprising,  for 
Muller  found  that  the  quantity  of  gas  obtained  in  boring 
under  water  was  in  some  cases  fifteen  times  as  large  as  in 
others. 

D.  If  the  gas  came  from  the  decomposition  of  water, 
solid  steel,   offering  more  frictional  resistance,   should 
yield  more  gas  per  cubic  inch  cut  than  porous  steel :  if 
from  the  pores,  porous  steel  should  yield  the  most.     Act- 
ually it  yields  on  an  average  nearly  four  times  as  much 
gas  as  solid  steel.     (See  Table  73,  p.  132.) 

E.  If  the  gas  came  from  the  water,  where  is  the  one  part 
of  oxygen  which  it  should  contain  for  every  two  of  hydro- 
gen?   Where  is  the  atmospheric  oxygen  which  should 
have  dissolved  in  the  water  along  with  the  atmospheric 
nitrogen,  and  with  it  should  have  been  released  by  the 
drill  ?    In  one  case  only  is  oxygen  found,  and  then  only 
0'37$  of  it.     To  the  suggestion  that  it  has  been  consumed 
in  oxidizing  the  iron,  suffice  it  to  reply  that,  in  some  of 
Muller's  experiments,  the  metal  was  cut  so  slowly  that  it 
would  not  have  grown  hot  enough  to  assume  oxide  tints 
if  cut  in  free  air  :a  that  in  the  arrangement  employed 
(Figure  16)  ingot  and  drill  were  always  cooled  by  con- 
tact with  water :  the  supposed  decomposition  of  water 
would  have  further  lowered  the  temperature :  a  fortiori 
the  metal  must  have  been  far  too  cold  to  take  up  even 
the  uncombined  oxygen  of  the  air :  how  then  could  it 
rapidly  decompose  previously  boiled  water  ?    Finally,  the 
first  portions  of  gas  evolved  would  depress  the  surface  of 
the  water  below  the  cutting  grinding  surfaces,  where  alone 
can  the  decomposition  of  water  be  even  dreamed  of. 

F.  As  elsewhere  stated,   in  certain  cases  the  gas  was 
under  such  pressure  in  the  metal  that  it  bubbled  out  from 
the  borehole  the  moment  that  the  drill  reached  the  first 
blowholes.     This  is  certainly  the  behavior  of  gas  pre- 
viously present  in  the  blowholes  and  not  of  that  recovered 
from  the  water. 


a  Muller,  Iron,  February  9th,  1883,  p.  115, 


G.  The  gas  in  the  borehole  was  subjected  to  pres- 
sure above,  not  below,  that  of  the  atmosphere  (cf.  Figure 
16) :  this  would  oppose  the  recovery  of  gas  from  the 
water,  and  would  rather  tend  to  cause  the  water  to  absorb 
the  gas  evolved  by  the  metal. 

The  second  line  of  reasoning  by  which  it  is  attempted 
to  show  that  hydrogen  and  nitrogen  of  the  boring  gases 
may  not  be  the  chief  causes  of  blowholes,  is  offered  pro- 
visionally by  Wedding."  He  suggests  that  carbonic 
oxide,  formed  by  reaction  in  the  solidifying  metal, 
causes  the  blowholes :  that  it  is  converted  into 
carbonic  acid  later  on,  I  suppose  by  the  reaction  2CO  — 
C  -f-  CO2 ;  that,  after  the  blowholes  have  been  formed, 
hydrogen  and  nitrogen  enter  them  :  that,  on  boring,  the 
carbonic  acid  is  absorbed  by  the  water  in  which  the  ingot 
is  immersed,  so  that  hydrogen  and  nitrogen,  though  per- 
haps innocent,  are  alone  found.  It  is  sufficient  to  reply 
1st,  that  though  some  carbonic  oxide  might  be  thus  con- 
verted into  carbonic  acid,  the  reaction  would  never  be 
complete,  but  would  be  arrested  as  soon  as  equilibrium 
was  reached.03  3d,  that  if  it  were  converted  into  carbonic 
acid,  much  of  this  would  be  immediately  reduced  to  car- 
bonic oxide  by  the  hot  metal.ce  3d,  that  the  water  in 
which  the  ingot  is  drilled  becomes  warm,  with  correspond- 
ing decrease  in  its  solvent  power  for  carbonic  acid.'  4th, 
that  in  boring  blisters  under  water  plenty  of  both  carbonic 
oxide  and  carbonic  acid  are  found,  (33  and  34,  Table  54) 
showing  that  the  water  by  no  means  necessarily  absorbs 
all  our  carbonic  acid.  5th,  that  on  boring  under  mercury 
and  oil  neither  carbonic  acid  nor  oxide  is  found.  6th,  that 
it  would  be  a  gratuitous  assumption,  which  really  begs 
the  whole  question,  to  hold  that  the  hydrogen  and  nitro- 
gen which  are  evolved  before  and  during  solidification 
along  with  the  carbonic  oxide  do  not  cooperate  with  it  to 
form  the  blowholes.  I  know  no  reason  to  suspect  even 
faintly  that  the  evolution  of  hydrogen  and  nitrogen  is 
temporarily  suspended  while  carbonic  oxide  is  forming 
the  blowholes,  to  recommence  when  they  have  been 
formed. 

§  219.  I  have  now  pointed  out  that  the  hydrogen  and 
nitrogen  which  clearly  come  from  solution,  not  reaction, 
constitute  a  large  part  of  the  blowhole-forming  gases  ; 
that  the  behavior  of  gases  toward  iron  is  so  closely  like 
their  behavior  towards  other  solvents  as  in  itself  to  indi- 
cate that  they  dissolve,  and  that  their  blowhole- forming 
escape  is  in  large  part  from  previous  solution  :  and  that 
in  checking  the  escape  of  gas  silicon  acts  through  the 
solvent  power  of  the  iron. 

That  blowholes  are  in  large  part  formed  by  the  escape 
of  hydrogen  and  nitrogen  from  previous  solution  may 
then  be  regarded  as  well  established.  But  carbonic  oxide, 
though  not  found  in  the  blowholes,  probably  cooperates 
with  hydrogen  and  nitrogen  in  causing  them.  Though  it 
involves  some  repetition  let  us  now  re-examine  the  evidence 
with  a  view  to  deciding  whether  this  carbonic  oxide,  like 
the  hydrogen  and  nitrogen,  escapes  from  solution  or  is 


bStahlundEisen.  III.,  p.  300,  1883. 

<=See§  183,  p.  118. 

"Bell,  Journ.  Iron  and  St.  Inst.,  1871,  I.,  pp.  140  to  143,  163,  184,  Experi- 
ments 345,  253,  343,  344,  and  254  to  263. 

eldem,  pp.  109  to  111,  Expts.  78-9.  Manufacture  of  Iron  and  Steel,  pp. 
185-6. 

t  Muller,  Stahl  und  Eisen,  III.,  p.  445,  1883  :  Iron,  Sept.  14,  1883,  p.  344. 
At  65-6°  C.  water  dissolves  only  about  one  fifteenth  as  much  carbonic  acid  as  at 
0'.  (Storer,  Diet.  Solubilities.) 


144 


THE    METALLURGY    OF     STEEL. 


formed  at  the  instant  of  its  escape  by  the  oxidation  of 
carbon. 

1 .  While  the  behavior  of  gases  towards  iron  resembles 
their  behavior  to  known  solvents  so  closely  as  to  indicate 
that  they  escape  in  large  part  from  solution,  it  does  not 
prove  that  they  escape  solely  from  solution.     Further 
study  may  reveal  discrepancies  due  to  the  escape  of  car- 
bonic oxide  from  reaction. 

2.  The  general  resemblance  of  the  behavior  of  carbonic 
oxide  to  that  of  hydrogen  and  nitrogen,  its  escaping 
simultaneously  with  these  gases  which  surely  come  from 
solution,  certainly  strongly  suggests   that  it  too  comes 
from  solution.     But  while  their  escape  is  usually  simul- 
taneous, yet  the  relation  between  the  proportion  of  car- 
bonic oxide  and  that  of  these  other  gases  varies  so  greatly 
with  varying  conditions,  as  to  permit  the  belief  that  their 
escape  may  be  due  to  different  ulterior  causes.     The  ratio 
of  hydrogen  to  nitrogen  in  the  gases  obtained  under  differ- 
ent conditions  indeed  varies,  but,  with  few  exceptions, 
within  much  narrower  limits  than  does  the  ratio  of  car- 
bonic oxide  to  these  gases :  moreover,  it  is  not  shown  that 
the  latter  variation  may  not  be  due  to  the  solubility  of  the 
hydrogen  group  and  the  non-solubility  of  carbonic  oxide. 
This  consideration  does  not  argue  against  the  solubility 
of  carbonic  oxide,  but  it  lessens  the  force  of  the  argument 
of  analogous  behavior. 

3.  Next  we  have  Bessemer' s  statement  that  raising  and 
lowering  the  pressure  completely  stopped  and  accelerated 
the  escape  of  apparently  pure  carbonic  oxide  from  molten 
iron.8    But  there  seems   to  be  room  for  a  difference  of 
opinion  as  to  whether  the  escaping  gas  was  really  pure 
carbonic  oxide,  and  indeed  whether  more  carbonic  oxide 
was  present  than  could  be  accounted  for  by  the  agitation 
due  to  the  escape  of  hydrogen  and  nitrogen  from  solu- 
tion.8 

4.  Again,  the  apparent  absorption  of  carbonic  oxide  ob- 
served by  Graham,  Parry,  and  Troost  and  Hautefeuilleb : 
the  escape  of  gas  noted  by  the  latter  observers  when  iron 
was  solidified  with  fall  of  pressure  after  long  tranquil 
fusion  in  an  atmosphere  of  carbonic  oxide" :    and  the 
greatly  increased  suddenness  of  escape  of  gas  when  iron 
was  suddenly  solidified  in  Brustlein's  experiment,"1  all 
point  to  the  escape  of  carbonic  oxide  from  solution.     But 
we  do  not  know  that  it  is  carbonic  oxide  and  not  simply 
its  dissociated  elements  that  is  absorbed  by  hot  iron :  and 
we  have  no  analyses  of  the  gas  evolved  on  solidification  in 
the  experiments  of  Troost  and  Hautefeuille  and  of  Brust- 
lein  to  tell  us  that  carbonic  oxide  was  among  the  gases  thus 
expelled. 

5.  Carbonic  oxide  escapes  from  iron  in  which  a  gas- 
forming  reaction  is  improbable,  both  from  oxygenated  and 
hence  nearly  carbonless  iron  and  from  presumably  oxygen- 
less  cast-iron. 

In  the  latter  case  it  is  possible  that  the  carbonic  oxide 
arises  from  external  oxidation. 

In  the  case  of  afterblown  basic  metal  it  would  indeed  be 
improbable  that  all  the  gas  escaping  during  solidification 
was  carbonic  oxide  arising  from  reaction,  for  probably 
at  least  three  volumes  of  gas  then  escape  per  volume  of 


a  §  188  C,  p.  1S4. 
b  §  190,  p.  134. 
c  §  188  A,  p.  133. 

a  §  sos  E. 


metal,  which  would  imply  the  oxidation  of  0'02$  of  car- 
bon, or  half  that  residue  which  the  enormous  excess  of  air 
of  the  afterblow  had  been  powerless  to  remove.6  But  we 
do  not  know  that  the  gas  from  afterblown  basic  steel  con- 
tains any  considerable  proportion  of  carbonic  oxide,  as  we 
have  no  analysis  of  it. 

The  gas  from  overblown  acid  Bessemer  metal  contains 
about  18$  of  carbonic  oxide.' 

The  escape  of  three  volumes  of  gas  containing  this  pro- 
portion of  carbonic  oxide  calls  for  the  oxidation  of  0'004$  of 
carbon.  We  would  hardly  expect  even  this  small  quantity 
to  be  oxidized,  especially  as  the  relative  affinity  of  carbon 
for  oxygen  probably  falls  with  falling  temperature :  yet  it 
is  far  from  incredible  that  it  should  be. 

In  short,  while  the  escape  of  carbonic  oxide  in  these 
cases  certainly  suggests  that  this  gas  had  been  dissolved 
in  the  metal,  it  by  no  means  proves  it. 

6.  The  fact  that  the  blowholes  in  ice,  clearly  formed  by 
gas  escaping  from  solution,  so  closely  resemble  those  in 
iron,  strongly  suggests,  but  does  not  prove,  that  the  gases 
which  form  the  latter  also  escape  from  previous  solution : 
and  carbonic  oxide  is  probably  one  of  these  blowhole- 
forming  gases. g 

7.  Next,  the  protracted  and  deferred  escape  of  gas,  in- 
cluding carbonic  oxide,  during  solidification  is  truly  far 
more  suggestive  of  escape  from  previous  solution  than  of 
deferred  reaction :  and  indeed  when  the  escape  of  gas 
from  the  molten  metal  has  once  ceased  but  begins  again 
later,  the  latter  source  seems  decidedly  improbable  :  but, 
though  no  exactly  similar  case  has  been  suggested,  even 
the  deferred  reaction  cannot  be  called  impossible,  and  the 
protracted  reaction  can  hardly  be  called  even  extremely 
improbable.11 

8.  Again,  we  have  seen  that  the  addition  of  silicon  and 
manganese  diminishes  or  even  completely  stops  the  evo- 
lution of  gas,  including  carbonic  oxide,  even  when  but 
little  of  these  elements  is  oxidized,  and  when  a  portion  of 
the  carbon  added  along  with  them  appears  to  be  oxidized, 
so  that  that  which  appears  to  stimulate  the  formation  of 
carbonic  oxide  stops  its  escape.1     Silicon  and  manganese 
here  undoubtedly  arrest  the  escape  of    hydrogen  and 
nitrogen  by  increasing  their  solubility :  but  it  is  possible 
that  they  arrest  the  escape  of  carbonic  oxide  by  being 
themselves  oxidized  and  thus  stopping  its  formation.    For 
either  silicon  or  manganese  is  oxidized  to  a  slight  extent 
in  every  case,  and  the  proportion  of  carbon  which  appears 
to  be  oxidized  is  so  minute  that  its  disappearance  may  be 
due  to  experimental  error.     We  have  further  seen  that  it 
is  improbable  on  a  priori  grounds  that  silicon  and  manga- 
nese should  have  the  power  of  preventing  the  oxidation 
of  carbon  under  these  conditions :  but,  though  improb 
able,  it  is  far  from  impossible. 

The  escape  of  carbonic  oxide  from  solution  and  from 
immediately  preceding  reaction  are,  however,  far  from 
mutually  exclusive. 

Be  it  remembered  that,  even  if  we  hold  that  carbonic 
oxide  does  dissolve,  we  must  still  admit  that  it  may  es- 
cape from  immediately  preceding  reaction  also.  In  this 
view  the  case  considered  in  the  last  paragraph  admits 


e§316,  p.  141. 

t  73-4,  Table  55,  p.  107. 

g  §  214,  C,  p.  139. 

h  §  214,  B,  p.  138. 

1  §  315,  A,  p.  138, 


THE  REACTION  AND  SOLUTION  THEORIES  OF  BLOWHOLE-FORMATION :  RESUME.     §  220.    145 


another  explanation,  to  wit,  that  the  carbonic  oxide  which 
was  escaping  before  the  recarburizer  was  added  was  being 
formed  as  it  escaped  by  the  oxidation  of  carbon,  and  that 
the  silicon  and  manganese  increased  the  metal' s  solvent 
power  so  that  it  was  able  to  retain  in  solution  not  only 
the  hydrogen,  nitrogen  and  carbonic  oxide  which  would 
have  continued  to  escape  had  the  recarburizer  not  been 
added,  but  also  that  carbonic  oxide  which  is  formed  by 
the  oxidation  of  a  portion  of  the  carbon  of  the  recarbur- 
izer. 

In  this  view  the  deferred  escape  of  gas  from  molten 
metal  may  be  explained  comparatively  simply.  If  the 
escape  of  carbonic  oxide  temporarily  ceases  after  the 
spiegel  reaction,  we  may  suppose  that,  though  this  gas 
is  constantly  being  generated  by  the  union  of  the  carbon 
and  oxygen  of  the  metal,  yet  with  falling  temperature 
(Figure  15)  its  solubility  increases  at  first  faster  than 
the  gas  forms :  hence  its  escape  ceases.  Later,  its  solu- 
bility perhaps  increasing  less  rapidly,  or  indeed  falling 
as  the  freezing  point  is  reached,  while  its  formation  con- 
tinues" unabated,  the  metal  again  becomes  supersaturated, 
and  escape  recommences. 

Those  who  hold  that  the  carbonic  oxide  escaping  from 
iron  is  always  generated  by  immediately  preceding  reac- 
tion, may  go  a  step  farther  and  claim  that  reaction  is  the 
sole  ulterior  cause  of  the  escape  of  gas,  both  before  and 
during  solidification  at  least  in  certain  cases  :  that  it  is 
the  agitation  or,  if  they  prefer  vagueness,  the  intermolec- 
ular  disturbance  due  to  the  escape  of  nascent  carbonic 
oxide  that  causes  the  hydrogen  and  nitrogen  to  escape  ; 
and  that  the  carbonic  oxide,  the  principal,  which  escapes 
during  plasticity  and  with  its  accomplices,  hydrogen  and 
nitrogen,  forms  blowholes,  is  later  decomposed  by  the  hot 
metal,  or  reabsorbed,  so  that  the  accomplices  alone  are 
found  on  boring.  But  this  does  not  bear  the  stamp  of 
probability  :  indeed  it  seems  almost  impossible  in  many 
cases,  e.  g.  in  Bessemer' s  and  Brustlein's  experiments, 
and  in  the  case  of  oxygenated  and  almost  carbonless  basic 
metal,  from  which  great  quantities  of  hydrogen  and  nitro- 
gen escape  on  solidification,  though  but  slight  oxidation 
of  carbon  can  occur,  and  though  the  violent  agitation  of 
the  Bessemer  process  had  failed  to  expel  this  hydrogen 
and  nitrogen. 

§  220.  RESUME. — To  sum  this  discussion  up,  very  nu- 
merous analyses  of  the  gases  which  iron  evolves,  before,  dur- 
ing and  after  solidification,  on  boring  and  on  heating  in 
vacuo,  prove  that  these  gases  usually  consist  chiefly  of 
hydrogen  and  nitrogen,  which,  according  to  the  definitions 
made  in  order  to  render  discussion  of  the  points  at  issue 
possible,  must  escape  from  solution. 

But,  wholly  independently  of  this  conclusive  evidence, 
the  behavior  of  gases  towards  iron,  their  absorption  and 
release  from  both  solid  and  molten  metal  on  rise  and  fall 
of  pressure,  their  expulsion  on  solidification  and  agitation, 
their  protracted  escape,  and  the  shape  and  position  of  the 
cavities  which  they  form,  is  closely  analogous  to  their  be- 
havior towards  other  solvents.  The  closeness  of  this 
analogy  ;  our  inability  to  reconcile  the  copious  escape  of 
gas  from  iron  rich  in  silicon  with  the  complete  arrest  of 
the  escape  of  gas  by  slight  additions  of  this  element  on  the 
reaction  theory,  and  the  complete  accord  of  these  phe- 


nomena with  the  solution  theory  ;  the  fact  that  gases  are 
copiously  evolved  from  both  oxygenless  and  nearly  car. 
bonless  iron  and  from  other  classes  in  which  no  gas-form- 
ing reaction  is  to  be  looked  for ;  and  that  their  escape 
cannot  be  accounted  for  qualitatively  or  quantitatively 
by  purely  mechanical  retention  of  insoluble  gas,  all  point 
with  varying  degrees  of  certainty  and,  taken  collectively, 
lead  irresistibly  to  the  conclusion  that  gases  dissolve  in 
iron,  and  that  at  least  a  very  large  part  of  the  gases  whose 
escape  forms  blowholes  are  dissolved  in  the  metal  before 
that  escape. 

If  successful,  the  attempt  to  show  that  the  hydrogen 
and  nitrogen  alone  found  on  boring  cold  iron  proceed  from 
the  water  in  which  it  is  bored,  not  from  the  iron,  would  not 
seriously  bear  against  the  remaining  evidence  and  reason- 
ing. But  the  ratio  of  nitrogen  to  hydrogen  in  these  gases 
and  their  freedom  from  oxygen  :  the  fact  that  the  gases 
obtained  in  the  two  instances  in  which  iron  has  been  bored 
under  oil  and  mercury  resembled  in  composition  those  ob- 
tained on  boring  under  water :  the  fact  that  compact 
yields  less  gas  than  porous  iron,  and  the  arrangement  of 
the  boring  apparatus,  collectively  argue  cogently  against 
the  aqueous  source  of  the  gases.  That  the  absence  of  car- 
bonic oxide  from  these  gases  is  not  due  to  its  conversion 
into  carbonic  acid  and  subsequent  absorption  by  the  bor- 
ing water,  is  indicated  by  the  facts  that  this  conversion 
could  not  be  complete,  that  neither  carbonic  oxide  or  acid 
is  found  on  boring  under  oil  and  mercury,  and  that  in 
case  of  blisters  both  these  gases  are  found  even  on  boring 
under  water. 

Further,  the  changes  in  the  composition  of  the  gases 
evolved  from  iron,  so  far  as  we  have  studied  them,  are 
quite  compatible  with  the  view  that  they  are  evolved  from 
solution. 

Turning  now  to  carbonic  oxide,  which  accompanies 
hydrogen  and  nitrogen  in  all  except  the  boring  gases,  there 
is  reason  to  believe  that,  in  spite  of  its  absence  from  the 
blowholes  when  the  metal  is  cold,  it  cooperates  in  forming 
them  while  the  metal  is  hot,  and  is  later  reabsorbed  or 
decomposed.  I  the  general  similarity  of  its  behavior  to 
that  of  hydrogen  and  nitrogen ;  2  its  expulsion  and  absorp- 
tion with  falling  and  rising  pressure  ;  3  its  escape,  occurring 
when  no  reaction  is  to  be  expected,  and  arrested  by  silicon 
when  this  element  appears  to  act  on  the  solubility  and  not 
by  being  preferentially  oxidized :  these  three  collectively 
very  strongly  indicate  that  carbonic  oxide  dissolves,  and 
that  its  blowhole-forming  escape  is  usually  from  previous 
solution.  But  it  may  reasonably  be  held  that  they  do  not 
prove  it.  Were  carbonic  oxide  known  to  dissolve,  then  in 
cooperating  with  hydrogen  and  nitrogen  in  the  formation 
of  blowholes  it  would  be  most  natural  to  suppose  that,  in 
the  majority  of  cases,  it  escaped  from  solution  like  its  com- 
panions. 

In  a  word :  it  is  practically  certain  that  in  the  many  and 
important  classes  of  cases  which  have  been  studied  the  blow- 
hole-forming gases  are  chiefly  hydrogen  and  nitrogen  escap- 
ing from  solution :  extremely  probable  that  carbonic  oxide 
cooperates :  and  probable  that  it  too  comes  in  large 
part  from  solution.  Under  other  and  yet  unstudied  con- 
ditions air  mechanically  drawn  down  in  teeming  may,  how- 
ever, prove  to  be  an  important  cause  of  blowholes. 


146 


THE    METALLUKGY    OF     STEEL. 


CHAPTER      XII. 
THE  PBEVENTION  OF  BLOWHOLES  AND  PIPES. 


As  a  preliminary  to  the  study  of  the  prevention  of  blow- 
holes and  pipes  in  steel  ingots  let  us  next  consider  their 
proximate  causes,  and  to  that  end  let  us  examine  their 
shape  and  position,  and  the  conditions  which  exist  while 
they  are  forming. 

§222.  SHAPE  AND  POSITION  OF  BLOWHOLES. — Blowholes 
are  usually  tubular  or  lenticular  cavities.  The  subcutane- 
ous ones  usually  lie  in  zones  nearly  parallel  with  the  outer 
surface  of  the  ingot,  (Figure  1 7),  and  with  their  axes 
perpendicular  to  it.  They  often  form  a  veritable  and 
decidedly  regular  honeycomb,  composed  of  egg-ended 
cylindrical  cells,  occasionally  of  nearly  uniform  diameter 
and  length.  In  some  ingots  fourteen  inches  square  I 
found  these  cells  three  inches  long  and  about  0.2  inches  in 
diameter,  and  in  volume  perhaps  twice  as  great  as  the 
intercellular  spandril  partitions  of  steel.  But,  while  these 
blowholes  very  constantly  lie  perpendicularly  to  the  ingot' s 
surface,  their  length  and  diameter  are  often  irregular. 

The  shape  and  position  of  those  blowholes  which  lie 
nearer  the  center  of  the  ingot  are  much  less  regular  than 
those  of  the  subcutaneous  ones.  In  some  cases  as  we  pass 
inwards  beyond  the  zone  of  subcutaneous  blowholes  we 
find  a  tolerably  compact  region,  while  the  proportion  of 
blowholes  again  increases  as  we  approach  the  center,  as 
shown  in  Figure  19.  This  represents  a  polished  bar  cut 


1st.  Stripes,  furrows,  or  foldings,  perhaps  caused  by  the 
compression  due  to  the  contraction  of  the  neighboring 
metal. 

2d.  Intrusions  apparently  caused  by  the  entrance  of  gas 
from  the  surrounding  metal  after  the  walls  of  the  blow- 
hole have  become  pasty.  They  consist  chiefly  (1)  of  lit- 
tle knobs,  which  the  gas  has  forced  into  the  blowhole  but 
has  not  burst :  (2)  of  pits,  the  remains  of  knobs  which 
have  burst  (Fig.  19  A). 


Figs.  19  A  to  19  D.    Microscopic  Intrusions  in  Blowholes.    Martens. 


3rd.  Intrusions  of  metal,  apparently  due  not  to  the  es- 
cape of  gas  but  to  change  of  volume  in  the  surround- 
ing metal,  whether  due  (A)  directly  to  the  necessarily 
irregular  changes  in  the  temperature,  which,  though 
generally  fulling,  yet  perhaps  occasionally  rises;  as  in  the 
" af  ter-glow  "  :  or  (B),  as  Martens  believes,  to  the  solidifi- 
cation of  the  different,  components  of  the  mass  at  different 
periods,  each  changing  volume  as  it  solidifies  :  or  (C),  as 


?,  BLOW-HOLES, 
(MULLER.) 


Fig.  18,  BLOW-HOLES, 
(GREENWOOD.) 


00 


/  /  i  0    0    0    0 

PQ  0  000(1  OOMOOCOOCnoV 


Fig.  19,  CENTRAL  CAVITIES,  (CHERNOFF.) 

BAR  CUT  RADIALLY   FROM  AN  ANNULAR   HAMMERED  BLOOM. 


fFROM  CENTRE  ) 


radially  from  a  hammered  bloom,  the  right-hand  end 
having  been  at  the  center  of  the  ingot.8 

The  surface  of  the  blowholes  is  here  smooth,  there  fur- 
rowed lengthwise:  .now  metallic  and  silvery,  now  oxi- 
dized, now  covered  with  an  extremely  thin  enamel  -like 
coating  of  a  more  or  less  greenish  or  yellowish  gray 
color,  and  even  brown  according  to  Walrand.  I  have 
confirmed  Walrand'  s  statement  that  this  coating  is 
instantly  removed  by  hydrochloric  acid  with  evolution  of 
sulphuretted  hydrogen,  recognized  by  smell  and  test-paper. 
On  the  whole  the  surfaces  of  rather  more  of  the  subcu- 
taneous than  of  the  deeper  seated  blowholes  seems  to  be 
oxidized  :  yet  the  reverse  is  often  true. 

In  the  upper  part  of  the  ingot  and  surrounding  its  axis 
is  the  pipe,  its  sometimes  almost  friable  sides  usually 
slightly  furrowed  lengthwise,  and  dotted  with  fine  crys- 
tals (Figures  29  to  31).  An  enamel-like  coating  like  that 
in  the  blowholes  often  lines  the  pipe,  and  in  certain  cases 
I  have  found  little  yellow  or  transparent  ruby  drops  and 
even  buttons  of  what  seems  to  be  slag,  apparently  liquated 
from  the  surrounding  metal. 

Martens  finds  with  the  microscope  three  sets  of  mark- 
ings and  intrusions  in  the  blowholes.1" 


a  Cbernoff,  Revue  Universelle,  2d  Ser,  VII. ,  1880.  The  hammering  has  dis- 
torted the  cavities,  so  that  their  axes  are  now  parallel  with  that  of  the  bloom. 

bStahl  und  Eisen,  VII  ,  p.  341,  1887,  I  understand  that  Figures  19  A  to  D 
represent  actual  intrusions, 


we  may  conjecture,  to  the  successive  births  of  different 
definite  minerals  from  the  mother  magma,  with  decrease 
or  increase  of  volume  as  the  new-born  mineral  is  denser  or 
less  dense  than  the  mass  from  which  it  springs.  While 
these  intrusions  sometimes  consist  of  simple  crystals, 
Figure  19  B,  they  are  more  often  irregular,  Figure  19  C, 
or  of  fir-tree  shape,  Figure  19  D. 

Chernoff,  too,  finds  twisted  dendritic  crystals,  like  those 
of  Figure  26,  on  the  upper  sides  of  the  blowholes. 

Figure  20  and  the  last  column  of  Table  71,  §  202  C,  indi- 
cate the  usual  positions  of  blowholes.  If  the  temperature 
be  excessively  high,  fine,  closely  packed,  elongated,  exter- 
nal blowholes  form,  as  A,  Figure  20,  together  with  spo- 
radic central  ones  if  the  metal  be  very  free  from  carbon  as 
in  I.  It  is  said  that  if  the  temperature  be  normal  or  low, 
the  blowholes  are  wider,  and  tubular  or  lenticular.  With 
a  normal  casting  temperature  they  lie,  in  case  of  hard 
steel,  chiefly  in  a  zone  very  near  the  exterior  as  at  B : 
in  softer  steel  they  lie  nearer  the  center  as  in  C,  D  and  J. 
If  the  temperature  be  rather  low,  the  blowholes  lie  as  in 
E  and  F  :  and  if  it  be  excessively  low  the  ingot  becomes 
spongy  as  at  G ;  while  if  the  metal  at  the  same  time  b^ 
very  soft  it  rises  violently,  nearly  half  emptying  the 
mould  as  at  H  and  K.° 

Pits.— The  fine  blowholes  which  in  case  of  extremely 


Van  Nostrand's  Eng.  Mag.,  XXXIII.,  p.  302,  1885. 


THE    SHAPE    AND     POSITION    OF     BLOWHOLES.       §  222. 


147 


hot-cast  steel  extend  nearly  or  quite  to  the  ingot' s  skin 
(A,  figure  20)  are  thought  to  be  the  cause  of  the  pittings 
with  which  boiler-plate  steel  is  liable  to  be  covered  :  at 
least  it  is  the  observation  of  some  open-hearth  steel- 
melters  that  these  pits  may  be  induced  by  an  extremely 
high  casting  temperature,  and  blowholes  so  close  to  the 
ingot's  skin  seem  well-calculated  to  become  filled  with 
iron  oxide  during  heating,  the  thin  skin  of  metul  outside 
them  being  comparatively  permeable  if  indeed  it  is  not  re- 
moved by  oxidation,  leaving  the  ends  of  the  blowholes 
open.  The  contents  of  these  pits  has  been  found  to  con- 
sist chiefly  of  iron  oxide. 

In  general,  the  regular  arrangement  of  the  blowholes 
in  a  zone  parallel  with  the  outer  surface,  and  with  the 
axes  of  the  blowholes  normal  to  that  surface,  as  in  E, 
Figure  20,  characterizes  rather  hard  steel :  with  soft  steel 
the  blowholes  are  less  regularly  disposed,  and  a  larger 
proportion  is  found  nearer  the  center. 

The  correlation  between  the  shape  and  position  of  the 
blowholes  on  the  one  hand,  and  the  conditions  of  casting 
and  the  composition  of  the  metal  on  the  other,  does  not 
seem  very  clearly  established. 

The  shape  and  position  of  these  blowholes  are  closely 


Into  a  bubble  already  formed  gas  evaporates  from  a  sat- 
urated liquid  much  more  readily  than  if  no  bubbles  are 
present,"  as  is  illustrated  by  the  bumping  of  many  boiling 
liquids.  Hence  whatever  gas  is  evolved  in  the  neighbor- 
hood of  the  bubble,  by  preference  passes  into  it  and  aug- 
ments its  size.  But  meanwhile  the  freezing  is  progress- 
ing, and,  as  a  bubble  is  a  poor  conductor  of  cold  (more  ac- 
urately,  of  heat),  freezing  occurs  by  preference  between 
the  bubbles.  And  so  freezing  and  tubule-growth  take 
place  together,  the  walls  expelling  gas  as  they  grow,  and 
on  this  gas  the  tubules  feed.  If  the  evolution  of  gas  in- 
creases more  rapidly  than  the  freezing,  the  tubule  will 
increase  in  diameter  as  it  elongates,  and  it  may  reach  such 
a  size  that  gravity  overcomes  capillarity,  and  that  a 
bubble  detaches  itself  and  swims  to  the  surface. 

Chernoif  believes  that  iron  solidifies,  not  in  approxi- 
mately regular  parallel  layers,  but  by  the  growth  of  pine- 
tree  crystals,  whose  trunks  and  branches  mechanically 
imprison  the  evolved  gas  and  prevent  its  swimming  to  the 
surface.  He  attributes  the  twisting  of  the  dendritic  crys- 
tals (Figure  26)  at  the  top  of  the  blowholes  to  the  partial 
rise  of  gas  bubbles,  which  part  and  even  detach  the 
branches  of  the  pine-tree  crystals.0 


TEMPERATURE 
VERY  HIGH. 


TEMPERATURE  NORMAL. 


TEMPERATURE  LOW. 


if°  ooir"i 

o  d 

/^oo-o.o.o  o  o  oA 
Q 

D        " 

d                                o 

o 

s  § 

i  8 

I             i 

1      i 

°       SOFT  STEEL     ° 
6, 

OO  OOOOO 
VERY  SOFT 

V  0-0   0  0   0  0  O'O'oV 

TEMPERATURE  VERY  LOW. 


-  -. 

F 

,0.0-0^000 

0  T> 


S  » 

OQ-OOOO 

VERY-SOFT 
,  6TEEL  „, 

OQ  o  o  o  o  ootooO^y 


y)t>  Hcaoooos 


ig.  20,  BLOW-HOLES, (WALRAND.) 


BASIC  INGOT  IRON, 
EXCESSIVELY  HOT. 


BASIC  INGOT  IR'ONv 
TEMPERATURE  HORMAU 


BASIC  INGOT  IRON, 

EXCESSIVELY  COLD, 


K 
* 


A  to  H,  Walrand,  Van  Nostrand's  Engineering  Magazine,  XXXIII.,  p.  853. 


I  to  K,  J.  Hartshorne,  private  communication. 


like  those  of  bubbles  in  ice,  which  are  in  general  tubular, 
occasionally  lenticular  or  even  spherical.  In  ice  ingots 
formed  by  freezing  water  in  glass  bottles  I  find  that  the 
axes  of  the  tubules  are  always  perpendicular  to  the  cooling 
surface,  and  nearly  independent  of  gravity.  The  tubules 
along  the  sides  of  the  bottle  are  horizontal :  at  its  shoulder 
they  point  downward.  In  some  ice  ingots  I  find  the  blow- 
holes arranged  quite  as  in  ingots  of  steel :  first  a  row  of 
elongated  external  tubules,  then  a  quite  compact  region, 
then  a  sharply  marked  zone  of  nearly  spherical  cavities, 
then  another  compact  zone,  and  finally  a  core  decidedly 
porous  or  even  friable.  The  striking  points  of  resemblance 
between  the  blowholes  in  ice  and  steel  are  (1)  that  they 
are  normal  to  the  cooling  surface,  (2)  that  they  are  ar- 
ranged in  well-ir  arked  zones  parallel  with  that  surface, 
(3)  that  the  tubular  form  is  most  marked  in  the  subcutane- 
ous blowholes,  the  deep-seated  ones  being  more  nearly 
spherical,  (4)  that  they  are  most  abundant  near  the  skin 
and  near  the  center. 

The  tubular  form  of  the  blowholes  in  ice  and  iron  is 
readily  accounted  for.  While  part  of  the  first-evolved 
gas  may  swim  to  the  upper  surface,  another  part  attaches 
itself  to  the  already  solidified  walls  in  minute  spheres." 


a  In  a  freezing  water-bottle  a  persistent  rising  of  minute  bubbles  occurs  simul 
laneously  with  the  formation  of  the  tubules. 


Now,  as  we  shall  see  in  Chapter  XIII.,  the  solidification 
of  iron  is  doubtless  a  species  of  crystallization :  witness 
the  ingot's  columnar  structure,  most  marked  near  the 
shell,  and  in  small  ingots  extending  to  the  center,  pro- 
ducing strong  radial  markings  in  circular  and  a  maltese 
cross  in  square  ingots,  (Figures  27-28).  Indeed,  iron  oc- 
casionally develops  beautiful  pine-tree  crystals,  actual  in- 
stances of  which  are  shown  in  Figures  25, d  29,  and  31. 
One  crystal  in  the  former  is  2 '25  inches  wide.  Still,  it  is 
improbable  that  the  tree-tops  usually  protrude  far  enough 
beyond  the  solid  growth  to  detain  bubbles  mechanically. 
For  Muller  found,6  on  pouring  out  the  interior  of  partly 
frozen  ingots  at  various  stages  of  solidification,  and  there- 
by revealing  successive  stages  of  the  growth  of  blowholes, 


*>  For  an  admirable  elementary  explanation  of  the  principles  of  surface  tension 
see  Maxwell,  Theory  of  Heat,  pp.  279  et  seq. 

In  a  freezing  ice  bottle  in  which  tubules  are  forming  the  spherical  ends  of  the 
gas  bubbles  in  the  tubules  appear  to  project  beyond  the  already  frozen  walls  into 
the  still  liquid  centre:  but  this  cannot  be  seen  very  distinctly.  Conversely,  when  a 
tubule-holding  lump  of  ice  melts  in  water,  the  ice  may  melt  quite  a  distance  back 
from  the  end  of  the  tubule,  leaving  a  spherical  bubble  of  air,  which  very  clearly 
projects  into  the  water,  but  eventually,  after  the  ice  has  melted  back  far  enough, 
the  bubble  detaches  itself  and  rises  to  the  surface. 

c Revue  TTniverselle,  2d  Ser.,  VII.,  p.  153,  1880. 

d  Figure  25,  from  a  photograph,  represents  a  bunch  of  crystals  kindly 
sent  me  by  Mr.  John  Fulton.  It  is  from  the  sinking-head  cavity  of  a  large  steel 
ingot. 

« Iron,  Jan.  5,  1883,  p.  18  :  Sept.  14,  1883,  p.  244. 


148 


THE    METALLURGY    OF    STEEL. 


that  the  inner  walls  of  the  hollow  ingot  were  remarkably 
smooth  and  even,  though  perforated  with  many  blow- 


Fig  29.— Crystal  from  a  pipe  in  steel.    Magnified  70  times.    Chernoff. 

holes  in  case  of  rising  steel.     (Figure  32).     Others  have 
observed  that  the  inner  walls  of    "bled"    ingots    are 
smooth. 
To  obtain  a  little  side  light  on  this  question  I  applied 


haps  one-sixth  of  the  whole  was  frozen.  From  the  posi- 
tion of  these  crystals  I  fancy  that  they  may  have  grown 
in  a  vug.  But,  though  great  pains  were  taken  to  pour 
the  water  from  this  ingot  so  gently  that  it  could  not  wash 
off  any  delicate  crystals,  the  sides  of  the  cavity  were  ex- 
tremely smooth,  showing  at  most  suggestions  of  crystal- 
line markings,  but  perforated  with  many  growing  blow- 
holes. In  the  same  way  I  have  often  noticed  that,  on 
pouring  out  the  interior  of  a  partly  solidified  block  of  slag, 
the  sides  of  the  cavity  were  smooth  and  free  from  crystal- 
line markings,  although  the  solidified  portion  had  a 
strong  columnar  structure,  and  although,  if  allowed  to 
solidify  completely,  the  vugs,  even  those  very  near  the 
upper  surface  which  were  probably  formed  early,  were 
usually  lined  with  beautiful  and  in  some  cases  marvel- 
ously  beautiful  crystals. 

This  is  the  result  of  many  hundreds  if  not  thousands  of 
observations :  for  a  long  while  I  had  the  interior  of  all 
pots  of  slag  emptied,  leaving  a  rather  thin  shell,  which  it 
was  my  custom  to  examine  daily  for  prills. 

In  all  these  cases  we  find  that,  in  spite  of  strong  colum- 


Fig.  26.— Dendrlte  from  a 
blowhole.    Chernoff. 


Fig.  27.— Columnar  structure  of 
ingots.    Chernort. 


Fi.j.  28. — Columnar  structure. 
Chernoti . 


r 


Fig.  80. — Crystals  from  a  pipe  in  st< 
Magnified  four  times.    Chernoff. 


>ipe  in  steel.  Fig.  81.    Pine-tree  crystal  from  iron.    Knop. 


Fig.  32.— Growth  of  blowholOB. 
MUller. 


the  same  device  to  freezing  ice-ingots  and  found  their 
walls  very  smooth,  though  perforated  with  many  tubules. 
With  a  lens  I  detected  a  slight  convexity  over  the  mouths 
of  certain  blowholes  :  but  apart  from  this  I  could  detect  no 
excrescences.  The  mouths  of  other  blowholes  were  open, 
showing  that  the  gas  bubble  probably  projected  into  the 
still  unfrozen  water.  Yet  in  the  central  vugs  of  one  ice- 
ingot  which  had  cracked  and  bled,  I  found  large  crystals 
of  extraordinary  beauty.  I  often  noticed  that  the  first 
.skimming  of  ice  on  the  upper  surface  of  the  water  would 
form  through  beautiful  long  needles,  which  shot  across 
from  side  to  side,  as  happens  in  ponds  on  still  nights  : 
yet  if  the  resulting  ice-ingots  were  emptied  when  partly 
frozen,  the  sides  of  the  cavity  were  invariably  smooth  and 
free  from  excrescences,  with  perhaps  one  exception.  In 
one  case  I  found  beautiful  fig-leaf  crystals  at  the  top  of 
an  ice-ingot  whose  interior  had  been  poured  out  when  per- 


nar  structure,  and  in  spite  of  the  strong  tendency  to  form 
large  interlacing  crystals  in  the  vugs,  solidification  appears 
to  take  place  in  smooth  parallel  layers. 

Possibly  the  crystals  are  minute  at  the  contact  of  solid 
and  liquid  because  growth  may  occur  from  numberless 
points  simultaneously,  and  the  growths  from  neighboring 
points  interrupt  each  other :  while  the  perfectly  smooth 
surface  of  contact  of  liquid  and  gas  offers  no  points  from 
which  new  growths  may  start,  and  so  permits  the  develop- 
ment of  large  crystals.  It  is  well  known  that  crystals 
deposit  more  readily  on  rough  than  on  smooth  surfaces. 

The  main  axes  of  growth  of  ice  and  iron  certainly  lie 
between  the  blowholes.  Whether  the  position  of  these 
main  axes  initially  determines  the  starting  point  of  the 
blowholes  or  vice  versa  I  will  not  attempt  to  say :  but, 
once  started,  the  poor  conducting  power  of  the  tubules 
and  the  tendency  of  solidification  to  proceed  along  axes 


CONTRACTION    CAVITIES.      THE    CENTRAL    PIPE.      §  224. 


149 


normal  to  the  walls  of  the  mould  should  both  tend  to  the 
same  result,  the  tubular  shape  of  the  blowholes. 

If  this  be  the  way  in  which  blowholes  form,  why  are 
they  confined  to  certain  distinct  zones  1  Why  does  not 
each  individual  tubule  extend  from  the  shell  to  the  center 
of  the  ingot  ?  The  explanation  is  easy.  Suppose  that 
our  molten  iron  contains  much  less  gas  than  it  is  capable 
of  retaining  while  molten,-  yet  more  than  it  can  retain  on 
solidifying.  When  the  very  first  layers  solidify  they  be- 
come supersaturated  with  gas  and  expel  the  excess:  but 
this  may  not  become  gasified,  but  may  simply  pass  in- 
wards still  dissolved,  to  the  adjoining  still  molten  layer. 
In  this  way  no  gas  would  be  evolved  as  gas  till  the  still 
liquid  layers  were  actually  supersaturated,  and  the  very 
outer  layers  might  be  quite  free  from  blowholes. 

But  beyond  this,  during  the  remainder  of  the  period  of 
solidification  many  complicated  conditions  determine 
whether  gas  shall  or  shall  not  escape  at  any  given  mo- 
ment. Primarily  this  depends  on  the  solvent  power  of  the 
metal  and  on  the  existing  pressure.  With  gradually  fall- 
ing temperature  the  curve  of  solvent  power  reverses  at  the 
freezing  point  (Figure  15,  §  214,  p.  137),  introducing  a  first 
complication,  while  the  factors  which  govern  pressure  are 
simply  bewildering.  The  pressure  depends  (1)  on  the 
temperature,  whose  curve  reverses  during  the  '  'afterglow," 
and  perhaps  at  other  periods  (§  224,  foot  note);  and  (2)  on 
the  available  space  offered  to  the  gas  within  the  ingot, 
which  depends  on  the  ratio  of  contraction  of  shell  to  that  of 
interior.  This  in  turn  is  governed  by  two  varying  quanti- 
ties, (1)  the  ratio  of  cooling  of  shell  to  interior,  which 
constantly  changes,  and  (2)  the  density  of  the  metal, 
which  probably  follows  a  very  irregular  curve  (Figure  34) 
even  with  regularly  falling  temperature.  Beyond  this, 
the  rupture  of  internal  partitions,  owing  to  contraction  or 
gaseous  pressure,  and  the  bending  in  or  out  of  the  shell 
of  the  ingot  are  liable  to  affect  the  pressure.  With  such 
complexity  it  is  not  surprising  that  the  formation  of  blow- 
holes now  ceases,  now  begins  again,  only  again  to  cease. 

§  223.  CONTRACTION  CAVITIES. — Chernoff  believes  that 
it  must  frequently  occur  in  the  solidification  of  steel  that 
the  trunks  and  branches  of  adjoining  pine-tree  crystals  com- 
pletely enclose  certain  spaces,  and  prevent  all  communica- 
tion between  them  and  the  rest  of  the  metal :  that  as  the 
metal  in  these  spaces  cools  it  must  contract,  and  as  its 
contraction  is  not  fed  from  without  local  contraction  cavi- 
ties must  arise,  and  these  must  be  scattered  through  the 
ingot.  Indeed,  in  a  crystal  growing  on  the  sides  of  the 
central  pipe  he  finds  a  cavity  which  he  attributes  to  contrac- 
tion (a,  Figure  29).  Where,  owing  to  slow  solidification, 
the  pine  trees  grow  slowly,  a  supply  of  liquid  metal 
should  more  easily  penetrate  to  feed  these  cavities,  than 
where,  as  at  the  outside  of  the  ingot,  the  growth  is  ex- 
tremely rapid  :  on  the  other  hand,  when  solidification 
approaches  the  middle  of  the  ingot  we  have  but  a  small 
supply  of  metal,  and  of  now  quite  pasty  metal  at  that,  to 
feed  these  contraction  cavities.  Hence  we  should  expect 
the  contraction  cavities  chiefly  at  the  outside  and  near  the 
center  of  the  ingot :  and  in  this  way  he  accounts  for  the 
increased  porosity  or  even  friability  near  the  axis  of  the 
ingot.a 

Local  contraction  may  under  certain  conditions  origin- 
ate cavities  near  the  outside  of  the  ingot :  gas  would  nat- 


Revue  Universelle,  8d  Ser.,  VII.,  p.  140,  1880. 


urally  pass  into  them,  first  because  they  are  cavities,  sec- 
ond because  a  complete  vacuum  would  initially  exist  in 
them  :  so  that  we  might  have  two  classes  of  subcutaneous 
cavities,  those  originated  by  gas,  and  those  originated  by 
contraction  and  then  filled  with  gas.  It  seems  improb- 
able, however,  that  local  contraction  often  originates  sub- 
cutaneous cavities.  In  the  first  place,  the  addition  of 
silicon,  etc.,  suppressing  the  escape  of  gas,  also  completely 
suppresses  the  subcutaneous  blowholes,  the  central  pipe 
and  the  porous  region  about  it  still  remaining :  silicon 
should  not  prevent  local  contraction,  hence  it  is  not  prob- 
able that  the  subcutaneous  cavities  which  it  suppresses  are 
true  contraction  cavities.  In  the  second  place  the  smooth- 
ness of  the  inner  surface  of  ingots  and  ice  bottles  which 
have  been  partially  frozen  indicates  that  the  solid  growth 
of  the  branches  and  the  solidification  of  the  matter  be- 
tween them  keep  pace  with  that  of  the  trunks  so  closely, 
and  that  the  growth  proceeds  through  trunks  so  closely 
adjacent,  that  none  but  microscopic  cavities  would  be 
formed  between  them.  In  the  third  place  it  is  probable 
that  iron  actually  expands  in  the  very  act  of  solidification, 
though  indeed  contracting  as  the  temperature  falls  still 
farther  :  contraction  would  not  occur  in  any  one  of  these 
local  retreats  till  the  metal  in  that  retreat  was  distinctly 
solid*:  it  is  very  doubtful  whether  contraction  would 
then  actually  cause  even  a  microscopic  cavity :  it  would  be 
more  likely  to  temporarily  distend  the  metal. 

It  is  clear  that  the  cavities  in  the  neighborhood  of  the 
central  pipe  are  far  too  large  to  have  been  caused  by  the 
contraction  of  matter  originally  completely  enclosed  within 
crystal  tree  trunks  and  so  shut  out  from  external  sources 
of  supply.  They  are  clearly  due  to  the  ebbing  away  of 
the  material  which  originally  existed  in  the  now  hollow 
spaces,  and  which  has  later  sunk  away  into  the  central 
pipe,  as  it  yawns  and  widens  with  the  contraction  of  the 
already  solidified  metal  between  it  and  the  ingot's  skin. 

§  224.  PIPING.  The  Position  of  the  Pipe.— Let  us 
neglect  for  the  moment  the  evolution  of  gas  during  solidi- 
fication and  cooling.  Iron  like  other  substances  contracts 
in  cooling :  but  during  solidification  it  appears  to  expand, 
so  that  its  volume  follows  a  reversing  curve,  whose  general 
form  may  not  be  wholly  unlike  that  of  Figure  34. b  In  a 
cooling  ingot  the  changes  of  volume  would  follow  the 

Fig.  34 


direction  of  the  arrow,  and  during  any  given  period  the 
changes  of  volume  of  the  central  part  of  the  ingot  would  lie 
in  this  curve  to  the  right  hand  of  those  of  the  outside.  Dur- 
ing the  first  moments  of  solidification,  while  the  outside  is 

a  The  trunks  themselves  cannot  form  till  the  metal  constituting  them  is  at  the 
freezing  point,  when  the  metal  between  them  must  necessarily  be  extremely  near 
to  that  point. 

b  The  curve  of  volume  is  probably  far  more  complex  than  that  here  shown.  In 
the  first  place,  there  is  at  least  one  reversal  of  the  direc'tion  of  change  of  tempera- 
ture, that  of  the  "after-glow/1  when,  the  temperature  having  fallen  to  low 
redness,  suddenly  rises  again,  on  the  change  of  hardening  to  cement  carbon. 
In  the  second  place,  Chapter  Xin.  givef  evidence  that  two  or  more  recrystalli 
zations  occur  during  cooling.  These  may  well  cause  change  of  volume  (for  the 
density  of  the  new  minerals  may  well  differ  from  that  of  the  old),  and  may  indeed 
cause  the  absorption  or  evolution  of  heat.  But  it  is  not  necessary  to  introduca 
these  complications  here. 


150 


THE    METALLURGY    OF    STEEL. 


freezing  and  the  inside  passing  slowly  through  A  B,  the  out- 
side tends  to  expand,  the  inside  to  contract :  later,  while  the 
shell  is  passing  quickly  through  C  D  and  the  inside  slowly 
through  A  B  or  even  B  C,  the  shell  tends  to  contract 
more  than  the  inside.  As  the  latter  is  incompressible,  it 
resists  and  may  tear  the  outside.  Later  still,  when  the 
shell  has  grown  comparatively  cool  and  hence  is  contract- 
ing slowly,  the  center  is  passing  through  B  C  while  the 
region  intermediate  between  shell  and  center  is  passing  com- 
paratively rapidly  through  C  D,  and  so  contracting  rather 
rapidly.  Eventually  a  time  t  will  be  reached  at  which  the 
contraction  of  the  region  intermediate  between  shell  and  cen- 
ter overtakes  and  begins  to  outweigh  both  the  contraction 
of  the  now  slowly  cooling  shell  and  the  expansion  of  the 
small  portion  of  the  center  which  is  passing  through  B  C  : 
when  this  point  is  reached  a-  cavity  or  pipe  will  tend  to 
form.  If  the  shell  of  the  ingot  is  still  hot  enough  to  be 
plastic,  it  may  bend  in  and  follow  up  the  contraction  of 
the  interior,  and  this  will  continue  till  the  time  t'  when 
the  crust  becomes  too  rigid  to  bend  farther.  This  bend- 
ing in  clearly  takes  places  much  more  readily  in  square 
than  in  round  ingots,  and  still  more  readily  in  oblong  ones  : 
and  we  consequently  find  that  round  ingots  are  more  and 
oblong  ones  less  subject  to  serious  piping  than  square 
ones." 

In  a  spherical  ingot  through  whose  walls  heat  is  con- 
ducted uniformly  in  every  direction,  this  cavity  would 
lie  at  the  center  (Figure  35)  but  for  gravity. 


Kig.35 


At  any  instant  during  cooling  we  may  distinguish  a  set 
of  isotherms,  such  as  are  sketched  in  broken  lines  in  Fig- 
ures 35,  36,  37.  Solidification  follows  approximately 
similar  lines.  Now  the  top  of  the  pipe  will  lie  at  the  top 
of  that  layer  or  isotherm  i,  (B,  Fig.  35),  which  at  the  time 
t'  is  just  too  viscid  to  flow  down  towards  the  bottom  of 
the  growing  cavity.  In  other  words  the  vacuous  bubble 
will  rise  through  the  still  liquid  layers,  and  through  the 
slightly  viscid  ones  till  it  reaches  one  just  too  viscid  to 


Fig.  36 


Flg.,37 


L_ 


Fipures  36-7.  —  Isotherms  and  position  of  pipe  in  prismatic  and  pyramidal  ingots,  the  latter 
exaggerated.  Figures  JiS-9.  —  Position  of  pipe  in  overturned  and  inverted  ingots.  Figure  40.  — 
]'i|.i'  distributed  by  rotating  ingot  during  solidification.  Figures  38,  89  and  40  from  Walrand, 
Von  Nostrand's  Eng.  Mag.,  XXXIIL,  p.  853. 

allow  it  to  rise  farther.  With  further  solidification  and 
contraction,  as  the  metal  draws  apart  centrifugally,  the 
still  fluid  portions  flow  down  to  fill  the  bottom  of  the 
growing  cavity,  whose  upper  surface  remains  ever  at  the 
same  point,  (though  indeed  cracks  may  rise  beyond  as  at 
D).  But  during  a  later  stage  the  metal  is  too  viscid  to 

»Cf.  Adamson  and  Snelus,  Journ.  Iron  and  Steel,  1887,  I.,  pp.  148,  156. 


flow,  and  as  it  still  contracts  it  draws  apart  somewhat  as 
in  C.  If  the  metal  contracts  a  great  deal  while  it  is  mo- 
bile enough  to  draw  apart  but  too  viscid  to  run  down  from 
above  to  fill  the  lower  parts  of  the  cavity,  a  deep  pipe 
may  arise  as  at  D. 

In  a  prismatic  ingot  the  pipe  will  lie  as  in  Figure  36  :  if 
overturned  it  lies  as  in  Figure  38  :  if  inverted,  as  in  Figure 
39  :  if  rolled  over  and  over  during  solidification  it  may  be 
broken  up  into  many  pipelets  as  in  Figure  40.  Figure  38 


tells  one  disadvantage  of  heating  ingots  on  their  sides  in 
common  reverberatory  furnaces,  instead  of  on  end,  as  in 
soaking-pits  and  similar  furnaces.  This  point  is  brought 
out  more  plainly  and  probably  more  accurately  in  Figure 
38  A,  which  shows  the  position  of  the  pipe  in  ingots  re- 
cently broken  at  an  American  Bessemer  works,  one  of  i 
them  standing  upright,  the  other  lying  on  its  side  while 
solidifying. 

In  order  that  the  pipe  may  injure  as  little  as  possible  of 
the  ingot,  it  and  hence  the  top  of  isotherm  i  should  lie  as 
high  as  possible :  in  other  words  solidification  should  be 
more  rapid  in  the  lower  than  in  the  upper  part  of  the 
ingot,  so  that  the  last  freezing  portion  which  must  hold 
the  pipe  may  be  as  near  the  top  of  the  ingot  as  possible. 
Hence  the  practice  of  certain  American  Bessemer  works 
of  filling  the  tops  of  the  rail-ingot  moulds  above  the  steel 
with  charcoal  or  coke  dust,b  and  Krupp's  plan  of  keeping 
the  top  of  the  ingot  hot,"  (1)  by  lining  the  top  of  the 
mould  with  refractory  material,  (2)  by  pouring  molten  slag 
upon  the  molten  steel  in  the  mould,  and  (3)  by  placing  a 
thick  cover  of  refractory  material  upon  the  molten  metal 
or  slag  :  these  expedients  further  serve  a  special  purpose 
in  connection  with  his  mode  of  compression.  Hence  too 
the  use  of  the  hot-top  sinking  head,  (§  227). 

To  the  same  end,  if  the  ingot  is  to  be  heated  or  soaked 
on  end,  it  should  be  placed  in  the  furnace  or  pit  as  soon 
after  teeming  as  possible,  so  that  as  much  as  possible  of 
its  upper  part  may  be  molten  and  so  available  as  a  sinking 
head  to  flow  down  and  fill  the  pipe. 

The  isotherms  and  through  them  the  pipe  are  liable  to 
be  lowered  by  strongly  tapering  moulds  and  by  bottom 


b  This  practice  involved  so  much  delay  that  it  has  recently  been  abandoned:  the 
manager  believes  it  more  profitable  to  allow  the  ingot  to  solidiry  rapidly,  and  to 
crop  off  a  larger  proportion  of  its  up|>er  end  on  account  of  unsoundness. 

>•  F.  A.  Krupp,  British  Patent  3,860,  June  30tn,  1881. 


THE    VOLUME    OF    THE    PIPE    IN    INGOTS.      §  225. 


151 


casting.  In  the  latter  the  h'rst  entering  portion  of  metal, 
which  forms  the  top  of  the  ingot,  is  cooled  much  by  the 
initially  cool  gate  and  runners  :  as  these  become  heated 
by  the  passing  iron  they  cool  the  last  entering  portion 
less."  In  strongly  tapering  moulds  as  in  Fig.  37  the 
isotherms  are  crowded  together  at  the  top  of  the  ingot, 
where  the  rnetal  freezes  across  early,  and  hence  cannot 
flow  down  to  fill  the  cavity  which  grows  beneath :  this 
tends  to  cause  a  deep-seated  pipe. 

Let  us  now  briefly  consider  the  effect  of  the  rate  of 
cooling  not  on  the  volume  but  on  the  position  of  the  pipe. 
Quick  cooling  crowds*  the  isotherms  together,  and  causes 
them  to  follow  each  other  inwards  rapidly.  Up  to  a  cer- 
tain time,  I",  the  upper  part  of  the  axial  metal,  or  sinking- 
head  metal,  will  be  hot  enough  to  flow  down  and  fill  the 
cavity  which  forms  beneath,  and  to  raise  it  to  a  relatively 
harmless  position.  Now  the  closer  together  the  isotherms 
are,  the  farther  will  the  cooling  and  contraction  of  any 
given  layer  have  proceeded  when  the  time  t"  is  reached, 
and  hence  the  less  will  that  layer  cool  and  contract  after 
t".  Hence,  the  more  rapid  the  cooling  the  more  of  the 
cavity  will  be  raised  by  the  sinking-head  metal  to  a  harm- 
less position,  and  the  less  of  this  cavity  will  be  formed 
after  the  sinking-head  metal  has  frozen. 

On  the  other  hand,  however,  quick  cooling  drives  the 
isotherms  inwards  rapidly.  In  a  long  ingot  an  appreciable 
length  of  time  is  needed  to  enable  the  sinking-head  metal 
to  flow  down,  and  it  is  quite  possible  that  very  rapid 
solidification  may  force  the  isotherms  inwards  so  rapidly 
that  freezing  overtakes  the  sinking- head  metal  before  it 
has  time  to  flow  far  down  the  walls  of  the  cavity,  and  so 
may  deepen  the  pipe.  Indeed,  as  the  pipe  is  due  to  differ- 
ence in  the  rate  of  contraction  of  shell  and  interior,  and  as 
this  difference  should  be  the  less  the  more  slowly  the  ingot 
cools,  slow  cooling  should  lead  to  a  smaller  pipe  than  rapid 
cooling.  When  ingots  are  placed  in  pits  or  furnaces  while 
their  interior  is  still  molten,  and  are  then  rolled  without 
great  fall  of  temperature,  it  is  not  clear  that  any  impor- 
tant pipe  forms  at  all.  Certainly  the  pipe  which  then 
forms  should  be  very  much  smaller  than  when  the  ingot 
is  allowed  to  solidify  and  cool  rapidly.  As  experiments 
on  the  size  and  position  of  pipes  have  usually  been  made 
on  ingots  which  have  cooled  comparatively  rapidly,  they 
are  liable  to  give  a  greatly  exaggerated  idea  of  the  size  of 
pipe  which  actually  arises  in  practice,  in  which  the  ingot 
cools  and  contracts  not  only  little  but  comparatively  uni- 
formly. 

Taking  the  above  considerations  together,  we  should  ex- 
pect that  rapid  cooling  would  raise  the  greater  part  of  the 
pipe  to  a  harmless  position,  while  at  the  same  time  it  may 
actually  cause  a  thin  tail  or  pipelet  to  extend  deeper  than 
it  would  were  the  cooling  slower. 

The  results  of  such  speculation  nmst  be  received  with 
extreme  caution  :  they  are  offered  simply  as  speculation, 
and  to  stimulate  thought  and  observation. 

Rapid  solidification  is  to  be  looked  for  A  in  ingots  cast 
too  near  their  freezing  point,  B  in  those  cast  in  iron  in- 
stead of  sand  moulds,  and  C  in  narrow  ingots. 

§  225.  THE  VOLUME  OF  THE  PIPE,  assuming  for  the 
moment  that  it  is  not  diminished  by  the  formation  of 
blowholes,  will  equal  the  excess  of  the  net  contraction  of 
the  interior  over  that  of  the  shell  during  the  cooling  sub- 


a  Walrand,  Van  Nostrand's  Eng.  Mag,,  XXXUL,  p.  3a6,  1885, 


sequent  to  t'.  If  we  knew  accurately  the  laws  which  the 
thermal  conductivity  and  dilatation  of  cooling  and  solidify- 
ing steel  follow,  we  could  discuss  with  confidence  the 
effect  of  variations  in  the  conditions  of  casting  and  cool- 
ing on  this  excess :  in  our  comparative  ignorance  we  may 
conjecture  that  it  will  be  roughly  proportional  to  the  dif- 
ference between  the  temperature  of  the  outside  and  the 
average  temperature  of  the  inside  at  the  time  t'  when  the 
shell  becomes  rigid,  and  that  this  difference  will  be  the 
greater  the  more  rapidly  heat  is  conducted  away  from  the 
metal  by  the  mould :  hence  the  pipe  should  be  greater  in 
ingots  cast  in  iron  than  in  those  cast  in  sand  moulds,  and 
greater  when  cold  than  when  hot  iron  moulds  are  employed. 
Even  the  iron  rail-ingot  moulds  are  now  intentionally 
heated  at  some  American  Bessemer  works  before  teem- 
ing, to  lessen  the  pipe. 

In  regard  to  ingots  of  large  as  compared  with  those  of 
small  cross-section  the  case  is  less  simple.  If  the  power 
of  the  mould  to  abstract  heat  increased  proportionally 
to  the  mass  of  the  ingot,  then  the  center  of  the  large  in- 
got should  be  hotter  than  that  of  the  small  ingot,  when 
the  outer  shell  becomes  rigid  :  being  hotter,  the  subse- 
quent contraction  of  the  center  of  the  larger  ingot  would 
be  greater,  and  hence  its  pipe  should  be  greater  than  that 
of  the  small  ingot.  But  the  thermal  capacity  of  the  mould 
of  a  large  ingot  relatively  to  that  of  the  ingot  itself,  and 
hence  its  power  of  abstracting  heat  from  the  ingot,  is 
usually  much  smaller  than  in  the  case  of  small  ingots. 
Before  the  .shell  of  the  large  ingot  begins  to  become  rigid 
its  mould  has  become  highly  heated  ;  that  of  the  small 
ingot  remains  cold  up  to  and  past  the  time  ff .  The  cold 
mould  of  the  small  ingot  may  well  lead  to  a  difference  be- 
tween the  average  temperature  of  outside  and  that  of  inside 
at  the  critical  time  t'  greater  than  the  corresponding  dif- 
ference in  case  of  the  large  ingot,  whose  hot  mould  ab- 
stracts heat  but  slowly  from  the  ingot's  shell,  which  long 
remains  hot  and  plastic.  This  would  give  the  small  ingot 
a  pipe  larger  in  proportion  to  its  size  than  that  of  the 
large  ingot. 

Similar  reasoning  applies  to  the  case  of  very  hot  and 
rather  cool-cast  ingots. 

We  have  no  very  satisfactory  data  as  to  the  total  con- 
traction of  volume  which  the  particles  of  steel  undergo 
during  solidification  and  cooling.  The  shortening  effected 
by  Whitworth's  fluid  compression  suggests  that  the  total 
contraction  is  not  far  from  13  or  14%  by  volume.  The 
enormous  pressure  which  he  employs  is  said  to  shorten  in- 
gots of  uniform  cross-section  by  12 ~5%  (1'5  inches  per  foot) 
in  addition  to  the  longitudinal  contraction  of  similar  un- 
compressed ingots,  which  varies  from  1  to  2'6$b  (l-8th  to 
5-16ths  inch  per  foot) ;  so  that  we  here  have  a  total  longi- 
tudinal contraction  of  at  least  13.5$.  If  we  knew  the  trans- 
verse contraction  and  if  we  knew  that  Whitworth's  com- 
pression left  no  cavities,  we  could  calculate  the  total  con- 
traction. But  we  do  not.  During  the  early  part  of  the 
compression  the  ingot  probably  expands  transversely,  the 
enormous  pressure  as  well  as  the  rising  temperature  dilat- 
ing the  mould,  and  the  ingot  spreading  laterally  and  fol- 
lowing up  this  dilatation.  Later,  after  the  walls  of  the 
ingot  have  grown  so  cold  that  they  defy  even  the  action 
of  Whitworth's  press,  say  from  dull  redness  down,  a  very 


b  In  a  case  within  the  writer's  knowledge  the  shrinkage  on  steel  cylinders  2  feet 
in  diameter  has  been  5-ieths  inch  per  foot,  or  3'6  per  cent,  linearly. 


152 


THE    METALLURGY    OF     STEEL. 


considerable  transverse  contraction  probably  occurs.  If 
we  assume  that  this  roughly  equals  the  transverse  dilata- 
tion which  occurs  earlier,  we  have  a  total  contraction  of 
13  5%  by  volume. 

The  volume  of  the  pipe  in  the  six-inch  steel  gun  lately 
cast  by  the  Pittsburgh  Steel  Casting  Company  must  have 
been  about  6 -4$  of  that  of  the  original  molten  metal." 

If  we  assume  that  the  external  shrinkage  here  was  0'25 
inch  per  linear  foot,  or  6 '12  •$  by  volume,  and  further 
assume  that  the  metal  was  free  from  blowholes,  we  have 
a  total  contraction,  external  and  internal,  of  12-49%  by 
volume,  which  is  not  far  from  that  deduced  from  Whit- 
worth's  compression.  And  the  contraction  should  be  sub- 
stantially the  same  in  both  cases,  since  Whitworth's  com- 
pression probably  does  not  affect  the  density  of  the  solid 
portion  of  the  cold  metal. 

This  total  contraction  should  be  composed  of  the  exter 
nal  shrinkage,  the  volume  of  the  blowholes,  and  that  of 
the  pipe.  Changes  in  the  shape,  size,  etc.,  of  castings,  or 
in  other  conditions,  which  increase  the  external  shrinkage 
diminish  the  pipe,  provided  the  volume  of  the  blowholes 
and  the  density  of  the  cold  metal  remains  unaltered.  To 
put  it  algebraically, 

Let  VM,  VC,  VP,  VSand  VB  =  the  volumes  of  the 
molten  metal,  the  cold  metal,  the  pipe,  the  external  shrink- 
age and  the  b'lowholes  respectively,  VC  of  course  being 
the  volume  occupied  by  the  ultimate  particles  of  the  cold 
metal,  excluding  all  cavities,  large  and  small, 

Then  VM  =  VC  +  VP  +  VS  +  VB. 

If  VM,  VC  and  VB  be  constant,  then  the  larger  VS  is 
the  smaller  will  VP  be. 

TJtff  maximum  volume  of  pipe.  The  smallest  linear  con- 
traction in  case  of  steel  castings  is  probably  about  1$, 
which  implies  a  contraction  of  3%  by  volume.  If,  as  we 
have  estimated,  the  total  contraction  be  about  14$,  then 
the  maximum  volume  of  pipe,  which  would  of  course 
occur  when  there  were  no  blowholes,  so  that  VB  =  0, 
would  be  14  —  3  =  11$  of  the  volume  of  the  metal  when 
molten,  or  11 '3$  of  that  of  the  cold  ingot. 

The  volume  of  the  pipe  is  usually  much  less  than  this. 
Of  78  rail  ingots,  each  weighing  about  3,300  pounds,  which 
were  broken  at  an  American  Bessemer  works,  all  but  two 
showed  decided  pipes  or  masses  of  honeycombed  cavities. 
In  thirty  instances  their  volumes  ranged  from  6  to  136 
cubic  inches,  the  average  being  30  inches. b  The  largest  of 
these  pipes  represents  only  about  1$  of  the  volume  of  the 
molten  metal. 

§  226.  Surface  cracks  in  steel  ingots  are  chiefly  vertical 
(longitudinal)  and  horizontal  (transverse). 

Longitudinal  cracks  appear  to  be  due  chiefly  (1)  to  the 
ferrostatic  pressure  of  the  molten  steel  against  the  thin 
shell,  when  the  mould,  expanding,  draws  away  and  leaves 
it  unsupported :  and  (2)  to  the  excess  of  the  early  contrac- 
tion of  the  shell  over  that  of  the  interior.  In  the  case  of 
square  ingots  this  excess  tends  to  relieve  itself  by  drawing 
in  the  corners  of  the  square  and  bulging  out  its  sides,  so 
that  its  section  becomes  more  nearly  circular,  as  in  A, 
Figure  41.  Later,  when  the  contraction  of  the  interior 
overtakes  and  out-runs  that  of  the  outside,  the  tables  are 
turned,  and  now  the  sides  of  the  square  tend  to  bend  in 


and  follow  up  the  contraction  of  the  interior.  This  bulg- 
ing and  approach  to  a  circular  section  can  take  place 
more  or  less  with  all  sections  except  one  initially  circular; 
hence  in  cylindrical  and  conical  ingots  the  excess  of  con- 
traction of  shell  over  interior  can  relieve  itself  only  by 
making  the  ingot  slightly  barrel  shaped,  which  must  tend 
to  cause  longitudinal  cracks,  such  as  would  arise  were  th<? 
staves  of  a  barrel  rectangular  instead  of  curved,  and  such 
as  are  shown  in  exaggeration  by  the  dotted  lines  in  Figure 


fig.  4|,    CRACKS.. EXTERNAL  AND  INTERNAL. 


a  This  number  is  reached  from  data  furnished  me  by  Mr.  Wm.  Hainsworth  of 
the  Pittsburgh  Steel  Casting  Company. 
i>  Private  communication,  F.  A.  Emmerton,  Feb.  4th,  1888. 


Supposed  bulging 
of  square  ingots. 


ELEVATION. 

Supposed  barreling  and  longitudinal 
cracks  on  round  ingotSi 


Internal  cracks  from  rapid  heating. 


41  B  :  and  hence  the  very  strong  tendency  of  round  ingots 
to  acquire  longitudinal  cracks. 

As  these  cracks  are  in  large  part  due  to  difference  be- 
tween the  rates  of  cooling  of  outside  and  inside,  they  are 
to  be  especially  looked  for  when  this  difference  is  greatest, 
e.  g.  in  ingots  cast  in  cold  metallic  moulds.  The  effects  of 
ferrostatic  pressure  are  most  severe  in  tall,  in  bottom-cast, 
and  in  hot-cast  ingots,  for  here  the  shell  of  the  lower  part 
of  the  ingot  is  comparatively  thin  after  the  ferrostatic 
pressure  has  become  severe. 

Transverse  cracks  as  well  may  be  due  to  the  more  rapid 
contraction  of  shell  than  of  interior.  They  may  also  arise 
if  the  ingot  attaches  itself  to  the  mould  at  different  levels, 
for  then  its  contraction  is  resisted  by  the  mould,  which  is 
indeed  expanding.  They  are  most  likely  to  occur  if  the 
mould  be  rough,  if  the  casting  temperature  be  excessively 
high,  and  if  the  steel  in  teeming  strike  against  the  sides 
of  the  mould.  Hence  transverse  cracks  arise  less  fre- 
quently with  bottom  than  with  top  casting.  Tapering 
moulds  also  lessen  the  tendency  towards  transverse  crack- 
ing, for  in  them  the  longitudinal  as  well  as  the  transverse 
contraction  of  the  ingot  and  expansion  of  the  mould  tend 
to  separate  mould  from  ingot.  Should  a  fin  of  metal  con- 
nected with  the  ingot  become  attached  to  the  top  of  the 
mould,  (and  this  often  occurs  from  leakage  while  the  ladle 
is  passing  from  one  mould  to  the  next),  as  with  their 
changing  temperatures  the  mould  elongates  and  the  ingot 
shortens,  this  fin  tends  to  suspend  the  ingot,  whose  weight 
may  tear  its  thin  skin.  These  fins  should  be  carefully  re- 
moved.0 

SnaTces,  sinuous  markings  on  steel  plates,  are  probably 
due  to  external  cracks,  which  are  drawn  out  into  irregular 
serpentine  shapes  as  the  ingot  is  rolled  now  longitudinally, 
now  diagonally,  now  transversely. 

Internal  Cracks.-- Just  as  the  too  rapid  contraction  of 
the  shell  in  cooling  causes  surface  cracks,  so  its  too  rapid 
expansion  in  heating  causes  internal  ones.  If  a  cold  in- 
got be  placed  in  a  hot  furnace,  the  shell  of  the  ingot  ex- 
pands and  may  elongate  so  rapidly  that  the  expansion  of 
the  slowly  heating  interior  cannot  keep  pace  with  it,  when 

o  Concerning  surface  cracks,  cf.  Walrand,  loc.  cit. 


PREVENTION    OF    BLOWHOLES    AND    PIPES— SINKING    HEAD. 


227. 


153 


internal  cracks  form  as  shown  at  C,  Figure  41,  often  with  a 
loud  report.  These  cavities  on  forging  become  elongated 
as  at  D,  and  may  break  through  to  the  surface,  causing 
incurable  defects,  sometimes  so  serious  that  the  ingot  must 
be  cut  to  pieces.  From  this  cause  the  proportion  of 
cracked  or  "second  quality"  rails  is  greater  when  rail 
ingots  are  allowed  to  cool,  than  when  they  are  charged 
into  the  heating  furnace  while  still  hot  from  teeming. 
Ingots  which  for  any  reason  are  allowed  to  cool  should 
not  be  charged  into  a  hot  furnace.  They  should  either  be 
charged  when  the  furnace  is  cool  (say  on  Sunday  night  or 
early  Monday  morning)  and  be  gradually  heated  with  it, 
or  else  be  preheated  to  redness  in  a  comparatively  cool 
auxiliary  furnace,  and  then  be  transferred  to  the  regular 
white-hot  heating  furnace. 

Thus,  in  order  to  guard  against  cracks  both  external 
and  internal  the  ingot  should  be  placed  in  the  heating 
furnace  as  soon  after  casting  as  possible.  Some  would 
teem  the  steel  into  moulds  standing  close  to  the  heating 
furnace.  A  more  practicable  plan  is  that  of  the  Pittsburgh 
Steel  Casting  Company,  in  which  the  steel  is  cast  in 
moulds  standing  on  a  car,  which  is  raised  by  a  hydraulic 
jack  immediately  after  teeming,  and  drawn  by  a  locomo- 
tive to  the  side  of  the  heating  furnace,  where  the  moulds 
are  stripped,  and  the  ingot  immediately  charged.  As  the 
wheels  of  the  car  are  liable  to  become  clogged  with  the 
metal  splashed  in  teeming,  it  might  be  better  to  cast  the 
ingots  in  a  group  on  a  single  base  plate,  which  could  then 
be  quickly  raised  by  a  crane  and  placed  on  a  car.  But 
these  matters  may  be  considered  more  advantageously 
elsewhere. 

Both  for  given  volume  and  for  given  cross -section,  the 
longer  the  ingot  the  more  liable  is  it  to  acquire  cracks, 
both  external  and  internal  :  in  other  words,  short  stumpy 
ingots  are  less  liable  to  cracks  than  long  and  than  thin 
ones. 

Hammering  between  Flat  Dies  is  liable  to  cause  a  cen- 
tral pipe-like  crack  in  round  steel  bars  :  hence  it  is  better 
to  employ  s wedges,  or,  if  possible,  grooved  rolls.*  It  i: 
said  that  this  same  tendency  is  met  in  rolling  round  bars 
by  Simond's  rolling  machinery,1"  in  which  the  pressure  ap- 
pears to  be  applied  along  two  lines  diametrically  opposite, 
just  as  in  hammering  between  flat  dies. 

Let  us  now  consider  the  means  of  preventing  blowholes 
and  pipes. 

§  227.  A  SINKING  HEAD  (rising  or  feeding  head) 
raises  the  pipe  to  a  more  or  less  harmless  position,  bu1 
probably  does  not  directly  affect  its  volume.  If  it  affect: 
the  volume  and  position  of  _the  blowholes  it  should  be 
through  increasing  the  ferrostatic  pressure  within  the 
ingot.  Usually  the  walls  of  the  sinking  head  are  of  the 
same  material  as  the  mould,  and  simply  form  a  continu- 
ation of  it.  In  order  that  the  sinking  head  shall  sink 
and  feed  efficiently  it  must  not  only  be  so  wide  that  it  wil] 
not  freeze  across  till  the  ingot  beneath  has  completely 
solidified,  but  its  volume  must  be  such  that  it  will  pre- 
serve molten  up  to  this  point  enough  metal  to  fill  the 
cavity  due  to  the  contraction  of  the  ingot's  interior. 
If  the  maximum  volume  of  pipe  is  as  we  have  estimated 
of  the  volume  of  the  hot  ingot,  and  if  from  one-third 


aCf.  Metcalf,  Trans.  Am.  Soc.  Civ.  Engineers,  XV.,  p.  290,  1887. 
b  Described  in  the  Iron  Age,  XLI.,  p.  269,  1888,  aud  in  Stahl  und  Eisen,  VIII. 
p.  355,  1888. 


TABLE  78.— SINKING  HEAD  AND  Cum-i-mcis,  KTC.,  FROM  Toi-  OK  STEEL  INOOTS  AND  CASTINGS, 
REJECTED  FOB  UNSOUNDNESS. 


American   Bessemer  rail   ingots :  Weight  of 
croppings  per  100  of  weight  of  ingot. 


Description  of  ingot  or  casting. 


Weight  ofporttoD  re- 
jected from  top  of 
ingot  or  <-:iMiiiLr, 
per  100  of  total 
weight. 


Name  of 
works. 

Size  of  ingot 

Bloom 
cropping  . 

Crop'ng  of 
per    end 
upper  ral 

A. 

14"  X  14" 

~~5 

1-00 

B. 

10"  X  10" 

9-0 

0-75 

0. 

H"  X  14" 

7-84 

0  74 

D. 

14-5'  X  14-5" 

5'3 

0-67 

E. 

14"  X  14" 

8'63 

0-75 

P. 

14"  X  14" 

5- 

O'CO 

Crucible  s'eel  ingots  :  Weight  of  upper  portion 
rejected  on  account  of  pipe,  per  100  of  total 
weight  of  ingot. 
Saw  steel 


Mild  steel 

High  carbon  steel 

Badly  melted  steel 

Ordnance  ingots. 

U.  8 .  Navy,  reject  at  least 

U.  8.  Army,  reject  at  least 

Miscellaneous  ingots  (Walrand). . 
"  "        (Chernoff) . 

Co-stings  proper. 

Terre  Noire,  10"  projectiles 

6"  steel  cast  gun,  Pittsburgh  Steel  Casting  Co. . 

Plain  cylindrical  castings  for  rolls,  Norway  Iron 
Works,  Boston  

Mitis  castings,  0-5  to  10  Ibs.,  weight  of  sprue  per 
lOOoftotal 

Do.  do.  do.  castings  weighing  10  to  100  Ibs 

Cast-iron  guns,  U.  8.  Army 


8-5 

9-75 

8-58 

6-47 

9-38 

5  60 


10  to  20 

20  to  85 

100 


83-8 


16-7  to  25 

"ii-'i' 


25 
10 
16-7 


Volume  of  sinking 
head  per  100  of 
total  volume  of 
casting  -f  sinking 
head. 


16-7 


20  to  25 
25-5 


25 


1  to  7.  Private  notes. 

8  to  10.  Wm.  Metcalf,  private  communication,  January,  1888. 
at.  D  A.  Lle      .  S    Arm,     rivate  communica'io 


got  is  rejected  from  the  top  end,  and  at  least   ^  from  te  ower  en. 

13  Walrand,  Van  Nostiand's  Eng.  Mag.,  XXXIII.,  p.  857,  1885. 

14  Chernoff,  Revue  Univ.  2nd.  Ser.,  VII.,  p.  145,  1880. 

15.  Terre  Noire  solid  steel  cas  ings  for  projectiles,  mould  proper  of  iron,  walls  of  sinking  head 
of  hot  sand      Holley,  Metallurgical  Review.  II.,  p.  879,  1878. 

16.  6-inch  cast  steel  gun  of  the  Pittsburgh  Steel  Casting  Co.,  private  communication,  Wm. 
IMnsworth,  Jan.  28th,  1888. 

Total  weight  of  head  when  cast,  estimated  at  ......................  8  700  Ibs. 

•'         "       "    "     whencold.        "         '•  ........................  2,850" 

Total  weight  of  gun  Including  sinking  head,  estimated  at  ............  16.200  " 

The  composition  and  properties  of  the  metal  of  which  this  gun  consists  are  given  in  Table  80. 
17   G.  II.  Billings,  private  communication. 

18,  19.  P.  Ostberg,  private  communication.    These  numbers  seem  to  me  surprisingly  low. 
20.  Capt.  D.  A.  Lyle. 


to  one-half  the  volume  of  the  sinking  head  is  available  for 
feeding,  then  the  greatest  needed  volume  of  sinking  head 
should  be  from  about  20  to  about  28%  of  the  total  vol- 
ume of  the  hot  ingot  or  casting  including  the  sinking  head 
itself,  or  from  25  to  38$  of  the  volume  of  the  casting 
proper  excluding  the  sinking  head.  The  volume  of  sink- 
ing head  actually  employed,  and  the  proportion  of  the 
ingot  or  other  casting  which  is  rejected  on  account  of  un- 
soundness  in  certain  cases,  are  given  in  Table  78.  As  pipes 
in  rail  ingots  are  partly  effaced  in  the  subsequent  rolling, 
while  in  castings  proper  (i.  e.  those  which  are  employed 
without  forging)  they  remain  of  their  full  initial  size, 
special  pains  are  taken  to  avoid  them  in  castings :  and 
we  note  that  the  proportion  of  sinking  head  by  weight  is 
much  smaller  in  rail  ingots  than  in  castings  proper, 
varying  in  the  former  between  the  narrow  limits  of  5 -6  and 
9-75$,  while  in  the  latter  it  runs  from  17 '6  to  25%.  That 
portion  of  the  top  of  the  rail  ingot  which  is  subsequently 
cropped  off  on  account  of  unsoundness  is  for  convenience 
here  classed  as  a  sinking  head :  and  with  it  may  be  in- 
cluded the  crop  end  of  the  rail  made  from  the  steel  next 
the  top  of  the  ingot.  Formerly  many  works  cropped 
from  the  bloom  only  5%  of  the  weight  of  the  ingot :  but 
this  brings  the  upper  end  of  the  upper  rail  uncomfortably 
near  the  porous  or  piped  region  of  the  ingot  top :  and 
as  the  rail  receives  the  hardest  usage  at  its  end,  the  im- 
pact of  the  approaching  wheel,  it  is  better  to  crop  off 
1-5% :  the  subsequent  rail  cropping  removes  another  \%  of 
the  top  end. 


154 


THE    METALLURGY    OF    STEEL. 


Since  the  above  was  written  I  learn  that  at  one  American 
Bessemer  works  10$  of  the  weight  of  the  ingot  is  cropped 
from  its  upper  end,  and  about  \%  more  in  the  upper  crop- 
ping of  the  upper  rail. 

Some  Bessemer  rail  ingots  from  a  well  known  American 
works  have  been  cut  in  two  longitudinally,  when  a  very 
deep  and  rather  narrow  pipe  was  found,  somewhat  as  in 
Figure  37,  §'  224.  It  would  be  manifestly  impossible  to 
remove  this  by  cropping.  Indeed,  the  unsoundness  of  the 
crop  end  of  the  rail  ingot  is  due  probably  more  to  im- 
prisoned gas  bubbles  which  have  risen  from  below,  than 
to  the  pipe  proper.  Crucible  steel  ingots  are  usually 
very  narrow,  and  are  cast  in  iron  moulds.  The  large  pro- 
portion of  their  weight  which  is  rejected  on  account  of 
piping  harmonizes  with  the  deductions  in  §  225. 

Hot-Top  Sinking  Head. — When  iron  moulds  are  em- 
ployed, the  sinking  head  will  solidify  relatively  slowly, 
and  so  feed  the  more  efficiently,  if  its  walls  be  of  clay  or 
other  poorly  conducting  substance  (as  in  Figure  42), 

Rig.  42 


Hot-top  sinking  head, 
(Walrand). 


especially  if  this  be  previously  heated,  as  in  the  Terre 
Noire  practice  of  casting  steel  projectiles.* 

The  feeding  of  the  sinking  head  may  be  assisted  in 
steel  as  it  is  in  iron  castings  by  working  a  rod  up  and  down 
through  it,  to  break  through  any  bridging  that  may  occur 
either  in  the  sinking  head  itself  or  the  upper  part  of  the 
ingot,  and  so  to  maintain  a  passage  through  which  feeding 
may  occur.  But  this  as  well  as  the  ' '  hot-top' '  sinking  head 
rather  encourages  the  late  escape  of  gas,  which  leads  to 
the  formation  of  blowholes.  For  if  the  top  of  the  ingot 
be  allowed  to  solidify  rapidly,  or  better  still  if  its  solidi- 
fication be  hastened  by  pouring  water  on  it,  the  upper 
crust  bottles  up  the  gas  set  free  within  the  ingot,  the  gase- 
ous pressure  within  rises  and  thus  tends  to  prevent  the 
further  evolution  of  gas. 

Special  Forms  of  Sinking -Head. — If  a  series  of  moulds 
be  placed  one  above  another,  with  perforated  diaphragms 
of  refractory  material  between,  each  ingot  serves  as  a 
sinking- head  to  the  next  lower  one  and  the  piping  may  be 
concentrated  in  the  upper  ingot.  This  arrangement  sug- 
gests itself  most  readily  for  tyre  and  similar  ingots :  but 
recent  inventions  aim  to  apply  it  to  common  pyramidal 
ingots  as  well.  This  is  done  by  lowering  the  ingot  as  soon 
as  its  crust  has  solidified,  and  casting  a  second  on  top  of 
it.  They  unite  in  the  center,  and  the  second  feeds  the 
piping  of  the  first.  In  the  case  of  small  ingots,  the  cold- 
shut  due  to  intermittent  teeming  makes  it  easy  to  separate 
the  ingots,  which  is  done  while  they  are  still  so  hot  as  to 
be  weak :  should  the  cold-shut  be  insufficient,  some 
special  device  is  employed.  The  steel  is  thus  cast  in  con- 
tinuous notched  bars,  later  broken  at  the  notches.  Each 

»  Holley,  Metallurg.  Eev.  II.,  p.  379,  1878. 


ingot  should  have  nearly  the  same  composition  as  the 
steel  fed  to  its  pipe,  as  otherwise  it  will  be  heterogeneous  ; 
this  means  that  successive  ingots  must  have  closely  similar 
compositions. 

In  Soultori's  arrangement,  which  consists  essentially 
of  a  vertical  frame  A  A,  in  which  four  moulds  are  held  in 
column  by  spring  clamps,  a  mould  with  a  bottom  is  first 
filled,  standing  in  the  position  occupied  by  the  empty  mould 
D  in  Figure  42,  A.  A  perforated  asbestos  diaphragm  is  now 


Fig.  42  A.    BOULTON'S  CASTING 
ARBANQEMENT. 


A  A,  frame  of  I  beams,  held  together  by  spiral  springs.  B,  pocket,  holding  the  lower  mould. 
C,  C',  rams  for  breaking  lower  ingot  away  from  next  higher  one.  D,  empty  mould,  ready  to  re- 
ceive the  next  lot  of  stud.  E,  hydraulic  cylinder  for  moving  the  ram  C. 


placed  upon  it,  and  on  this  an  empty  bottomless  mould, 
when  both  moulds  are  forced  down  by  appropriate  mechan- 
ism, the  empty  mould  now  occupying  the  position  origin- 
ally held  by  the  first  mould.  The  second  mould  having 
been  filled,  it  receives  its  asbestos  diaphragm,  a  third  mould 
is  placed  upon  it,  all  three  are  pushed  down,  and  so  on. 
After  three  moulds  have  been  filled,  matters  stand  as  in 
Figure  42  A,  a  fourth  mould  being  now  in  position  for 
teeming,  and  the  first  having  reached  the  pocket  B.  The 
ram  C  in  the  hydraulic  cylinder  E  is  now  forced  against 
the  first  mould,  breaking  its  ingot  away  from  that  in 
the  second  mould,  as  shown.  The  opposite  ram  C' 
returns  the  first  mould  to  its  former  position,  the  column 
of  moulds  and  ingots  is  again  forced  down,  and  so  on. 
The  asbestos  diaphragms  which  separate  the  ingots  make 
it  easier  to  break  them  apart.b 

Hinsdale  uses  a  single,  stationary,  bottomless,  water  or 
steam-cooled  mould.  The  ingot  is  drawn  down  by 
mechanism  as  soon  as  its  crust  has  solidified,  till  only  its 
upper  end  remains  in  the  mould,  when  a  second  is  cast 
upon  it,  uniting  with  it  in  the  centre  and  feeding  its  pipe, 
yet  readily  detached  later.0  In  order  that  the  top  of  one 
ingot  may  fully  close  the  bottom  of  the  mould  while  the 
succeeding  ingot  is  being  cast,  there  must  be  little  or 
no  taper :  hence  difficulty  in  drawing  the  weak  tender 
ingot  through  the  mould,  and  danger  of  cracking  and 
bleeding. 

b  J.  B.  D.  A.  Boulton,  IT.  S.  Patent  365,902,  July  5th,  1887.  Messrs.  Bpauld- 
ing  and  Jennings,  West  Bergen,  New  Jersey,  who  haveoneof  Boulton's  machines, 
write  me  (April  25th,  1888)  that  they  regard  it  as  successful.  The  first  cast  in 
it  was  made  on  December  20th,  1887. 

e  W.  R.  Hinsdale,  priv.  com.,  April  21-26th,  1888.  U.  8.  Patent  Application, 
222,371. 


LIQUID     COMPRESSION.       §  229. 


§  228.  AGITATION  DURING  SOLIDIFICATION.— Imagining 
that  the  pine-tree  crystals,  already  referred  to  in  §  222, 
were  an  important  cause  of  blowholes,  their  tops  protrud- 
ing so  far  beyond  the  completely  solidified  portion  of  the 
ingot  and  into  its  still  molten  center  as  to  mechanically 
detain  rising  gas  bubbles,  imprisoning  them  in  the  solidi- 
fying mass  and  thus  causing  blowholes,  Chemoff  would 
wash  these  crystals  off,  swashing  the  molten  metal  against 
them,  by  rotating  the  solidifying  ingot  at  a  constantly 
altering  speed,  with  occasional  reversals.8  Webb  has  used 
this  method  successfully  in  casting  locomotive  driving 
wheels,  the  rate  of  rotation  gradually  increasing  till  it 
reaches  some  fifty  revolutions  per  minute,  then  gradually 
decreasing.11 

Forsyth0  would  rapidly  hammer  the  sides  of  the  ingot 
mould,  the  jarring  thus  caused  interfering  with  crystalli- 
zation, and  the  waves  set  up  washing  off  the  delicate  in- 
cipient crystalline  axes. 

On  repeatedly  applying  Chernoff  s  method  to  freezing 
ice  bottles  I  find  that  the  formation  of  tubules  is  wholly 
prevented  :  many  very  minute  spherical  cavities  result, 
whose  total  volume  is  much  less  than  that  of  the  tubules 
usually  present.  On  romelting  one  lot  of  ice  thus  frozen 
and  allowing  it  to  resolidify  tranquilly  without  removal 
from  the  bottle,  it  developed  a  great  mass  of  tubules,  whose 
volume  I  estimated  as  at  least  ten  times  as  large  as  that 
of  the  spheres  formerly  present. 

Both  with  ice  and  steel  •  it  is  probable  that  agitation, 
whether  due  to  rotation  or  jarring,  simply  mechanically 
detaches  the  gas  bubbles  which  adhere  to  the  solidifying 
surfaces,  and  so  promotes  solidification  in  continuous 
layers  free  from  blowholes. 

•  Rotation  should  greatly  diminish  the  volume  of  the 
pipe,  by  stirring  up  the  molten  and  even  pasty  metal,  thus 
rendering  its  temperature  more  uniform  throughout  its 
cross  section.  Hot  metal  from  the  interior  is  washed 
against  the  frozen  shell,  the  cooling  of  the  former  is  hast- 
ened, that  of  the  latter  retarded  :  thus  the  difference  be- 
tween the  mean  temperature  of  interior  and  that  of  shell 
at  all  times  during  freezing,  including  of  course  the  time 
t',  is  greatly  dimished,  and  we  have  seen  that  the  volume 
of  the  pipe  should  depend  on  this  difference  at  the  time  P. 
(§225.) 

Rotation,  in  that  it  hastens  the  cooling  of  the  center  of 
the  ingot,  should  oppose  segregation  :  but  if  extremely 
rapid  it  might  possibly  favor  segregation  by  forcing  the 
heavier  components  centrifugally  and  the  lighter  compo- 
nents centripetally,  somewhat  r.s  the  rapid  rotation  of  milk 
hastens  the  separation  of  cream. 

§229.  LIQUID  COMPRKSSIO.N,  or  subjecting  the  steel 
while  still  molten  to  pressure,  was  described  by  Besse- 
mer in  1850,  and  has  since  been  often  tried,  and  abandoned 
because  it  did  no  good  commensurate  with  its  cost.  It  is 
said  to  be  practiced  by  Whitworth  and  at  Aboukoff,  with 
what  result  we  will  shortly  consider. 

A.   WhitwortJi d  casts  his  steel  in  a  flask  consisting  of 


•  Kevuo  universelle,  3nd  scr.  VII.,  p.  154,  1H80 

b  F.  W.  Webb  of  Crewe,  Journ.  Iron  and  St.  Inst.,  1882,  II.,  p.  5<22. 

=  Private  communication. 

d  Kept.  Select  Committee  of  U.  S.  Senate  on  Ordnance  and  War  Ships,  1886, 
p.  23  :  Proc.  U.  S.  Naval  Inst.,  X.,  p.  687,  Jaques.  In  British  patent  1292,  May 
31st,  1856,  Bessemer  shows  anil  describes  an  ingot  mould  with  a  vertical  liydrau- 
lic  rain  at  the  bottom,  and  a  sliding  cover,  for  compressing  the  ingot  when  semi- 
fluid or  after  solidification.  Whitworth,  whose  earliest  patent  whi'-h  I  hnvo  met 
relating  to  the  compression  of  steel  is  that  of  HJV.  24lh,  1865,  No.  3,018  (Brilish), 


a  steel  cylinder  L,  Figure  4:?,  supported  by  steel  hoops  K. 
Within  this  is  arranged  a  lining  of  unconnected  iron  rods 
M,  pierced  with  numerous  small  holes  for  the  escape  of 
gas  as  shown,  and  within  this"  a  layer  of  moulding  sand, 
.  By  means  of  the  car  C,  flask  and  steel  are  quickly 


Fig.  43. 
Whit-worth's  Casting  Press  for  Liquid  Compression. 

(Press  In  elevation,  mould  in  section.) 

A,  Main  compressing  cylinder.  B,  its  plunger.  C,  carriage  on  which  the  flask  rests.  D  D, 
four  hollow  pillars  guiding  and  supporting  the  main  cross-heal.  E,  the  main  cross-head,  raised 
and  lowered  by  a  hydraulic  cylinder  above  it.  F F,  nuts  for  locking  the  main  cross-Lead.  Cr, 
bocs  against  which  the  steel  in  the  mould  is  forced.  H,  indicator,  showing  the  rise  of  the  main 
plunger  B.  1 1,  split  stops,  fastened  to  the  pillars  with  bolts  and  clips,  to  support  the  main  cross- 
!u-;id  \vhen  the  press  is  Dot  in  use.  K  A",  stuel  jackets  for  mould.  L  L,  the  mould.  J/X', 
perforated  cast-iron  lagging.  JV  N,  inner  sand  lining. 

transferred  to  the  top  of  the  vertical  plunger  B  of  a 
powerful  hydraulic  press.  A  is  the  cylinder  in  which 
this  plunger  plays. 

A  massive  crosshead  E  forming  the  cap  of  the  press  is 
immediately  lowered  until  a  projection  G  on  its  lower  sur- 


thus  seems  to  be  antedated  by  some  nine  years  :  but  his  u  i.iu  lias  become  so 
firmly  attached  to  this  method  of  compression  that  it  would  be  difficult  to  replace 
it  with  Bessemer's,  if,  indeed,  Whitworth's  successful  development  of  this  process 
docs  not  justify  naming  it  after  him.  (Cf.  Journ.  Iron  and  :  teel  Inst.,  1881,  I.,  p. 
197.)  Gf.  Greenwood,  Liquid-Compression.  Proc.  Inst.  Civ.  Engrs.,  XCVIII.. 
Part  IV.,  1889.  •  "  Steel  and  Iron,"  Greenwood,  p.  510. 


156 


THE    METALLURGY     OF     STEEL. 


face  comes  in  contact  with  the  upper  surface  of  the  liquid 
steel,  completely  closing  the  mould,  when  the  crosshead 
is  locked  in  position,  and  the  plunger  B  on  which  the 
flask  and  its  carriage  rest  is  raised,  forcing  the  steel  up- 
wards against  the  rigidly  fixed  crosshead.  The  device  of 
moving  the  crosshead  hastens  matters,  since  it  can  be 
moved  much  faster  than  the  slowly  moving  plunger  of  the 
hydraulic  press :  and  it  moreover  enables  us  to  restrict 
stroke  of  the  latter  to  the  distance  by  which  the  ingot  is 
actually  compressed  longitudinally. 

The  pressure  on  the  steel  is  gradually  increased,  usually 
till  it  reaches  6  tons,  occasionally  till  it  reaches  20  tons 
per  square  inch  of  the  horizontal  section  of  the  ingot. 
The  press  at  Aboukoff  exerts  a  total  pressure  of  10,000 
tons."  With  a  45  ton  ingot  the  maximum  pressure  is 
reached  in  about  35  minutes. 

During  this  time  there  is  a  "  continuous  and  violent " 
evolution  of  gas  and  flame,  and  the  ingot  is  compressed  by 
one  eighth  of  its  length.  A  pressure  of  1,500  Ibs.  per 
square  inch  from  an  accumulator  is  now  substituted  for 
the  direct  pressure  of  the  pump,  and  is  maintained  until 
the — "metal  is  sufficiently  cooled  to  insure  no  farther 
contraction  in  the  mould  "  —(which  taken  literally  means 
till  it  is  completely  cold,  so  as  to  follow  up  the  contract- 
ing steel  and  prevent  the  formation  of  external  contrac- 
tion cracks,  from  local  adhesion  to  the  sides  of  the  mould 
or  from  other  cause. 

The  gas  evolved  is  said  to  be  chiefly  carbonic  oxide,  and 
its  evolution  Is  said  to  cease  towards  the  end  of  the  com- 
pression. 

At  St.  Etienne,  at  Worcester,  Mass.,  and  at  Neuberg  in 
Styria  somewhat  similar  methods  of  compression  have 
been  employed.  At  Neuberg  a  total  pressure  of  from  400 
to  700  tons  was  applied,  and  maintained  only  for  from  30 
to  60  seconds. b 

Whitworth  attacks  the  ingot  at  its  strongest  point,  so 
that  to  accomplish  given  compression  he  has  to  expend 
the  maximum  of  energy.  To  create  even  a  slight  pres- 
sure within  the  soft  interior  he  must  actually  compress 


Fig.  4,5 

tt 


Daelen's  Liquid  Compression  Apparatus. 

the  most  unyielding  portion,  the  early  freezing  walls,  and 
that  too  in  a  direction  in  which  they  resist  most  power- 
fully. In  other  methods  the  ingot  is  attacked  at  much 
weaker  points. 


B.  Daelen  employs  a  number  of  expedients  for  com- 
pressing steel,  one  of  which  is  illustrated  in  Figure  44. 
The  steel  is  cast  in  a  powerfully  clamped  iron  mould  A  A, 
(which,  however,  might  be  lined  with  sand,  with  an 
arrangement  like  Whitworth' s  for  the  escape  of  gas),  filling 
it  to  the  top  of  the  cover  D.  The  plunger  F  of  a  hydraulic 
cylinder  E  is  then  forced  down  into  Gr,  driving  the  metal 
into  the  body  of  the  ingot.  With  small  ingots  the  steel 
is  bottom-cast  in  groups  (Figure  45)  with  rather  large  run- 
ners, and  the  moulds,  whose  tops  are  closed,  are  strongly 
clamped  to  the  base  plate.  A  horizontal  plunger  A  is 
forced  by  hydraulic  pressure  into  one  of  these  runners  D, 
which  had  been  temporarily  closed  with  a  brick  plug  E, 
forcing  the  steel  thence  into  the  moulds.  The  gas  may 
escape  through  small  holes  in  the  mould-top,  K.c  Daelen's 
apparatus  is  not  now  in  actual  use.d 

0.  S.  T.  Williams*  employs  a  mould,  one  of  whose  inner 
faces  is  concave  as  shown  in  Figure  46,  which  represents 
the  apparatus  after  the  compression  has  taken  place.  As 


S.  T.  Williams'  Apparatus.     W.  B.  Hinsdale's  Apparatus. 

soon  as  the  shell  of  the  ingot  has  solidified  he  opens  the 
mould,  which  is  covered  with  a  hot  brick  A  to  retard 
solidification,  and  slips  a  plano-convex  pressure-plate  B 
between  mould  and  ingot.  The  two  sides  of  the  mould  are 
now  gradually  forced  together  by  hydraulic  pressure  ap- 
plied through  the  plunger  C.  The  plane  face  of  the  pressure 
plate  presses  against  the  convex  side  of  the  ingot,  forces  it 
in,  and  drives  the  liquid  steel  from  the  interior  of  the  ingot 
into  the  already  partially  formed  and  rapidly  deepening 
pipe,  completely  filling  it.  Slabs  which  I  examined, 
hammered  from  these  compressed  ingots  and  broken  across, 
showed  clearly  that  the  pipe  had  been  filled  to  over- 
flowing. This  process  has  been  in  use  at  Henry  Disston  & 
Sons'  Tacony  Works  for  over  two  years,  and  I  am  informed 
that  during  this  time  not  a  saw  has  split  on  account  of 
piping.  Fifteen  presses  are  now  in  use,  and  12  more  are 
building.  Formerly  about  30$  of  the  weight  of  the 
ingot  had  to  be  rejected  on  account  of  piping,  now  only 
5%.  The  cost  of  remelting  the  piped  end  is  estimated 
by  Mr.  Williams  at  two  cents  per  pound,  if  direct  firing 
be  used.  This  seems  to  me  excessive.  Another  and  most 
competent  crucible- steel  maker,  who  fires  with  gas,  esti- 
mates it  at  half  a  cent  a  pound.  Let  us  take  it  at  VO 
cents  per  pound  for  direct  firing  and  0-5  cents  for  gas 
firing.  At  Tacony  one  man  at  $2.00  per  day  compresses 
one  ton  of  ingots  in  one  hour.* 


a  "Steel and  Iron,"  Greenwood,  p.  510. 
o  Engineering,  XX.,  p.  107,  1875. 


c  Engineering,  XX.,  p.  278,  1875;  Jeans,  Steel,  p.  501. 
a  R.  M.  Daelen,  private  communication,  Feb.  13,  1888. 
e  U.  S.  Patent  331,856,  Dec.  8th,  1885. 

*  S.  T.  Williams,  Superintendent  of  the  Tacony  Works,  private  communication, 
March  38th,  1888. 


LIQUID    COMPRESSION.      §  229. 


157 


From  this  we  may  calculate  as  follows,  assuming  that 
each  man  engaged  in  compression  does  eight  effective 
hours  work  daily.  I  think  it  more  conservative  to  assume 
that  the  weight  to  be  remelted,  when  compression  is  not 
employed,  at  25^  than  at  3(% 


Saving  by  diminishing 

' 
Labor  of  com  pn-ssion 


$  per  ton  of  ingots. 
Direct  Gas 

%       %  tiring.  firing. 

inK  K\         U>S. 

'  X  2240  X  (0-01  and  0-005) $448 


100 


$-2.24 


0.25 


O.SB 


Difference  per  ton  of  ingots  $4.23  $l.'Ji* 

"          ••    pound    "      O'ISct.  0-09cts. 

0-19  cent  per  pound  will  certainly  and  0'09  cent  will  per- 
haps more  than  cover  the  incidental  costs  of  compression, 
such  as  power,  depreciation,  and  the  shorter  life  of  the 
moulds. 

In  1883  Mr.  William  Metcalf  believed  that  compres- 
sion would  cost  more  than  remelting  for  small  crucible  steel 
ingots. a  This,  however,  referred  to  a  much  more  costly  and 
probably  much  less  effective  method  of  compression  :b  more- 
over, the  cost  of  remelting  at  his  admirably  conducted  estab- 
lishment, especially  with  natural  gas,  is  comparatively  low. 

While  this  method  is  well  suited  to  the  flat  saw  ingots, 
it  remains  to  be  seen  whether  it  can  be  applied  readily  to 
common  square  pyramidal  ingots. 

D.  G.  W.  Billings  employs  a  common  mould,  replacing 
its  bottom  by  a  piston,  which  is  forced  upwards  as  soon  as 
teeming  is  completed,  pressing  the  top  of  the  ingot  against 
a  resistance  plate  which  has  been  slipped  in  meanwhile. c 

E.  W.  R.  Hinsdale  found  that  an  ingot  of  high-carbon 
steel,  3 '5  inches  square,  to  which  a  pressure  of  12,000 
pounds  per  square  inch  was  applied  within  five  seconds 
after  casting,    contained  when  cold  innumerable    blow- 
holes.  Under  a  pressure  of  60,000  pounds  per  square  inch, 
applied  30  or  40  seconds  after  casting,  it  shortened  by 
about  one  eighth  of  its  length,  to  wit,  from  2/5  to  22  inches, 
and  after  cooling  had  a  fracture  like  that  of  a  forged  bar  ; 
but  the  pipe  remained  in  the  attenuated  shape  of  such  a 
flaw  as  one  finds  in  a  bar  forged  from  the  piped  end  of  an 
ingot.     When,  however,  a  pressure  of  20,000  pounds  per 
square  inch  was  applied  after  the  same  interval  through 
a  perforated  plunger  D,  Figure  47,  the  crust  of  metal 
under   the  perforation  broke  with  a  loud  report,   and 
a  punching,  followed  by  gas  and  molten  metal,  shot  into 
the  perforation,  forming  a  stud  which  was  the  only  scrap, 
as  the  ingot  itself  was  absolutely  solid. d 

Daelen  bulges  in  the  top  or  bottom,  Williams  the  side 
of  the  ingot :  both  avoid  the  enormous  waste  of  energy 
implied  in  compressing  the  already  frozen  walls  longitudin- 
ally. There  appears  to  be  no  limit  to  the  pressure  which 
can  be  obtained  by  Daelen' s  system.  Were  a  high  pres- 
sure applied  in  Williams'  system  it  would  probably  burst 
the  top  or  convex  side  of  the  ingot,  which  would  hardly 
fit  the  mould  as  exactly  as  is  shown  in  the  cut.  It  may 
be  questioned  whether  it  be  practicable  to  arrange  his 
mould  so  that  its  different  parts  shall  slide  past  each 
other,  and  still  be  strong  enough  and  tight  enough  to  pre- 
vent the  escape  of  molten  metal  under  heavy  pressure. 

Hinsdale' s  modification  might  well  increase  the  effi- 
ciency of  Whitworth's  system  as  a  means  of  obliterating 
the  pipe. 


aProc.  Engineers  Soc.  West.  Penn.,  1883,  251. 
b  G.  W.  Billings'  method. 
cU.  S.  Patents  298,  661-2,  May  13th,  1884. 

a  W.  R.  Hinsdale,  private  communication,  March  13th,  April  26th,  1888,  U.  S. 
Patent  333,656,  Dec.  15th,  1885. 


GASEOUS  PRESSURE  has  been  applied  to  molten  steel  in 
several  ways.  It  has  an  advantage  over  Whitworth's 
method,  in  that  the  compressed  gas  attacks  the  ingot  at 
every  point,  including  the  weakest  ones.  Even  if  the  ex- 
ternally applied  gas  does  not  itself  enter  or  compress  the 
metal,  it  still  tends  to  prevent  internally  liberated  gas  from 
escaping  through  the  ingot' s  shell,  to  raise  the  pressure 
within  the  ingot,  and  thus  to  check  the  internal  liberation 
of  gas  and  the  formation  of  blowholes.  In  this  it  tends  to 
increase  the  pipe  :  but  if  powerful  enough  to  bend  in  the 
sides  or  top  of  the  ingot  by  ever  so  little,  it  lessens  and 
may  obliterate  the  pipe. 

F.  Bessemer  patented  in  1869  methods  of  creating  a 
gaseous  pressure  in  ingot  moulds  by  the  combustion  of  gas 
yielding  substances,  and  by  the  vaporization  of  liquids. 

G.  Krupp  employed  liquid  carbonic  acid,  and  is  said  to 
have  obtained  a  pressure  of  five  tons  per  square  inch.6 

The  interior  of  a  massive,  tightly  closed  mould,  after  it 
has  received  the  molten  steel,  is  connected  with  a  vessel 
containing  liquid  carbonic  acid  :  part  of  the  carbonic  acid 
immediately  volatilizes,  raising  the  gaseous  pressure,  which 
may  be  regulated  by  controlling  the  temperature  of  the 
carbonic  acid.  This  is  readily  done  by  raising  or  lowering 
the  temperature  of  an  oil  or  water  bath  in  which  the  ves- 
sel containing  it  is  immersed,  by  circulating  steam  or  cold 
water. 

To  prevent  the  escape  of  carbonic  acid  from  his  mould 
Krupp  tightens  the  joint  between  mould  and  cover  by  a 
thin  ring  of  copper  or  steel,  with  a  channel-,  angle-,  or  T- 
shaped  cross  section  (A,  B,  C,  Figure  48),  which  acts  like 
the  leather  cup-packing  of  hydraulic  cylinders,  and  be- 
comes tighter  the  higher  the  pressure  rises.  Another 
expedient  is  to  squeeze  a  round  copper  or  steel  ring  in  a 
rectangular  recess  between  cover  and  mould  (D,  Figure  48). 

Fig.M.-JOINTS  BETWEEN  INGOT-MOULD  AND  COVER  (F.  A.  KRUPP). 


He  would  keep  the  upper  surface  of  the  ingot  hot  by 
placing  on  it  a  layer  of  molten  slag  or  of  refractory 
material,  or  by  lining  the  mould  top  with  non-conducting 
material,  apparently  so  that  the  ingot  top,  long  remaining 
soft  and  flexible,  may  transmit  the  pressure  to  the  interior 
of  the  ingot. 

H.  The  explosion  of  gunpowder  within  the  firmly  closed 
mould,  proposed  by  Galy-Cazalat, '  might  lend  pyrotechnic 
interest.  Ingenious  methods  of  introducing  and  explod- 
ing the  powder  and  of  rendering  its  presence  effective  are 
proposed  by  James  Henderson,  who  also  suggests  obtaining 
steam  pressure  by  introducing  ice.g 

I.  W.  R.  Jonesh  of  Pittsburgh  formerly  blew  steam  into 
the  tops  of  his  ingot-moulds,  at  a  pressure  of  80  to  150  Ibs., 
immediately  after  casting.  The  moulds  were  tightly 
closed  at  the  top,  while  their  stools  had  grooves  5-8th  inch 


e  British  pateut  2,860,  June  30,  1881,  F.  A.  Krupp  to  A.  Longsdon.  Krupp 
here  describes  ingot  moulds  of  many  forms  for  compression,  both  for  top  and  bot- 
tom castings. 

t  U.  8.  patent  62,113,  Galy  Cazolat  (sic),  Feb.  19,  1867.  British  patent  3,300, 
Dec.  21st,  1865,  Galy-Cazalat. 

KU.  S.  patents  315,741,  April  14th,  1885,  and  316,544,  April  28th,  1885. 

h  Journal  of  the  Iron  and  Steel  Institute,  1879,  II.,  p.  476;  Jeans,  Steel,  p.  503. 


158 


THE    METALLURGY    OF    STEEL. 


wide  and  1  -16th  inch  deep,  for  the  escape  of  gas,  and  com- 
municating with  the  outer  air.  It  is  said  that  the  molten 
steel  considerately  does  not  enter  these  grooves,  but  that 
the  gases  escape  from  them  with  a  loud  roar,  and  that  the 
ingot  is  freer  from  piping  then  when  cast  in  the  usual  way. 
What  appears  to  be  a  slight  modification  of  this  method 
is  said  to  have  been  adopted  at  Barrow  and  at  the  works 
of  Messrs.  Bolckow,  Vaughan  &  Co." 

Now  as  the  ingot,  whose  outer  crust  solidifies  almost 
instantly,  cools  and  contracts,  it  would  be  expected  to 
draw  away  from  the  sides  of  the  mould,  which,  being 
rapidly  heated,  expands  and  increases  the  space  between 
itself  and  the  contracting  ingot.  The  steam  blown  in  at  the 
top  of  the  mould  is  thus  permitted  to  pass  down  between 
the  ingot  and  mould  and  to  escape  (together  with  any  gas 
actually  evolved  from  the  ingot)  through  the  holes  which 
have  been  provided  in  the  stool  of  the  mould.  That  the 
steam,  with  such  ample  means  of  escape,  should  under 
these  conditions  exert  a  pressure  on  the  steel  at  all  com- 
mensurate with  that  which  the  rapidly  cooling  exterior  of 
the  ingot  exerts  on  the  comparatively  slowly  cooling  in- 
terior, or  that  indeed  it  should  exert  any  pressure  worth 
considering,  is  improbable.  It  seems  like  merely  substi- 
tuting an  atmosphere  of  steam  for  one  of  ingot  gas. 
Whatever  influence  the  steam  has  would  naturally  be  at- 
tributed to  its  cooling  the  crust  of  the  ingot  and  thus 
preventing  rising,  acting  like  so  much  water. 

In  practice  it  is  difficult  to  tighten  the  joints  quickly, 
and,  in  spite  of  the  many  advantages  claimed  for  this  pro- 
cedure, Captain  Jones  does  not  now  employ  it.b 

J.  The  Accumulation  of  Gaseous  Pressure  within  the 
ingot  itself  is  promoted  by  chilling  its  top  with  water, 
which  bottles  up  the  gas  evolved  during  solidification 
This  of  course  tends  to  arrest  further  evolution  of  gas,  and 
thus  to  check  the  formation  of  blowholes :  but  this  local 
cooling  must  tend  to  lower  the  pipe  by  hindering  the  steel 
in  the  top  of  the  ingot  from  flowing  down  to  feed  it. 

§  230.  EFFECT  OF  LIQUID  COMPRESSION. — Let  us  first 
consider  what  benefits  should  be  expected  from  liquid 
compression,  and  then  what  have  actually  been  traced  to  it. 

We  may  divide  the  compression  into  two  periods,  before 
and  after  the  passage  from  the  liquid  to  the  plastic  state, 
or  into  "liquid"  and  "plastic  compression." 

It  is  hard  to  see  how  liquid  compression  can  have  any 
beneficial  effect.  Liquids  are  practically  incompressible  : 
that  the  steel  is  not  enduringly  compressed  will  be  shown. 
If  the  liquid  steel  is  not  giving  off  gas,  applying  compres- 
sion will  effect  nothing.  If  it  is,  compression  cannot  hasten 
the  escape  of  the  gas-bubbles, c  which  will  rise  by  gravity 


a  Journ.  Franklin  Inst.,  CX.,  p.  19,  191,  1880. 

b  In  a  paper  read  in  December,  1878,  Chernoff  speaks  of  casting  under  a  steam 
pressure  of  88  to  147  pounds  per  sq.  inch,  the  method  of  la  Chaleassiere,  in  France. 

c  The  mental  fogginess  of  many  prominent  metallurgists  on  this  subject  is  dis- 
heartening. We  hear  them  talk  of  pressure  applied  to  the  upper  surface  of  liquid 
steel  forcing  gas  bubbles  to  travel  downwards.  Let  them  experiment  with  an 
ordinary  soda-water  syphon,  which  is  in  precisely  the  condition  of  ordinary  gas- 
bearing  liquid  steel,  and  endeavor  to  grasp  the  A  B  C  of  physics.  Let  them 
slightly  release  the  pressure  by  drawing  a  little  water  :  bubbles  will  immediately 
rise  :  let  them  immediately  increase  the  pressure  again.  Will  the  upward  path  of 
these  bubbles  be  reversed  by  the  pressure,  and  will  they  now  travel  downwards  ? 
The  increased  pressure  may  cause  their  reabsorption,  but  it  will  not  alter  the 
direction  of  their  travel,  which  is  determined  by  gravity  alone.  The  effect  of 
pressure  in  expelling  fluids  from  pasty  solids  is  clearly  shown  in  the  expulsion  of 
cinder  from  a  puddle-ball  by  squeezing  :  the  direction  which  the  cinder  takes  in 
escaping  is  not  directly  away  from  and  in  the  line  of  the  compressing  force,  but 
each  particle  follows  its  own  path  of  least  resistance,  which  will  in  general  be 
nearly  normal  to  the  nearest  surface.  A  gas  would  be  affected  in  precisely  the 
same  way  but  it  is  not  so  easy  to  illustrate  this  experimentally. 


to  the  surface  with  or  without  compression  ;  but  it  must 
tend  to  retard  or  even  stop  the  evolution  of  gas,  whose 
solubility  increases  with  the  pressure,  and  thus  to  increase 
the  quantity  of  gas  retained  by  the  steel,  the  supersatura- 
tion  which  occurs  at  the  moment  of  solidification,  the  vol- 
ume of  gas  then  evolved,  and  the  extent  to  which  blow- 
holes form. 

Plastic  compression,  however,  may  actually  squeeze  the 
blowhole-gas  out  through  the  crust  of  the  ingot  as  we 
squeeze  water  out  of  a  sponge  :  it  may  cause  the  reabsorp- 
tion of  part  or  indeed  all  of  the  gas  contained  in  the  blow- 
holes, and  may  squeeze  and  weld  the  sides  of  the  pipe  to- 
gether :  and  if  gas  remain  which  is  neither  squeezed  out 
nor  reabsorbed,  the  pressure  will  diminish  the  size  of  the 
cavities  which  contain  it.  The  gas  which  is  thus  reab- 
sorbed and  compressed  is  not  indeed  eliminated  :  and  it  is 
possible  that  it  may  be  re-evolved  and  may  re-expand 
should  plasticity  without  compression  recur :  but  it  could 
then  hardly  form  in  the  relatively  stiff  pasty  metal  as  large 
cavities  as  it  would  have  caused  at  the  higher  temperature 
and  in  the  less  viscous  metal  of  its  first  liberation.11 

In  this  view  it  seems  desirable  to  postpone  compression 
as  long  as  possible,  so  that,  before  it  begins,  as  much  as 
possible  of  the  gas  may  voluntarily  escape.  Indeed,  it 
would  be  well  to  hasten  its  escape  from  the  molten  metal 
by  creating  a  partial  vacuum. 

Small  ingots  may  solidify  so  quickly  that  we  cannot  in 
practice  discriminate  between  liquid  and  plastic  compres- 
sion :  but  the  distinction  may  be  valuable  for  large  in- 
gots.6 

Nearly  two  years  after  the  above  was  written,  and  shortly 
before  going  to  press,  I  receive  what  seems  to  be  a  strik- 
ing confirmation  of  the  correctness  of  these  inferences.  On 
applying  a  pressure  of  12,000  pounds  per  square  inch  to 
the  bottom  of  some  3 '5  inch  square  ingots  soon  after  teem- 
ing, Mr.  W.  B.  Hinsdale  found  that,  if  the  pressure  were 
applied  as  soon  as  possible,  the  ingot  contained  innumer- 
able round  cavities  :  while  if  he  waited  a  little  before  ap- 
plying the  pressure,  blowholes  were  found  only  in  the 
upper  part  of  the  ingot,  and  the  longer  he  waited  the  nearer 
to  the  pipe  the  blowholes  were,  till  at  last  they  disap- 
peared, the  pipe  remaining.'  Now  the  pressure  should 
not  retard  the  upward  swimming  of  bubbles,  provided  that 
they  remain  as  bubbles ;  indeed,  in  the  belief  of  many, 
pressure  tends  to  liquefy  iron  as  it  does  ice.  The  most 
simple  explanation  seems  to  be  that  gas  bubbles  were  ris- 
ing through  the  steel :  (they  would  naturally  be  found 
latest  in  the  top  of  the  ingot,  because  it  is  cast  latest,  and 
because  bubbles  rise  thither  from  below) :  that  pressure 
caused  their  reabsorption :  that  this  gas  was  again  set 
free,  either  on  solidification  or  fall  of  pressure,  causing 
blowholes.  Hence  the  longer  compression  was  deferred 
the  less  gas  was  present  to  be  temporarily  absorbed,  and 
the  fewer  blowholes  formed  on  its  re-emission. 

Plastic  compression  then  is  sound  in  principle :  the 
difficulty  is  in  applying  it.  Whitworth  is  able  to  employ 
an  enormous  pressure,  but  at  a  disadvantage.  Daelen's 
method  permits  as  great  a  pressure  at  much  better  ad- 
vantage :  his  method  appears  much  the  more  reasonable ; 
yet  it  is  not  employed. 


d  Cf.  the  author,  Proc.  Soc.  Arts,  Mass.  Inst.  Technology,  1886-7,  p.  18. 

e  See  experiment  by  H.  W.  Lash,  §  202,  F. 

'  W.  R.  Hinsdale,  Private  Communication,  March  13,  1888. 


EFFECT    OF    LIQUID    COMPRESSION.      §  229. 


159 


In  the  case  of  small  ingots  several  of  the  methods  which 
we  have  considered  might  be  expected  to  completely  pre- 
vent both  pipes  and  blowholes. 

In  the  case  of  large  ingots  it  should  be  comparatively 
easy  to  prevent  blowholes  in  the  layers  which  solidify 
first :  but  it  is  far  from  clear  that  any  of  these  methods 
should  be  able  to  prevent  cantral  cavities,  or  that  the  com- 
pression which  they  effect  should  even  compensate  for  the 
increased  proportion  of  gas  in  the  solidifying  metal,  due 
to  the  immediately  preceding  liquid  compression.  To 
make  the  center  of  a  large  ingot  compact,  the  compression 
must  follow  up  the  contraction  till  the  very  central  por- 


mit  any  pressure  whatever  to  them  through  an  enormous 
thickness  of  outer  and  resistance  metal. 

In  comparing  Whitworth's  compression  with  forging  it 
is  to  be  remembered  that,  while  the  former  has  advantages 
in  acting  before  blowholes  form  instead  of  attempting  to 
efface  those  already  created,  and  in  being  applied  at  a 
temperature  which  is  higher  and  hence  more  favorable  to 
the  welding  of  cavities  than  is  permissible  in  forging,  yet 
it  labors  under  the  disadvantage  of  having  to  compress  the 
whole  cross-section  of  the  ingot  at  once,  attacking  it  in  the 
path  of  greatest  resistance.  Forging  under  a  powerful 
hydraulic  press  has  the  great  advantage  of  concentrating  its 


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rals  indicate  the  length  in  inches  in  which  the  percentage  of  elongation  is  taken  :  the  letters  indicate  the  origin  of  the  steel,  thus  :  C  =  Cambria,  Johnstown,  ] 
O  =  Otis,  Cleveland,  Ohio.     W  =  Whitworth.     +=  Unforced  castings.     Most  of  the  Cambria,  Midvale  and   Otis  cases  are  from  the  reports  of  the  Chief  of  Ordi 

tions  have  cooled  far  below  their  freezing  point,  which 
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a  Wall-ami  states  (Vau  Nostrand  Eug.  Mag.,  XXXIII.,  p.  362,  1885)  tbat  he 
finds  that  a  pressure  of  from  74  to  88  pounds  per  square  inch  always  greatly 
lessens  the  blowholes:  and  Chernoff  states  (Rev.  Univ.,  3d  ser.,  VII.,  p.  149, 
1880)  that  but  slight  pressure  suffices  to  arrest  the  escape  of  gas.  The  extreme 
violence  with  which  gas  escaped  from  previously  tranquil  steel  in  Bessemer's  experi- 
ment (§  188  C.)  on  lowering  the  pressure  by  some  13  to  13  pounds  per  square  inch 
certainly  suggests  that  a  small  increase  of  pressure  should  materially  reduce  the 
escape  of  gas. 


pressure  on  a  small  portion  of  the  metal,  attacking  it  piece- 
meal. It  is  by  no  means  clear  a  priori  that  this  may  not  out- 
weigh its  disadvantage  of  working  at  a  lower  temperature. 
I  see  no  reason  to  anticipate  that  liquid  compression 
should  benefit  the  metal  otherwise  than  by  preventing  the 
formation  of  cavities.  Indeed  one  would  hardly  expect 
that  it  could  produce  the  kneading  and  rubbing  together 
of  the  particles  which  forging  gives,  and  which  is  generally 
thought  to  be  extremely  beneficial,  since  this  implies  mo- 
tion of  the  particles  on  each  other.  It  should,  however, 
tend  to  prevent  external  cracks 


160 


THE    METALLURGY    OF    STEEL. 


Evidence  of  the  Effects  of  Compression. — The  only  two 
methods  which  have  stood  the  test  of  experience  are  those 
of  Whitworth  and  of  Williams.  The  evidence  of  the  ef- 
fect of  the  latter  has  already  been  stated  :  let  us  now  con- 
sider the  evidence  of  the  effect  of  Whitworth' s  method. 

It  is  reported  that  his  compression  shortens  large  ingots 
by  12-5%,  which  certainly  implies  that  it  greatly  dimin- 
ishes their  cavities,  but  not  that  it  eliminates  them  com- 
pletely. It  is  further  stated  his  compression  has  been 
successfully  applied  only  to  pieces  of  simple  form,  and 
that  even  these  are  subsequently  forged. 

I  know  no  evidence  that  his  compressed  ingots  are  freer 
from  cavities  than  steel  cast  without  compression  is  after  it 
has  been  forged  with  suitable  apparatus,  i.  e.  rolls  and  ham- 


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The  numerals  Indicate  the  length  In  inches  in  which  the  percentage  of  eloniralion  is  taken:  the 
letters  indicate  the  orhrfn  of  the  steel,  thus:  C  =  Cambria,  Johnstown,  Pa.  M =  Mid  vale,  Nice 
town.  Pa.  O  =  Otis,  Cleveland,  O.  W  =  Whitworth.  -f  =  Unfnrged  castings.  Most  of  the 
Cambria,  Midvalc  and  Otis  cases  are  from  the  reports  of  the  Chief  of  Ordnance,  U.  S.  Ariuy,  from 
1877  to  ISSti  inclusive. 

mers  for  small  pieces,  hydraulic  presses  for  large  ones.  I 
here  except  the  sinkiug-head  portion  of  uncompressed  steel. 

Liquid  compression  probably  does  not  increase  the  den- 
sity :  Percy  finds  the  specific  gravity  of  liquid  compressed 
steel  identical  with  that  of  similar  steel  uncompressed.8 

Greenwood,  indeed,  finds  the  specific  gravity  of  com- 
pressed steel  of  0'54$  of  carbon  7'8791,  while  that  of  the 
bottom  of  an  ingot  of  the  same  steel  cast  in  a  chill  mould 
was  7-8.")43  ;  but  this  difference  of  Oni24(.)  maybe  due  to  the 
sudden  cooling  caused  by  the  walls  of  the  chill  mould,  or 
to  minute  blowholes.  Indeed,  the  important  question  is 
whether  forgings,  etc.,  from  an  uncompressed  ingot  are 
lighter  than  those  from  a  compressed  one. 

Nor  do  I  find  any  evidence  that  Whitworth's  compres- 
sion benefits  the  properties  of  steel  otherwise  than  by 
diminishing  cavities.  We  have  plenty  of  vehement  asser- 
tions on  one  side  and  on  the  other:  but  the  experienced 
metallurgist,  who  to  his  sorrow  knows  the  difficulty  of 
tracing  the  causal  relation,  will  receive  them  cautiously 
till  the  nature  of  their  supporting  evidence  is  made  clear. 

Members  of  the  United  States  Gun  Foundry  Board  of 
1883  saw  Wiiitworth's  compressing  apparatus  in  actual 
use.  From  the  board's  report,  whicli  commends  Whit- 
worth's  procedure  most  highly, b  one  might  infer  that  it 


meant  to  indorse  liquid  compression  as  such.  But  his 
procedure  consists  of  two  wholly  distinct  operations,  1, 
liquid  compression,  2,  forging  under  the  hydraulic  press 
after  solidification.  I  questioned  a  member  of  the  board,0 
whose  name  carries  certainly  as  much  weight  as  that 
of  any  of  his  associates.  From  his  reply  I  gather  that 
the  board  was  convinced  (1)  that  Whitworth's  steel  ex- 
celled all  others  and  (2)  that  the  action  of  the  hydraulic 
forging  press  was  far  more  beneficial  to  large  masses  than 
that  of  the  hammer :  but  that  it  did  not  intend  to  in- 
dorse liquid  compression  specially,  though  impressed  by 
Whitworth's  conviction  that  it  was  valuable.  It  is  possi- 
ble that  they  weighed  philoprogenitiveness,  the  inventor's 
natural  parental  bias,  too  lightly. 

Indeed,  one  could  hardly  know  that  the  admirable  quaii 
ties  of  Whitworth's  steel  were  at  all  due  to  liquid  compres- 
sion, without  comparing  a  great  number  of  his  hydraulic- 
forged  pieces  which  had  been  compressed  while  molten  with 
others  similar  but  not  compressed.  If  such  a  comparison 
has  ever  been  made,  its  results  have  not,  I  believe,  been 
offered  to  the  public,  nor,  I  am  very  confident,  to  the 
board.  Judging  from  its  report  and  from  the  answers  of 
two  of  its  members  to  my  inquiries,  it  seems  to  me  pretty 
clear  that  the  evidence  which  the  board  obtained  was  of 
such  a  nature  that,  while  it  might  suggest,  it  could  not 
begin  to  prove  that  liquid  compression  benefits  large  masses 
which  are  to  be  forged  afterward  under  the  hydraulic 
press,  otherwise  than  by  diminishing  the  pipe  and  pre- 
venting external  cracks  :  but  we  may  reasonably  doubt 
whether  these  advantages  would  repay  the  cost  of  a  liquid 
compression  apparatus. 

The  hold  which  a  long-used  brand  and  a  famous  name  1  ike 
Whitworth's  have  on  the  imagination,  and  the  difficulty  of 
substituting  for  a  familiar  material  anew  one  which,  though 
of  equal  or  even  greater  fitness,  differs  slightly  from  it, 
suffice  to  explain  the  frequent  belief  of  gunmakers  in  the 
unapproachable  quality  of  Whitworth's  steel.d 

General  Benet,  commenting  on  the  properties  of  some 
steel  hoops  from  Midvale,  remarks  that  they  "are  fully 
equal  to  the  highest  claimed  by  Whitworth  &  Co.  for  the 
characteristics  of  their  steel  hoops."6 

Greenwood  says  of  the  many  compressed  ingots  cut  up 
at  Abouchoff  that  they  "  presented  either  no  visible 
cavity,  or  only  perhaps  an  axial  pipe  or  porosity  into 
which  a  pin  or  wire  might  be  inserted."  Hence  in  de- 
signing ingots,  whils  allowance  is  of  course  made  for  loss 
in  forging  and  turning,  none  is  made  for  unsoundness  at 
the  ingot-top,  of  which  from  5  to  '35%  is  rejected  in  case  of 
uncompressed  ingots.  He  mentions  a  liquid- compressed 
ingot  34'2,;)  inches  in  diameter  and  70'o  inches  long,  cut 
lengthwise  into  three  pieces,  which  showed  no  sign  of 
honeycomb  or  blowhole  ;  and  he  states  that  two  trunnion- 
pieces  for  1 2-inch  breech -loading  guns,  weighing  118  cwt., 
as  finished  forgings,  are  habitually  cut  and  forged  from  a 
liquid-compressed  ingot  38  inches  in  diameter  and  48 
inches  long,  weighing  146  cwt.,  and  that  five  trunnion- 
pieces  for  6-inch  guns,  weighing  as  finished  forgings  62 
cwt.,  are  habitually  cut  and  forged  from  a  liquid-com- 
pressed ingot  22  inches  in  diameter  and  66  inches  long 
weighing  65  cwt.  The  total  loss  due  to  cutting,  punch- 
ing and  oxidation  is  about  20$  in  these  cases.'  This  is 
certainly  excellent  practice,  and  Greenwood's  importune 
and  welcome  evidence  puts  matters  in  much  better  light. 
There  is  much  evidence,  however,  which  is  less  favorable. 
Thus  Maitland,  whom  Greenwood  quotes,  says  guardedly 
of  Whitworth's  castings  that  they  are  very  sound  as  a 
rule,  thus  implying  exceptions.  Greenwood  admits  that 
seams  and  roaks  occur,  and  that  there  are  even  excep- 
tional rejections  on  account  of  faulty  metal. 


a  Journ.  Iron  and  Steel  Inst.,  1885,  I.,  p.  29. 

b  Proc.  U.  S.  Naval  Inst.,  X.,  pp.,  633,  637,  642;  also  Kept.  U.  S.  Gun  Foundry  B'd. 

c  Lt.  Col.  Henry  L.  Abbot,  Private  Communications,  Feb.  14th  and  29th,  1888. 

<i  Hotchkiss,  the  famous  jjun-maker,  stated  in  August,  1884,  that,  though  forced 
by  government  to  try  Schneider  steel,  it  is  very  different  from  (meaning  apparently 
very  inferior  to)  Whitworth  steel.  Yet  in  November,  1885,  Hotchkiss  &  Co.  state 
that  they  use  Schneider  steel  extensively,  and  that  it  possesses  the  qualities  needed 
for  cuns.  Report  of  Select  Committee  on  Ordnance  and  War  Ships,  p.  443. 

r  Rept  Chief  of  Ordnance,  U.  S  Army,  1884,  p.  12. 

f  Tiie  Treatment  o£  Steel  by  Hydraulic  Pressure,  Proo.  Inst,  Civ.  Eng.,  XCVUI., 


PREVENTION    OF    BLOWHOLES    AND     PIPES— EXHAUSTION,     SLOW    COOLING.       §  232.    161 


Though  his  compression  is  patented,  Whitworth  has 
never,  I  believe,  permitted  experts  to  observe  it,  if  we 
except  the  distinguished  members  of  the  United  States 
Gun  Foundry  Board  :  and  they  do  not  appear  to  be  experts 
in  metallurgy.  Asked  by  Hewitt  if  he  compressed  large 
gun  tubes,  he  hesitated  and  finally  admitted  that  he  did 
not."  It  has  seemed  to  many  that  Whitworth' s  attitude 
has  not  been  one  of  confidence  in  the  value  of  his  com- 
pression. 

Gautier  states  that  Whitworth' s  former  superintendent, 
Annable,  exposes  the  futility  of  liquid  compression  in  a 
paper  presented  to  the  Iron  and  Steel  Institute  but  dis- 
creetly rejected." 

Annable  states  that  he  is  not  confident  that  a  single  one 
of  the  1,500  ingots  which  he  compressed  was  really  solid  : 
that  the  compressed  ingot  contains  a  pipe  whose  volume 
rises  to  244  cubic  inches,  filled  with  gas  found  to  be  explo- 
sive :  that  to  obtain  sound  metal  the  upper  third  of  the 
ingot  must  be  cut  off :  that  compressed  steel  forges  exactly 
like  uncompressed :  and  that  the  walls  of  the  mould 
become  glazed,  preventing  the  escape  of  gas. 

Gautier' s  paper  gives  the  impression  that  he  and  Annable 
are  strongly  biased ;  and  such  bias  on  Annable' s  partis 
easily  understood.  His  bad  results,  in  view  of  Green- 
wood's success,  seem  to  teach  merely  that  great  care,  or 
special  knowledge,  or  special  precautions  are  needed. 

To  throw  seme  light  on  the  qiiestion  whether  liquid 
compression  gives  a  higher  combination  of  either  ulti- 
mate or  elastic  tensile  strength  with  ductility  than  is 
otherwise  attainable,  I  have  endeavored  to  find  the  best 
recorded  combinations  of  these  properties  both  in  Whit- 
worth's  steel  and  in  that  of  other  makers.  The  best  which 
I  have  found  are  given  in  Figure  48,  and  a  few  of  the  very 
best  are  collected  in  Table  79. 

While  the  results  here  brought  together  show  what  no 
one  doubted,  that  Whitworth' s  steel  is  admirable,  it  fur- 
ther shows  that,  unless  I  have  accidentally  met  the  rec- 
ords of  only  his  poorer  steel,  it  does  not  excel  the  best 
American  steel  in  its  combination  of  ultimate  or  elastic 
tensile  strength  with  ultimate  elongation.  One  of  Whit- 
worth's  steels  does,  indeed,  greatly  excel  all  others:  but 
one  swallow  makes  no  summer. 

To  sum  tip,  in  proper  hands  the  liquid  compression  of 
large  masses,  if  powerful  enough,  according  to  our  present 
evidence,  does  prevent  pipes,  blowholes  and  cracks  almost 
completely,  so  that  we  may  avoid  the  expense  to  which  we 
arc  pat  in  common  practice  of  remelting  from  5  to  'A*>%  ot 
the  weight  of  each  ingot  on  account  of  unsoundness.  But 
it  is  doubtful  whether  this  is  in  itself  sufficient  to  repay  the 
cost  of  the  apparatus  :°  and  1  find  no  evidence  that  liquid 
compression  improves  the  metal.  The  compression  of  small 
ingots  has  received  one  satisfactory  solution  (§  229,  C.) 

§231.  EXHAUSTION,  already  hinted  at  in  discussing 
liquid  compression,  has  been  proposed.4  Removing  gas 
from  the  molten  steel  leaves  so  much  the  less  to  escape 


a  Appendix  to  Report  U.  8.  Commission  on  Ordnance  and  War  Ships,  1885, 
p.S7. 

bGenie  Civil,  II.,  p.  385. 

c  The  additional  cost  of  equipping  a  gun  making  plant  {or  liquid  compression 
was  estimated  by  the  Gun  Foundry  Board  at  $175,000  (Report,  p.  50  ; 
Proc.  U.  S.  Naval  Inst.,  X.,  p.  851,  Jaques),and  by  Mr.  J.  Morgan,  Jr.,  Chief- 
Engineer  of  the  Cambria  Iron  Company,  at  $200,000  to  $300,000  (Appendix  to 
Rept  U.  S.  Commission  on  Ordnance  and  War  Ships,  appointed  under  resolution 
of  July  6,  1884,  p.  27). 

d  Proposed  by  L.  Nessel,  Metallurg.  Rev.,  I.,  p.  494,  from  Oest  Zeit.,  No.  43, 
i877, 


TABLE  79. — Hum  COMBINATIONS  OF  STRENGTH  AND 


Number. 


Elongation, 


|  In 


WIIITWOKTIPS  STEEL. 


94,720 
100,56(1 
98,000 
92,120 
91,960 
16,000 


78,880 
79,820 
88,400 
96,280 
82,840 

86,040 
89,320 
84000 

104,000 
98,280 
97000 

100,569 
91,600 

S'.l.f.UM 

® 

112,000 

106,624 

71.680 

@ 

NI.6III 

212,800 


107,520 
129.920 


152,820 
161.280 


52,000 

39',<Vm 
411,000 
;;n,oon 
81,000 
83.000 
30,000 
fxl.OUO 
55,000 
31,000 
84,000 
53,000 
54,000 
44000 
CO  800 
52,800 
59,760 
53,000 
51,000 
56.000 

© 

67,200 

42566 

& 
51,520 


17-5 
14  8 
18-5 
IT- 
17-8 
17  8 

2-1 
19- 
23-3 
22- 
25-5 
81-5 
28- 
24  7 
24- 
20- 
21- 
20- 
17-8 
12- 
20- 
20- 

© 
15- 
20- 
28- 

@ 
24- 

a- 

32- 
24- 
17' 
10- 
14- 


47-2 
89-2 
44-6 
52  2 
52-2 
47'2 
30-6 
36-4 
88-5 
47'2 
52-2 
49-7 
49'7 
47-2 
47-2 
44-6 
44-6 
36-4 
86-4 
11-8 
36-4 


STEEL  OTHER  THAN  WHITWOKTH'S. 


38                  

00,000 

22' 

B 

34            

140.000 

12- 

4 

35                    

147,200 

15- 

4 

86         

128,800 

17- 

4 

87        .     ...    

132,700 

84,803 

16- 

1 

81-07 

88      

155,000 

16-6 

89           

119,969 

16  5 

40               

102,000 

61,400 

26 

41                           

180.000 

14- 

10 

42            

104,000 

17-2 

48   

114,000 

54,000 

17  50 

4 

44                

® 

116,000 

© 

57,000 

& 
12  2 

4 

45       

126,000 

70,000 

17  0 

46        

112,000 

64,000 

18  6 

47                

117,410 

72,000 

14'5 

6 

48-T 

48          

117,810 

72,000 

13-83 

fi 

48-7 

49          

117,440 

73,000 

17-00 

8 

47.2 

50            

118.000 

73,000 

17  83 

8 

48-1 

51      

112,300 

59.500 

12  8 

8 

19-0 

j  145,400 

82,810 

5-5 

8 

9-2 

58                     .  . 

115,160 

66000 

13-67 

A 

39-2 

54              .     

105.200 

65,000 

19-88 

a 

62  U 

55           

109,240 

66,000 

17-67 

3 

44-6 

56      .  .    

79,601) 

85.000 

24- 

8 

80-8 

57                

82,400 

41,000 

28- 

8 

42  0 

58         

79,120 

40,000 

26- 

8 

42  0 

59                 

79,880 

45000 

30-7 

8 

66  8 

60      

78,480 

40,000 

84- 

8 

56  8 

61  

105,000 

60,000 

19- 

2 

1  to  13,  Rept.  Chf.  Ordnance.  U.S.  A.,  1884,  p.  557.  14to21,Maj  F  II.  Parker,  U.  8.  A., 
Rept  Select  Committee  Ordnance  and  War  Ships,  p.  834,  1886  22  to  26,  Proc.  U.  S.  Naval 
Inst. 

28  i 

private  communication ;  also  American  Manufacturer,  March  4th.  1887.  38,  U n forged  casting, 
Chernoff,  Revue  Univorselle,  1877, 1.,  p  405.  39,  Metealf,  unhardened  crucible  steel.  Metallurg. 
Rev.,  I.,  p.  402.  40,  Pittsburgh  Ste.-l  Casting  Co.,  Rept.  Select.  Comm.  Ord.  and  War  Ships,  p. 
856  41,  Bethlehem  Bessemer  steel,  private  communication.  42,  Creusot,  Bessemer  steel, 
.lourn.  Iron  and  St.  lust.,  18S3,  It.,  p.  803.  43-4,  Turre  Noire,  nnforged  nnnealed  open-hearth 
caRtin"  Jc-ans,  Steel,  p  507.  45-6,  two  bars  prepared  by  Oruncr.  Journ.  Iron  and  Steel 
Inst  .  1SS3,  II.,  p.  811,  from  Ann.  MinrS,  1S83,  I.  47  to  50,  Midvale,  Rept.  Select  Comm.  Ord. 
and  War  Ships,  p.  334.  5  1-2,  Cambria,  Idem,  p.  309.  53  to  6O,  Midvale,  Idem,  p.  885  :  uli- 
tempcrcd.  61,  Midvale.  Proc.  U.  B.  Naval  lust.,  XIII.,  p.  25. 


during  plasticity  and  cause  blowholes  :  but  of  course  the 
exhaustion  must  cease  before  solidification  sets  in  even  in 
the  exterior  of  the  ingot,  or  the  cure  will  but  aggravate 
the  malady.  Except  in  the  very  largest  castings  this  con- 
dition might  be  hard  to  comply  with. 

§  232.  SLOW  COOLING.  We  have  already  seen  that  slow 
cooling  should  diminish  the  volume  of  the  pipe,"  and  it 
appears  that  it  tends  to  prevent  blowholes  as  well.  Thus 
ChernofF  finds  that  if  moderately  hot  steel  be  cast  in  a 
mould  one  side  of  which  is  of  sand  and  the  other  of  iron, 
blowholes  form  next  the  iron  side  of  the  mould  but  none 
along  the  sand  side.  (Fig.  51.)  In  two  sets  of  experi- 
ments I  thought  there  were  more  tubules  in  rapidly  frozen 
than  in  slowly  frozen  ice  from  the  same  water :  but  the 
indications  were  not  conclusive. 

e  §  225. 

t  Revue  UuiverseUe,  3d  Ser.,  VII.,  p.  135,  1880. 


162 


THE    METALLURGY    OF    STEEL. 


I  am  not  sure  that  I  understand  Chernoff'  s  explanation 
of  the  greater  solidity  of  the  slowly  cooled  steel.  It  seems 
to  be  as  follows.  The  steel  is  less  prone  to  wet  the  sand 
than  the  iron  side  of  the  mould,  because  at  the  sand  side 
both  steel  and  mould  are  hotter  than  at  the  other :  as  the 
steel  wets  the  mould  less,  so  bubbles  are  less  likely  to  be 


v\  ' '      ^ 

Fig.  51 
Influence  of  rate  or  cooling  on  subcutaneous  blow-holes.    (Chernofl.) 

detained.  Now  this  may  be  true  before  solidification  sets 
in :  but  I  see  no  reason  to  expect  that,  after  the  outer 
shell  has  frozen,  the  fact  that  before  freezing  it  had  not 
wet  the  mould  should  now  prevent  it  from  retaining  gas 
bubbles. 

Wetting  the  mould  can  have  nothing  to  do  with  the 
greater  abundance  of  blowholes  in  rapidly  than  in  slowly 
frozen  ice,  for  here  the  initial  conditions  are  the  same  in 
both  cases,  and  the  mould  as  wet  as  possible  in  each.  I 
offer  the  following  as  a  simpler  explanation,  but  not  as  the 
sole  nor  indeed  as  necessarily  the  chief  one. 

When  the  first  layers  solidify,  their  falling  solvent 
power  expels  a  portion  of  their  gas,  which  however  may 
not  be  evolved  as  gas,  but  remaining  dissolved  may  pass 
by  diffusion  into  the  adjoining  still  molten  layers,  much 
as  the  alcohol  of  freezing  cider  is  forced  towards  the 
centre.  If,  however,  the  layers  adjoining  that  which  is 
freezing  are  saturated  and  hence  unable  to  receive  more 
gas,  that  expelled  from  the  outer  freezing  layer  will  be  gasi- 
fied and  may  form  blowholes.  Now  diffusion  is  a  slow  pro- 
cess, and,  if  the  metal  solidifies  rapidly,  the  previously  dis- 
solved gas  will  be  driven  inwards  from  the  freezing  layers 


into  the  adjoining  ones  faster  than  it  can  pass  by  diffu- 
sion through  these  intermediate  layers  into  the  central 
region  :  the  intermediate  layers  soon  become  supersatu- 
rated, gasification  and  the  formation  of  blowholes  set  in. 

Again,  if  it  be  true  that  during  solidification  the  tops  of 
pine-tree  crystals  project  beyond  the  compactly  frozen 
mass  into  the  molten  interior,  they  would  appear  more 
likely  to  entrap  and  mechanically  arrest  rising  gas  bubbles, 
and  to  prevent  growing  bubbles  from  detaching  themselves 
and  rising,  if  their  growth  and  the  shooting  out  of  their 
branches  were  rapid  than  if  these  processes  were  slow. 

Indeed,  whatever  be  the  manner  in  which  the  solid 
portion  of  the  metal  grows,  rapid  growth  would  seem  to 
offer  less  opportunity  for  evolved  gas  to  free  itself  and 
swim  to  the  surface  than  slow  growth. 

It  is  much  harder  to  prevent  blowholes  in  small  than  in 
large  castings,  and  probably  because  the  former,  the  ratio 
of  their  mass  to  that  of  their  moulds  and  to  the  cooling 
surface  being  relatively  small,  cool  and  solidify  faster. 

While  slow  cooling  tends  to  prevent  piping  and  blow- 
holes, it  may  lead  to  segregation,  the  concentration  of  the 
foreign  elements  in  certain  portions  of  the  casting.  A 
double  injury  results  :  the  metal  is  heterogeneous,  and  it 
has  not  the  composition  aimed  at. 

Wellman  would  cool  slowly  by  lining  common  prismat- 
ic cast-iron  ingot-moulds  with  refractory  matter.* 

§  233.  CHEMICAL  ADDITIONS,  silicon, "manganese,  carbon 
aluminium.0  The  action  of  the  latter  is  obscure :  as  that 
of  the  former  three  is  probably  due  to  their  increasing  the 
solubility  of  the  gases  in  the  metal,  they  should  be  and  are 
added  immediately  before  casting.  Needless  to  say  that, 
by  checking  the  escape  of  gas  during  solidification  and  so 
preventing  the  formation  of  blowholes,  they  favor  the 
formation  of  pipes. 

The  proportion  of  silicon  and  manganese  which  are 


a  U.S.  Patent,  a98,643,  May  13th,  1884,  S.  T.  Wellman.  The  immediate 
object  of  the  invention  is  to  cool  the  ingot  so  slowly  and  hence  uniformily  that  it 
may  be  forged  immediately  on  removal  from  the  mould,  without  furnacing. 

b  Cf.  S  215. 

c  Cf.  §  149,  B,  p.  87. 


TABLE  80.— COMPOSITION  AND  PROPERTIES  or  UKFOEGED  STEEL  CASTINGS  (Cr.  TABLE  9,  PAGE  19). 


Number. 

Authority. 

Description. 

Composition. 

Physical  properties. 

C. 

Si. 

M. 

P. 

S. 

Tensile  str<>ngth, 
Ibs.  per  sq.  in. 

Elastic  limit, 
Ibs.  per  sq.  in. 

Elong 
%• 

ation. 
In. 

Contraction 
of  area. 

1  
2  

A. 
P.  N. 

H 
P. 

B. 

it 

ii 

Terro  Noire  projectiles  

•45®  -60 

•2oa-flo 

•SB®  '50 
•60 
•65 
•11 
•23 
•88 
•27 
•28 
•4  ©-5 
•25 
•4 
•18± 
•7  ©1-2 
•18@'SO 
89 
•95 
•42 
1-15 
•45 
•57 
•685 
•425 
•260 

•25©  -80 
•10©  '15 
•2  @-20± 
•20± 
•25@-80 

•19 
•89 
•88 
•26 

Is®'* 
•20 
•263 
5  ©'6 

•io@-25 

•299 
•498 
•42 
•77 
•11 
•29 
•55 
•275 
•26 

•50@'60 
'5  @1'0 
1'0± 
l'± 
1-     @l-2 

•43 
25 
•89 
•88 
•45®-60 
•8  @'4 
•4  ©6 
•66 
•7  @t"6 
•40@1-20 
1-01 
•74 
•96 
1-30 
•65 
•42 
•95 
•76 
•41 

8  

"     0  

4  

Rolls:  Works  C  

6       

Cylinders  about  6'  X  6'  and  2"  thick  

70,0004- 
63,000 
68,000 
55,000 
70,000 
64,000 

84- 

6 

ti 
12 
9 

8 
7'5 

2" 
2" 
2" 
2" 
2" 

7    

8      
9..  .. 

ii                 11 

ii                 ii 

10 

ii                 » 

H 

12  

J.  H. 

H 

A.(H. 

W.  H. 
W.  H. 
B. 
B. 
B. 
B. 
E. 
E. 
E. 

Large  sound  castings  

18 

Small      '•            "       

14        

72,576 

88,080 

25-6 

4" 

43-5 

15... 

*'         "    very  hard       "      

16  
21 

"         "       "    soft        "      

92,700 
132,700 

51,960 
84,803 

12-6 
16 

2"  ' 

22  

20  foot  steel  cast  cylinder,  FOKGED  

31-07 

28  

Rolling  mill  roll,  open-hearth  steel;  broke  in  use  

£4 

26  

•'        "     "           **              "       remarkably  tough  

26  
27  

Hard  steel  for  projectiles  Terre  Noire 

1- 

8-93" 

28  .     .  .. 

12- 

22-8 

8-93" 
8-93" 

29... 

Soft  metal  **       " 

I.  Akerman,  Journ.  Iron  and  Bt.  Inst,  1879,  II.,  p.  530. 
2  to  4.  Private  notes. 

5.  Pourcel,  Journ.  Iron  and  St.  Inst.,  1882,  II.,  p.  509. 

6  to  10.  Salom,  Trans.  Am.  Inst.  Mining  Engrs.,  XIV.,  p.  128,  1886. 

II.  Graz,  Steel  Castings,  Engineering,  1882,  II.,  p.  352. 

12,  13.  Hardisty,  Journ.  Iron  and  St.  Inst.,  1886,  I.,  p.  128. 

14    Hollcy.  Priv.  Kept,  on  Terre  Noire  process,  2d  Scr.,  VII.,  p.  47. 

15,  16.  Holley,  Priv.  Kept.,  2d  Ser..  IX.,  p.  24. 

21.  6  in.  cast-steel  gun,  cast  by  the  Pittsburg  Steel  Casting  Co.    Private  communication,  Wm.  Hainsworth.    Eight  tests  made  at  Washington  on  pieces  from  this  gun  are  reported  to  have  given 

the  following  average  results :  Tensile  strength,  80,198;  elastic  limit,  49,395;  elongation,  9  5;  reduction  of  area,  11 '79. 

22.  Cylinders  20  feet  by  20  feet,  bv  the  Pittsburg  Steel  Casting  Co.,  for  a  hydraulic  forging  press.    The  tests  were  made  by  Carnegie,  Phipps  &  Co.  on  a  piece  forged  from  the  casting.    Prlr»t« 

communication  March  25,  1887. 

23  to  26.  O    H.  Killings,  Norway  Iron  Works.     Private  communication,  Feb.  10,  1883. 
87  to  28.  Euverte,  Mem.  HociOti  des  Ingenjeurs  Cjvjls,  1877,  p,  138,    Bag.  »na  Mining  Jl.,  1877,  p.  869, 


THE     STRUCTURE    OF     IRON     IN     GENERAL.       §  237. 


163 


needed  to  prevent  blowholes  may  be  inferred  from  the 
examples  in  Table  80,  while  the  proportion  of  these  ele- 
ments that  should  be  added  in  order  to  produce  given 
composition  will  be  considered  in  treating  of  the  open- 
hearth  process.  Suffice  it  here  to  say  that,  in  general,  the 
more  carbon  is  present  the  less  silicon  and  manganese  are 
required. 

Of  especial  present  interest  is  No.  21  of  Table  80,  the 
six-inch  steel  cast  gun  lately  made  by  the  Pittsburgh 
Steel  Casting  Company.  The  composition  and  physical 
properties  of  many  other  unforged  steel  castings  are  given 
in  Table  9,  p.  19. 

It  is  in  large  part  owing  to  the  great  advances  in  pre- 
venting blowholes  by  the  use  of  silicon  and  manganese 
that  methods  of  liquid  compression  have  received  so  little 
attention  of  late. 

§234.  DESCENDING  MOULD-BOTTOM. — In  order  to  shorten 
the  fall  of  the  metal  diiring  teeming,  and  thus  to  diminish 
the  quantity  of  air  drawn  down  by  the  friction  of  the  fall- 
ing stream,  G.  W.  Billings  places  within  his  vertical  pris- 


matic mould  a  piston  moved  by  a  cylinder  standing 
beneath.  When  teeming  begins  this  piston  is  raised  to 
near  the  top  of  the  mould,  and  is  gradually  lowered  as 
teeming  proceeds,  so  as  to  keep  the  upper  surface  of  the 
molten  metal  always  near  the  mould  top."  As  the  mould 
can  have  little  or  no  taper  and  as  there  must  therefore 
be  considerable  play,  one  fears  that  the  molten  metal 
may  run  down  past  the  piston,  jam  it,  and  perhaps  freeze 
upon  the  mechanism  beneath  ;  and  that  the  ingot  may 
stick  to  the  mould  and  refuse  to  descend  with  the  piston. 

§  235.  DEAD-MKLIING  OB  KILLING,  i.  e.  holding  steel  in  a 
molten  state  before  casting,  greatly  lessens  the  formation 
of  blowholes.  Thus  crucible  steel  which  would  yield  honey- 
combed ingots  if  poured  as  soon  as  melted,  yields  solid 
ones  if  "killed,"  /.  e.  simply  held  molten  for  say  an  hour. 

As  shown  in  §  361,  killing  in  the  crucible  process  pro- 
bably acts  chiefly  through  enabling  the  molten  metal  to 
absorb  silicon  from  the  walls  of  the  crucible,  thus  increas- 
ing its  solvent  power  for  gas,  so  that  it  is  able  to  retain 
during  solidification  the  gas  which  it  contains  while  molten. 


CHAPTER     XIII. 

STRUCTURE  AND  RELATED  SUBJECTS. 


§  236.  IN  GENERAL. — The  structure  of  iron  may  be 
studied  by  microscopic  examination  of  polished  and  of 
etched  surfaces,  and  through  its  fracture.  The  former 
tells  us  the  true  condition  of  the  metal  before  it  is  subjected 
to  the  strains  which  cause  rupture :  while  the  fracture 
rather  tells  us  of  the  planes  of  weakness  in  the  metal, 
functions  of  the  structure  and  of  the  method  of  rupture 
jointly.  Each  method  throws  valuable  light  on  the  struc- 
ture. 

Passing  ever  from  the  simpler  to  the  complex,  let  us  first 
consider  the  former.  But  let  it  not  be  thought  that  be- 
cause the  simpler  it  is  the  easier.  The  difficulties  attend- 
ing the  microscopic  study  of  the  ultimate  structure  as 
revealed  by  polished  sections,  due  in  part  to  the  consider- 
able length  of  the  waves  of  light  when  compared  with  the 
size  of  the  ultimate  crystals  of  the  metal,  are  so  great 
that  the  results  obtained  by  one  observer  only,  Sorby, 
have  given  us  any  important  insight  into  the  question. 

Pushing  the  etching  of  polished  surfaces  a  degree  fur- 
ther leads  to  a  third  method  of  study,  differential  solution, 
or  dissolving  certain  of  the  components  of  the  metal  by 
appropriate  solvents,  as  in  WeyFs  method,  obtaining  the 
other  components  as  a  skeleton  which  preserves  the  original 
structure.  By  this  plan,  which  promises  a  rich  harvest, 
Osmond  and  Werth  have  already  reached  valuable  results. 

After  considering  the  facts  reached  by  these  methods, 
we  may  in  this  connection  conveniently  study  segregation 
(a  cause  of  local  variation  of  structure),  as  well  as  the 
effects  of  heat  treatment,  forging,  cold-rolling,  wire-draw- 
ing and  punching  on  the  physical  properties  of  the  metal 
as  taught  by  the  testing  machine. 

PART    1ST,    MICROSCOPIC    STUDY    OF    POLISHED    8KCTIONS. 

§  237.  GENERAL  PHENOMENA. — Prom  the  microscopic 


study  of  polished  sections  iron  appears  to  be  constituted, 
like  granite  and  similar  compound  crystalline  rocks,  of 
grains  of  several  distinct  crystalline  minerals,  of  which 
seven  common  ones  have  already  been  recognized,  through 
peculiarities  of  crystalline  form  and  habit,  color,  lustre, 
hardness  and  behavior  towards  solvents.  Their  nature, 
size,  shape  and  orientation,  and  through  these  the  struc- 
ture and  physical  properties  of  the  metal  as  a  whole,  seem 
to  depend  chiefly : 
1  On  the  ultimate  chemical  composition  of  the  mass  ; 

2.  On  the  mechanical  treatment  which  it  has  under- 
gone; 

3.  On  the  conditions  under  which  it  has  been  heated  and 
cooled,  i  e.,  its  "heat-treatment,"  which  may  induce  the 
ultimate  components  of  the  mass  to  regroup  themselves  in 
new  combinations,  thus  causing  one  set  of  minerals  to  give 
place  to  another. 

It  is  too  early  to  insist  that  these  apparently  distinct 
substances  are  true  minerals,  that  the  general  features  of 
their  life-history, — e.  g.  the  constancy  of  their  composi- 
tion, crystalline  form,  hardness,  density,  color,  etc., — are 
so  far  like  those  of  the  minerals  of  nature  as  to  make  it 
expedient  to  class  them  permanently  in  the  same  division 
of  nature's  objects.  Some  distinct  class-name  suggesting 
their  resemblance  to  minerals,  such  as  "metarals,"  may 
be  found  desirable.  Meanwhile,  the  known  phenomena 
can  be  conveniently  presented  by  classing  these  substances 
provisionally  as  minerals,  and  by  provisionally  assigning 
them  mineralogical  names. 

During  the  initial  crystallization  of  the  mass  from  a 
molten  or  semi-molten  state  some  one  dominant  mineral, 


a  U.  S.  Patent,  298,661-S,  May  13,  1884.     Cf.  U.  8.  Patent,  319,779-SO,  June 
9,  1885,  F.  Billings  and  W.  R  Hmwlale. 


164 


THE    METALLURGY    OF     STEEL. 


dominant  through  its  abundance,  though  its  higher  freez- 
ing point,  through  strong  crystallizing  tendency  or  what 
not,  seems  to  determine  the  form,  size  and  orientation  of 
its  own  crystallization  :  it  displaces  the  other  components 
to  a  certain  extent.  A  second  component  mineral  crystal- 
lizes next,  and  has  the  second  place  in  determining  the 
structure.  As  the  dominant  mineral  has  already  deter- 
mined the  position  of  the  components  of  this  secondary 
mineral,  the  crystallization  of  the  latter  can  do  little  more 
than  to  determine  the  size,  shape  and  orientation  of  its 
own  crystals,  and  even  these  may  have  been  already  deter- 
mined to  a  great  extent  by  the  space  which  the  dominant 
mineral  has  left  the  second  one  to  form  in.  And  so  on 
with  a  third  and  fourth. 

To  illustrate.  Certain  meteoric  irons  consist  chiefly  of 
three  minerals,  a  dominant  metallic  one,  a  second 
metallic  one,  and  a  phosphide  ot  iron  and  nickel,  schrei- 
bersite.  The  dominant  metallic  one  appears  to  crystallize 
first  in  strongly  marked,  regular,  thin  meshes  of  the 
Widmanstatten  figuring  (figure  52).  Between  these 
meshes  the  second  mineral  crystallizes,  while  the  schrei- 
bersite  lies  between  these  two  sets  of  crystals,  dislodged, 
residual  from  the  solidification  of  its  more  powerful  elder 
brothers. 

Now     after     this     original     crystallization     has     oc- 


curred, with  change  of  temperature,  affinities  changing, 
the  elements  present  may  re-group  themselves  forming 
new  minerals,  or  the  old  minerals  may  assume  new  crys- 
talline shapes.  But  the  position  and  the  general  outline 


Fig.  52. 

Tazewell  meteoric  iron,  Sorby,  showing  Widmanstatten  figuring. 

of  the  crystals  of  the  new  species  may  still  be  determined 
by  the  original  crystallization,  for  this  has  distributed  the 
elements  in  certain  proportions,  and,  in  recrystallizing 


TABLE  81.— MINERALS  WHICH  COMPOSE  IEON. 


Number.  h 

II 

Name. 

Probable  com- 
position. 

Occurrence. 

Color  by 

Lustre. 

Behavior  on 
heating. 

Form,  habit,  etc. 

Hardness. 

Relative 
solubility 

Sorby's. 

Suggested 
here. 

An  important  con- 
stituent of 

Little  or 
none  pres- 
ent in. 

Occurs 

chiefly 
in. 

Direct 

illumin- 
ation. 

Oblique 
Illumin- 
ation. 

1. 

2. 
8. 
4. 

6. 
6. 

T. 

8. 

g. 

10. 

11. 

Free  Iron. 

Iron    c  o  m- 
bincd  with 
carbon= 
the      in- 
tensely 
hard  com- 
pound. 
"The  pearly 
constituent 
or     com- 
pound" re- 
crystallized 

"The  pearly 
constituent 
or     com- 
pound" un- 
recry  s  tal- 
ked. 

Ruby    and 
dark  crys- 
tals. 

Graphite. 

Slag. 

Un  determine 

More    solubl 
substance. 

I>83      BOlllbU 

substance. 
Schreibersite 

Ferrite. 

Cementite 
Pearlyto. 
Ilardcnite 

Sorbitc. 

(1  residue. 

e    metallic 
metallic 

Nearly  pure 
iron. 

Iron  with  ce- 
ment carbon. 

A  mixture  ol 
about  i  fer- 
rite  and  i 

cement!  te. 

Iron  and  hard- 
ening carbon 
probably  in 
all  propor- 
tions up  to  2 
or  possibly 
3#. 

Perhaps  silicon 
or  nitride  ol 
titanium. 

Carbon. 

Malleable      Iron, 
chiet  component. 
Open  grey  cast- 
iron,     especially 
when    annealed. 
Forms    about  1 
of  pearly  te. 

About  £  of  refined 
white    cast-iron, 
and  \  of  speigel- 
eisen. 
About  i  of  pearly  te 

Ingot-    and    weld- 
steel  of  all  kinds 
unless  hardened. 
Almost  sole  com- 
ponent of  mod- 
erately hard  steel 
(-70  %  carbon  ?). 
In    Bessemer   and 
probably  all  other 
classes    of  steel 
when  quenched. 
Arises   from 
union  of  all  min- 
erals present. 

Mallea- 
ble iron. 

Crystal  I  i  z  e  s, 
s  e  g  r  e  g  at«s 
from   thin 
platen    to 
grains. 

Changes  little, 
segrating 
somew  hat. 
Changes    to 
ferrite       on 
losing     its 
carbon. 
Compo  n  e  n  t  s 
combine  at  a 
high  temper- 
ature      to 
form  harden- 
ite. 

S  e  p  a  r  a  tes 

(probably  be- 
low W)  into 
pearlyte  and 
free  ferrite  or 
cemontlte. 

Crystals,    probably    interfering    cubes   or 
octahedra,       homogeneous,      malleable 
Nearly  or  quite  equiaxed  after  hot  forg- 
ing:    elongated    by    cold-work  :      made 
equiaxed  by  reheating.      Sometimes   as 
sheila    surrounding    and    shooting    into 
crystals  of  pearlyte  :  also  as  parallel  plates 
within  and  dowelling  the  crystals  together. 
In    grey   pig    probably   as    stout    layer 
against  graphite 
Usually  structure-less,  occasionally  in  flat 
plates,  say,  '00,001@-02   in.    thick.      In 
blister-steel  as  net-work  surrounding  and 
occasionally    shooting   into     crystals    of 
pearlyte. 

Pearly,    fine    parallel   plates,    curved    and 
straight,  of  ferrite,  1-40,000  in.   alternated 
with  cementite    1-80,000'  in.   thick.      In 
soft    ingots  in   irregular    groups,   often 
1-30    in.    diam.,     independent  of  ingot- 
structure.     Also  in  ostrich  -feather  crys- 
tals in  white  pig  iron. 
Very  minute  grains,  about  1-20,000  in.  diam. 

Triangles,    rhombs,     hexagons,      complex 
crosses,  less    than    1-1000  in.   in    diam- 
eter. 

Comparatively    large,  somewhat  irregular 
plates,  often  bent,   tapering  edges,  lam- 
inar.    In  grey  Scotch  pig1,  uniformly  dis- 
tributed, '03@  05  in.  broad,  -0005®,  '0010 
in.  thick.     In  No.  3  pig  partly  in  irregular 
radiating  groups, 
[n  hammered  blooms  is  in  irregular  patches; 
in  bar,   plate,  etc.,   iron  in  fine  threads. 
Very  irregularly  distributed. 

A  rhombic  lattice-  or  net-work,  orientation 
often  uniform  over  a  considerable  area. 

)ften  crystallized  in  relation  to  the  orient- 
ation of  the  inclosing  net-work  of  No.  10, 
)ften  a  thin  skin  covering  the  net  -work  of 
No.  10. 

Compara- 
tively soft. 

Intensely 
hard. 

6(?Muller) 

Intensely 
hard. 

Ito2. 

More    sol- 
uble than 
cementite 

Less     sol- 
uble than 
i'trrite. 

More    sol* 
uble  than 
cementite 

Insoluble. 

VI  ore   sol- 
uble than 
10. 
^ess     sol- 
uble than 
9. 

Open     grey 
cast  -iron, 
soft  steels, 
weld-  and 
ingot-iron. 

Very   s  o  f  1 
iron. 

Annealed  or 
slowly 
cooled 

steel    and 
cast  -  iron 
and  in  very 
soft     iron 
under    al 
conditions 
Weld      Iron 
and    good 
cast-  steel. 

Steel,    ingol 
and    weld 
iron. 

Ingot     iron 
and   ingot 
steel. 

Intensely 
brilliant. 

Dark     on 
brilliant 
metallic 
ground 
in  refined 
white 
pig- 

Perfectly 
black. 

Bright  ant 
pearly  on 
blac  k 
grounc 
in  refinec 
white 
Pig- 

Cast- 
iron. 

Cast- 
iron. 

Ruby  and  deep  blue. 
Iron  black. 

Black. 

Cast-iron. 

Weld     iron     and 

steel. 

Cast-iron. 

Componen  t;  I 
of    meteoric  | 
iron. 

Metallic 

Changes  bul 
little  and 
slowly. 

Probably  ma- 
trix or  resi- 
due from  for- 
mation of 
substances  1 
to  6,  and 
hen  ce  ol 
widely  vary- 
ing compo- 
sition. 

Metallic 

Iron,    55-4© 

87  '2  56.  Nick. 
el,  4-2@28-l 
%.  P  h  o  s- 
phsrus,  7*3 
©14-9  %. 

4 

STRUCTURE.      THE    COMPONENT    MINERALS    DESCRIBED.      §  238. 


165 


the  crystallizing  force  can  move  each  molecule  but  a  short 
distance.  Thus  in  certain  meteoric  irons,  while  the 
original  Widmanstatten  figuring  is  readily  traced  by  the 
layer  of  schreibersite  which  still  exists,  the  ultimate 
structure  of  the  material  composing  the  net-work  is  in  no 
way  related  to  the  shape  of  the  net-work  itself,  but  con- 
sists "of  a  mass  of  interfering  granular  crystals,""  appar- 
•Mitly  <lue  to  recrystallization.  Under  other  conditions 
the  recrystallizing  force  may  be  so  great  as  to  efface  all 


Fi-g.  53. 

Hammered  wrought-iron  bloom,  Sorby,  showing  largo  black  patches  of  slag. 

pre-existing  crystallization.  Bxamples  will  follow  :  suf- 
fice it  here  to  say  that  in  commercial  iron  we  now  find  the 
effects  of  but  a  single  crystallization,  now  the  superim- 
posed effects  of  two  if  not  three  successive  ones.  As  a 
mineral  is  more  likely  to  be  the  dominant  one  when 
abundantly  present,  so  we  find  that  a  given  mineral, — here 
forming  the  bulk,  there  but  a  small  fraction  of  the  whole,— 
may  here  form  the  nucleus  around  which  the  others  crys- 


Fig.  54. 


fig.    O-i. 

Longitudinal  section  of  wrought-iron  armor-plate,  Sorby,  showing  welds  and  crystals  (of  f.-rrite  *) 

tallize,  may  there  lie  as  a  residual  layer  between  the  crys- 
tals of  the  other  minerals. 

§  238.  TIIE  COMPONENTS  OF  IRON  DESCRIBED. — Both 
for  brevity  and  clearness  in  describing  the  chief  minerals 
which  have  been  recognized  in  iron,  I  venture  to  substitute 
mineralogical  names  for  Sorby' s  cumbrous  ones. 

It  is  not  improbable  that  some  of  our  present  species 
may  hereafter  be  subdivided.  Their  form,  composition 
and  other  characteristics,  like  those  of  many  natural 
minerals,  probably  vary  within  rather  wide  limits.  As 


agorby,  Journ.  Iron  and  Steel  Inst.,  1887,  I.,  p.  285. 


most  of  them  occur  in  minute  if  not  microscopic  crystals 
which  have  not  been  separated  for  analysis,  we  can  only 
arrive  at  their  composition  indirectly. 

Table  81  describes  the  properties  of  these  minerals. 

A.  Ferrite  is  probably  nearly  pure  iron.  It  occurs  in 
two  distinct  conditions,  I  ,  as  a  separate  constituent,  II., 
as  a  component  of  pearlyte. 

I.  Asa  separate  mineral,  ferrite  is  the  chief  component  of 
all  irons  nearly  free  from  combined  carbon,  to  wit  soft  weld- 


Fig.  55. 

Longitudinal  section  of  wrought-iron  bar,  Sorby,  showing  rods  of  slag,  and  crystals  of  ferrite. 

and  ingot-iron  and  certain  very  open  gray  cast-irons,  which 
consist  chiefly  of  iron  and  graphite,  the  iron  here  usually 
containing  considerable  silicon.  In  general  the  propor- 
tion of  ferrite  decreases  as  that  of  combined  carbon 
increases,  so  that  it  is  nearly  or  quite  absent  from  hard 
steels  and  from  all  cast-iron  except  the  very  gray. 
When,  as  in  soft  ingot-  and  weld-iron,  it  is  almost  the 


27 

1 


L.  I  V  •  ••>' 


Fig.  56. 

Transverse  section  of  Bessemer  ingot  (0-49£  C),  Sorby.  Polygons  are  pearlyte,  net-work  is  ferrito. 

sole  constituent,  it  occurs  in  grains  which  are  almost  cer- 
tainly more  or  less  imperfect  interfering  crystals,  cubes, 
octahedra,  pentagonal  dodecahedra,  and  perhaps  other 
forms  of  the  monometoic  or  regular  system.  (Figures  53, 
54  and  55.)  Individually  malleable  grains  0'25  inch  in 
diameter,  probably  of  ferrite,  are  mentioned  in  §  k<i46,  B. 
When  much  slag  is  present,  as  in  weld-iron,  it  is  drawn 
out  by  rolling  into  fibres  :  the  mass  as  a  whole  is  fibrous  : 
but  even  here  the  metallic  or  ferrite  quasi-fibres  usually 
consist  of  separate  equiaxed  grains. 


166 


THE    METALLURGY    OF    STEEL. 


When,  as  in  rather  soft  steels  and  in  gray  cast-iron, 
ferrite  as  a  separate  mineral  is  present  in  but  small  quan- 
tity, it  is  distributed  as  a  net-work  or  as  a  series  of  shell 
surrounding  crystals  of  the  other  components.     Thus,  in 


Fig.  67. 

Grey  cast-iron,  Sorby.    Prominent  plates  are  graphite:  matrix  probably  ferrite  and  pearlyte. 

an  ingot  of  rather  soft  steel  (figure  56),  what  appears  to  be 
ferrite  is  indicated  by  the  dark  parallel  plates  and  the  net- 
work enclosing  irregular  grains  which  consist  of  pearlyte. 
The  spines  which  run  from  the  net-work  of  ferrite  appear 
to  dowel  the  crystals  of  pearlyte  together.  Here,  too,  the 
ferrite  in  the  thicker  strings  may  be  seen  to  consist  of 
small  grains  like  those  in  weld-iron. 

In  some  gray  cast-iron,  on  the  other  hand,  what  appears 
to  be  ferrite  exists  as  stout  layers  in  contact  with  the 
crystals  of  graphite.  (Figure  67.) 

II.  Ferrite  as  a  constituent  of  pearlyte  is  described  below. 

B.  Cementite  (Sorby's  "intensely  hard  compound") 
occurs  I.  as  a  separate  mineral,  II.  as  a  component  of 
pearlyte.  From  Sorby's  researches  it  appears  to  be  an 
intensely  hard,  brilliant,  homogeneous,  structureless  car- 
bide of  iron,  containing  the  whole  of  the  cement  carbon. 
It  has  not  been  recognized  in  and  is  probably  absent  from 
hardened  steel,  but  is  abundantly  present  in  that  which 
is-unhardened. 


Fig.    58. 

Longitudinal  section  of  blister  steel,  Sorby.      Lipht  polygons  ore  pearlyte,  black  net-work  is 

cementite. 

Osmond  and  Werth  thought  their  cell-shells  (§  239), 
which  were  probably  cementite  enclosing  kernels  of 
pearlyte.  more  hard  and  rigid  than  the  kernels:  and,  on 
etching  polished  sections  of  cold-hammered  steel,  they 
found  that  while  the  kernels  (pearlyte  ?)  were  elongated, 


the  shells  (cementite  ?)  were  shattered  so  as  to  suggest  the 
schistosity  of  rocks." 

The  relation  between  the  proportion  of  cementite  pres- 
ent as  a  separate  mineral  and  that  of  combined  carbon  will 
be  considered  in  C.  In  blister  steel  Sorby  found  the  cemen- 
tite as  a  net-work  surrounding  irregular  grains  of  pearlyte 
(figure  58),  and  occasionally  shooting  into  them  so  as  to 
dowel  them  together,  like  but  less  than  the  ferrite  of  soft 
steel  (figure  56).  In  bar  iron  which  had  been  partly  con- 
verted into  blister  steel  by  cementation,  he  found  plates  of 
cementite  towards  the  outside,  which  were  visible  to  the 
naked  eye  on  etching.  In  spiegeleisen  cementite  appears 
to  form  the  large  plates  "  so  conspicuous  in  fractures," 
here  perhaps  containing  much  manganese. 

The  carbide-residue  b  obtained  by  Miiller  on  dissolving 
unhardened  steel  in  dilute  sulphuric  acid,  probably  repre- 
senting cementite  perhaps  more  or  less  altered  by  the 
solvent,  consists  of  rough-surfaced,  silver-lustred,  gray, 
irregular,  generally  roundish  grains,  seldom  over  0-0004 
inch  (O'Ol  mm.)  in  diameter,  apparently  of  a  single  sub- 
stance. They  scratch  glass  and  felspar,  but  not  quartz 
(H  =  6),  are  exceedingly  brittle,  pyropaoric,  attracted 


Fig.  59. 

TranaTerse  section  of  wbite  refined  cast-iron,  Sorby.    Feather  crystals  are  pearlyte;  the  black 
matrix  is  cementite. 

and  permanently  magnetized  by  the  magnet,  unmelted  at 
redness,  insoluble  in  cold  dilute  acids,  attacked  with  ex- 
treme difficulty  by  copper-salt  solution,  but  soluble  in 
boiling  moderately  concentrated  hydrochloric  and  sul- 
phuric acid,  leaving  a  slight  residue.0 

Cementite  as  a  component  of  pearlyte  is  described  in  the 
next  paragraph. 

C.  Pearlyte  (Sorby's  pearly  constituent)  is  composed  of 
very  minute  parallel  curved  or  straight  plates,  often  show- 
ing very  brilliant  interference  colors,  and  composed  alter- 
nately of  cementite  and  ferrite,  which  form  about  one- 
third  and  two-thirds  of  the  whole  respectively.  It  is, 
therefore,  as  its  spelling  implies,  a  lithological  rather  than 
a  mineralogical  unit.  It  is  clearly  not  a  mere  accidental 
mixture,  nor  are  its  plates  due  to  cleavage,  but  they  are 
apparently  joint  paramorphs  after  a  single  pre-existing 
mineral,  probably  hardenite. 

Our  present  data  give  no  certain  information  about  the 
composition  of  pearlyte :  but  they  tend  to  show  that  it 
varies  within  rather  wide  limits,  some  facts  suggesting 
that  it  contains  not  over  Q'67%  of  carbon,  others  that  it 


a  Ann.  Mines,  8th  ser.,  VIII.,  pp.  15,  79,  1885. 

b  Cf.     §  9.  p.  6. 

c  Stahl  und  Eisen,  VIII.,  p.  291,  1888. 


STRUCTURE.      THE    COMPONENT    MINERALS    DESCRIBED.      §  238. 


167 


contains  not  less  than  1'5%."  Whether  the  discrepancy  is 
due  to  variations  in  the  composition  or  in  the  relative  pro- 
portions of  its  two  components,  or  to  errors  of  observation, 
is  uncertain. 

It  appears  that  cementite  and  ferrite  usually  unite  as  far 
as  possible  to  form  pearlyte,  so  that  any  free  cementite  is 
simply  an  excess  over  that  which  is  needed  to  form  pearlyte 
with  the  whole  of  the-ferrite,  present :  so  with  the  ferrite, 
mutatis  mutandis.  Thus  pearlyte  may  be  accompanied  by 
either  ferrite  or  cementite,  but  not  usually  by  both  together 
in  the  same  the  region.  Hence,  as  the  proportion  of  com- 
bined carbon  increases  in  unhardened  metal  from  nil,  we 
have  first  pure  ferrite,  then  ferrite  with  a  proportion  of 
pearlyte  which  increases  up  to  100$,  and  in  turn  diminishes 
as  the  proportion  of  combined  carbon  increases  further, 
being  replaced  more  and  more  by  free  cementite. 

For  example,  Sorby  finds  that  the  least  carburetted  iron 
consists  of  free  ferrite  with  only  a  little  pearlyte,  and  appar- 
ently no  free  cementite:  that  moderately  hard  steel  (with 
say  '67$  of  carbon)  consits  almost  solely  of  pearlyte,  with 
very  little  of  either  free  cementite  or  free  ferrite:  that  hard 
steel  (with  say  1  •()&%  of  carbon)  contains  pearlyte  together 
with  some  free  cementite :  that  still  harder  steel  (with 
perhaps  2%  of  carbon)  contains  pearlyte  with  much  cemen- 
tite :  that  white  cast-iron  is  composed  of  about  two-thirds 
pearlyte  and  one-third  cementite :  while  spiegeleisen, 
finally,  contains  about  5Q%  of  each. 

So,  too,  lie  finds  that  the  centre  of  a  bar  of  soft  iron, 
partly  converted  into  steel  by  cementation,  consists  chiefly 
of  grains  of  ferrite:  around  this  is  a  ring  of  almost  pure 
pearlyte:  while  the  outside,  the  most  carburetted  part,  con- 
sists of  pearlyte  with  scattered  plates  of  cementite.  After 
further  cementation  he  found  that  the  cementite  now 
penetrated  to  the  centre  of  the  bar,  replacing  the  ferrite  : 
but  the  outer  part  of  the  bar  now  contained  little  or  no 
more  cementite  than  before. 

Pearlyte  crystallizes  most  characteristically  in  ingots  of 
moderately  hard  steel,  of  which  it  is  almost  the  sole  com- 
ponent, occurring  chiefly  in  irregular  groups  of  plates 


,  a  These  numbers,  arrived  at  somewhat  as  in  the  reconstruction  of  fossils,  must 
be  taken  as  very  rough  approximations.  In  Bessemer  steel,  apparently  of  0449$ 
of  carbon,  Sorby  finds  pearlyte  and  ferrite,  apparently  about  10%  the  latter, 
which  would  imply  that  pearlyte  here  contains  about  0'54$  of  carbon.  A  soft  steel 
ingot  which  was  composed  almost  solely  of  pearlyte,  and  whose  composition  may 
therefore  be  taken  as  approximately  that  of  this  mineral,  was  the  softest  of  three 
whose  average  carbon  was  about  1  "25$:  the  carbon  of  the  ingot  of  intermediate 
hardness  was  1  '08$.  This  ingot  consisted  of  pearlyte  with  cementite,  and  was  there- 
fore clearly  more  highly  carburetted  than  cementite.  Hence  cementite  contains 
somewhere  between  0'49  and  1-08$  of  carbon.  Now  the  hard  ingot  of  the  three, 
described  as  "  very  hard  steel"  made  from  Swedish  iron  by  cementation  and 
crucible  melting,  would  not  be  likely  to  contain  more  than  2%  of  carbon.  If  it 
had  S$,  then  our  data  imply  that  the  softest  of  the  three  had  0'67$  of  carbon.  If 
the  hard  ingot  held  less  than  2%  of  carbon,  the  soft  one  must  hold  more  than  0'  67$. 
But  the  soft  ingot  is  described  as  of  "  soft"  (crucible)  "  steel,"  a  term  which  would 
hardly  bo  used  if  more  than  0-67$  of  carbon  were  present. 

If,  as  Sorby  estimates  by  the  eye,  pearlyte  consists  of  two  parts  by  volume  of 
ferrite  and  one  of  cementite,  and  if  these  two  minerals  have  nearly  the  same 
density,  theu  the  conclusion  that  pearlyte  has  about  0'67$  of  carbon  implies  that 
cementite  has  about  Z%. 

-On  the  other  hand,  Sorby  finds  that  spiegeleisen  of  the  kind  made  twenty  years 
ago  consists  of  about  equal  parts  of  cementite  and  pearlyte.  This  implies  that  the 
free  cementite  together  with  that  in  the  pearlyte  constitute  about  67$  of  the  whole 
mass.  It  is  not  likely  that  the  spiegeleisen  contained  less  than  3$  of  carbon:  hence 
the  cementite  should  contain  not  less  than  4  "5$  of  carbon,  or  the  pearlyte  not 
less  than  l'5jg. 

If,  as  is  more  likely,  the  spiegeleisen  contained  5$  of  carbon,  its  cementite 
should  contain  7 '5  of  carbon.  This  is  almost  exactly  the  composition  of  the  car- 
bide which  Abel  and  Miiller  isolate  on  dissolving  steel  in  mild  solvents.  (Cf. 
Miiller,  Stahl  und  Eisen,  VIII.,  p.  293,  1888.) 

Were  the  spiegeleisen  to  contain,  in  addition  to  pearlyte  and  cementite,  a 
mineral  exceedingly  rich  in  carbon,  the  discrepancy  would  disappear. 


radiating  at  all  azimuths  from  central  points  distributed 
with  little  or  no  relation  to  the  primary  crystals  (the  con 
spicuous  prismatic  or  columnar  ones,  normal  to  the  cooi 
ing  surface,  and  seen  on  fracture,  figures   04,  65,  68),  and 
indeed  often  branching  from  one  into   another,  dovetail- 
ing them  together. 

In  softer  and  harder  steel  ingots  and  in  gray  cast-iron 
the  radiate  grouping  of  the  pearlyte  is  interfered  with  by 
the  presence  of  ferrite,  cementite,  and  graphite  respective- 
ly, while  in  forgings  less  time  is  usually  available  for 
recrystallization  than  in  ingots  :  small  bars  indeed  do  not 
show  the  characteristic  "  structure,  but  look  as  if  the  con- 
stituents had  been  broken  up,  irregularly  mixed,  and 
cooled  so  rapidly  as  to  prevent  the  development  of  definite 
crystals."" 

In  Sorby' s  "forge"  and  "white  refined"  cast-iron 
pearlyte  forms  ostrich-feather  crystals,  figure  59,  in  the 
latter  metal  within  a  matrix  of  cementite. 

The  crystalline  form  of  the  minerals  which  compose  the 
crystalline  rocks  varies  in  a  similar  way.  Thus,  among  the 
varieties  of  a  single  mineral,  amphibole,  we  have  the 
granular  pargasite,  the  needle-like  actinolite,  and  the  fine 
thread-like  asbestus. 

Long  exposed  to  a  high  temperature,  as  in  annealing, 
pearlyte  draws  together  and  separates  itself -in  more  per- 
fect crystals  from  the  ferrite  or  cementite  which  accom- 
panies it;  and,  in  some  cases,  part  of  it  is  resolved  into  thicker 
laminae  or  even  more  solid  masses  of  free  cementite  and 
ferrite.  If,  however,  the  pearlyte  be  initially  accompanied 
by  graphite,  its  cementite  apparently  tends  to  split  up 
into  graphite  and  ferrite  at  a  moderately  high  temper- 
ature, which  suggests  that  the  graphite-forming  tendency 
initially  unsatisfied,  with  favoring  temperature,  now  reas- 
serts itself. 

D.  Hnrdenite  is  the  characteristic  -component  of  hard- 
ened steel,  a  compound  of  iron  and  hardening  carbon.  On 
quenching  a  steel,  which  had  consisted  of  a  net-work  of 
ferrite  enclosing  kernels  of  pearlyte  (figure  56),  Sorby 
could  still  detect  traces  of  the  the  original  net-work:  but 
the  ultimate  structure  was  now  so  fine  that  even  a  power 
of  400  linear  showed  little  more  than  that  the  grains  were 
now  about  1-20, 000th  inch  in  diameter,  and  no  longer  re- 
vealed the  fine  laminations  of  pearlyte.  The  abrupt 
changes  in  the  chemical  behavior,  hardness,  fracture  and 
microscopic  structure  effected  by  quenching  leave  little 
doubt  that  the  ferrite  and  cementite  of  pearlyte  unite  at 
a  high  temperature  to  form  a  new  compound,  which  we 
may  term  hardenite,  in  which  the  carbon  exists  in  the 
hardening  state.  All  the  evidence,  from  whatever  source, 
indicates  that  this  hardenite  is  preserved  by  quenching, 
but  gradually  splits  up  during  slow  cooling,  ultimately 
yielding  ferrite  and  cementite,  and  thus  forming  pearlyte. 

The  micro-structural  changes  induced  by  quenching  are 
not  fully  understood:  the  comparative  coarseness  of  the 
waves  of  light  makes  their  study  very  difficult.  It  is 
probable  that  the  change  from  pearlyte  to  hardenite  coin- 
cides with  the  change  from  cement  to  hardening  carbon, 
and  hence  that  it  occurs  at  or  about  a  low  yellow  heat 
(Brinnell' s  W) :  but  direct  evidence  is  lacking. 

Now  the  composition  of  hardenite  may  be  approximate- 
ly constant,  or,  like  that  of  obsidian,  it  may  be  altogether 
indefinite.  If  constant,  we  may  suppose  that,  when  steel 


b  Sorby,  Op.  Cit.,  p.  376, 


168 


THE    METALLURGY    OF     STEEL. 


TABLE  82.  —  COMPOSITION  OF  SLAG  IN  WELD  IUON. 


No. 

1 

2 

8 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

18 

Silica  

12-86 

1'55 

2-01 

3  87 

0 

4-63 

6  49 

3-62 

9-21 

5-44 

10  84 

2  87 

T39 

7"65 

9-4 

2  'SO 

0 

Phosphoric  acid  

8-28 

•52 

Ferrous  oxide     

55  71 

85  87 

Ferric  oxide  

26  64 

11  •.-><> 

89  42 

69  24 

94-20 

82-09 

81-68 

88  71 

63  20 

87  'is 

76  21 

96  28 

94-16 

90-74 

'.'in  114 

96  19 

93  23 

Oxide  of  Manganese  

•51 

•82 

0-48 

7-07 

1  01 

0  40 

0  S7 

Alumina  ,  

1-84 

Sulphur  

•124 

•028 

Chromic  oxide  

14-60 

80  -56 

3-62 

16-70 

15-77 

i2-88 

12'08 

8'04 

5'52 

roi 

6-94 

2-62 

5'21 

Cuprous  oxide     

0 

0 

(I 

d 

0 

0 

0 

0 

tr. 

0 

0  14 

tr. 

0 

tr. 

0 

1.  Sl.iff  from  puddled  ball,  Bell,  Manufacture  of  Iron  and  Steel,  { 

2*  Slas  from  West  Yorkshire  boiler-plate,  idem. 

3  to  17.  Calculated  from  data  in  Kept,  of  IT.  8.  Bd.  on  Testing  Iron,  Steel,  etc.,  1881,  I.,  p.  228. 


is  strongly  heated,  the  components  of  pearlyte  alone  unite 
to  form  hardenite,  the  initially  separate  ferrite  or  cemen- 
tite  remaining  separate.  If  indefinite,  and  this  seems  to 
me  far  the  more  probable  view,  we  may  suppose  that  it  is 
formed  by  the  union  of  the  initially  separate  cementite  or 
ferrite  jointly  with  the  two  components  of  pearlyte,  yield- 
ing a  single  substance,  which  is  preserved  during  sudden 
cooling  simply  because,  like  obsidian,  it  has  not  time  to 
separate  into  definite  compounds.  That  such  an  indis- 
criminate union  occurs  when  steel  melts  is  altogether 
probable :  but  whether  it  occurs  at  lower  temper- 
atures, say  between  a  dull  yellow  and  whiteness,  is  un- 
certain. 

The  fact  that  hardened  steel  usually  contains  some 
cement  carbon,  indicating  the  presence  of  cementite, 
might  suggest  that  hardenite  tends  toward  certain  definite 
compositions,  and  that,  when  some  one  of  these  is  reached 
(which  one  would  depend  on  the  special  conditions  of  the 
case),  it  declines  to  assimilate  the  rest  of  the  carbon, 
which  remains  as  cementite.  Thus  in  hardened  steel 
Abel"  found  some  4-7$  of  the  total  carbon  insoluble  in  his 
solvent,  i.  e.  as  cement  carbon:  by  Weyl's  method 
Osmond  and  Werthb  found  in  hardened  steel  a  delicate 
net-work  holding  by  indirect  calculation  about  Q2%  of  the 
total  carbon.  But  a  far  more  probable  explanation  is 
that,  even  in  their  rapid  coolings,  the  interior  of  the 
metal  passed  slowly  enough  through  the  range  of  tem- 
perature in  which  hardenite  changes  to  cementite  and 
ferrite,  to  permit  a  considerable  formation  of  these  latter 
minerals.  In  harmony  with  this  is  Miiller's  finding  abso 
lutely  no  cement  carbon  in  fine  shavii  gs  of  tool  steel 
quenched  extremely  rapidly.  In  white  cast-iron,  how- 
ever, he  found  a  certain  quantity  of  cement  carbon,  evA 
after  extremely  rapid  quenching."  Further  observations 
are  needed. 

Again,  the  apparently  constant  proportions  of  cemenlite 
and  ferrite  of  which  pearlyte  consists  strongly  indicate 
that  it  springs  from  the  decomposition  of  some  mineral  of 
tolerably  constant  composition  :  this  in  turn  suggests  that 
hardenite  has  the  definite  ultimate  composition  of  pearlyte, 
and  that,  just  as  annealed  steel  consists  of  pearlyte  with 
either  ferrite  or  cementite,  so  hardened  steel  consists  of  a 
mixture  of  one  of  these  two  minerals  with  hardenite. 
This  view  is  opposed  (1)  by  the  homogeneous  appear- 
ance of  hardened  steel,  in  which  the  highest  powers 
fail  to  discover  a  trace  of  either  ferrite  or  cemenlite, 
and  (it,)  by  the  fact  that  hardened  steel  of  2%  of  carbon  is 
harder  than  that  of  say  0-67$,  though  the  latter  should  be 
nearly  pure  hardenite  (if,  as  this  view  assumes,  hardenite 
has  the  same  ultimate  composition  as  pearlyte),  and  the 
former  hardenite  mixed  with  much  cementite,  while  the 


«Cf.  p.  6. 

b  Ann.  Mines,  8th  ser..  VIII. ,  p.  20,  1885. 

c  Stahl  uiid  Eisen,  VIII.,  p.  294,  1888,  May. 


softness  of  annealed  steel  indicates  that  cementite  is  softer 
than  hardenite. d 

Yet,  by  a  possible  if  unwelcomely  complex  supposition, 
we  may  hold  that  hardenite,  obsidian-like,  is  of  indefinite 
composition — the  sole  constituent  of  hardened  steel — and 
yet  that  pearlyte  springs  from  the  decomposition  of  a 
mineral  of  definite  composition.  For  during  slow 
cooling  our  indefinite  hardenite  may  first  split  up  in- 
to (1)  a  suppositions  mineral  of  definite  composition — call 
it  "  mother-of -pearlyte  " — and  (2)  separate  cementite  or 
ferrite  as  the  case  may  be.  Later  the  mother-of-pearlyte 
splits  up  into  the  well-known  parallel  layers  of  ferrite  and 
cementite,  which  constitute  pearlyte.  But  without  more 
facts  we  can  hold  no  theory  confidently." 

E.  Sorbite  (sorby's  ruby  and  deep  blue  crystals)  has 
been  detected  by  Sorby  in  many  cast-irons,  but  in  no  other 
class  of  iron,  as  beautiful  triangles,  rhombs,  hexagons  and 
complex  crosses,  sometimes  imbedded  in  graphite,  usually 
less  than  l-1000th  inch  in  diameter,  in  his  opinion  modifi- 
cations of  one  substance,   possibly  silicon  or  nitride  of 
titanium.' 

F.  Slaff,  occurring  chiefly  in  weld  metal,  initially  in  ir- 
regular patches  (figure  53),  is  drawn  out  into  threads  by 
forging  (figure  54),  and  probably  contributes  to  the  fibrous- 
ness  of  the  enclosing  metal. g    At  a  high  temperature  it 
probably  tends  to  draw  together,  for  it  has  been  found  in 
almost  perfect  spheres  within  half-inch  crystals  of  iron, 
probably  of  ferrite,  in  iron  long  held  in  the  puddling  fur- 
nace.11 

Goedicke  reports  about  \%  of  slag  in  once  re-rolled  fine- 
grained puddled  iron,  and  1  '5  to  2%  in  fibrous  puddled 
iron.1  43  specimens  of  chain-cable  weld-iron  examined 
by  the  United  States  Board  on  Testing  Iron,  etc.,  contained 
from  -192  to  2  262  of  slag,  or  0'904$  on  an  average.1  The 
composition  of  these  and  other  slags  from  weld  iron  is  given 
in  Table  82,  while  Table  26,  p.  58,  gives  the  composition 
of  slag  from  the  puddling  furnace,  which  is  here  invari- 
ably much  richer  in  silica  than  that  from  weld-iron  itself. 
This  suggests  that  during  heating  and  forging  the  propor- 
tion of  iron  oxide  in  the  slag  of  weld  iron  increases,  by 
the  oxidation  of  neighboring  metal.  As  no  such  oxida- 
tion has  been  observed  within  ingot  iron,  which  is  usually 
nearly  or  quite  free  from  slag,  this  in  turn  suggests  that 
the  presence  of  slag  induces  the  oxidation  of  the  iron 


d  It  will  be  remembered  that  cementite  is  much  richer  in  carbon  than  pearlyte, 
(which  is  a  mixture  of  cementite  with  the  carbonless  ferrite)  and  hence  than 
hardeuite  in  this  view:  Sorby  found  that  unhardened  soft  steel  ingots  consisted  of 
nearly  pure  pearlyte,  more  highly  carburetted  ones  of  pearlyte  with  much 
cementite. 

e  I  believe  that  this  idea  is  here  suggested  for  the  first  time. 

'  Cf.  §  63,  p.  37.  Journ.  Iron  and  Steel  Inst,  1886,  I.,  p.  144;  1887,  I.,  p. 
278,  261. 

g  The  fibrousuess  of  weld  iron  is  discussed  in  §  359. 

h  Sorby,  Journ.  Iron  and  Steel  Inst.,  1877,  I.,  p.  262. 

l  Oest.  Zeitschift,  XXXIV.,  p.  536,  1886. 

i  Kept.  Bd.  on  Testing  Iron,  Steel  aud  other  metals,  I.,  p.  223,  1881:  Trans, 
Am.  Inst.  Mining  Engrs.,  VI.,  p.  102. 


THE    STRUCTUKE    OF    IRON    IS    COMPOSITE 


239. 


169 


itself.  It  is  indeed  conceivable  that  the  silica  of  the  slag 
is  reduced  by  the  excess  of  metallic  iron  surrounding  it. 

Table  83,  calculated  from  the  data  of  this  board' s  report, 
shows  how  little  connection  can  be  traced  between  the  pro- 
portion of  slag  and  the  physical  properties  of  these  irons. 

Ingot-metal  also,  especially  if  poor  in  manganese,  un- 


TABLK 


3. — ANALYSIS  or  THE  INFLUENCE  OP  SLAG  ON    THE  PROPERTIES  OF  WELD  IHON,  AND 
ON  ITS  PEKCENTAGE  OF  CARBON. 


Twelve  weld  irons  numbered  according  to  their  tensile  strength,  etc.,  (1  highest)  and  placed  in  the 
order  of  the  percentage  of  slag  (highest  first). 

Number  for 

1 
14 
10 
9 
13 
4 
1 

9 
8 
1 
4 

I 

13 
2 
4 
2 
1 
11 
3 

14 
16 

15 

ii 

T 
4 

16 
1 
8 
8 
4 
6 
5 

5 
10 
8 
12 
11 
5 
fi 

G 
6 

2 
10 
9 
8 
7 

8 
9 
9 
6 
6 
9 
8 

15 
4 
6 
5 
4 
10 
9 

10 

5 
11 

"6 
8 
10 

2 

9 
13 
13 
12 
2 
11 

1 
11 
16 

ii' 
i 

12 

This  table  is  derived  from  data  in  tho  Report  of  the  U.  S.  Board  to  Test  Iron.  Steel,  etc., 
1881,  I.,  p.  224,  Table  III. 

doubtedly  sometimes  contains  slag,  probably  springing 
chiefly  from  the  formation  of  silica  by  reactions  within  the 
metal.a  But  we  have  little  information  concerning  this 
slag.  It  has  been  thought  to  weaken  the  metal,  and  even 
to  render  it  hot-short. 

At  Avesta  slag  was  at  one  time  mixed  with  the  Besse- 
mer ingot  iron  when  this  was  poured  into  the  moulds. 
(Cf .  §  259). 

Wedding  finds  the  slag  in  fibrous  iron  in  the  form  of  thin 
pods,  which  completely  envelope  every  fibre  of  iron. b  But 
Sorby,  whose  authority  is  of  the  very  highest,  and  who 
questions  the  trustworthiness  of  Wedding' s  method  of  ex- 
amination," finds  the  slag  in  lumps  in  iron  blooms,  which, 
by  forging,  are  drawn  out  into  long  thin  rods,  not  pods, 
(figures  53  and  55). d  But,  even  if  uncontradicted,  we 
could  hardly  accept  Wedding's  statement. 

If  such  continuous  surfaces  of  slag  stretch  across  an  iron 
bar,  no  matter  how  zigzag,  involved  and  complex  those  sur- 
faces may  be,  so  long  as  they  are  continuous  they  must  re- 
ceive and  transmit  the  entire  tensile  stress  to  which  the 
bar  is  subjected :  and,  as  the  strength  of  a  chain  is  that  of 
its  weakest  link,  so  the  strength  of  such  a  bar  would  be  the 
strength  of  slag,  not  iron  :  of  slag  protected  if  you  will 
from  transverse  stress  by  iron :  of  slag  so  hooked  into 
fibres  of  iron  that  the  stress  is  evenly  distributed,  but  still 
of  slag.  And,  moreover,  these  involved  surfaces  of  slag 
which  have  to  finally  support  the  total  stress  are  so  at- 
tenuated that  they  often  represent  only  some  1  •&%  of  the 
weight  of  the  bar.  This  seems  so  preposterous  that  I  be- 
lieve that  Dr.  Wedding  must  mean  something  very  differ- 
ent from  what  he  seems  to :  and  certain  phrases  of  his 
support  this  belief. 

G.  Other  substances.  Carbide  of  titanium,  found  in 
cast-iron,  has  already  been  described.6 

H.  The  Residual  Compound1  which  occurs  in  cast-iron 
is  probably  of  wholly  indefinite  composition,  being  the 
residue  left  from  the  crystallization  of  definite  minerals. 
Thus  in  a  gray  cast-iron  it  appeared  to  be  cementite  modi- 
fied by  impurities:  in  an  annealed  number  3  cast-iron  it 
appeared  to  be  a  mixture  of  metallic  iron  with  some  other 
metallic  substance,  and  resembled  complex  ripples. 


a  Cf.  81,  p.  43.     Journ.  Iron  and  Steel  Inst.,  1877, 1.,  p.  44. 

b  Jeuru.  Iron  and  Steel  Inst. ,  1885,  I. ,  p.  193.  "  None  of  these  wires  or  fibres 
is  directly  connected  with  its  neighbors,  either  in  a  lateral  or  longitudinal 
direction." 

c  Idem,  203. 

dldem,  1887,  I.,  p.  363. 

e  §  13,  p.  7. 

t  Sorby,  op.  cit.,  pp.  361,  377,  380, 


§  239.  OTHEK  EVIDENCE  OF  THE  COMPOSITE  STRUCTURE 
OF  IRON. — Osmond  and  Werth,  on  attacking  with  cold 
dilute  nitric  acid  plates  of  annealed  cast-steel,  — ?_  to  — 

'    lo.uuo  10,000 

of  an  inch  thick,  fastened  to  glass  with  Canada  balsam, 
obtained  a  residual  net-work  of  iron-carbide  (cementite?), 
what  they  took  for  iron  but  what  was  probably  pearlyte 
having  existed  as  kernels  within  the  meshes  of  the  net- 
work and  having  dissolved. g 

They  find  the  minute  cells  of  this  net-work  grouped  in 
composite  cells  of  a  larger  net-work,  whose  meshes  are  of 
a  comparatively  soluble  substance  which  is  free  from  car- 
bide, but  whose  composition  seems  most  uncertain.  Their 
description  suggests  that  these  two  sets  of  meshes  are  the 
fruit  of  a  primary  and  a  secondary  crystallization  respec- 
tively. Indeed  the  composite  cells  appear  to  them  to  re- 
sult from  dendritic  growths,  which,  developing  independ- 
ently, have  limited  each  other.  As  the  residual  net-work 
of  iron-carbide  obtained  on  dissolving  steel  by  Weyl's 
method,  I.  e.  on  immersing  it  as  the  positive  pole  in  a 
Bunsen  cell,  in  dilute  hydrochloric  acid,  retains  the  form 
and  dimensions  of  the  steel,  they  infer  that  this  net- work 
is  continuous  within  the  metal. 

Hardened  steel,  in  which  as  we  have  seen  Sorby  could 
detect  little  evidence  of  structure,  they  too  find  much  less 
complex,  the  rapid  cooling  having  apparently  opposed 
the  formation  and  segregation  of  definite  minerals,  as  it 
does  in  case  of  obsidian,  and  as  it  opposes  the  devitrifica- 
tion of  glass.  The  simple  cells  alone  are  found,  and  the 
carbide  which  surrounds  them  is  now  in  much  smaller 
proportion  than  in  annealed  steel,  so  that  most  of  the  car- 
bon present  seems  to  be  uniformly  dissolved  within  the 
metallic  kernels. 

On  these  and  other  important  observations  they  base 
their  "  cellular  theory  of  steel, '"'which,  based  on  certain 
known  and  supposed  properties  of  the  metal's  constitu- 
ents, may  be  regarded  as  a  special  case  of  the  more  general 
proposition  that  the  properties  of  the  composite  mass 
depend  on  those  of  its  components  and  on  their  mutual 
adhesion,  a  proposition  which  is  self-evident  if  the  com- 
posite nature  of  steel,  earlier  pointed  out  by  Sorby,  be 
admitted. 

Treating  copper  and  zinc  ingots  separately  by  Weyl' s 
method  with  a  Bunsen  cell  (zinc  in  5  of  concentrated  hy- 
drochloric acid  to  95  of  water,  copper  in  5  of  sulphuric 
acid  to  95$  water),  they  found  the  same  general  organi- 
zation as  in  steel  ingots, — metallic  kernels  dendritically 
arranged,  their  mutually  limiting  surfaces  grouping  them 
in  composite  cells.  The  residue  from  zinc  consisted  of 
spangles  of  an  alloy  containing  about  30$  of  tin,  56%  of 
lead  and  15%  of  zinc,  though  the  ingot  as  a  whole  con- 
tained only  0-28$  of  tin  and  1-05$  of  lead.  They  justly 
ay  that  this  concentration  of  the  impurities  as  a  skeleton 
of  very  thin  leaves  throughout  the  mass,  goes  far  towards 
xplaining  the  wonderful  influence  of  minute  quantities 
of  impurities  on  the  properties  of  the  metals  in  general.1 
For  the  properties  of  these  leaves,  minute  as  they  are, 
may  affect  the  properties  of  the  whole  as  markedly  as  the 


g  Comptes  Rendus,  C.,  p.  450,  1885.  Ann.  Mines,  8th  Ser.,  VIII.,  p.  9.  Journ. 
Iron  and  Steel  Inst.,  1885,  1.,  p.  373. 

h  This,  together  with  its  supporting  evidence,  is  set  forth  at  great  length  in  the 
Annales  des  Mines,  loc.  cit.  Additional  discussion  and  facts  appear  in  Stahl  und 
Eisen,  VI.,  p.  539,  1886:  while  Ledebur  reviews  it  on  p.  374  of  the  same  volume. 
For  our  purposes  it  is  more  convenient  to  consider  certain  features  of  it  in  appro- 
priate places,  than  to  discuss  it  as  a  whole. 

l  Stahl  und  Eisen,  VI . ,  p.  541,  1§86 .    Cf .  pp.  3,  3,  4  of  the  present  worfc 


170 


THE    METALLURGY    OP    STEEL. 


minute  flakes  of  mica  in  gneiss,  or  as  certain  weak  links  i 
a  powerful  chain. 

Wedding  observed  that  ingot  metal,  unless  very  quicklj 
cooled,  consisted  of  kernels  enclosed  in  a  mesh-work 
which  he  names  "crystalline"  and  ''homogeneous''  iron 
respectively  :  and  he  further  noticed  that  the  mesh-work 
was  some  times  harder  and  sometimes  softer  than  the  kernels 
But  later  investigation  shows  that  these  provisional  names 
must  be  discarded,  because  with  changing  proportions  a 
given  mineral  now  forms  the  mesh-work,  now  the  kernels. 

Sorby,  Osmond  and  Werth,  and  Wedding  all  noticec 
that  the  composite  structure  was  most  strongly  marked  in 
unforged  castings,  and  became  less  and  less  pronouncec 
as  the  sectional  area  was  reduced  by  forging. 

PART   2D,    FKACTUKE. 

§  240.  IN  GENERAL. — If  iron  were  perfectly  homo- 
geneous and  without  cleavage  or  crystallization  of  any 
kind,  then  the  path  of  least  resistance  would  be  a  shorl 
one,  and  the  fracture  would  be  smooth  :  but  it  never  is. 
On  some  cases,  e.  g.  in  that  of  the  columnar  structure  at 
the  outside  of  steel  ingots,  the  fracture  follows  certain 
large  and  well  defined  planes  :  it  is  coarse-crystalline.  In 
others,  as  in  properly  hardened  tool-steel,  it  follows  very 
minute  or  even  microscopic  planes,  and  so  has  a  porcelanic 
look.  In  general  it  follows  planes,  be  they  large  or  small 
The  large  columnar  fracture-planes  at  the  outside  of 
ingots  pretty  clearly  bound  individual  crystals,  but  in 
many  cases  it  is  as  yet  uncertain  whether  the  planes 
shown  on  fracture  are  the  boundaries  of  true  crystals — 
distorted  and  imperfect,  but  crystals  still — or  merely 
cleavage  planes  within  those  crystals. 

Now  whether  we  admit  that  iron  is  composed  of  crystals 
of  dissimilar  minerals  or  hold  that  its  different  grains  are 
of  similar  nature,  it  is  clear  that  these  grains  may  be  so 
shaped  and  constituted  that  the  cohesion  between  the 
particles  of  the  individual  crystal  may  be  greater  or  may  be 
less  than  the  adhesion  between  adjoining  crystals.  In  the 
former  case  (1)  rupture  passes  between  the  faces  of  adjoin- 
ing crystals,  in  the  latter  (2),  it  strikes  across  their  bodies, 
or,  if  the  difference  is  slight,  follows  the  general  direction 
of  the  crystal  faces,  yet  deviating  slightly  to  the  right  and 
left,  so  that  some  particles  of  each  crystal  adhere  to  the 
face  of  its  neighbor.  Again,  large  strongly-adhering  crys- 
tals may  be  separated  by  a  thin  weak  mesh- work,  through 
which  rupture  passes.  Or  some  crystals  may  be  readily  de- 
tached from  their  neighbors  while  others  adhere  tenacious- 
ly, when  (3)  rupture  passes  in  part  between  the  crystals 
and  in  part  through  their  bodies.  Strong  adhesion  may  be 
in  large  part  due  to  dowelling  or  branching  spines  shoot- 
ing from  one  crystal  into  its  neighbor.  It  is  natural  to 
refer  fractures  whose  facets  are  smooth  and  bright  to  the 
first  of  these  cases,  those  whose  facets  are  dull-faced  to 
the  second,  and  those  in  part  bright  in  part  dull  to  the 
third.  But  till  the  relations  between  the  fracture  and  the 
ultimate  structure,  as  revealed  by  polished  sections,  is  far 
more  clearly  made  out,  these  references  must  be  provisional. 
It  is  not  to  be  expected  that,  in  our  present  ignorance 
of  these  relations  and  our  consequent  inability  to  fully 
interpret  the  phenomena  of  fracture,  these  phenomena 
can  be  reduced  to  simple  laws.  Indeed,  we  have  to  be 
thankful  that,  probably  owing  to  the  predominant  influ- 
ence of  three  of  .the  constituent  minerals,  Brinnell's  re 


searches  permit  us  to  reduce  an  important  part  of  them  to 
even  cumbrous  laws.  We  must  here  recaU  the  changes 
which  heat-trealment  induces  in  the  condition  of  carbon, 
sketched  in  Figure  60. b 


100 


CONJECTURED 


TENDENCY  TO  FORM  HARDENING  CARBON 


Fig.  60 


W 

LOW  YELLOW 


V 

LOW  RED 


Above  W  carbon  tends  to  become  wholly  hardening,  be- 
low V  to  become  wholly  cement,  between  W  and  V  to  dis- 
tribute itself  between  both  states  according  to  unknown 
laws.  The  change  from  hardening  to  cement,  always  slow, 
is  the  slower  and  the  more  incomplete  the  lower  the  tem- 
perature, and  cannot  occur  in  the  cold.  Hence  steels  (A) 
slowly  cooled  and  (B)  quenched  from  W  or  above  are  (A) 
TO  ft  and  (B)  hard  respectively,  because  the  former's  car- 
:>on  has  while  the  latter' s  has  not  had  time  to  change  from 
lardeningto  cement:  tempered  steel  has  intermediate  hard- 
ness because  gentle  reheating  has  peimitted  partial  change. 

These  views,  deduced  from  wholly  independent  data,  are 
supported  by  Brinnell's  very  important  experiments,  the 
•esults  of  which  are  graphically  represented  in  Figure  61 . 

He  finds0  that  when  hardened  steel  is  dipped  into  nitric 

acid  of  1-23  sp.  gr.  it  becomes  covered  with  a  black-brown, 

sooty,  amorphous  layer  of  carbon,  giving  a  brown  streak  on 

white  paper :  that  unhardened  steel  under  these  conditions 

acquires  a  coating  which  inclines  to  blue,  gives  a  black  gray 

treak,  and  appears  to  be  crystalline.     We  may  join  him 

n  provisionally  terming  these  hardening  and  cement  car- 

)on  respectively,  remembering  that  we  use  these  names 

omewhat  generically,  to  indicate  conditions  of  carbon 

each  of  which  may  be  shown  later  to  comprise  several  dis- 

inct  varieties.3    How  far  these  changes  of  carbon-condition 

igree  with  those  of  hardness  will  be  shown  in  §  257. 

The  following  paragraphs  detail  the  teaching  of  Brin- 
nell's experiments,  first  as  to  the  condition  of  carbon  as 
nferred  from  the  tests  just  described,  second  as  to  frac- 
ure.  Many  of  the  inferences  are  my  own  :  but  this  mat- 
ers little,  for  the  evidence  in  support  of  each  is  given,  and 
he  reader  can  satisfy  himself  as  to  its  validity. 

§  242.  BRINNELL'S  EXPERIMENTS  ON  THE  CONDITIONS 
>F  CARBON. — /.   That  the  change  from  cement  to  har- 
dening carbon  does  not  occur  below  W,  but  is  sudden  and 
omplete  at  W,  is  indicated  by  the  following  experiments, 
n  3,  4,  20  and  2lcthe  carbon  is  initially  cement.     On 


Juuru.  iron  and  Steel  lust.,  1885,  I.,  p.  194. 


b  Figure  2,  which  sketched  these  tendencies,  was  complicated  by  the  graphite- 
orming  tendency,  which  may  be  neglected  here.    Whether  the  curve  reaches  its 

maximum  at  W,  or  whether  it  continues  to  rise  from  W  to  the  melting  point,  is 
ncertain.  The  hardness  seems  to  increase  as  the  quench  ing-temperature  con- 
nues  to  rise  beyond  W,  but  this  may  be  because  the  higher  quenching-temper- 
;ui  e  leads  to  greater  stress  from  uneven  cooling,  or  to  changes  in  crystallization. 
c  J.  A.  Brinnell,  Stahl  und  Eisen,  V.,  p.  611,  1885  :  from  Jerukontoret's  An- 
aler,  1885.  Also  a  mu;-h  over-condensed  unintelligible  translation  in  "Notes  on 
onstruction  of  Ordinance,  No.  37,"  Ordnance  Dept.,  Washington,  June  22, 1886. 
f.  Coffin,  Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  p.  318.  This  paper  is  by  far  the 
iost  important  contribution  to  our  knowledge  of  the  fracture  of  steel  since  Cher- 
off's  classical  work. 

<l  It  has  been  proposed  to  abandon  the  name  "cement"  for  "non-hardening."  We 
an  adopt  Rinman's  name  "cement"  as  meaning  the  carbon  of  unhardened  steel, 
ithout  thereby  committing  ourselves  to  any  particular  theory  as  to  its  compo- 
fcion.  These  names  are  only  provisional.  As  "cement"  is  well  established,  and  as 
•ery  new  name  increases  confusion,  we  may  as  well  keep  the  old  till  we  know 

enough  to  frame  moderately  permanent  new  ones. 


BRINNELL'S    RESULTS    CONCERNING    CARBON.      §  242. 


171 


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HEATED  TO  STRONG  WHITENESS  AND  QUENCHED  IN  WATER. 


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HEATED  TO  A  GENTLE  YELLOW, 
AND  QUENCHED  IN  WATER. 

F 


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EXPERIMENT.        j  p 


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SAME  AS  GROUP  VI. 


Group  X. 

COMPLETELY  MOLTEN 
AND  FLUID. 


LEGEND. 


j  Beginning  of  .Experiment  o          End  of  Experiment  V         Gradual  Changes  of  Temperature 

( Condition  of  Carbon  alt  Cement  *  Partly  Cement  Partly  Hardening  *          Ml  Hardening^  blank 


Sudden  Changes  of  Temperature  - 


Fig.  61  —Effect  of  Heat-Treatment  on  Fracture.    Graphical  Representation  of  Brinnell's  Results.    Steel  of  0-52  of  Carbon. 

This  fisure  represents  the  conditions  and  results  of  82  experiments  on  steel,  all  (except  group  X  f)  from  one  and  the  same  ingot,  containing  carbon,  0  52;  silicon,  'IS;  manganese,  -48;  phos- 
phorus, '020;  sulphur,  tr.  Kach  line  brginiriBif  with  O  and  ending  with  V  represcntsone  experiment.  The  condition  of  the  metal  before  the  experiment  is  indicated  on  the  lowest  lines  below  the 
diagram.  In  each  cuse  except  the  last  six  ilie  metal  is  gradually  heated  to  a  certain  temperature,  indicated  by  the  point  at  which  the  line  doubles  and  begins  to  descend.  In  most  cases  the  tempera- 
ture now  descends  without  Interruption  :  but  in  many  cases,  befrinning  with  54,  the  cooling  is  interrupted,  as  indicated  by  a  second  doubling  and  the  re-ascent  of  the  line.  In  group  X  steel  was  re- 
moved from  the  very  liquid  bath  in  the  open-hearth  furnace  in  a  clay-washed  ladle.  In  most  cases  it  solidified  and  cooled  more  or  less  completely  in  this  ladle:  in  79  it  was  poured  in  a  very  thin 
stream  into  cold  water. 


heating  nearly  to  W  and  quenching  it  remains  wholly 
cement  (B  and  20)e  while,  if  we  heat  just  to  W  and  quench, 
we  find  it  wholly  hardening  (4  and  21).  Again,  in  36-7, 
43-4  and  67-8  the  carbon,  either  initially  hardening  or  (as 
in  67-8)  first  made  hardening  by  heating  above  W,  is  partly 
changed  to  cement  by  stay  in  the  region  blue-tint — W. 
(That  this  partial  change  occurs  will  be  shown. )  Now,  in 
36,  43  and  67  the  steel  is  quenched  after  heating  nearly 
but  not  quite  to  W,  while  in  37,  44  and  68  it  is  quenched 
after  heating  just  to  W.  In  the  former  three  the  carbon 
remains  partly  cement,  in  the  latter  it  is  found  to  be 
wholly  hardening. 

2.  That  carbon  remains  in  the  hardening  state  at  all 
temperatures  above  W  is  shown  by  the  fact  that,  when- 
ever steel  is  quenched  from  a  point  above  W,  and  so  hur- 
ried through  the  range  W  X  in  which  it  is  possible  for 
the  carbon  to  change  back  from  hardening  to  cement,  only 
hardening  carbon  is  found.  This  is  true  whether  the 
quenching  be  from  a  yellow  heat  (73),  a  bright  yellow  (5, 
7,  22,  38  45,  60,  66,  69),  a  bright  white  (6,  23,  39,  46,  61), 
or  from  a  temperature  above  the  melting  point  (79):  and 
whether  it  be  preceded  by  a  fall  (7,  8  78)  or  a  rise  of  tem- 
perature, and  whether  this  rise  be  direct  from  the  cold  (5 
6,  22-3,  38-9,  45-6),  or  be  preceded  by  oscillations  of  tem- 


o  I"  tMs  and  the  succeeding  section,  unless  otherwise  stated,  numerals  refer  to 
the  Biimbers  of  BrinnelTs  experiments,  Figure  61. 


perature  (60-1,  66,  69,  73)  and,  finally,  whether  the  car- 
bon be  cement  or  hardening  initially. 

3.  That  carbon  tends  to  become  wholly  cement  at  tem- 
peratures between  X  and    W  but  not  including  W  is 
shown  by  the  following  facts.   A,  if  steel  containing  har- 
dening carbon  be  long  exposed  to  this  range  of  temperature 
its  carbon  becomes  wholly  cement.     This  occurs  when  the 
steel  cools  slowly  from  W  to  X  (11,  15,  29,  30,  31,  51  to 
57,  63-4,  70-1,  74-5-6,  80-1) ;  when  it  is  cooled  from  W  to 
blue,  heated  to  V  and  quenched  (58) ;  and  in  two  out  of 
three  cases  in  which  it  is  slowly  heated  and  cooled  between 
X  and  V++  (27-8). 

B,  when  the  carbon  is  initially  all  cement  none  of  it 
changes  to  hardening  below  W,  even  at  temperatures 
barely  below  W  (3,  14,  20). 

C,  when  it  is  initially  all  hardening  or  is  made  harden- 
ing by  heating  to  W,  at  least  part  of  it  always  becomes 
cement  during  any  subsequent  appreciably  long  exposure 
to  temperatures  between  a  brown  tint  and  W. 

These  last  two  facts  are  true  whether  the  steel  be 
quenched  after  the  exposure  (B,  1,  2,  3,  18  to  20  ;  C,  9, 10, 
32  to  36,  40  to  43,  67,  77),  or  slowly  cooled  (B,  12  to  14 ; 
C,  24  to  26,  47  to  49). 

4.  That  the  change  from  hardening  to  cement  carbon 
is  always  slow  is  shown  by  the  fact  that  no  cement  car- 
bon is  formed  when  steel  passes  rapidly,  as  in  quenching. 


THE    METALLURY    OF     STEEL. 


through  the  range  W  X,  (6  to  8,  21  to  23,  37  to  39,  44  to 
46,  5;.)  to  61,  65-6,  68-9,  72-3,  78-9,  82),  and  that  if  the  car- 
bon be  hardening  it  does  not  change  completely  to  cement 
iinless  the  steel  be  long  exposed  to  temperatures  between 
a  blue  tint  and  W.  E.  g.  this  change  is  only  partial  if  the 
steel  be  heated  from  X  only  to  V  or  some  lower  point  and 
slowly  cooled  (24  to  26,  47  to  40),  or  from  X  only  to  some 
point  below  W  and  quenched,  (32  to  36,  40  to  43),  or  if 
it  be  cooled  slowly  from  above  W  only  as  far  as  V  and 
then  quenched  (9,  10,  77). 

5.  TJial  the  change  from  hardening  to  cement  carbon 
^s  most  rapid  at  Fis  probable,  though  not  readily  proved, 
•as  Brinnell's  test  for  these  two  forms  of  carbon  is  qualita- 
tive only. 

We  thus  have  two  critical  temperatures,  W  and  V.  At 
W  and  all  higher  points  the  carbon  becomes  hardening 
instantly  ;  at  all  points  below  W,  even  those  very  slightly 
below  it.  the  carbon  becomes  cement  slowly.  This  latter 
change  appears  to  occur  most  rapidly  at  V. 

§  243.  BRINNELL'S  RESULTS  CONCERNING  FRACTURE.— 
He  recognizes  nine  distinct  simple  types  of  fracture,  sup- 
posed to  result  from  nine  corresponding  types  of  structure, 
set  forth  at  length  in  Table  85,  and  more  briefly  here. 


Hardening  carbon. 

Cement  carbon. 

Transition  from  hardening  to  cement  carbon. 

Bright  porcelanlc,  a 
Bright  granular  (  Fine 
crystalline.  1  Coars 

F. 

K. 

3D. 

Bright          (  F*"6  c- 
hackly  b     1  Medium  B. 
crystalline.  |  Cokr8e  A. 

Dull  poreelanic  a  H. 
Leafy  crystalline  G. 
Dull  coarse  crystalline  I. 

As  Table  85  indicates,  there  is  reason  to  suspect  the  ex- 
istence of  four  more  types. 

Usually  the  whole  fracture  belongs  to  some  one  of  these 
types:  but  in  some  cases,  in  which  the  transition  from 
one  type  to  another  is  incomplete,  different  portions  of 
one  and  the  same  fracture  belong  to  two  quite  distinct 
types:  i.  e.  the  fracture  is  composite. 

The  chief  changes  of  fracture  as  inferred  from  our 
present  data  are  probably  as  follows. 

1 .  When  cold  steel  is  gradually  heated  the  fractures 
change  thus  :c 

TABLE  84  —  GESERAI.  SUMMABY  OF  FEACTURE  CHANGES. 


Fracture  of  cold  steel. 

Change  at  a  gentle 
glow  to 

• 
• 

be 

§ 
j 

*  o 

p 

fi 

Further  change  at 
V  +  to 

Further  change  at 
V  +  +  to 

Is 

o 

1 

|3 

I* 

to 

Further  change  at 
light  yellow  to 

Further  change  at 
bright  white  to 

p                

FH 

II 

C 

C(?) 

F 

E 

D 

E                  

E  II  (?) 

II(?) 

(?) 

(?) 

F<?) 

E(?) 

»m 

D                             

DH 

K 

G 

G  F 

F 

E 

D 

C 

C 

C 

C 

F 

E 

D 

B                   

B(?) 

B(?) 

B(?) 

B(?) 

F(?) 

E(?) 

Dm 

A  

A 

A 

A 

A 

F 

E 

D 

2.  The  fractures  thus  set  up  may  be  preserved  by  sud- 
den cooling:  but,  if  cooled  slowly  instead  of  suddenly  from 
the  temperatures  at  which  they  are  thus  formed,  they 
behave  as  follows  : 


E  I  Chan 
D) 


gu  between  W  and  X  to 


is! 


Coarse  follows  coarse,  fine 
yields  fine. 


CC?)) 

B  (?)  V  Remain  unaltered. 

A 


These  statements  will  be  verified  in  §  244. 


a  Brinnell  terms  these  fractures  "  amorphous:"  as  this  word  signifies  absolute 
freedom  from  crystalline  structure,  such  as  is  found  in  glass,  and  as  these  frac- 
tures are  probably  simply  extremely  fine-grained  yet  crystalline,  "  porcelanic'' 
seems  to  me  more  accurate. 

b  "  Zackig."  Others  translate  this  "  pointed  crystalline."  "  Hackly"  is  well-es- 
tablished, briefer,  and  I  think  more  expressive. 

c  Where  a  letter  is  followed  by  (?)  direct  evidence  is  lacking. 


Under  the  special  conditions  of  Brinnell's  experiments 
changes  of  temperature  appear  <o  affect  the  fracture  thus: 

1.  Those  either  rising  or  falling  which  change  the  con- 
dition of  the  carbon,  always  change  the  fracture  from  the 
hardening-carbon  (granular)  group  toward  the  cement- 
carbon  (hackly)  group,  or  back,  the  change  of  structure- 
group  being  simultaneous  with  and  like  in  direction  and 
rapidity  to  that  of  carbon,  sudden,  direct,  and  at  W  from 
cement  to  hardening;  slow,  through  intermediate  transition 
fractures,  and  between  W  and  X  from  hardening  to  cement. 

2.  Those  which  do  not  change  the  condition  of  carbon, 

A.  If  falling  do  not  change  the  type  of  fracture, 

B.  If  rising  do  not  change  the  existing  fracture  till  they 
pass  the  temperature  at  which  it  was  acquired  :    beyond 
this  they  coarsen  it. 

3.  Exposure  to  a  white  or  higher  heat  without  subse- 
quent forging  always  causes  coarse  crystallization  (the 
higher  the  coarser),  which  indeed  cannot  be  originated 
otherwise. 

4.  To  break  up  by  heat-treatment  coarse  crystalline  struc- 
ture once  acquired,  the  temperature  must  be  varied  so  as 
to  change  the  condition  of  carbon  :  heating  to  or  slightly 
above  TFis  probably  the  only  way  of  effacing  it  com- 
pletely. 

5.  Finer  structures  F  and  C  once  acquired  can  be  mate- 
rially coarsened  only  by  heating  above  W,  the  structure 
remaining  moderately  fine  up  to  a  bright  yellow. 

Brinnell  adopts  the  usual  assumption  that  sudden  cool- 
ing (e.  g.  by  quenching)  does  not  in  itself  alter  the  struc- 
ture of  the  metal,  but  merely  preserves  that  which  existed 
at  the  instant  preceding  the  quenching.  This  is  neither 
self-evident  nor  experimentally  proved.  It  is  certainly 
improbable  that  quenching  should  originate,  but  not  that 
it  should  modify  crystalline  structure.  Indeed,  in  the 
case  of  pieces  of  large  cross-section,  the  different  layers 
must  cool  and  contract  during  quenching  at  such  different 
rates  that  interstratal  movements  must  arise  which  might 
well  alter  or  destroy  pre-existing  crystallization.  In  small 
bars,  however,  this  motion  is  probably  slight,  and  here  the 
assumption  that  quenching  fixes  the  existing  structure  is 
hardly  improbable:  as  it  greatly  facilitates  discussion, 
we  may  adopt  it  provisionally. 

As  it  appears  to  be  a  general  rule  that  the  finer  the  frac- 
ture, other  things  being  equal,  the  better  the  condition  of 
the  steel,  so  the  means  of  acquiring  and  preserving  the 
fine  fractures,  F  of  properly  hardened  steel  and  C  of  un- 
hardened  steel,  are  of  great  importance:  not  less  impor- 
tant are  those  of  avoiding  the  coarse  fractures  D  and  A. 

§  244.  DETAILS  OF  FRACTURES. — We  will  now  consider 
in  more  detail  the  nine  fractures  and  the  conditions  under 
which  they  are  acquired  and  lost.  But  the  true  way  to 
obtain  a,  clear  notion  of  them  and  of  their  changes  is  to 
study  them  at  the  forge,  a  task  which  I  heartily  commend 
to  my  readers. 

The  general  scheme  of  the  subject,  as  far  as  I  under- 
stand it,  is  set  forth  in  Table  85. 

a.  Group  1.  The  lower  member,  F,  bright  poreelanic, 
the  characteristic  fracture  of  properly  hardened  steel,  is 
acquired  under  two  sets  of  conditions, 

1,  When  molten  steel  is  suddenly  solidified  and  im- 
mediately completely  cooled  (79).  In  the  brief  instant  af- 
forded, the  crystalline  force  can  only  assert  itself  far 
enough  to  produce  a  poreelanic  structure. 


BRINNELL'S    RESULTS    CONCERNING    FRACTURR       §  243. 


173 


TABLK  85.— GBNERAL  S<  HKMK  OF  BRINNELL'S  FRACTURES.    Condition  of  Carbon  :  tt  all  hardening  ;  t*  part  hardening,  part  cement ;  **  all  c 

Krad  from  left  to  right,  and  from  above  downwards. 


GROUP  1.  ft 

IGROUP2'  transition  from  tt  to  ^be- 
tween W  and  V. 

GROUP  3.  ** 

GROUP  4,    Traflsitian  t  to  *  between  20°  Cent,  and  redness. 

§  1.                                                               §  2. 

"5 

i  •   .  t  j  Porcelanic,  and 
I  granular-crystalline 

)ull  crystalline. 

Bright  hackly  (pointed  crys- 
talline). 

)ull  porcelanic. 

j  Fine  hackly, 
j  Leafy  crystalline. 

JS 

^ 

Color    ot    the 

fracture   inclined 

to- 

DAKK  <;UAY,  fib 

rous,  wholly  without 

Lolor  of  the  Ji-aclure  inclined  towai 

ds 

a 

wards  IH.UK. 

crystallization. 

BLUE. 

a 

Acq  uired. 

Lost. 

Acquired. 

Lost. 

Acquired. 

Lost. 

Acq  uired. 

Lost.                  Acquired. 

Lost. 

All   the  *    groups 

Change   to    cor 

•e- 

1 

-»• 

} 

* 

1 

"* 

1  ± 

1  ^ 

1 

* 

•T 

c 

& 

"o 

r. 

•5 

•i      »,    4)    rhangf 
uddcnly  to  F  al 
V,  as  *  changes 
ot. 
?  and  T>  acquired 
an  .solidification. 

s  ponding  members 
>f  groups  -J4  j- 

wht'ii  t  changes  to 
*  at    teinpn-;itin-f> 
f  between       W  1 
and  V 
-{  between  20°  C.  }- 
i     and  low  red- 
l    ness. 

u  c  c  e  e  d  B  " 
•roup  1  grad- 
ally        \\  hen 
c  in  p  erature 
etcends  from 
bove    W    to- 

p' 

Changes  to 
Group  ;i  grad- 
mlly,       when 
'.  em  p  erature 
Ifscemls  from 
above     V     to 

If 

"H.-*- 

T> 

Gradually  suc- 
ceed    Groups 
1,   2,   as  tem- 
perature     do- 
sci'tids  slowly  ' 
from      W      or 
ibo\  c  to  some 
joint  below  W 

I 
1 

* 

e 

H 
*r 

S 

\ 

Change      sud- 
U-nly      to     F 
when  temper-  ] 
ature  rises  to 
W. 

Do  not  change 
ow\V. 

~ 
c 

be- 

Gradually  suc- 
t-ed  4iioup  1 
s       tempcra- 
nre  rises  from 
o°       C.       to  ; 
»o  i  n  t«    be  - 
ween  a  brown 
int   tempera- 
lire  and  V 

5' 
ti 

- 

Change  to  §  2 

lure  I  !>«•«  still 
further,  to  be- 
twi'i'li    V  anil 
W. 

:hanging  to  *  more  c 

ucoeed  §  1  as 
i-  in  p  erature 
ises     to     bc- 
wcen  V  and 
V. 

;h;inging  tu  *  more  c 

L'hange  to  F 
is  teuipcra- 
in  t'  HM'.S  t«t 
\V;  i  ».  crys- 

iflkced. 

J 

changing  to  t 

'iiu-r  members  j  ^ 

change  to  coarser 

•ardsV. 

*  r+ 

o 

bt-low  V. 

J 

* 

J 

5 

J 

s 

* 

c 
-r 

-; 
S 
— 

j  1  J  [•  when    temperature     rises 

to 

~ 

p 

i  bright  yellow  ( 

J  '7 

J    ^ 

|  blight  white  f 

F. 

Tbe  transition  fracture  from  F 
towards  C  has  not  been 
described. 

c. 

H-from-F.a 

C.b 

BRIGHT    rORCEi.ANio,      no    decided 

FINE  HACKLY.- 

:*ORCF.I,ANIC  :  dull  :  fibrous. 

•'INF.    HACKLY. 

crystallization  visible  to  the  naked 
eye. 

facets  SHINING. 
Frncture  color  Inclined  towards  ULTTK. 

\Vliolly  without  crystallization. 
)ARK  GRAY. 

facets  SHINING. 
fracture-color  inclined  towards  BLUE. 

Acquired. 

Lost. 

Acquired. 

Lost. 

' 

Acquired. 

' 

Lost. 

Acquired.                     Lost. 

.  On  sudden   sol- 
diflcation. 

2  to  7.  Sue-  }       * 
ceedsgroups  \S? 
2,  3,  4  at  W,  j  -+^ 
suddenly. 

S.ChangestoC"1 
when  temper- 
ature descends 
froiiiWpast  V.  ' 
9.  Changes  to 
H  when  tem- 
perature rises 

T  changing  t 

S.  Succeeds  F 
as      tern  pera- 
,ure  descends 
from     W    to 
some       lower 

t  changing 

3.       Changes 
.suddenly  to  F 
when  temper- 
ature rises  to 
W. 

*  changing  tu 

9.     Gradually 

succeeds  F  as 
he    tempera- 
ure  rl-es  from 
20°       C.       to 

I 

^ 

IS  Changes  to 
C  when  tem- 
perature rises 
still  farther  to 

t  changing  to 

8.    Succeeds 
I-from-F    as 
temp  erature 
rises     to     be- 

t changing  to 

6.  Changes  to 
F  as  tempera- 
ture rriiciicH 
W. 

*  changing  to 

from  20°  C.  to- 

c 

>oint.  Change 

£• 

•4 

>  o!  n  ts  be- 

a  between  Vaad 

* 

tween   V  and 

* 

•* 

wards  V. 

* 

•robably  grad- 

* 

Does  not    change 

ween  a  brown 

fw. 

g 

W. 

c" 

10.  Changes  to 

E 

ual. 

g 

below  W. 

int     temper- 

B 

S. 

2. 

when  temperature 

s 

ature  and  V. 

fl 

D 

\ 

rises    from    W 

In 

• 

g 

-' 

j  • 

lighter  yellow. 

, 

. 

d. 

E. 

The  transition  fracture  from  E 
towards  B  has  not  been 
described. 

B. 

The  changes  from    E 
from  20°  centigrade 

as  the  temperature  rises 
have  not  been  investigated. 

s 

FINE  GRANITLAK-CBVSTALLINE, 

HACKLY. 

E 

Facets      SILVER-RUINING      (Mete 

ilf, 

facets  SHINING 

[BL 

CE. 

£ 

tiery). 

Color  of  the  fracture  inclined  towards 

1 

Acquired  . 

Lost. 

Acquired. 

Lost. 

i  members  of  « 

10     Keplaces       F 
when  temperature 
rises  to  bright  yel- 
low. 

11.  Changes  to 
B  when    tem- 
perature    de- 
scends    from 
light      yellow 
past  Wand  V. 

t  changing  to  * 

11.  Succeeds  E 
as      tempera- 
.ure  descends 
rom         light 
yellow      to 
tome       point 

t  changing  to 

4.      Probably 
changes    nud- 
denly     to     F 
when  temper- 
ature rises  to 
W. 

*  changing  to 

« 

12   Changes  to  D 

>  e  1  o  w     W. 

* 

•* 

a 

when  temperature 

Change   prob- 

? 

C. 

rises  from    brigh 

ably  gradual. 

yellow    to    brigh 

• 

c 

whiteness. 

1 

D. 

I. 

A. 

H  f  rom-D  « 

G. 

tf. 

COARSE  GRANULAR-CRYSTALLINE. 

COARSE  CRYSTALLINE. 

COARSE  HACKLY. 

PORCELANIC  :  dull  :  fibrous. 

LEAFY  CRYSTALLINE. 

i 

FACETS  SILVER-SHINING  (Metcalf,  very 
lustrous). 

Facets  shine  like  dull-beaten  silver. 

Facets  SHINING. 
Jolor  of  the  fracture  inclined  town 

rd 

Wholly  without  crystallization. 
DARK  GRAY. 

FACETS  SHINING. 
Color  of  the  fracture  inclined  towarda 

£ 

Fracture  WHITE  (Metcalf,  yellowish). 

BLUE. 

BLUE. 

.c 

o 

Acquired.        |             Lost. 
12.  Keplaces       E|l4.  Changes  to! 

Acquired 
14.    Gradually 

_,. 

Lost. 

1           0 

Acquired. 

Lost. 

< 

A"q  uired. 

-1 

Lost. 

Acquired. 

Lost. 

1    « 

when  temperature 
rises    to      bright 
whiteness. 
13.   Acquired     on 
slow  solidification. 
13*5  .      Sometimes 

I    when   tem- 
perature    de- 
scends     from 
brigfit    white- 
ness past    W 
and  V. 

t 

replaces        D 
when  temper- 
ature descends 
Tom  a  bright 
white  past  W 
toward  V. 

beginning  U 
change  to  * 

IT.      Changes 
gradually  to  A 
when  temper- 
ature          de- 
scends   below 

hange  from  1 
ielng  comple 

IT.    Gradually 
succeeds  I  as 
temp  erature 

changing  to 

15.    Changes 
suddenly  to  F 
when  temper- 
ature rises  to 
W. 

j 

1  + 

15.   Gradually 
succeeds       D 
when  the  tem- 
perature rises 
from  20°  C.  to 

beginning  to 

10.  Changes  to 
G  when  tem- 

changing to 

19.    Succeeds 
II  -  from  -  D 

changing  to  ' 

7.  Changes  to 
F  as  tempera- 
ture    reaches 
W. 

changing  to 

replaces   I-from-D  15.  Changes  to 
when  temperature  H  when  tern- 
returns  to  W.d       |perature  rises 
from  20°  C.  to- 
1  wards  V. 

s 

1  . 

16.     Replaces 
A  when  tem- 
perature rises 
from  V  to  W 

III 

1  o  — 

V. 

2.  I  -  from  -  A 
changes  to  F 

-i      ^ 

descends  from 
a  bright  white 
to  some  point 
below  W. 

f  * 

H 
)~. 

16.      When 

freshly    form- 
ed, changes  to 
I    when   tem- 

1 ( 
j" 

points         be- 
tween a  brown 
tint   tempera- 
ture and  V. 

change  to 

perature  rises 
still  farther  to 
between       V 
and  W. 

*  more  con 

when  temper- 
ature rises  to 
between  V  and 
W. 

!•  more  con 

I  -*•  c 

when  temper- 
ature rises  to 

s| 

* 

perature  rises 
from     V     to- 

f 

J   « 

~ 
e 

1 

W 

J     1 

wards  W. 

j  S 

I 

" 

13-5.  I-from-D 

some 

Does     not 

J  ^ 

times  returns 

to  E 

cbange  below 

( 

when     tempe 

raturt 

. 

V. 

returns  to  W.d 

2,  Whenever  cement  carbon  changes  to  hardening: 
this  change  seems  to  be  so  violent  that  it  effaces  all  pre- 
existing crystallization,  and  here  too  the  steel  becomes 
porcelanic.  When  cold  steel  is  heated  to  just  below  W 
its  carbon,  if  not  initially  cement,  becomes  cement :  and 
on  reaching  W  the  change  to  hardening  carbon  occurs 
suddenly :  hence,  whenever  cold  steel  is  heated  to  but  not 
far  above  W  and  quenched,  a  porcelanic  fracture  isfounda 
(4,  21,  37,  44).  Simple  exposure  to  W  does  not  in  itself 
destroy  pre-existing  crystallization  and  render  the  steel 
porcelanic :  the  change  from  cement  to  hardening  carbon 


a  This  is  shown  by  direct  experiment  for  steel  whose  fracture  is  either  C,  A  or 
G  initially.  The  analogy  of  C  and  A  leaves  little  doubt  that  B  would  undergo  the 
same  change.  D  and  H  certainly  and  E  probably  change  to  G  when  cold  steel  is 
heated  to  V  +  + ,  and  hence  eventually  yield  P  at  W.  The  behavior  of  I,  a  transition 
fracture  unlikely  to  arise  in  practice,  has  not  been  studied,  but  all  analogy  indi- 
cates that  it  too  would  change  to  F  at  W. 


must  occur ;  otherwise  the  pre-existing  crystallization  re- 
mains. Thus  if  steel  be  heated  above  W  its  carbon  remains 
hardening :  if  we  now  cool  it  to  W  no  change  of  carbon  oc- 
curs, and  the  steel  if  now  quenched  will  not  be  found  por- 
celanic (8,  78).  But,  by  cooling  the  steel  far  enough  be- 
low W  (e.  (jr.  to  below  V)  to  change  its  carbon  to  cement, 
and  again  heating  to  W,  this  cement  carbon  reverts  to  the 
hardening  state,  and  the  steel,  if  now  quenched,  will  be 
found  porcelanic  (59,  65,  82). 

If  the  temperature  fall  from  above  W  to  some  point  so 
slightly  below  it  that  but  a  part  of  the  hardening  carbon 
changes  to  cement,  and  if  the  temperature  be  again  raised 
to  W,  it  appears  that  only  those  crystals  which  had 
changed  to  cement  will  now  undergo  a  change  of  carbon, 
and  they  alone  will  now  become  porcelanic,  F:  the  rest  will 
preserve  the  crystallization  which  they  had  before,  when 


174 


THE  METALLURGY    OP    STEEL 


their  temperature  was  above  W,  and  a  composite  fracture 
arises  (68). 

Easily  acquired  by  quenching  from  W,  F  is  as  easily 
lost,  by  exposure  to  any  high  temperature  either  above  or 
below  W.  Below  V  it  only  changes  to  the  dull  porcelanic 
fracture  H  (41-2,  48-9):  between  V  and  W  to  the  fine 
grained  fracture  C  (43,  50):  while  above  W  it  changes  to  the 
coarser  members  of  its  own  group,  E  and  D  (5-6,  22-3, 
38-9,  45-6).  In  short,  below  W  (carbon  changing)  it 
changes  only  +o  fine-grained  and  hence  desirable  fractures, 
while  above  (carbon  constant)  it  like  all  others  grows 
coarser. 

E  and  D,  the  upper  members  of  this  group,  thus  ac- 
quired, are  not  removed  or  rendered  finer  by  simply  lower- 
ing the  temperature  again  towards  W  (7-8).  E,  acquired 
at  a  bright  yellow,  grows  coarser  and  changes  to  D  as  the 
temperature  rises  to  bright  whiteness  (5,  6,  22-3,  38-9, 
45-6,  60-1).  In  slow  cooling  below  W,  E  and  D  change 
gradually  with  changing  carbon  in  passing  through  and 
below  the  critical  range  W-V  to  the  cement-carbon  hackly 
B  and  A  respectively,  the  former  medium,  the  latter 
coarse  (B,  16,  30,  52,  56  ;  A,  17,  31,  53,  57).  During  this 
transition  D  passes  through  the  dull-crystalline  fracture  I 
(9,  10,  67),  and  it  is  probable  that  further  study  would  de- 
tect similar  transitions  states  following  E  and  F. 

D  is  also  acquired  during  slow  cooling  from  the  melting 
point  to  W  (78). 

If  D  be  preserved  by  sudden  cooling,  and  if  the  metal 
be  again  gently  heated,  as  its  carbon  gradually  changes  to 
cement  its  fracture  first  becomes  dull  porcelanic,  H,  as  V 
is  approached  (25-6,  33-4),  changing  further  to  flaky  crys- 
talline Gr  as  the  temperature  nears  W(27-£;,  35-6),  at  W  of 
course  changing  suddenly  to  the  bright  porcelanic  F  (37). 
Similar  changes  probably  occur  in  case  of  fracture  E. 

b.  Group  2,  Transition  fracture,  I.  Our  data  are  too 
scanty  to  permit  us  to  speak  with  certainty  concerning 
this  transition  fracture,  but  the  following  hypothesis 
appears  to  fit  our  present  facts.  The  transition  from  the 
granular-crystalline  hardening-carbon  group  (F  E  D),  to 
the  hackly  cement-carbon  group  (C  B  A),  is  not  sud 
den  like  the  reverse  change,  but  occurs  gradually  as 
the  steel  cools  through  the  range  W  V,  thus  correspond- 
ing to  the  gradual  simultaneous  change  of  carbon  from 
hardening  to  cement.  While  this  change  is  occurring  the 
faces  of  the  crystals  become  dull :  this  suggests  that  the 
cohesion  between  the  particles  of  each  individual  crystal 
is  no  longer  in  great  excess  over  the  adhesion  between  the 
faces  of  adjoining  crystals,  and  hence  the  surface  of  frac- 
ture penetrates  here  and  there  beneath  the  crystalline 
faces,  and  the  particles  of  one  crystal  adhere  to  and  dull 
the  faces  of  its  neighbor.  Though  the  crystals  are  thus 
dulled,  we  have  no  evidence  that  their  form  is  changed 
This  dulling  of  the  facets  is  apparently  the  essential  fea- 
ture of  the  transition  fracture  I. 

Let  us  now  trace  this  transition,  and  note  the  effects  of 
arresting  it  at  different  stages,  whether  by  sudden  cooling, 
or  by  a  rise  instead  of  a  further  fall  of  temperature.11 

I.  At  V-4-.  If  D  be  acquired  by  heating  to  bright  white- 
ness, and  if  the  steel  be  now  slowly  cooled  to  V-f ,  and  if 
the  structure  acquired  thereby  be  fixed  by  quenching  (9, 


a  The  transition  from  D  to  A  has  been  studied  :  those  from  E  to  B  and  from  F 
to  C  have  not :  but  it  is  not  improbable  that  transition  fractures  analogous  to  I 
may  be  developed  in  these  latter  oases  by  interrupting  the  transition. 


77),  we  find  that  part  of  the  crystals  have  entered  the 
transition  stage,  are  dull-faced,  I,  suggesting  that  fracture 
penetrates  beneath  their  faces.  Others  remain  unchanged, 
mirror-bright,  as  D,  suggesting  that  the  fracture  still  fol- 
lows their  faces  accurately.  Part  of  the  carbon  has  sim- 
ultaneously changed  from  hardening  to  cement.  But  in 
descending  from  W  to  V-f-  the  change  of  crystallization 
appears  to  be  so  slight,  so  merely  incipient  that  the  old 
crystallization  has  simply  tottered,  not  fallen  ;  so  that  if 
the  temperature  immediately  return  to  W  (72)  the  old 
regime,  fracture  D,  is  completely  restored  even  in  those 
crystals  which  at  V+  had  changed  to  I. 

D  thus  regained  is  not  further  changed  by  raising  the 
temperature  above  W  (73),  but  it  changes  as  usual  to 
A  (doubtless  through  I)  when  the  temperature  again  falls 
slowly  past  W  and  V  (74-5),  carbon  changing  to  cement. 

II.  At  V.  If  D  be  acquired  by  heating  to  bright  white- 
ness, and  if  the  steel  be  slowly  cooled  a  little  farther  than 
in  the  case  last  considered,  to  wit  to  V,  and  if  the  struct- 
ure now  acquired  be  fixed  by  quenching  (10),  we  find  that 
those  crystals  which  at  V+  had  become  dill,  I,  have  now 
apparently  changed  to  hackly,  A,  while  the  rest  have 
become  dull,  I,  preparatory  to  that  change,  and  we  have 
the  composite  fracture  AI.     In  verification  of  his  belief 
that  the  carbon  of  some  crystals  had  changed  to  cement, 
while  that  of  the  others  still  remained  hardening,  Brinnell 
found  that  on  polishing  a  bar  of  steel  thus  treated,  shin- 
ing specks  scattered  across  the  surface  stood  up  above  the 
surrounding  steel :  with  a  diamond  he  found  them  harder 
than  the  rest :  while  etching  for  twenty-four  hours  with 
very  dilute  nitric  acid  made  one  set  of  crystals  stand  forth 
sharply  beyond  the  others,  which  were  far  more  corroded 
by  the  acid.     This,  however,  is  not  conclusive  :  the  harder 
crystals  may  have  been  cementite,  surrounded  by  the  soft- 
er pearlyte. 

If,  after  this  slow  cooling  to  V,  we  raise  the  tempera- 
ture, the  hackly  A  (cement  carbon)  crystals  change  back 
to  F  on  reaching  W,  their  carbon  claanging  to  hardening  : 
but  the  transition  I  crystals  remain  as  I,  and  on  now 
quenching  we  get  a  composite  fracture  IF  (68).  If,  in- 
stead of  quenching  from  W,  we  cool  slowly  to  below  V,  I 
and  F  naturally  change  to  A  and  C  respectively,  and  the 
composite  fracture  AC  arises  (70).  If  the  reheating  from  V 
be  carried  above  W,  the  transition  I  crystals  still  remain 
unchanged,  while  F  of  course  changes  to  E,  and  we  natur- 
ally obtain  the  composite  fractures  IE  and  AB  on  sudden 
and  slow  cooling  respectively  (69,  71). 

When  the  slow  cooling  was  interrupted  at  V-f-  and  the 
temperature  then  raised  to  \V,  the  I  crystals  changed 
back  to  D  :  but  in  our  present  case  (68-9)  they  remain  un- 
changed at  and  above  W.  We  may  conjecture  that  this  is 
because  the  more  extended  slow  cooling  in  the  present  case 
affects  the  structure  more  profoundly,  so  that,  on  the  re- 
turn to  W,  the  pre-existing  crystallization  no  longer  as- 
serts itself  as  before,  the  pre-existing  great  excess  of  the 
cohesion  of  the  particles  of  each  individual  crystal  over 
the  cohesion  between  adjoining  crystals  is  not  so  com- 
pletely restored,  fracture  does  not  follow  the  crystal  faces 
so  accurately  as  before,  dull  faced  crystals,  I,  persist. 

III.  Below    V.    If    the  slow  cooling  be  carried  but 
slightly  below  V,  the  transition  probably  becomes  com- 
plete. This  is  indicated  indirectly.  On  immediately  reheat- 
ing steel  whose  temperature  has  fallen  from  bright  white- 


CHANGES    OF    FRACTURE-GROUP. 


245. 


175 


ness  to  slightly  below  "V ,  fractures  F  and  E  arise  as  soon  as 
we  reach  W  and  bright  yellow  respectively  (05-6).  Now 
if,  on  cooling  to  just  below  V,  the  change  from  granular 
to  hackly  were  incomplete,  then  when  the  temperature 
rises  again  to  W  and  a  bright  yellow  we  would  find  com- 
posite fractures,  as  in  the  cases  under  II.  :  while  in  fact 
we  obtain  F  and  E  unmixed.  Again,  Coffin  states*  that 
if  steel  be  heated  to  W,  quenched  to  V  and  thence 
slowly  cooled,  its  fracture  is  perfectly  porcelanic.  The 
means  at  his  disposal  did  not  permit  close  measurements 
of  temperature,  and  it  is  probable  from  analogy  that  his 
quenching  cooled  the  steel  slightly  below  instead  of  just 
to  V.  This  indicates  that  F  does  not  change  to  C  at  tem- 
peratures materially  below  V,  and  suggests  that  the 
change  from  F  to  C,  which  occurs  regularly  when 
steel  with  fracture  F  is  slowly  cooled  from  W  to  X,  is 
completed  before  the  temperature  has  fallen  materially 
below  V. 

V  then  appears  to  be  a  critical  temperature  for  these 
changes  of  fracture. 

IV.  Finally,  if  the  slow  fall  of  temperature  be  carried 
far  below  V  and  arrested  at  a  blue  oxide-tint,  and  if  the 
temperature  be  raised  again  to  W  or  bright  yellow  or 
bright  white  with  subsequent  quenching,  we  still  obtain 
the  characteristic  fractures  of  these  three  temperatures,  F, 
E  and  D,  just  as  in  the  last  paragraph  (59,  60,  61),  which 
naturally  change  to  hackly  C,  B  and  A  if  slow  cooling, 
which  changes  the  carbon  to  cement,  replace  this  quench- 
ing (55,  56,  57). 

c.  Group  3.  The  eventual  change  of  the  granular-crystal- 
line hardening  carbon  fractures  F,  E  and  D,  to  the  hackly 
cement-carbon  ones  C,  B  and  A  on  slow  cooling  from  the 
formation-temperatures  of  the  former  to  below  V,  is  illus- 
trated by  experiments  15,  29,  and  51 ;  by  16,  30  and  52  ; 
and  by  11,  17,  31,  f3  and  75  respectively.     In  each  case 
we  assume  that  a  granular  fracture,  F,  E  or  D,  existed  be- 
fore the  slow  cooling,  becaiise  we  find  it  in  a  parallel  ex- 
periment in  which  sudden  is  substituted  for  slow  cooling. 

The  hackly  fractiires  thus  acquired  do  not  change  un- 
less the  carbon  changes  back  to  hardening,  /.  e.  unless  the 
temperature  rises  again  to  W,  at  which  point  they  are 
effaced  and  changed  to  F.  Repeated  heating  and  cooling, 
swift  or  slow,  between  the  cold  and  V,  do  not  affect  them.b 

d.  Group  4    Transition  from  Hardening  to  Cement  Car- 
bon, temperature  rising  from  X  toward  W. — If  the  hard- 
ening-carbon  granular-crystalline  fractures  of  group  1,  F,  E, 
D,  are  preserved  by  sudden  cooling,  they  gradually  change 
as,  with  gradually  rising  temperature,  the  carbon  changes 
to  cement     At  first  the  change  of  carbon  seems  to  outrun 
that  of  structure,  for  by  the  time  that  a  brown  tint  is 
reached  part  of  the  carbon  has  changed  to  cement  (v!4,  32, 
40,  47)  while  no  corresponding  change  of  structure  has 
been  recognized.  With  further  rise  of  temperature  the  dull 
porcelanic  H  replaces  the  fractures  of  group  1,  partially  at 
an  incipient  glow  (25,  33,  41,  4-),  wholly  at  V,  (26,  34,  42, 
49).     With  still  further  rise  to  slightly  above  V  crystalli- 
zation again  sets  in,  and  appears  to  be  the  coarser  the  coarser 
the  preexisting  fracture  of  group  1  had  been,  C,  fine 
hackly,  replacing  F,  (43),  G,  leafy  crystalline,  succeeding  D 
(35).  This  suggests  that  the  change  of  carbon  from  harden- 


R  Mechanics,  Dec.,  1887,  p.  318,   Proposition  9:  Trans.  Am.    Soc.    Mech.  Engi- 
neers, IX. ,  1888.    Coffin  terms  this  fracture  "  Perfectly  amorphous," 
b  Idem,  proposition  5. 


ing  to  cement  had  not  destroyed  the  pre-existing  crystalli- 
zation of  group  1 ,  but  had  merely  masked  it  by  strengthen- 
ing the  inter-crystalline  adhesion,  so  that  the  fracture  ob- 
tained at  V  struck  across  the  crystals  themselves,  in  pref- 
erence to  following  their  faces:  and  that  the  inter-crystal- 
line adhesion  again  falls  on  rise  of  temperature  to  V  +,  the 
effects  of  the  old  crystallization  are  felt  again,  again  frac- 
ture tends  to  follow  the  faces  of  the  crystals,  those  which 
had  formerly  yielded  the  coarse  D  now  affording  the  leafy 
G,  those  which  had  given  rise  to  F  now  yielding  the  fine 
hackly  C. 

The  changes  which  fracture  E  undergoes  on  reheating 
have  yet  to  be  investigated. 

§  245.  CURTAIN  FEATURES  OF  THE  CHANGE  FROM  GROUP 
TO  GROUP. — There  are  three  chief  changes  of  carbon-con- 
dition, I,  from  cement  to  hardening  when  the  tempera- 
ture rises  past  W  ;  from  hardening  to  cement,  2,  in  slow 
cooling  from  above  W  to  V,  and  3  when  the  temperature 
of  quenched  steel  rises  from  X  towards  V. 

The  suddenness  of  the  first,  corresponding  to  the  sud- 
denness of  the  accompanying  carbon-change,  and  the 
slowness  of  the  second  and  third,  harmonize  well  with  if 
they  do  not  explain  the  fact  that  pre-existing  crystalliza- 
tion is  completely  and  permanently  effaced  by  the  first, 
but  only  modified  by  the  second  and  temporarily  masked 
by  the  third. 

But  though  in  the  experiments  of  Figure  6 ' ,  and  in  those 
of  Coffin  on  steel  containing  like  Brinnell's  0'50^  of  car- 
bon, by  this  first  change  the  pre-existing  crystallization 
seems  to  be  effaced,  so  that  it  does  not  influence  the  results 
of  subsequent  manipulation,  yet  Coffin  found  that,  when 
only  0-20$  of  carbon  was  present,  heating  to  W  and 
quenching  only  partly  broke  up  the  pre-existing  coarse 
structure,  some  of  whose  coarse  crystals  still  remained. 
A  second  heating  to  W,  however,  induced  the  expected 
porcelanic  fracture.  The  first  sudden  change  of  carbon 
from  cement  to  hardening  seemed  to  weaken  the  crystal- 
line structure,  the  second  to  efface  it.0  In  his  view  the 
destruction  of  crystallization  requires  energy :  this  is  sup- 
plied by  the  changing  condition  of  carbon.  Little  carbon 
present,  means  little  carbon  to  change,  little  energy  ex- 
erted, little  effect  on  crystallization. 

Even  in  relatively  highly  carburetted  steel  it  may  be 
necessary  to  repeat  this  heating  to  W  if  the  crystalline 
structure  has  been  tenaciously  fixed,  as  Metcalf  pointed 
out  years  ago.d 

Position  of  W.  According  to  Chernoff,  while  the  changes 
in  the  temperature  of  b  ( W)  ar,}  not  readily  recognized  by  the 
inexpert  eye,  this  point  rises  slightly  as  the  proportion  of 
carbon  falls,  being  at  a  not-brilliant  red  for  certain  steels, 
while  for  wrought-iron  it  lies  at  a  white  heat.'  Metcalf 
recognizes  and  employs  fifteen  different  temperatures  for 
refining  steel  of  different  percentages  of  carbon,  i  e.  for 
rendering  them  porcelanic  by  heating  to  W.e  Coffin, 
however,  finds  that  W  lies  at  practically  thi  same  tem- 
perature for  steels  whose  carbon  varies  between  0-25  and 
1  '5%.s  Exact  pyrometic  observations  are  probably  needed. 


c  J.  Coffin:  Steel  Car  Axle?,  Trans.  American  Society  of  Mechanical  Engineers, 
IX.,  1888;  "  Mechanics,"  1887,  p.  317. 

d  "The  Treatment  of  Steel,"  p.  85. 

e  Trans.  Am.  Soc.  Civil  Engineers,  XV.,  p.  385,  1887.  The  Treatment  of  Steel, 
p.  35. 

'  Rev.  Universelle,  3d  ser.,  I.,  p.  401,  1877.     "  Le  rouge  non  brillant." 

g  Trans.  Am.  Soc.  Civ.  Engineers,  XV.,  p.  326,  1887, 


176 


THE    METALLURGY    OP    STEEL. 


It  is  possible  that  W  represents  a  range  of  temperature, 
not  a  point :  or  that,  while  the  critical  point  is  constant, 
it  is  expedient  to  quench  soft  steels  from  slightly  above 
it,  hard  ones  from  slightly  below. 

There  are  two  points,  nearly  constant  for  most  classes  of 
malleable  iron  and  steel,  at  which  the  metal  evolves  an 
abnormal  quantity  of  heat  during  falling  temperature. 
The  lower  one  lies  between  660°  and  705°  C.,  and  very 
probably  corresponds  to  V.  The  upper  lies  according  to 
Pionchon  between  1,000°  and  1,500°C.,  according  to  Osmond 
between  810°  and  900°,  and  may  possibly  be  W.  The 
position  of  each  is  nearly  independent  of  the  proportion 
of  carbon  present.  (Of.  §  257.) 

§  246.  INFLUENCE  OF  RATE  OF  COOLING  ON  COARSE- 
NESS OF  GRAIN. — There  appears  to  be  a  maximum  degree 
of  coarseness  or  size  of  grain  for  each  temperature,  vary- 
ing with  the  composition  of  the  metal  and  rising  with  its 
sectional  area  and  with  the  temperature,  at  least  when 
this  is  above  W.  The  development  of  crystallization  of 
course  takes  time.0 

A.  With  small  bars  the  necessarily  rather  slowly  ris- 
ing temperature  appears  to  afford  time  for  developing  ap- 
proximately the  maximum  coarseness  corresponding  to 
the  temperature  reached,  so  that  their  fracture  depends 
chiefly  on  the  highest  temperature  to  which  they  have 
been  exposed,  and  but  little  on  the  rate  of  cooling. b    Of 
course,  if  the  metal  be  forged  or  fused  after  the  rise  of 
temperature,   the  crystallization    acquired  is  destroyed 
again:  and  so  it  is  if  the  rise  of  temperature  be  to  W.     In 
any  of  these  cases  the  coarseness  of  fracture  must  increase 
with  the  slowness  of  cooling.     That  it  does  after  forging 
and  fusion  is  well  known  :  and  Coffin  finds  that  it  does  in 
case  of  the  hackly  C,  formed  during  slow  cooling  from  W.c 

Wedding  says  unqualifiedly  that  the  size  of  grain  in- 
creases with  the  slowness  of  cooling,  cceteris  paribus  :d 
but  qualification  is  surely  needed. 

Coffin  concludes  from  his  experiments  that,  after  the  max- 
imum coarseness  for  given  temperature  has  been  reached, 
further  exposure  merely  changes  "the  relative  cohesion 
between  different  (crystal)  faces,  causing  cleavage  sur- 
faces." I  suppose  that  he  means  that  it  increases  the  ratio 
of  the  intercrystalline  adhesion  to  that  of  the  cohesion  of 
the  particles  of  the  individual  crystal,  so  that  rupture  oc- 
casionally penetrates  into  the  individual  crystals,  and  fol- 
lows their  cleavage  planes.6 

B.  Large  masses  seem  to  present  rather  different  con- 
ditions.    Though  Percy  reports  buttons  of  iron  whose 
crystals  were  so  large  that  their  cleavage  planes  extended 
completely  across  the  fracture,*  yet  it  is  probably  true 
that  crystals  tend  to  a  larger  size  in  large  masses  of  iron 
than  in  small  bars. 

Thus  the  diameter  of  crystals  occurring,  not  in  vugs  but 

a  Brinnell  indeed  slates  that  when  the  carbon  has  wholly  or  mainly  changed 
from  hardening  to  cement,  whether  with  rising  or  falling  temperature,  crystalli- 
zation occurs  instantaneously,  (ganz  plotzlich.  Stall]  und  Eisen,  V.,  p.  620, 
1885).  Coffin,  however,  states  that  many  experiments  of  his  refute  Bnnnell's  prop- 
osition which  contains  this  statement,  and  thinks  that  Brinnell's  experiments  do 
not  verify  it  (Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  p.  319).  I  have  not  succeeded  in 
reconciling  it  with  Brinnell's  experiments,  e.  g.  with  his  9  and  10,  figure  61. 

b  This  statement  applies  to  the  coarseness,  not  the  kind  of  fracture.  We  have 
seen  that  rapid  cooling  from  above  W  preserves  the  granular,  while  slow  cooling 
yields  the  hackly  fractures. 

c  Op.  cit.,  p.  325.  Table  87,  §  250,  gives  absolute  measurements  of  the  increase 
in  size  of  grain  on  slow  cooling  from  W  to  V. 

<J  Jour.  lion  and  Steel  Inst.,  1885,  I.,  p.  190. 

e  Trans.  Am.  Soc.  Mech.  Eng.,  IX.,  1888,  propositions  7  and  8. 

I  Iron  and  Steel,  p.  10, 


in  the  metal  itself,  reaches  0"<?5  inch  in  slowly  cooled, 
friable  ingot-iron  reported  by  Bessemer,8  and  0'5  inch 
in  Chernoff's  forged  steel  shaft,"  in  Percy's  long-heated 
puddled  iron,1  and  in  a  long-used  porter-bar  described  by 
Thurston.J  Ordinary  heating  does  not  appear  to  occupy 
time  enough  to  satisfy  the  crystallizing  capacity  of  large 
masses,  which  therefore  tends  to  assert  itself  during  cool- 
ing ;  and  here  the  rate  and  duration  of  cooling  probably 
affect  the  size  of  the  grain  much  more  than  in  case  of 
small  bars.k 

Another  possible  reason  why  the  rate  of  cooling  should 
affect  the  structure  of  large  more  than  small  pieces,  lies 
in  the  fact  that,  in  quenching,  the  difference  between  the 
rates  of  cooling  of  outside  and  inside  is  greater  in  the 
former  than  in  the  latter.  Hence  severe  interstratal  move- 
ments may  be  expected  in  large  masses,  Avhich  like  forg- 
ing might  be  expected  to  break  up  already  existing  crys- 
tallization, while  when  small  bars  are  quenched  the 
different  layers  cool  and  contract  at  more  nearly  similar 
rates.  Metcalf  admits'  that,  while  the  influence  of  the 
rate  of  cooling  is  hardly  appreciable  in  case  of  bars  0'125 
inch  thick,  it  is  more  readily  detected  in  those  0'25 
inch  thick,  and  conspicuous  in  bars  1'5  inches  square. 
The  outside  of  such  a  bar  quenched  from  a  very  high 
temperature  consists  of  coarse  crystals  :  they  become  rigid 
so  instantaneously  that  they  preserve  the  form  acquired 
at  the  high  temperature.  The  interior  is  flaky,  and  might 
even  be  called  fine-grained  :  it  is  indeed  much  finer  than 
if  the  bar  had  been  slowly  cooled.1  The  fracture  of  such 
a  bar  is  sketched  at  the  right  of  figure  62. 


a  r      i    2     3          %  b 

Size  of  grain  in  a  steel  bar  quenched  from  different  temperatures* 

Fig.  62. 

§  247.  FORGING  strongly  opposes  crystallization,  in  case 
of  both  iron  and  steel,  ingot  and  weld.  Like  agitation  in 
the  case  of  salts  crystallizing  from  aqueous  solution,  it 
appears  to  arrest  the  development  of  crystalline  structure, 
and  to  break  up  more  or  less  completely  that  which  has 
already  been  developed.  The  former  action  is  probably 
due  to  its  altering  the  position  of  the  particles  with  refer- 
ence to  the  axes  around  which  they  were  about  to  crystal- 
lize. 

The  second  (in  case  of  iron)  is  probably  due  in  part  to 
its  increasing  the  cohesion  between  adjoining  crystals,  i.  e. 
welding  their  faces  together,  so  that  fracture  now  follows 
the  shorter  path  across  their  bodies  :  perhaps  also  in  part 
to  its  breaking  them  up  into  cleavage  blocks,  like  the 
blocks  readily  broken  from  many  crystals  of  galena,  or  to 
its  destroying  the  original  crystals  altogether,  new  and 
smaller  ones  springing  Tip  from  their  ruins :  and  possibly 
to  its  elongating  the  crystals  themselves,  and  so  elongating 
the  path  which  rupture  would  have  to  take  were  it  to  fol- 
low their  faces,  and  thus  the  more  inclining  it  to  strike 


g  Cf.  §  54,  p.  33.     Cf.  Iron  Age,  XLII.,  p.  57,  1888. 

h  Rev.  Univ.,  2d  Ser.,  I.,  p.  409. 

1  Sorby,  Jour.  Iron  and  Steel  Inst.,  1887,  I.,  p.  S63. 

j  Thurston,  Mat'ls  of  Engineering,  II.,  p.  580. 

k  Coffin,  op.  cit.  proposition  6th,  states  that  if  steel  be  heated  "  above  W,  its 
crystallization  is  in  the  most  part  determined  by  the  temperature  and  occurs 
while  heating:"  it  is  probable  that  he  hero  generalizes  from  experiments  with 
small  bars,  and  overlooks  the  very  different  conditions  which  accompany  larger 
masses. 

!  Trans.  Am.  Soc.  Civ.  Engs.,  XV.,  p.  388,  1887. 


CHANGES    OF    FRACTURE. 


243. 


177 


T  AI-.I.F.  Mi.—  MKTrAl.K'K  YlKWS   (IN  TJIK  iNFI.l'KNCK  OK  TIIK   Ijl    1  M   H  I  M  .  -  T  l:M  !•  KF.  ATURK  ON  TIIK   >'l:  AITt'  1:  K,   KTr. 

Number  

1. 

2. 

8. 

4. 

s. 

6. 

;. 

8. 

Qiienchlng-ti-iniifratiirr 

Scintillating. 

White. 

Bright  yellow. 

Orange.                      Blight  nd. 

Red. 

Low  red. 

Black. 

s  OF  TIIK  (JIKN«  IIKD  MKTAL. 


Hardness  .   . 

SrntrhrS  g]li»B. 

Extremely  hard. 

Well  hardened. 

Hard  enough  for  t:n 

Not  burdened. 

IJrittlencss  

Like  glass. 

Almost  like  (,'l^ss. 

SHffhtly  tougher  th:m 
'2. 

Tougher  than  3. 

Tougher      than      4  : 

breaks  e:isilv. 

Stronger  than  8. 

Fracture  

Coarse:      very    lus- 
trous :  yellowish. 

Coarse  :    less  yellow 
than  1. 

Finer  than  2  :  fiery. 

Slightly  finer  th;m  '••  : 
lit-ry. 

•vimi-   si/.o    as    8,   but 
flery.  Finer  than  4. 

Much      finer  :       not 
iiery  :    refined. 

Kil^cs  reUned      mid- 
dle coarser. 

Coarser  than  G  and 
7  :  the  original 
grain. 

SpcriJir    uni\itv 


T'7-7 


across  their  bodies  or  to  follow  the  imperfectly  developed 
cleavage  planes.  But,  whatever  be  the  rationale  of  its 
action,  it  is  certainly  a  most  powerful  means  of  counteract- 
ing the  crystallizing  tendency,  and  little  crystallization 
will  arise  during  forging  which  is  sufficiently  powerful  to 
make  its  effect  felt  to  the  middle  of  the  mass. 

The  case  of  rivets  illustrates  this  forcibly.  It  is  said  that 
when  they  fail  it  is  always  at  the  head  which  is  not  struck 
during  riveting;  the  riveter's  blows  against  the  struck 
head  while  it  is  cooling  prevent  crystallization  and  conse- 
quent brittleness." 

Coffin  has  observed  that,  while  a  bar  quenched  after  its 
temperature  has  risen  slowly  to  a  light  yellow  is  coarse 
grained,  if  it  be  quenched  from  this  temperature  immedi- 
ately after  rolling  it  is  fine  grained." 

If  forging  be  followed  by  slow  cooling,  it  is  clear  that 
the  higher  the  temperature  at  which  it  ceases  the  coarser 
will  the  crystallization  become,  the  worse  the  steel. 
Hence  the  importance  of  a  low  finishing-temperature  in 
forging,  to  which  §  250  and  §  264etseq.  refer  again.  Suffice 
it  here  to  say  that  the  superiority  of  thin  over  thick  forg- 
ings,  usually  attributed  to  extra  work,  is  probably  due  in 
large  part  to  lower  finishing-temperature,  especially  in 
case  of  ingot-metal. 

§  248.  THE  VIEWS  OF  OTHERS  ON  HEAT-TREATMENT  AND 
FRACTURF. — A.  Metcalf  believes  that  the  fracture  depends 
first  and  apparently  foremost  on  the  last  maximum  temper- 
ature, secondly  and  apparently  secondarily  on  the  rate  of 
cooling.0  He  sketches  in  Figure  62  the  influence  of  the 
last  maximum  temperature  on  the  size  of  the  grain  in 
different  portions  of  a  steel  bar  which  has  been  quenched 
after  heating  its  right-hand  end  to  bright  whiteness,  the 
left-hand  end  being  below  redness,  and  the  intermediate 
portions,  heated  by  conduction,  being  at  intermediate  tem- 
peratures. We  note  the  coarse  grain  (D)  of  the  white-hot 
parr,  the  finer  grain  (E)  of  the  portion  which  had  been  at 
a  bright  yellow,  the  extremely  fine  grain  (F)  of  that  which 
had  been  at  W,  and  the  gradually  increasing  size  as  we 
pass  to  the  left  from  W.  I  have  interpolated  these 
letters. 

I  attempt  in  Table  86  to  condense  his  views  on  the  frac- 
ture, etc..  of  different  parts  of  bars  thus  treated,  set  forth 
fully  in  the  Metallurgical  Review,  L,  p.  245. 

He  points  out  that  the  rate  of  cooling/row  the  melting 
point  influences  the  size  of  grain  greatly,  slow  and  rapid 
cooling  yielding  large  and  small  crystals  respectively. 

The  minor  differences  between  his  views  and  Brinnell's 
we  may  reasonably  refer  to  the  searchingness  of  the 


•Metcalf,  Iron  Ase,  XXXIX.,  May  19th,  1887,  p.  17. 
b  Private  communication,  March  28th,  1888. 

c  Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  pp.  284,  287,  386,  388,  1887.     Cf. 
ment  of  Steel."  pp.  23,  32. 


'  Treat- 


latter' S  investigation,  bringing  out  details  which  in  com- 
mon practice  would  escape  notice." 

S.  CJiernoff  in  the  main  anticipated  Brinnell's  general 
conclusions  regarding  structure,  besides  reaching  other 
important  ones  which  lay  outside  the  field  of  the  latter' s 
researches,  yet  naturally  failing  to  note  important  dis- 
tinctions which  the  subtle  experiments  of  the  Swedish  in- 
vestigator have  brought  to  light.  In  certain  diagrams,  which 
I  have  rotated  90"  in  Figure  68  to  facilitate  comparison  with 
Brinnell's,  (Figure  61)  he  indicates  four  points  which  ap- 
parently coincide  with  Brinnell's  cold,  V,  W,  and  the 
melting  point.  II is  a  is  a  dark  cheriy-red,  his  b  a  "not 
brilliant"  red.  These  temperatures  are  slightly  below 
those  of  Brinnell's  V  and  W,  but  not  more  than  may  be 
readily  due  to  the  probable  difference  between  the  steels 
which  these  two  observers  employed.  Chernoff  points 
out  that,  the  higher  the  carbon,  the  lower  are  these  points. 
He  employed  an  ordinary  hard  steel,  which  we  may  sup- 
pose had  between  '75  and  1  00%  of  carbon.  For  very  soft 
steel  he  puts  5  at  a  white  heat.  Brinnell,  on  the  other  hand 
employed  a  steel  with  0-52$  of  carbon,  whose  W  would 
stand  between  the  "not  brilliant  red"  and  the  white  of 
Chernoff' s  hard  steel  and  very  soft  steel,  or  just  about 
where  Brinnell  places  it,  at  a  low  yellow. 

His  chief  results  are  as  follows. 

1.  Steel  cannot  be  hardened  below  V. 

2.  Between  X  and  W  heating  and  cooling,  fast  or  slow, 
affect  the  structure  little  if  at  all.0    Very  protracted  ex- 
posure to  temperatures  approaching  W,  however,  probably 
gradually  alters  the  structure, t  though  he  could  observe 
no  change  on  exposing  steel  bars  for  about  eight  hours 
to  temperatures  near  W. 

3.  As  soon  as  the  temperature  reaches  W  the  structure 
changes  rapidly  from  granular  or  crystalline  to  amorphous.8 

4.  With  rising  temperature  it  remains  amorphous  up 
to  the  melting  point. K 

d  Rejecting  the  carbon-theory  of  hardening,  he  says  of  Brinnell's  fracture-re- 
sults, "the  results  given,  as  far  as  they  can  be  explained  in  words,  agree  with  our 
shop  experience,  and  they  indicate  clearly  what  has  long  been  an  axiom  with  us,  i .  <>. 
that  a  fracture  of  steel  always  indicates  the  highest  temperature  to  which  the  steel 
was  last  subjected,  no  matter  how  it  may  have  been  cooled,  provided  it  had  not 
been  hammered  or  rolled,  or  otherwise  worked  mechanically."  Op.  cit.,  p.  385. 
Mr.  Metcalf  quotes  me  (Idem.,  p.  389)  assaying  that  slow  cooling  always  produces 
coarse  crystals,  and  quick  cooling  fine  ones.  I  think  he  must  have  quoted  from 
memory,  for  I  do  not  believe  that  I  have  ever  written  so  dogmatically  and  unquali- 
fiedly on  this  point.  He  probably  refers  to  my  statements  in  this  journal,  pp.  315, 
332,  April  30th  and  May  7th,  1887,  which,  though  incomparably  less  sweeping,  I 
now  regard  as  overstatements.  I,  like  many,  was  misled  by  Chernoff. 

e  "  Quand  la  temperature  s'eleve  de  o  &  b  (W)  la  texture  de  1'acier  est  invari- 
able." "  L'acier,  chauffi;  en  dessous  de  b  ne  change  pas  de  structure,  qu'il  soil 
refroidi  brusquement  ou  lentement."  Rev.  Universelle,  2d  ser.,  I.,  p.  402,  1877. 

f  "  Toutefons,  cette  expression  doit  gtre  prise  sous  cette  reserve."  "  En  ce  que 
concerns  I'e'tat  d'un  acier  chauff<5  et  par  suite  ramolli,  surtout  a  des  temperatures 
voisines  de  B,  il  est  probable  que  le  changement  de  texture  sera  plus  grande." 
Loc  cit. 

e  "  Aussitdt  que  la  temperature  a  atteint  le  point  B,  1'acier  passe  rapidement  de 
r<5tat  grenu  ou  crystallin  fc,  V<5tat  amorphe,  qu'il  conserve  jusqu'  a  son  point  de 
fusion."  Loc,  cit. 


178 


THE    METALLURGY    OF     STEEL. 


5.  Falling  temperature  between  W  and  the  melting 
point  induces  crystallization,   the  more  powerfully  the 
higher  the  temperature,  so  that,  as  the  descending  tem- 
perature approaches  W,  the  strength  of  the  tendency  to 
crystallize  falls  off  sharply,  as  sketched  by  the  abscissae 
of  the  curve  in  Figure  63.     This  crystallization  makes  the 
metal  very  tender  as  long  as  the  temperature  remains  high. 

His  remarks  suggest  that  coarse  crystallization  does  not 
occur  at  stationary  high  temperature  :  but  I  do  not  find 
that  he  states  this  directly. 

6.  If  steel  thus  made  tender  be  again  cooled  completely, 
the  individual  crystals,  if  they  have  not  been  parted  me- 
chanically at  the  high  temperature,    become  so  strongly 
coherent  that  fracture  now  occurs  across  their  bodies,  and 
not  along  their  faces. 

The  last  two  propositions  are  not  distinctly  enunciated 
by  Chernoff.  They  give  his  views  as  I  understand  them, 
and  the  reader  must  allow  for  refraction 

§249.  DISCUSSION  OF  CHEKNOFF'S  VIEWS.—  The  first 
three  propositions  accord  with  the  results  of  Brinnell  and 
of  others. 

The  first  agrees  with  Brinnell' s  observation  that,  if  pre- 
viously annealed  steel  be  quenched  from  V  or  even  from 
V+,  its  carbon  remains  wholly  cement  and  it  retains  the 
cement-carbon  hackly  fracture:  and  with  mine  (p.  12),  that 
no  readily  perceptible  increase  in  hardness  is  produced  by 
quenching  from  below  dull  redness,  though  as  the  quench- 
ing temperature  rises  still  farther  the  hardness  increases 
suddenly.* 

The  second  agrees  exactly  with  BrinnelTs  results  as  re- 
gards the  cement-carbon  fractures  A,  B,  C,  and  pretty 
closely  as  regards  the  porcelanic  F,  which  changes  com- 
paratively little  at  temperatures  below  W,  but  not  as  re- 
gards the  coarse-crystalline  D,  which  according  to  Brinnel 
becomes  dull-amorphous  at  H.  But,  as  D  is  only  rendered 
visible  by  unusual  treatment,  there  is  little  doubt  that  the 
chunge  which  it  suffers  at  V  escaped  ChernofF  s  observation. 

The  third  agrees  exactly  with  Brinnell' s  and  Metcalf  s 
results. 

For  the  sixth  (pardon  the  inversion)  I  find  no  evidence. 
I  am  tempted  to  ascribe  it  to  heterophasia  or  to  error  in 
translation,  for  it  is  certain  that  the  brittleness  of  over- 
hearted  steel  and  its  tendency  to  break  with  sharp,  well- 
defined  crystals  does  in  a  measure  survive  cooling. 

The  fourth  and  fifth  contain  what  I  regard  as  an  ex- 
tremely serious  error,  to  wit,  that  coarse  crystallization 
does  not  set  in  while  the  temperature  is  rising.  I  first 
offer  evidence  in  rebuttal,  and  then  point  out  certain  pos- 
sible reasons  for  Chernoff' s  statement. 

].  In  Brinnell' s  experiments  5,  22,  38  and  45  (Figured) 
the  fracture  is  granular-crystalline,  E,  and  in  his  6,  23,  39 
and  46  it  is  coarse  granular-crystalline,  D,  when  steel  is 
quenched  immediately  after  slow  rise  of  temperature. 


a  Metcalf  indeed  states  (op.  cit,  p.  384),  that  a  hardening  effect  is  produced  by 
quenching  from  100°  C.,  and  that  quenching  from  any  temperature  above  that  of 
the  atmosphere  produces  appreciable  hardening. 

It  is,  indeed,  by  no  means  improbable  that  slight  changes  in  hardness  proper 
may  occur  on  quenching  from  temperatures  far  below  W  and  V,  changes  due 
in  turn  to  slight  variations  in  the  crystallization,  arrangement,  or  even  composi- 
tion of  the  component  minerals  of  steel,  to  changes  of  stress  or  what  not.  But 
these  trifling  changes  are  comparable  to  those  which  occur  in  other  metals  under 
varying  treatment,  and  not  to  the  unparalleled  change  which  occurs  ia  steel  when 
thequanching  temperature  rises  to  the  critical  point  W,  a  change  so  vastly  greater 
that  it  differs  from  them  in  kind.  A  theory  which  explains  this  change  is  not  to 
be  rejected  because  it  explains  these  minor  independent  changes  of  hardness  in  a 
different  way. 


2.  In  the  following  experiments  I  compared  the  frac- 
tures which  followed  slowly  rising  with  these  which  fol- 
lowed slowly  falling  temperature. 

A  A  bar  of  hard  open-hearth  steel  0'37  inch  square 
was  cut  into  three  pieces  each  two  feet  long.  These  were 
placed  in  contact  with  each  other,  imbedded  in  pulverized 
fire  clay,  and  heated  at  one  end  to  dazzling  whiteness,  the 
remainder  being  heated  solely  by  conduction.  The  first 
and  second  were  drawn  and  quenched  after  160  and  320 
minutes  respectively.  The  third  was  cooled  extremely 
slowly  by  allowing  the  fire  to  burn  out  gradually,  while 
the  bar  remained  undisturbed  and  still  imbedded  in  the 
hot  clay.  Thus  the  first  bar  should  record  the  structure 
at  different  temperatures  during  rising  temperature,  the 
second  when  the  temperature  was  nearly  stationary,  the 
third  the  structure  induced  by  slow  cooling  from  these 
various  temperatures. 

Fractures  made  at  points  0  5  inch  apart  formed  a 
series  in  each  bar  like  that  of  Metcalf 's  experiment,  Figure 
6J.  The  first  two  had,  at  about  the  same  points  in  their 
length,  the  characteristic  porcelanic  or  refined  fracture  F. 
In  the  third  this  was  replaced  by  a  fine  crystalline  frac- 
ture, which  I  take  to  correspond  to  Brinnell' s  C.  But  the 
important  point  is  that  the  highly  heated  portions  of  the 
three  bars  gave  fractures  with  nearly  the  same  degrees  of 
coarseness. 

B.  Two  pieces  of  the  same  steel  were  heated  in  white- 
hot  pulverized  fire  clay  in  a  muffle  for  90  minutes  :  then 
one  was  withdrawn  and  quenched  to  dull  redness,  then  re- 
placed against  the  other  till,  by  transfer  of  heat,  their 
temperatures  became  apparently  identical  :  both  were 
then  quenched.  Here  the  conditions  were  the  same,  ex- 
cept that  the  temperature  of  one  had  been  rising,  that  of 
the  other  falling,  immediately  before  quenching.  Accord- 
ing to  Chernoff  the  former  should  have  been  porcelanic, 
the  latter  crystalline.  I  could  detect  no  difference  in  the 
coarseness  of  their  fractures  with  a  lens,  nor  could  Mr.  F. 
L.  Garrison  with  the  microscope."  Similar  results  were 
obtained  in  many  other  experiments. 

Fig.  63.-HEAT-TREATMENT  PROCESSES:  CHERNOFF'S  VIEWS  ON  STRUCTURE 


MELTING  POINT 
BRIGHT  WHITE 
WHITE 
BRIGHT  YELLOW 
YELLOW 

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3.  In  the  following  experiment  of  Coffin's  coarse  crystal- 
lization was  acquired  without  slow  cooling  :  but  the  ex- 
periment does  not  show  directly  whether  the  coarse 
crystallization  which  arose  was  acquired  during  rising  or 
during  stationary  temperature,  or,  as  is  more  probable, 
during  both.  Two  pieces  of  steel,  1  and  2,  containing 

I)  I  have  to  thank  Mr.  Garrison  for  kindly  examining  with  the  microscope  some 
fifty  fractures  of  steel  which  had  been  treated  with  a  view  to  testing  the  truth  of 
this  statement  of  Chernoffs. 


METHODS    OF    HEAT-TREATMENT.      §  250. 


179 


0  4$  of  carbon,  cut  from  the  same  bar  I  inch  by  4  inches, 
were  both  held  during  30  hours  at  temperatures  which 
varied  between  low  whiteness  and  a  point  very  slightly 
lower.  1  was  then  quenched  in  oil,  while  2  was  cooled 
slowly  to  W  and  then  quenched.  The  fracture  of  1  was 
but  slightly  finer  than  that  of  2.a  Both  were  coarse 
crystalline. 
Seek  we  now  explanations  of  ChernofFs  statements. 

1.  The  context  indicates  that  they  are  based  in  large 
part  on  the  analogy  of  the  crystallization  of  certain  hy- 
drated  salts.     As  I  understand  him,  there  is  quite  a  range 
of  temperature  above  the  melting  point  of  alum,  that  point 
at  which  the  crystals  dissolve  in  their  own  water  of  crys- 
tallization, through  which  this  salt  remains  liquid  while 
the  temperature  is  rising,  but  solidifies  and  crystallizes  if 
the  temperature  falls,  and  that  too  long  before  it  falls  to 
the  original  melting  point.b    Slow,  quiet  cooling  favors, 
sudden  cooling  and  agitation  oppose  the  formation  of  large 
crystals. 

He  conceives  that  the  carbon  of  steel  in  a  roughly  sim- 
ilar way  "dissolves"  the  iron  itself,  I.  e.  renders  the 
whole  mass  amorphous  at  temperatures  above  W,  and 
holds  it  amorphous  as  long  as  the  temperature  is  rising 
(or  stationary) :  but  when  the  temperature  falls,  and  long 
before  it  reaches  W  again,  crystallization  sets  in,  and  is 
the  coarser  the  higher  the  temperature  has  been,  the  slower 
and  more  tranquil  the  cooling.  Such  analogies  only  sug- 
gest, never  prove,  often  mislead. 

2.  They  seem  to  be  further  based  on  the  fact  that  cer- 
tain steel  ingots,  which  had  been  held  unnecessarily  long 
at  a  high  temperature,  and  which  had  cooled  slightly  be- 
fore forging,  broke  with  a  strongly  developed  crystalline 
fracture  at  the  first  blows  of  the  hammer.     In  one  case  the 
ingot  was  raised  to  a  bright  orange  :  then,  while  awaiting 
its  turn  at  the  hammer  and  without  removal  from  the 
furnace,  its  temperature  was  allowed  to  fall  to  a  bright  red. 
It  was  then  hammered,  but  broke  at  the  first  blow. 

In  another  case  when  a  forging  which  had  been  thus 
treated  was  turned  in  a  lathe,  a  cavity,  lined  with  crystals 
some  of  which  were  0.5  inch  in  diameter,  was  found, 
formed  in  his  opinion  by  the  first  blows  of  the  hammer, 
which  separated  the  weakly  united  crystals. 

A  s  he  describes  these  cases,  however,  long  exposure  to 
a  high  temperature  seems  quite  as  competent  as  the  slow 
decline  of  temperature  to  explain  the  crystallization  and 
consequent  brittleness. 

3.  The  evidence  rebutting  ChemofFs  statements  is  based 
on  experiments  with  small  bars.      In  these,  as  already 
shown,  the  interstratal  movements  which  quenching  pro- 
duces and  which  tend  to  break  up  crystallization,  should 
be  much  less  severe  than  in  large  masses.     As  to  the  effect 
of  quenching  on  the  fracture  of  large  masses  I  have  no 

ividence.  It  is  possible  that  in  them  extremely  rapid 
cooling  may  completely  efface  crystallization,  thus  sug- 
gesting fallaciously  that  slow  cooling  alone  originates  the 
coarse  crystallization  which  it  preserves. 

4.  At  the  melting  point,  and  perhaps  at  temperatures 
•between  it  and  bright  whiteness,  pre-existing  crystalliza- 
tion is  effaced,  and  so  it  is  when  the  temperature,  rising 
from  the  cold,  reaches  W.     It  is  possible  that,  finding 
steel  quenched  from  these  temperatures  porcelanic,  Cher- 


•  Private  communication,  March  28th,  1888. 

'•  Of  course  the  melting  and  freezing  points  of  a  substance  do  not  necessarily  co- 
incide. 


noff  inferred  that  it  would  be  when  quenched  from  inter- 
mediate temperatures. 

I  have  shown  at  this  length  the  opportunities  for  error, 
because  the  positive  and  generally  accepted  statements  of 
this  most  brilliant  metallurgist  cannot  be  dismissed  lightly. 

To  sum  up,  in  most  of  the  points  in  which  Brinnell's 
statements  are  opposed  by  those  of  others  it  seems  quite 
clear  that  he  is  right. 

§  250.  METHODS  OF  HEAT- TREATMENT. — PRACTICAL 
APPLICATIONS  of  the  foregoing  follow.  1.  The  more  or  less 
complete  restoration  of  overheated  and  even  of  burnt  steel, 
by  reheating  to  W,  repeatedly  if  need  be,  followed  by 
forging,  by  quenching,  or  by  undisturbed  slow  cooling  ac- 
cording to  the  requirements  of  the  case.  (See  §  263.) 

2.  The  annealing  of  steel  castings,  which  not  only  re- 
lieves the  initial  stresses,  but  effaces  the  columnar  struc- 
ture, renders  the  fracture  very  much  finer,  and  greatly 
increases  strength,  elastic  limit  and  ductility."  (Cf.  Table 
9,  p.  19.) 

On  account  of  the  tendency  to  crystallize  above  W,  and 
also  while  the  temperature  is  falling  from  W  to  V,  Coffin 
anneals  by  heating  to  or  slightly  above  W,  cooling  rather 
rapidly  to  V  by  opening  the  furnace  doors,  then  closing 
them  and  finishing  the  cooling  very  slowly. d  To  hasten 
cooling,  one  side  and  the  top  of  the  furnace  may  be  movable 
and  counter- weighted :  while,  if  the  piece  be  large,  it  may 
be  run  in  and  out  on  a  truck  whose  top  forms  the  furnace- 
bottom,  and  which  with  its  load  is  run  into  the  open  air  in 
cooling  to  V. 

Here,  as  in  annealing  in  general,  while  the  temperature 
should  reach  W,  it  should  rise  no  further  beyond  W  than 
is  needed  to  assure  us  that  this  point  has  been  reached : 
and  the  cooling  should  not  be  excessively  slow.  Igno- 
rance of  these  cardinal  principles  has  probably  been  the 
chief  cause  of  the  injury  so  often  done  by  annealing,  and 
thus  of  the  somewhat  widespread  distrust  of  this  operation. 

3.  Means  of  accelerating  cooling  after  forging  has 
ceased. — Power  is  saved  by  using  a  high  temperature  for 
forging — the  metal  being  then  the  softer — but  at  the  risk 
of  excessive  crystallization  during  the  subsequent  cooling. 
Hence  expedients  to  hasten  this  cooling.6 

Coffin's  rail-process  (Figure  63)  consists  in  immersing 


o  The  almost  complete  lack  of  ductility  of  many  unannealed  steel  castings  which 
on  annealing  become  very  ductile,  shows  the  accuracy  of  the  definition  of  steel 
"  an  alloy  of  iron  which  is  cast  while  in  a  fluid  state  into  a  malleable  iueot."  The 
ingot  is  usually  not  malleable,  and  does  not  become  so  till  reheated.  (Cf.,  p.  1.) 

d  Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  p.  335,  1887. 

e  While  the  undisturbed  slow  cooling  from  an  excessively  high  temperature 
to  which  rails  rolled  unduly  hot  are  exposed,  doubtless  tends  to  induce  a  coarse 
crystalline  structure  and  consequent  brittleness,  especially  in  case  of  phosphoric 
iron,  this  tendency  has  unfortunately  been  most  grossly  exaggerated.  So  well 
conducted  a  journal  as  the  "Railroad  Gazette"  (1886,  p.  316),  gravely  stated 
that  a  prick  punch  could  be  driven  by  a  moderate  blow  nearly  up  to  the  hilt  into 
a  rail  which  had  been  finished  unduly  hot,  and  that  the  best  steel  can  "  be  so  soft- 
ened by  heating  and  annealing  as  to  be  almost  as  soft  as  lead,  and  equally  unable  to 
resist  impact  and  abrasion."  From  this  nonsense  and  from  positive  and  absurdly 
untrue  statements  which  follow  as  to  the  existing  method  of  rolling,  the  editor 
appears  to  have  been  the  victim  of  a  hoax.  It  is  doubtful,  indeed,  whether  one 
could  readily  detect. the  difference  between  the  hardness  proper  of  two  rails,  one 
of  which  had  been  finished  at  a  light  yellow  and  the  other  at  a  cherry-red,  though 
the  difference  in  structure  would  indeed  be  readily  seen.  What  is  surprising  and 
depressing  is  that  such  a  person  could  be  made  to  believe  such  rubbish.  (Cf.  Engi- 
neering and  Mining  Journal,  XLI.,  p.  390,  1886.) 

R.  W.  Hunt  reports  rails  which,  under  apparently  identical  conditions,  greatly 
outlasted  others  apparently  similar  in  all  respects  including  section,  except  that 
the  latter  had  much  thicker  (deeper)  heads  than  the  former,  and  hence  for  given 
quality  of  metal  should  have  lasted  much  the  longer.  The  inferiority  of  the  thick- 
headed rails  is  reasonably  referred  to  their  higher  finishing  temperature  and 
slower  cooling.  ("Steel  Rails,"  a  paper  read  before  the  Am.  Inst.  Mining  Engi- 
neers, Oct.  5tb,  1888,  to  appear  in  Transactions,  Vol.  XVII.,  1889.) 


THE  METALLURGY    OF    STEEL 


the  rail  in  water  immediately  after  leaving  the  rolls,  till 
its  temperature  falls  to  V,  then  allowing  it  to  cool  slowly 
in  the  air.  To  equalize  the  cooling,  submerged  jets  of 
water  play  on  the  thick  rail-head.  The  rapid  cooling  to 
V  removes  the  opportunity  for  crystallization  :  the  slow 
cooling  from  V  down  allows  most  of  the  carbon  to  pass  to 
the  cement  state,  and  avoids  the  stresses  of  unequal  con- 
traction which  would  arise  were  the  sudden  cooling  more 
complete.  Toughness  is  promoted  in  both  ways." 

To  further  equalize  the  cooling,  I  suggest  holding  the 
rail  by  a  guard,  which  incloses  web  and  flange  so  as  to  re- 
strict the  circulation  of  water  about  these  thinner  parts,  as 
is  successfully  done  in  hardening  mowing-machine  knives. 

4.  Lowering  the  finishing-temperature,  whether  by 
rolling  slowly,  by  rolling  double  or  quadruple  lengths— 
this  has  been  found  to  improve  the  quality  of  wrought- 
iron  greatly, — by  employing  thicker  piles  or  ingots,  or  by 
throwing  a  jet  of  water,  steam  or  air  on  the  metal  during 
the  last  part  of  the  rolling  so  as  to  cool  it  nearly  or  quite 
to  V,  as  is  done  in  tyre-rolling.  In  case  of  rails  the  thick, 
slowly  cooling  head  may  be  advantageously  cooled  thus 
during  the  late  passes. 

Three  uniformly  heated  steel  bars  cut  from  a  single  bil- 
let were  rolled  by  a  competent  American  metallurgist,  one 
very  fast,  one  normally,  one  very  slowly  :  their  merit  was 
inversely  as  their  finishing  temperature. 

The  tyre-roller's  aim  in  lowering  the  finishing  tempera- 
ture is  that  scale  may  not  form  after  rolling  ceases,  and 
thus  that  the  tyre's  surface  may  be  smooth  :  doubtless  he 
is  sometimes  ignorant  of  the  incidental  great  structural 
benefit  to  his  metal.  Eye-bar  makers,  however,  formerly 
ignorant  of  the  structural  injury  due  to  hot  finishing, 
have  lately  been  forced  by  the  repeated  failures  and  re- 
jection of  hot-finished  eye-bars  when  tested  whole,  to 
lower  their  finishing  temperature  expressly  to  benefit  the 
metal  structurally.  They  hold  the  bars  before  the  last 
passes,  till  they  have  cooled  properly. 

Thermo-tension*  or  subjecting  the  red-hot  metal  to 
high  tensile  stress  which  is  maintained  during  cooling, 
may  perhaps  come  under  this  head.  If,  owing  to  the  ten- 
sion, the  piece  elongates,  or  does  not  shorten  in  conformity 
to  the  cooling,  its  diameter  must  decrease  more  than  con- 
formably to  the  cooling,  which  implies  a  movement  of  the 
particles  among  themselves  :  this,  like  forging,  may  so 


a  U.S.  Patents  368, 133  and  378,083,  August  9th,  1887,  and  February  31st 
1888.  After  leaving  the  rolls  the  rail  has  its  crop-ends  sawn  off  at  ouce  as  usual, 
and  thence  passes  between  feed-rollers,  of  which  several  pairs  grasp  it  firmly,  and 
which  lie  above  a  water-bosh.  When  the  rail  has  arrived  above  this  bosh  the 
rollers  are  stopped,  and  the  bosh  raised  by  bell-crank  levers,  submerging  the  rail, 
while  sprays  of  water  play  on  its  bead  to  equalize  the  cooling,  the  thick  head 
naturally  tending  to  cool  more  slowly  than  the  web  and  flange.  When  the  rail  has 
cooled  so  f  jr  that  its  remaining  heat  would  suffice  when  evenly  distributed  to  bring 
its  temperature  to  V  (a  low  red),  the  bosh  is  lowered,  and  the  rail  thenceforth 
allowed  to  cool  slowly. 

"  Thurston,  Matls.  of  Engineering,  I.,  p.  526  :  Metallurg.  Rev.,  I.,  p.  10.  Also 
Jarolimek,  Journ.  Iron  and  Steel  Inst.,  1885,  II.,  p.  643,  from  Dingler's  Pol. 
Journ  ,  CCLV.,  pp.  1-9,  56-60. 


long  as  it  lasts  suffice  to  prevent  crystallization.  It  is  pos- 
sible that  this  destruction  of  previous  crystallization  oc- 
curs chiefly  or  even  wholly  as  the  metal  cools  past  the  tem- 
perature of  weakness  at  or  near  V,  which  will  be  described 
in  §  256,  D. 

5.  ClemandoF  subjects  bars  of  cherry-red-hot  high-car- 
bon steel  to  a  pressure  of  say  14,000  to  43,000  pounds  per 
square  inch,  exerted  preferably  by  the  smooth,  cold  faces 
of  a  hydraulic  press.     The  steel  is  said  to  be  fine-grained, 
harder  and  stronger  than  unhardened  steel,  yet  practically 
as  ductile,  and  specially  suitable  for  magnets.    The  scanty 
statements  about  it  are  not  over-convincing.  The  rationale 
is  not  known.     It  may  be  that  the  distortion  due  to  the 
pressure  rapidly  breaks  up  any  crystallization  acquired 
during  rising  temperature,  while  the  cold  press-faces  cool 
the  steel  so  fast  as  to  prevent  further  crystallization  and 
to  hinder  the  change  of  carbon  from  the  hardening  to  the 
cement  state.     Indeed,  Lan  finds  that,  under  identical 
conditions,  a  decidedly  larger  proportion  of  the  total  car- 
bon is  in  the  hardening  state  in  steel  treated  by  Cleman- 
dot's  process  than  in  that  cooled  in  the  usual  way.     The 
mean  of  five  pairs  of  concordant  analyses  showed  that  a 
steel  containing  0'70$  of  carbon  had  0'585$  of  hardening 
carbon  when  thus    compressed,  but   only   0'49$   when 
uncompressed. 

This  process  is  probably  inapplicable  to  large  pieces,  as 
the  removal  of  heat  from  them  would  necessarily  be  slow. 
It  is  said  to  be  applied  to  magnets  successfully*1  and  with 
surprising  results,  imparting  to  them  a  coercive  force,  less 
intense  indeed  than  that  due  to  quenching-hardening,  but 
apparently  more  enduring.  For,  while  the  coercive  force 
of  quenching-hardened  steel  falls  greatly  on  tempering, 
Carnot  states  that  that  of  compression-hardened  steel  is 
not  lessened  even  by  reheating  and  forging."  Compres- 
sion-hardening has  further  advantages  over  quenching- 
hardening  in  that  it  neither  cracks  even  the  hardest  steels, 
nor  makes  them  untoolably  hard.  Unlike  quenching- 
and  hammer-hardening  it  apparently  does  not  lower  the 
density.  The  results  in  Table  86  A  are  reported.6 

I  suggest  hastening  the  cooling  by  pressing  with  thick 
copper  blocks,  iced  before  or  during  compression. 

6.  In  Chernoff'1  s  process  the  cooled  forging  or  casting 
is  heated  to  W,  so  as  to  acquire  a  porcelanic  structure, 
then  slowly  cooled.     As  it  is  impracticable  to  heat  exact- 
ly to  W,  and  as  the  porcelanic  structure  is  not  acquired 
till  W  is  reached,  he  recommended  heating  slightly  above 
W ;  and,  on  account  of  the  tendency  to  crystallize  in  cool- 
ing from  above  W,  to  quench  till  the  temperature  fell  to 


c  "Trempe  par  compression,"  Le  Genie  Civil,  V.,  p.  317,  1884 :  Comptes  Rendus 
XCIV.,  p.  952,  April  3d,  1882  :  Journ.  Iron  and  St.  Inst.,  1883,  I.,  pp.  335, 
382.  Cf.  Percy,  idem,  1885, 1.,  p.  31,  who  incorrectly  thinks  that  the  principle  is 
covered  by  Whitworth's  method  of  compression :  the  rate  of  cooling  forms  an 
essential  difference. 

dli.  CMmandot,  Private  Communication,  Sept.  21,  1888. 

«  A.  Carnot,  Kept.  Committee  on  Chemical  Arts,  of  la  Soci4te  d'Encourage- 
ment.  Reprint  "  La  Trempe  par  Compression,"  Paris,  Steinheil.  1886. 


TABLE  86  A.— INPLCEHCE  op  CLEMANDOT'S  PROCESS  OF  COMPRESBION-IIAEDENINO  (CARNOT,  op.  err.). 


Composition. 

Properties  under  tensile  test. 

Specific  gravity. 

Carbon. 

Silicon. 

Mangnn- 
cse. 

Phos- 
phorus. 

Sulphur. 

Tungsten. 

Uncompressed  . 

Compressed. 

Natural. 

Hardened. 

Com- 
pressed. 

Tensile 
strength,    Its. 
per  sq.  in. 

Elastic     limit, 
Ibs.  per  sq.  in. 

Elongation, 
%  in  3  in. 

Tensile 
strength,    Ibs. 
per  sq.  in. 

Elastic     limit, 
Ibs.  per  sq.  in. 

Elongation,    % 
In  8  In. 

1   . 

2  
8 

•10 
•25 

•00 
07 

34 
•12 

•02 
•03 

•03 
•03 

57,600 
60,800 

K!.'.'ll» 

34,180 
32,000 
41,200 

42 
82 
25 

65,100 
73,600 
103,800 

46,900 
49,100 
81,100 

87 
80 
24 

^  .. 

6   

•62 

•81 

•16 
•19 

•22 
•32 

•08 
•03 

•08 
•03 

8-02 

89,000 
118,100 

44,800 
69,700 

24 
10 

108,500 
194,150 

72,500 
113,800 

20 
10 

7-998 
7-769 

V-982 
7  720 

7-ys8 
7-777 

METHODS    OF    HEAT-TREATMENT.       §  250. 


181 


or  below  W,  then  to  cool  slowly  so  as  to  avoid  the  stresses 
which  quenching  to  the  cold  would  cause." 

7.  Coffin's  axle-process,  in  use  at  the  Cambria  Iron 
Works,  goes  a  distinct  step  beyond  ChernofF  s.  Recog- 
nizing  the  tendency  to  crystallize  during  slow  cooling 
from  W  to  V,  Coffin  heats  to  slightly  above  W,  quenches 
to  V,  then  cools  slowly. 

Six  axles  tested  within  a  month  of  adopting  this  process 
showed  the  following  admirable  properties. 


Tensile   stri'n^th.  pounds 
per  si|ii:ire  inch. 

Klonjration 
in  S  inches. 

Contraction 
of  area. 

Elastic. 

Ultimate. 

46,940 
39.120 
42,420 

95,800 
90.900 

87,830 

20 
13  7 
16  5 

42 
16  5 
80-9 

Two  halves  of  an  axle,  one  treated  by  this  process,  the 
other  untreated,  gave  the  following  results." 

Tenstle  strength  *,  pounds 
per  square  inch. 

Klonpation 
In  4  inches. 

Contraction 
of  area. 

Elastic. 

Ultimate. 

Untreated     

80,000 
44,000 

71,S2lt 
72.020 

24-5*  • 
24  07* 

51  5* 
57  1% 

Treated  

Chernoff  obtained  the  following  results.  Of  three  sam- 
ples broken  from  the  same  bar  of  steel,  A  was  simply 
cooled  slowly  after  forging :  B  was  reheated  to  W°  and 
slowly  cooled  :  C  was  reheated  to  W,d  quenched  in  water 
to  a  reddish  brown,  then  slowly  cooled.  The  size  of  grain 
was  as  follows : 

TABLK  87.— EFFECT  OF  COFFIN'S  PROCESS  ON  Sim  OF  GRAIN. 


» 

Mean  dianiet 
pra 

er  of  central 

IIS. 

Inches. 

Mm. 

0-1414 

0  0048 
0  0004 

8-675 
0  122 
0  010 

C,  reheated  a  little  higher  than  B,  quenched  to  V,  then  slowly  cooled  .  . 

A  broke  under  a  single  hand-hammer  blow,  B  required 
five  such  blows,  C  could  be  broken  only  by  a  steam-hammer. 
Of  a  similar  series  from  a  railway-tyre,  A  broke  under  one 
blow  of  a  5-ton  hammer,  B  under  four  blows,  and  C  under 
five  heavy  blows. 

In  thus  quenching  nearly  to  V  instead  of  barely  below 
W  as  he  himself  thought  sufficient,  Chernoff  practically 
used  Coffin's  process  in  these  cases,  but  apparently  blind- 
ly, and  without  recognizing  its  nature  or  advantages,  for 
clearly  he  believed  that  no  important  crystallization  oc- 
curs below  W.  Hence  in  practicing  his  own  process,  he 
and  others  might  often  or  even  habitually  cool  to  but 
slightly  below  W  instead  of  to  V. 

The  rail-process  seems  specially  adapted  to  rolled,  the 
axle-  to  hammered  pieces  :  for  the  time  offered  for  crys- 
tallization in  one  part  of  a  hammered  piece  after  it  has 
been  hammered,  and  while  the  remainder  of  the  piece  is 
hammering,  may  permit  much  crystallization,  which 
simple  quenching  would  not  remove,  but  which  is  removed 
when  the  temperature  is  later  raised  to  W  Beyond  this 
the  more  expensive  axle-process  should  give  a  finer  frac- 
ture and  hence  better  quality  than  the  rail -process. 

These  methods  differ  from  Jarolimek's  interrupted  cool- 
ing (p  24),  in  that,  while  retaining  a  fine-grained  struct- 


a  Revue  Universelle,  8d  Ser.,  VII.,  p.  415,  1877. 

bTrans.  Am.  Soc.  Mechan.  Engineers,  IX.,  p.  143:  Mechanics,  Dec.,  1887, 
p.  317. 

c  "  Un  peu  au-dessus  du  rouge  clair  non  brillant." 

11  "  Au  rouge  clair."  Thus  the  second  piece  may  have  been  raised  to  a  little 
higher  temperature  than  the  third  :  yet  hardly  enough  to  account  for  the  great 
difference  in  the  size  of  their  grains. 


ure,  they  aim  to  avoid  hardening.  Lead-hardening6 — 
quenching  in  molten  lead,  said  to  be  used  in  France  for 
armor-plates — should  give  an  intermediate  result,  retain- 
ing part  of  the  carbon  in  the  hardening  state,  while  setting 
up  far  less  severe  stresses  than  those  due  to  oil-quenching. 
The  severity  of  these  has  led  many  eminent  engineers— 
among  them  Adamson,  Bramwell,  Maitland  and  J .  Eiley,— 
to  question  the  advisability  of  oil -hardening.'  It  seems 
probable  that  hardening  must  in  many  cases,  e.  g.  those 
of  guns,  projectiles  and  armor-plates,  be  made  less  severe 
than  at  present,  retaining  much  of  the  carbon  in  the  hard- 
ening state,  but  avoiding  great  intensity  of  stress,  whether 
by  less  violent  cooling,  (as  with  molten  lead):  or  by  inter- 
rupting or  retarding  the  cooling  after  it  has  passed  a  cer- 
tain point,  (as  by  dipping  momentarily  in  oil,  then  in 
lead,  or  vice  versa,  according  to  the  conditions  of  the  case): 
or  by  tempering  after  hardening. 

To  Find  the  Temperatures  W  and  V. — A  cold  steel  bar, 
preferably  but  not  necessarily  of  like  composition  with 
the  steel  to  be  treated,  and  about  f  "  square  by  four  feet 
long,  is  placed  in  a  hot  furnace,  its  ends  resting  on  two 
bricks.  When  its  temperature  reaches  W  it  will  bend 
down  suddenly.  Remove  and  support  it  at  its  ends  in  the 
open  air:  when  its  temperature  falling  reaches  V  it  will 
again  bend  suddenly.  Da  capo,  quantum  libet.  (Cf.  § 
254,  B,  3,  and  §  256,  D). 

Or  heat  such  a  bar  to  redness,  nick  all  around  at  nine 
points  half  an  inch  apart,  the  first  next  to  one  end;  cool 
gently  ;  heat  this  end  to  dazzling  whiteness,  the  heat 
running  back  by  conduction  till  the  last  nick  is  nearly 
red  ;  note  the  temperature  at  each  nick  ;  quench  ;  wipe  ; 
break  at  the  nicks.  That  which  has  the  finest  grain  was 
near  W  when  quenched.  Here  the  color  produced  by 
spotting  with  nitric  acid  of  1'23  sp.  gr.,  the  hardness,  and 
probably  the  coercive  force  change  abruptly. 

V  may  be  recognized  by  the  sudden  loss  and  the  sudden 
recovery  of  magnetism  as  the  temperature  rises  and  falls 
past  it. 

Enormous  advantages  may  be  anticipated  from  the  sys- 
tematic study  of  heat-treatment,  of  which  we  now  know 
but  little.  In  treating  important  pieces  the  temperature 
should  be  controlled  by  pyrometer,  not  the  eye. 

CHANGES   OF  CRYSTALLIZATION,    ETC. 
THE  SALIENT  FEATUKKS  OF  CRYSTALLIZATION  Can    now 

be  considered  in  a  more  general  way. 

§251.  Governing  Crystallization.  The  following  cases, 
though  insufficient  to  establish,  go  to  show  that  in  the 
struggle  for  dominance  between  the  component  minerals 
of  steel,  those  (1)  which  separate  earliest  and  (2)  those 
most  abundantly  present  arc  best  equipped  :  one  of  these 
will  usually  determine  the  general  structure  of  the  mass, 
and  distribute  the  others,  often  as  a  mesh  work  between 
its  own  crystals. 

Sorby  finds  that,  in  those  parts  of  wrought-iron  which 
have  but  little  pearlyte,  this  mineral  is  distributed  as  a 
mesh  work  between  the  crystals  of  ferrite :  in  adjoining 
regions,  where  pearlyte  is  in  relatively  large  proportion,  it 


e  Gauticr,  Jour.  Iron  and  St.  Inst.,  1S88,  I.,  p.  159. 

f  Maitland,  "The  Treatment  of  Gun-Steel,"  excerpt  Proc.  Inst.  Civ.  Eng., 
LXXXIX.,  pp.  21,  48,  58,  77,  129;  1887.  It  appears  to  be  no  uncommon  thing 
for  hardened  steel  projectiles  to  crack  or  even  burst.  Bramwell  states  that  a 
visitor  to  a  projectile-factory  was  warned  lately  that  '•  those  things  are  going  off 
at  aU  times,  and  occasionally  they  fly  with  very  considerable  violence,"  (Prince 
Rupert's  d;  ops  one  would  say)  and  that  a  steel  gun-tube  has  broken  to  pieces  iu 
the  lathe. 


isa 


THE    METALLURGY     OF    STEEL. 


apparently  has  crystallized  first  and  distributed  the  fer- 
rite  between  its  crystals.  So,  tor,  in  cast-iron  :  in  grey 
iron,  rich  in  graphite,  the  graphite  appears  to  have  crys- 
tallized first  and  determined  the  structure  of  the  whole : 
in  No.  3  pig-iron  Sorby  finds  that,  in  those  regions  which 
contain  the  most  graphite,  this  mineral  appears  to  govern 
the  crystallization,  and  we  may  surmise  that  this  happens 
because,  though  the  total  quantity  of  graphite  is  small, 
yet,  owing  to  its  high  melting  point,  it  tends  to  crystallize 
very  early.  In  the  less  graphitic  portions  of  the  same  pig 
the  pearlyte  appears  to  govern  the  crystallization  of  the 
whole,  and  so  it  does  throughout  the  still  less  graphitic 
forge  pig. 

Again,  in  refined  white  cast-iron,  in  which  there  is  about 
twice  as  much  pearlyte  as  cementite,  the  pearlyte  seems 
to  govern  :  in  spiegeleisen  these  two  minerals  are  in  about 
equal  proportions,  and  here  cementite  seems  to  govern. 

§252.  RECRYSTALLIZATION. — We  can  readily  under- 
stand that  the  minerals  thus  distributed  as  a  meshwork 
between  the  crystals  of  their  more  powerful  elder  brothers 
should  be  in  unstable  equilibrium,  and  that,  when  oppor- 
tunity offers,  they  should  seek  to  acquire  their  normal 
crystalline  polarity,  to  break  their  bonds,  to  crystallize 
anew.  So,  too,  crystals  which  have  been  distorted  by 
forging  or  by  the  interstratal  motion  due  to  quenching, 
and  crystals  of  minerals  new-created  by  change  of  affin- 
ities due  to  change  of  temperature  as  at  V  and  W,  should 
seek,  the  former  to  recover,  the  latter  to  attain  their  nor- 
mal polarity.  Those  whose  growth  has  been  dwarfed  by 
short  or  feeble  heating  may,  when  softening  high  temper- 
ature again  permits,  remarshal  their  squads  into  platoons, 
companies,  regiments,  the  aggregating  crystalline  ten- 
dency asserting  itself  and  forming  larger  and  larger  crys- 
tals. Each  crystal  in  growing  must  feed  on  its  neighbors, 
drawing  a  little  perhaps  from  the  mesh-work  which  sur- 
rounds it.  Hence,  if  the  average  size  of  the  crystals  is  to 
increase,  some  must  cease  to  exist,  must  merge  in  their 
neighbors.  If,  be  it  from  more  robust  individuality,  be  it 
because  separated  by  a  greater  thickness  of  mesh-work, 
the  neighbor  on  one  side  resist  assimilation  more  stub- 
bornly than  that  on  the  other,  growth  will  be  uneven : 
while  under  extremely  favorable  conditions,  e.  g.  during 
very  long  strong  heating,  these  asymmetrical  grains  may 
give  and  take  till  symmetrical  cubes  or  octahedra  result. 
And  such  is  the  case. 

The  structure  of  many  minerals,  e.  g.  magnetite,  reminds 
us  in  one  respect  of  that  of  iron.  We  find  the  grains 
usually  of  most  irregular  shape,  approaching  by  insensi- 
ble gradations,  as  conditions  are  more  and  more  favorable, 
to  the  almost  absolute  perfection  of  crystalline  form  which 
individiial  magnetite  crystals  occasionally  show.  So  too  in 
granular  iron,  the  grains,  usually  irregular,  under  favor- 
ing circumstances  are  occasionally  extremely  well  de- 
veloped crystals  ;  and  between  the  two  extremes  the  grada- 
tions appear  as  insensible  as  in  case  of  magnetite. 

Hence  we  ma  y  regard  the  uneven,  asymmetrical  but  often 
smooth-faced  grains  as  very  imperfect  crystals,  or  at  least  as 
fragments  of  crystals  broken  through  their  cleavage  planes.8 


a  Thurston  indeed  thinks  that  granular  structure  is  confounded  with  real  crys- 
tallization :  and  that  granular  fracture  and  crystalline  structure  are  apparently 
distinct  in  nature  (Mat'ls  of  Engineering,  II.,  pp.  579-82).  Most  of  us,  how- 
ever, would  accept  the  dictum  "All  granular  and  fibrous  (inorganic)  bodies" 
—"must  be  regarded  as  collections  of  imperfectly  formed  crystals,"  at  least  for 
cases  like  the  present.  (Watts,  Dictionary  of  Chemistry,  II.,  p.  115). 


Finally,  special  conditions  may  force  a  certain  mode  of 
growth,  to  which  the  metal  is  not  naturally. inclined  :  on 
heating  after  these  conditions  have  ceased  to  exist,  these 
quasi  abnormal  crystals  may  readily  give  way  to  more 
normal  ones.  Such  are  the  columnar  crystals  forced  on 
solidifying  steel  ingots  by  the  rapid  removal  of  heat  by 
the  mould,  and  removed  by  simple  reheating. 

Our  fracture  studies  tell  us  little  of  the  nature  of  the 
crystalline  changes  which  they  record :  but  of  this 
nature  something  has  been  learnt  from  polished  sections. 
AVe  will  now  consider  certain  prominent  cases  of  recrystal- 
lization,  and  incidentally  certain  features  of  the  initial 
crystallization. 

§  253.  RECKYSTALLIZATION  ON  SLOW  COOLING  FROM 
THE  MELTING  POINT. — In  an  ingot  of  hard  cast  steel  there 
are,  to  judge  from  Sorby' s  description,  the  records  of 
three  successive  crystallizations.  First  we  have  the  large 


Fig.  63A. 

TranBverse  section  of  cftst-stocl  inpot,  Sorby.    Nrarly  wholly  pearly te. 

prismatic  columnar  crystals,  normal  to  the  cooling  sur- 
face, and  conspicuous  on  fracture  (Figures  64,  65  and  68). 
They  apparently  represent  the  first  crystallization,  be  it 
of  hardenite,  be  it  of  the  hypothetical  mother-of-pearlyte, 
which  in  this  case  has  expelled  the  excess  of  cementite 
present,  distributing  it  as  an  elongated  mesh-work  between 
the  crystals.  Secondly,  these  columnar  crystals  are 
chiefly  composed  of  groups  of  pearlyte,  disposed  with  lit- 
tle or  no  relation  to  the  columnar  structure,  indeed  shoot- 
ing from  one  column  into  another,  and  apparently  formed 
from  the  substance  of  the  primary  crystals  by  a  second 
crystallization.  Finally,  by  a  third  crystallization,  each 
of  the  individual  members  of  the  radial  groups  of  pearlyte 
has  split  into  parallel  layers  of  cementite  and  ferrite, 
which  apparently  occupy  the  space  previously  occupied  by 
a  simple  undivided  crystal. 

The  composite  ingot-structure,  recognized  in  large  part 
by  color-differences  and  by  the  use  of  high  powers,  is 
shown  very  imperfectly  by  photography,  Figure  63  A. 

So  Osmond  and  Werth,  on  etching  the  polished  section 
of  an  ingot  containing  0-50$  of  carbon,  find  that  it  is  com- 
posed of  (a)  simple  cells  in  (b)  dendritic,  mutually  limit- 
ing groups,  and  these  again  may  form  (c)  complex  cover- 
less  agglomerations." 

In  connection  with  these  evidences  of  repeated  recrys- 
tallization,  it  is  interesting  to  recall  the  repeated  evo- 
lutions of  heat  during  the  slow  cooling  of  iron,  which 

b  Annales  des  Mines,  8th  ser.,  VIII.,  p.  13,  1885. 


RECRYSTALLIZATION.      §  253. 


183 


manifest  themselves  by  retarding  or  even  reversing  the 
fall  of  temperature  (§§  254-7). 

This  columnar  ingot-structure  is  the  less  marked  the 
freer  the  steel  from  carbon,  perhaps  because  the  soft  steels 
pass  less  directly  from  the  liquid  to  the  solid  state  than  the 
harder  ones,  the  pasty  condition  which  characterizes  their 
solidification  being  opposed  to  the  formation  of  crystals." 
In  small  ingots,  say  three  inches  in  diameter,  the  columns 
may  extend  to  the  centre  (Figures  27-8,  §  222,  p.  148) :  in 
larger  ones  they  form  an  external  layer,  which  often  ends 
quite  abruptly,  and  is  succeeded  by  a  region  with  a 
granular  or  polyhedral  structure.  The  columnar  crystals 


wards  slackens,  the  prismatic  tendency  weakens  :  the  sud- 
den transition  from  the  prismatic  to  the  equiaxed  formation 
suggests  that  no  resultant,  no  compromise  is  possible,  so 
that  from  the  moment  when  the  equiaxial  tendency  out- 
weighs the  prismatic  it  reigns  alone,  as  if  its  rival  were  not. 
Chernoff0  pointed  out  that,  in  large  ingots,  this  granular 
region  is  succeeded  by  an  inner  more  compact  one.  He 
refers  the  granular  region  to  the  interstratal  movements 
which  must  occur  during  even  slow  cooling,  and  which 
must  be  especially  great  in  large  ingots,  and  more  marked 
near  the  outside  than  in  the  centre,  because  much  of  this 
motion  must  have  ended  before  the  centre  has  solidified. 
We  may  conceive  that  this  motion,  occurring  while 
the  region  which  we  find  granular  is  at  a  certain  critical 
temperature  of  inter-crystalline  weakness,  breaks  or 
weakens  the  mesh-work  which  surrounds  the  crystals, 
or  at  least  weakens  the  inter-crystalline  adhesion,  so 


Fig.  64.  Fig.  65. 

adhere  to  each  other  comparatively  feebly  :  this  favors 
external  cracking,  both  in  cooling  and  in  the  early  passes 
in  the  blooming  mill.  These  cracks  usually  pass  between 
the  columnar  crystals,  revealing  their  surfaces,  rather  than 
across  them.  Figures  64-5  show  bunches  of  these  crys- 
tals in  my  collection,  from  the  outside  of  a  "cobble"  or 
ingot  which  cracked  so  badly  that  it  had  to  be  cut  up.  In 
Figure  64  the  columns  have  been  twisted  by  the  rolls  :  the 
granular  structure  is  also  seen.  Figure  68  shows  the  col- 
umnar structure,  and  its  abrupt  change  to  the  granular. 

The  asymmetry  of  these  columns  may  be  referred  to 
three  facts. 

1.  The  distance  between  the  main  axis  of  adjoining 
columns  varies  irregularly.  2.  The  directions  of  the  lat- 
eral axes  of  neighboring  crystals  bear  little  relation  to 
each  other.  For  both  these  reasons  the  lateral  growth  of 
a  given  column  is  likely  to  be  interrupted  by  that  of  its 
neighbors  at  different  distances  from  its  main  axis  on  its 
different  sides.  3.  That  the  different  lateral  axes  of  a 
given  column  appear  to  grow  at  different  rates."  These 
lateral  axes  are  sketched  in  Figure  66,  and  the  boundaries 
of  the  columns  in  Figure  67. 

The  exterior  columnar  structure  is  clearly  due  to  the 
rapid  escape  of  heat  from  the  shell  of  the  ingot  into  the 
mould.  We  may  suppose  that  the  metal  naturally  tends 
to  crystallize  in  equiaxed  grains  :  that  there  is  a  struggle 
between  this  tendency  and  the  tendency  to  crystallize  in 
indefinitely  long  prisms  which  the  rapid  outward  cooling 
sets  up.  As  the  walls  thicken  and  the  flow  of  heat  out- 


Longitudinal  sections  of  steel  ingots,  transverse  to  main  axes  of  the  columnar  crystals.  (Cbernoff.) 

Fig.  66.  Fig.  67. 

Supposed  lateral  axes  of  the  columnar  crystals.  Resulting  irregular  cross-section  ot 

the  columnar  crystals. 


a  Chernoff,  Rev.  Universelle,  3d  ser.,  VII.,  p.  139,  1880. 
bldem,  p.  141. 


Fig.  68. 

Cross-section  of  stee  ingot,  natural  size,  showing  columnar  and  granular  structures,  and  blowholes. 

(Martens.) 

that  when  rupture  subsequently  occurs  it  passes  be- 
tween the  crystals  :  while  in  the  central  portion,  the  inter- 
crystalline  adhesion  being  unimpaired,  rupture  strikes 
more  or  less  into  the  bodies  of  the  crystals,  the  fracture  is 
more  compact. 


*  Idem,  pp.  131,  143.    I  have  carried  these  speculations  a  step  beyond  his. 


THE    METALLURGY    OF    STEEL. 


Osmond  and  Werth*  explain  the  granular  region  by 
supposing  that  it  begins  at  the  moment  when  the  interior 
as  a  whole  has  reached  the  freezing  point :  from  this  time 
on  solidification  occurs  from  internal  centres  of  organi- 
zation growing  in  all  directions.  But  is  there  such  a 
moment  ?  Will  not  each  successive  layer  reach  this  point 
after  the  one  outside  it  ? 

§  254.  RECKYSTALLIZATION  ON  REHEATING  SLOWLY 
COOLED  METAL. — A.  On  simple  prolonged  exposure  to  a 
TiigJi  temperature,  to  judge  from  Sorby's  microscopic 
studies,  it  seems  that,  even  when  no  chemical  change  is 
apparent,  each  of  the  several  minerals  draws  together 
and  separates  more  distinctly  from  the  others.  Thus  the 
pearlyte  and  free  ferrite  separate  from  each  other  as  more 
distinct  crystals  when  wrought-iron  is  annealed,  and  some 
of  the  combined  cementite  separates  from  the  pearlyte : 
when  steel  of  0'49$  of  carbon  is  annealed,  the  free  ferrite, 
originally  distributed  as  mesh-work  plates  within  and  be- 
tween the  dominant  crystals  of  pearlyte  (Figure  56),  draws 
together  into  grains. b 

B,  at  V. — During  the  gradual  heating  of  iron  several 
marked  phenomena  occur  at  or  near  V.  The  rise  of 
temperature  is  retarded  or  perhaps  even  reversed*1 :  the 
expansion  is  checked  and  reversed,  so  that  the  metal 
contracts  momentarily,  and  then  re-expands" :  a  dry  crack- 
ling sound  is  heard0 :  the  thermo-electric  deportment 
becomes  anomalous6 :  the  coercive  f orcefgh  and  the  power 
of  being  rendered  a  temporary  magnetg  (whether  by 
electric  current  or  by  another  magnet)  and  hence  of  being 
attracted  by  the  magnet,'  almost  disappear,  the  latter  at 
least  through  a  series  of  distinct  and  separate  diminutions8: 
and  the  specific  heat  (as  inferred  from  the  quantity  of  heat 
given  out  by  the  metal  when  immersed  in  a  calorimeter) 
suddenly  increases,  remaining  astonishingly  high  from  660 
to  720°  C.,  when  it  again  descends  somewhat,  but  remains 
about  twice  as  great  as  at  the  ordinary  temperature.1  The 
changes  in  attraction  by  the  magnet  and  in  specific  heat 
have  been  directly  proved  to  be  simultaneous3 :  the  other 
changes,  too,  as  far  as  we  can  tell  withoiit  precise  measure- 
ments, occur  simultaneously  with  these. 

Nickel  and  cobalt  lose  their  power  of  being  attracted  by 
the  magnet,  and  undergo  like  simultaneous  changes  in 
specific  heat,j  nickel  between  220°  and  400°  C.,  cobalt  at 


a  Annales  des  Mines,  8th  ser.,  VIII.,  p.  60,  1885.  The  resemblance  which  they 
note  between  llie  granular  region  and  lead  bullets  powerfully  pressed  together  in 
a  mould  does  not  imply  that  the  former  grows  under  p  essure,  for  the  granulation 
occurs  in  central  regions  which  are  not  likely  to  be  in  compression  during  or  after 
freezing.  The  hexagonal  structure  of  the  bee's  honey-comb  does  not  imply  press- 
ure, unless  indeed  of  circumstances. 

b  Jour.  Iron  and  Steel  Intl.,  1887,  I.,  pp.  269,  272. 

c  Barrett,  Phil.  Mag.  XLVL,  p.  473,  1873. 

d  Osmond,  Transformations  du  Fer  et  du  Carbone,  1888. 

eTait,  Trans.  Roy.  Soc.  Edinbgh.,  XXVII. ,  p.  135,1873:  Proc.  Roy.  8oc. 
Edinbgh.,  VIII.,  p.  33,  1873. 

f  Gilbert. 

gGore,  Phil.  Mag.,  XL.,  p.  170,  1870. 

h  Coercive  force,  or  retentiveness,  the  power  of  becoming  and  of  remaining  a 
permanent  magnet. 

i  Pionchon,  Comptes  Rendus,  CII.,  p.  1455,  1886.  Pionchon  obtained  the 
following  expressions  for  the  specific  heat  of  iron  : 

From 0°  to  660°  q*  =  0-11012t  +  0-000025,333.33«'  +  0-000,000,054,66664<:'. 

Prom  660°  to  720°  q*  =  0-57803J  —  0'001,435,987(2  +  0-000,001,195t3. 

From  720°  to  1,000°,  g0'  =  0'218(  —  39. 

From  1050°  to  1200°,  g0'  =  0-198,87*  —  23  44. 

Comptes  Rendus,  CII.,  pp.  675,  1454  :  GUI.,  p.  1122. 

From  this  it  appears  that  during  the  cooling  of  iron  two  abnormal  evolutions 
of  heat  occur;  a  lower  one  between  660°  and  720°  C.,  a  r  i,  absorbing  5-3  calories, 
and  a  higher  one  at  about  1050°. 

1  Idem.,  CIII.,  p.  1184,  1886, 


about  900°  C.  The  thermo-electric  power  of  nickel,  also, 
behaves  anomalously  at  the  critical  point  of  this  metal.6 
Of  these  phenomena,  the  loss  of  magnetism,  the  thermo- 
electric change,  the  change  of  specific  heat  and  the  retard- 
ation of  rise  of  temperature  have  been  noted  in  almost  and 
in  some  cases  quite  carbonless  iron  :  the  momentary  con- 
traction, however,  readily  detected  in  hard  iron  and  espe- 
cially in  steel,  could  not  be  detected  in  very  soft  iron,  ft 
least  in  certain  specimens. 

If  the  quenching-temperature  of  steel  be  gradually 
raised,  the  coercive  force  of  the  quenched  metal  remains 
nearly  constant  till  some  temperature  reported  to  be  §75° 
C.,  or  between  V  and  W,  is  reached  :  with  further  rise  of 
temperature,  at  least  to  above  1,075°  C.,  the  coercive  force 
increases  rapidly. 

C,  at  W.  To  the  sudden  porcelanization  of  fracture  which 
occurs  when  steel  is  heated  to  W,  correspond  not  only  the 
apparently  simultaneous  sudden  change  from  cement  to 
hardening  carbon  and  sudden  increase  of  hardening  power, 
but  also  the  appearance  of  polished  sections,  and  certain 
very  marked  thermal  and  other  phenomena. 

/.  Polished  Sections  :  By  their  study  Sorby  finds  that 
when  a  steel  ingot  of  (V49$  of  carbon  is  quenched  from 
redness,  the  composite  structure  with  its  marks  of  succes- 
sive crystallizations  is  no  more.  Traces  of  the  original 
net-work  can  be  seen :  "but  on  the  whole  the  grain  is  so 
fine  and  uniform  that  even  a  power  of  400  linear  fails  to 
reveal  the  ultimate  constitution,  and  shows  little  more 
than  that  the  grains  are  somewhere  about  ?^n  inch  in 
diameter." k  Just  as  our  fracture  studies  show  that  the 
crystalline  force  exerted  when  cement  changes  to  harden- 
ing carbon  at  W  is  so  great  as  to  completely  eradicate  all 
previous  crystallization,  so  the  microscope  teaches  that 
this  force  here  reunites  the  comparatively  widely  scattered 
particles  of  the  different  minerals,  forming  a  single  new 
compound,  hardenite,  though  to  do  this  it  probably  has 
to  move  some  of  them  considerable  distances.  Osmond 
and  Werth  too  cannot  find  their  composite  cells  in  etched 
polished  sections  of  hardened  steel ;  and  its  structure  as 
revealed  by  Weyl's  method  differs  greatly  from  that  of 
unhardened  steel.1  While  the  temperature  at  which  these 
changes  in  the  appearance  of  polished  sections  occurs  has 
not  been  determined  directly,  we  infer  that  it  probably 
is  W,  from  the  fact  that  the  fracture  and  the  condition  of 
carbon  change  at  this  point,  and  that  the  hardening  power 
is  acquired  here. 

2.  Coffin's  Wefd.m — If  a  bar  of  tool  steel,  say  f  inch 
square,  be  broken,  and  the  fresh  fractures  placed  in  appo- 
sition ;  or  if  two  of  its  surfaces  be  accurately  planed  by 
grinding  and  put  together :  and  if  the  pieces  thus  in  close 
contact  be  inclosed  in  platinum  foil  to  exclude  the  air, 
and  heated  to  W  in  the  flame  of  a  Bunsen  burner  or  other- 
wise, they  will  unite  more  or  less  completely.  This  does 
not  seem  to  be  like  the  cold  welding  of  lead,  for  it  does 
not  appear  to  occur  below  W.  It  is  here  interesting  to 
note  ChernofFs  remark  that  the  intimate  contact  of  two 


k  Jour.  Iron  and  Steel  Inst.,  1887,  I.,  p.  276. 

1  Annales  des  Mines,  8th  Ser.,  VIII.,  pp.  14,  8. 

mTrtns.  Am.  Soc.  Mecb.  Eng.,  IX.,  to  appear.  Mr.  Coffin  performed  this  ex- 
periment successfully  at  the  Philadelphia  meeting  of  this  society,  using  a  Bunsen 
burner  :  and  I  have  pieces  which  he  has  welded,  which  by  their  sharpness,  color 
and  freedom  from  scale  show  bey<  nd  question  that  they  were  united  either  at  a 
temperature  very  far  below  the  usual  welding  point  of  steel,  or  else  with  almost 
perfect  exclusion  of  oxygen. 


PHENOMENA    DURING    HEATiNG    AND    COOLING.       §  256. 


185 


surfaces  of  iron  of  the  same  nature  heated  to  a  tempera- 
ture above  B  (i.  e.  W  ?)  suffices  to  unite  them.* 

Mr.  Coffin  reasonably  ascribes  the  tmion  to  the  sudden 
and  violent  change  of  crystallization  which  occurs  at  W. 
The  elements  rearrange  themselves,  seeking  new  alliances 
with  such  energy  that  neighboring  molecules,  not  only  in 
different  crystals  but  actually  in  different  bars,  unite. 

3.  Coffin' s  Bend. — A  steel  bar  A  was  heated  to  above  W 
and  then,  without  removing  it  from  the  furnace,  supports 
were  placed  beneath  its  ends,  and  the  temperature  held  con- 
stant for  thirty  minutes,   during  which  no  perceptible 
deflection  occurred.  It  was  withdrawn,  cooled,  and  replaced 
on  supports  in  the  hot  furnace.  When  its  temperature  had 
again  risen  to  about  W  the  bar  began  to  deflect.1" 

In  a  similar  experiment  tried  in  my  presence,  two 
straight  steel  bars,  2  and  3,  containing  0-67$  of  carbon,  $• 
inch  square  and  4  feet  long,  were  heated  near  each  other 
in  a  reverberatory  furnace.  3  was  supported  at  its  ends 
only,  2  lay  on  the  level  hearth.  150  seconds  after  enter- 
ing the  furnace  and  while  at  a  low  yellow  3  began  to  bend, 
and  bent  about  one  inch  in  the  next  120  seconds.  It  then 
appeared  to  cease  bending.  Removed  from  the  furnace 
5'5  minutes  later  and  slowly  cooled,  its  total  deflection 
was  found  to  be  1  '06  inches,  showing  that  practically  all 
the  bending  had  occurred  during  two  minutes  while  it  was 
passing  a  certain  critical  range,  above  which  it  ceased  to 
bend.  2,  now  apparently  hotter  than  3  had  been  when 
bending,  was  supported  at  its  ends :  no  deflection  could  be 
detected. 

Clearly  the  bending  here  is  not  due  to  the  temperature 
as  such,  but  to  something  which  happens  while  the  tem- 
perature is  passing  W,  and  apparently  during  the  change 
from  the  cement-  to  the  hardening-carbon  crystallization. 
Like  instances  of  the  temporary  weakening  of  steel  during 
other  changes  of  crystallization  will  be  described  in  §§  255 
and  256  D. 

4.  Tliermal  PJienomena. — The  apparent  specific  heat, 
at  least  of  pure  iron,  rises  suddenly  at  about  1,050°  C. 

§255.  RECKYSTALLIZATION  ON  REHEATING  QUENCHED 
STEEL. — In  line  with  Brinnell's  experiment  showing  that, 
though  the  cement-carbon  hackly  fractures  of  annealed 
steel  do  not  change  on  reheating  to  below  W,  the  harden- 
ing-carbon granular  fractures  do  ;  with  the  heat  evolution 
and  with  the  change  of  carbon  from  hardening  to  cement 
which  occur  when  hardened  steel  is  reheated  to  210°  C. 
(410°  F.,  a  pale  straw  color),  is  the  following  experiment 
of  Coffin's,  showing  that  hardened  steel  becomes  more 
flexible  on  slight  rise  of  temperature  than  tempered,  i.  e. 
partly  annealed  steel  does. 

Two  exactly  similar  half-inch  square  steel  bars,  five 
inches  long,  A  and  B,  Figure  69,  were  hardened.  A  was 


EA 

C 

B 

3 

e 

Fig.  69. 

then  heated  to  a  blue  tint,  part  of  its  carbon  presumably 
becoming  cement.  They  were  then  clamped  together  at 
the  ends,  wedged  apart  slightly  in  the  middle,  heated 
and  uniformly  to  a  light  straw  color,  and  slowly 


•  Revue  Universelle,  1877, 1. 

b  Trans.  Am,  Soc.  Civ.  Eng.,  XV.,  p.  324,  1887. 


cooled.  A,  in  which  no  change  of  carbon  should  have 
occurred,  retained  its  previous  shape,  while  B,  whose  car- 
bon should  have  changed  in  part  to  cement  during  heat- 
ing, became  slightly  concave  towards  its  mate.c 

The  flexibility  of  steel  under  these  conditions  seems  to 
be  known  and  taken  advantage  of  by  makers  of  steel  tools, 
who  correct  the  shape  of  the  hardened  tools  slightly,  by 
pressure  applied  on  reheating  them  to  but  not  above  a 
very  light  straw  tint.*1 

§  256.  RECRYSTALLIZATION  DURING  SLOW  COOLING 
FROM  W. — Here  a  remarkable  evolution  of  heat,  known 
as  the  "after-glow,"  ' •  recalescence "  or  "Gore's  phe- 
nomenon," manifested  by  marked  rise  of  temperature  and 
re-expansion,  and  accompanied  by  great  temporary  in- 
crease of  flexibility,  occurs,  beginning  apparently  as  the 
temperature  approaches  V,  which  as  we  have  seen  ap- 
pears to  be  a  critical  point  for  the  change  of  carbon  from 
hardening  to  cement,  and  of  fracture  from  granular  to 
hackly.  Its  intensity  increases  with  the  proportion  of 
carbon  present.  Barrett  failed  to  detect  it  in  case  of  man- 
ganese steel,"  nor  could  I  detect  it  by  the  eye  in  case  of 
the  tungsten  steels  Nos.  5  and  6  of  Table  34.  But  I  found 
it  well  marked  in  case  of  chrome  steel. 

Other  but  less  marked  liberations  of  heat  during  cool- 
ing, and  also  during  rise  of  temperature,  will  be  consid- 
ered in  §  257. 

A.  The  rise  of  temperature,  so  marked  as  to  force  itself 
on  the  attention  of  several  observers  independently,  is 
readily  detected  by  watching  in  a  dark  place  the  gradual 
cooling  of  a  flat  high-carbon  steel  bar,  which  has  been 
highly  heated  at  one  end.  The  color  does  not  die  out 
gradually,  as  in  the  case  of  a  bar  of  platinum,  copper  or 
wrought-iron  (7  to  10,  Figure  70),  but  we  get  the  remark- 
able phenomena  observed  by  Brinnell  and  shown  in  1  to  5, 
Figure  70.  A  bright  band  suddenly  appears  near  the 
boundary  between  the  yet-glowing  and  the  non-glowing 
portions  of  the  bar,  and  gradually  spreads  over  the  whole 
surface  of  the  glowing  region.  This  indicates  that  as  the 
temperature  of  each  point  falls  to  a  certain  critical  degree, 
probably  V,  it  again  rises.  After  this  the  color  dies  out  nor- 
mally, as  in  7  to  10.  The  after-glow  may  also  be  detected 
by  comparing  in  a  dark  place  the  appearance  during  cool- 
ing of  a  wrought-iron  and  of  a  high-carbon  steel  bar, 
initially  at  the  same  temperature.  The  cooling  of  the 
steel  first  outstrips  that  of  the  wrought-iron  :  but  soon  the 
wrought-iron  overtakes  the  steel,  which  indeed  brightens 
visibly. 

Barrett  has  proved  that  there  is  an  actual  increase  of 
thermal  as  well  as  of  luminous  radiation'  at  the  critical 
point  in  case  of  cooling  steel. 

C.  The  actual  expansion  which  accompanies  the  after- 
glow has  been  detected  by  Gore,g  Barrett,11  and  Coffin,1 
and  has  set  hundreds  or  thousands  of  mill-men  puzzling 
over  the  numerous  reversals  of  curvature  of  rails  on  the 
hot-bed.1  Coffin  found  that  the  retardation  of  contraction 
increased  greatly  with  the  proportion  of  carbon.  A  four- 


c  Trims.  Am.  Soc.  Civ.  Eng.,  XV  ,  p.  324,  1887. 
dT.  R.  Almond,  Trans.  Am.  SDC.  Mech.  Eng.,  IX.,  p.  151,  1888. 
e  Discussion  of  a  paper  on  manganese  steel,    excerpt  Proc.   Inst  Civ. 
XCIII.,p.  116,  1887-8. 
f  Phil.  Mag.,  XLVI.,  p.  476,  1873. 
gPhil.  Mag  ,  XXXVIII.,  p.  59,  1869. 
b  Idem,  XLVI.,  p.  472,  1873. 
1  American  Machinist,  Jan.  15th,  1887,  p.  4. 
J  Sweet,  Trans.  Am.  Soc.  Mech.  Eng.,  VII.,  p.  154,1886. 


186 


THE    METALLURGY    OF     STEEL. 


foot  bar,  with  0-90^  of  carbon,  in  cooling  from  an  orange 
heat  contracted  £",  re-expauded  33",  then  again  contracted 
ie":  a  similar  bar  with  0-17$  of  carbon  contracted  pretty 
regularly  during  45  seconds,  then  ceased  to  contract 
measurably  for  20  seconds,  then  again  contracted.  A  bar 
with  0'07$  of  carbon  contracted  continuously  but  not  quite 
regularly.  Barrett,  too,  though  unable  to  detect  this  ex- 
pansion in  some  very  .soft  wrought-iron,  found  it  very 
marked  in  hard  wrought-iron,  and  especially  so  in  steel. 

The  after-glow  has  been  referred  to  an  evolution  of  heat 
due  to  the  pressure  of  the  more  rapidly  cooling  outside 
on  the  interior.  In  thick  bars,  whose  outside  is  appreci- 


Fig.   70. 

Appearance  during  slow  cooling  of  a  bar  of  tool  steel  heated  at  one  end.    Brinnell. 

ably  cooler  than  the  inside  during  cooling,  the  after-glow 
occurs  somewhat  gradually,  and  might  possibly  be  re- 
ferred to  such  a  cause.  Were  this  the  true  cause,  how- 
ever, when  we  come  to  small  wires,  whose  outside  and  in- 
side^ cool  at  nearly  identical  rates,  the  after-glow  should 
become  very  faint.  But  it  is  precisely  in  these  that  it  is 
remarkable.  Not  only  are  heat  and  light  evolved,  but  the 
wire  expands  with  a  sudden  jerk  when  the  cooling  reaches 
a  certain  point.  Barrett,  using  a  multiplying  index  to 
follow  the  movement  of  the  wire,  which  was  heated  by  an 
electric  current,  reports  among  other  tests  "wire  bright 
red  :  contact  broken,  index  fell  from  32  to  20,  jerked  for- 
ward to  24 -5,  then  fell  to  4 :  wire  cold."  The  suddenness 
of  the  phenomena,  the  actual  expansion  and  other  features 
seem  to  show  conclusively  that  some  molecular  change 


occurs  within  the  metal,  and  that  the  recalescence  is  not 
simply  due  to  the  pressure  of  shell  on  core. 

D.  Coffin's  Bend. — Coffin  finds  that  the  change  from 
hardening  to  cement  carbon  in  slow  cooling  past  V,  like 
the  same  change  on  heating  to  a  straw  tint,  and  like 
the  change  from  cement  to  hardening  carbon  in  heating 
past  W,  is  accompanied  by  a  great  depression  of  the  trans- 
verse elastic  limit.      In  an  experiment  which  he  carried 
out  with  my  assistance,  a  steel  bar  four  feet  long  and  f 
inch  square,  with  0'67$  of  carbon,  was  heated  on  the  level 
hearth  of  a  reverberatory  furnace  to  a  low  yellow,  say 
W,  then  removed,  supported  at  its  ends  in  the  outer  air, 
and  loaded  in  the  middle  with  7'5  pounds.     During  the 
first  90  seconds  after  removal  it  did  not  bend  perceptibly : 
in  the  next  35  it  bent  1  '5  inches,  and  then  stopped  bend- 
ing altogether.     The  bending  began  and  ended  gradually. 
In  several  other  experiments  we  found  that  the  deflection 
was  proportional  to  the  theoretical  deflecting  power  of  the 
loads.     In  one  case  a  f  inch  steel  bar,  four  feet  long,  with 
a  load  of  7  5  pounds  in  the  middle,  began  bending  135 
seconds    after    leaving  the  furnace,  and  bent  0'3  inch 
between  the  135th  and  the  250th  second :  a  load  of  about 
150  pounds  applied  'SO  seconds  later  produced  no  further 
deflection  that  we    could    detect  with    our  rough   ap- 
pliances." 

Finally,  the  total  deflection  under  given  load  appears 
to  be  the  same  whether  the  temperature  descend  rather 
rapidly  or  extremely  slowly  past  the  critical  range. 

In  straightening  railway  axles  Coffin  takes  advantage 
of  this  temporary  increase  of  flexibility,  by  applying  to 
the  axle's  convex  side,  while  the  temperature  is  falling 
past  V,  a  very  gentle  pressure,  one  which  would  not  bend 
the  axle  if  after  cooling  it  were  reheated  to  V. 

E.  The  magnetic  and  thermo-electric  properties  undergo 
changes  opposite  in  sign  to  those  which  occur  in  heating 
past  V.     A  cooling  iron  wire  in  contact  with  a  magnet  and 
surrounded  by  a  coil  of  copper  wire    induces  an  electric 
current  in  this  wire  as  its  temperature  passes  some  point 
which  is  at  or  near  V.b 

It  is  noteworthy  that  neither  this  last  phenomenon  nor 
the  expansion,  the  evolution  of  heat  nor  the  momentary 
depression  of  the  elastic  limit  occur  in  cooling  past  V, 
unless  the  temperature  has  previously  been  far  above  V, 
presumably  at  Wc :  nor  do  the  carbon-condition,  the 
fracture  and  the  hardening  power  change  in  cooling  past 
V,  unless  the  temperature  has  just  before  reached  W. 

Moreover,  some  at  least,  of  these  phenomena  which  oc- 
cur at  V  are  much  more  intense  in  cooling  than  in  heat- 
ing. Thus,  the  increase  of  magnetizability  in  cooling, 
though  indeed  composed  of  three  successive  steps,  has  one 
which  is  much  more  sudden  xand  violent  than  .any  which 
occufs  during  heatingd  :  the  expansion  at  V  during  cool- 
ing is  much  greater  than  the  contraction  during  heating. 
Gore,  indeed,  could  detect  no  contraction" :  in  two  ex- 
periments of  Barrett's  the  expansion  in  cooling  seems  to 
have  been  about  thrice  as  a  large  as  the  contraction  on 
heating.'  This  accords  with  the  fact  that  marked  changes 
in  the  hardening  power,  the  fracture,  and  the  condition 


a  These  experiments  will  be  described  in  the  Technology  Quarterly, 

bPhil.  Mag.,  XXXVIII.,  p.  66. 

cldem,  XLVI.,  p.  475. 

d  Gore,  Phil.  Mag.,  XL.,  p.  174, 

eldem,  XXXVIII.,  p.  62, 

f  Idem,  XLVI.,  p.  474, 


Tolume  II. 


THERMAL    PHENOMENA    DURING    HEATING    AND    COOLING.      §  257. 


187 


T.UII.K87  A.—  IlETAKDATIONa  IN    THK   HKATINO    AND    COOLINCl    CrKVIM   or    IRON.      OsMONII    ANM    I'loNCMOX   (Vic,.    71). 

Description  of  metal. 

INo  of  curve  in 
fig.  71. 

Composition, 

per  cent. 

as. 

32. 

"1. 

C.      8 

i.  Mn. 

P. 

S. 

Limit.     Max.    Limit. 

Size. 

Limit. 

Max. 

Limit. 

Size. 

Limit.  Max.   Limit.         SUe. 

Un hardened  metal. 


A. 
0. 

I). 

E. 
F. 

a. 

H. 

I. 

.T. 
K. 
L. 
M. 

N. 
O. 

r. 
Q. 

R. 

s. 

T. 

n. 

Iron  by  ]iv<lr<i^<>n,  I'ionchon. 
Phosphoric  iron  

.... 
9 

Heating 
Cooling.  . 

"•OS" 
•08 

•<» 

°tr.° 

:38 

'":6'i" 

1,050 

°C 
"'9K 

1,000 

Small  

°C 

°C 

'727 

°C 

sinail  

7  2O 

°O 

lil'r*! 

°C 
C.GO 

Very  slight. 
Very  slight. 

mmfr 

Small.1 
Very  obscure. 

Of  pood  size. 

V-^ry  strong 

BM 

900 

845 
920 

A»V 

855 
867 

822 
900 
880 

803 
•xami 

ea 

855 
840 

800 
835 

led. 

Sudden,       high, 
brief.  .  . 

750 
730 

755 
755 

780 

750 

733 
720 

730 
725 

721 

095 

720 
710 

710 
"'C80 

I'.IB 

3 

4 
6 
8 

7 

Heating 

Cooling.  . 
Heatiny 

(!n(»linu'. 

Cooling.  . 

Slight  

Slight,  ver-u  tint 
Small 

Extra  soft  steel,  basic  open- 
hearth  

•16 

•in 

•11 

•08 

•02 

Moderate.  .  .  . 

680 
'"680 

658 
6JMH 

660 

661 
7O5 

674 
705a 

695 
MO 
625 
620 

670 
515 

680 
676 

645 

'"did 

645 
090 

«r> 
«98ii 
660 
620 
600 
595 

Nlir/ht  

Sliriht  
Strong  

Soft  Sterl,  Imsir  IH-SX-MHT.  .  . 
Half-hard    sh-el,   arid     UJM-II- 

"29 
•57 

•oc 

•08 

•27 
•28 

•nr, 
•on 

•oc 

•02 

Vi-ry  slight  
Very  slight  

720 

720 

720a 

710 
660 

llaui  steel,  crucible  

11 

15 

Tooling  . 

1-H5 

•HI 

•1(1 

•02 

•08 

Absent  

IMn-iiidystrong. 
Hardened  steel. 
Very  strong. 
)tr6ng. 
Very  strong. 

Strong. 
Enormous. 

Moderale, 
Temperature 
rises  to  690*  and 
716°. 

Strong. 

White  cast  iron.  Swedish  
Basic  Besscrii'T  sl<>el,  1 

13 

Cooling.. 

4-10 
•32 

•22 

•nr. 

•12 
•W 

•02 
•115 

•114 
•02 

'"855 

1'nibablv  absent. 
Very  slight.  . 

"'741) 

'"760 
660 

'"ceo 

Cooling.. 
il 

Cooling.. 

•42 
•40 

•71 

•83 

•5®  -6 
2-00 

•48 

•u:: 
•07 

•11 

roo 

1'08 
•73 

•(111 
•07 

•01 

•03 
•08 

•04 
Cr. 

j-oo 

865 

Slight 

varying.                      i 

Tungsten      steel,     tungsten 
3-4T*  

8-0 
10 

BOO 

Extremely  slight 
Probably  absent. 
Extremely  Blight 

658 

(TOO 
1  680 

727 



Small  
Extremely  slight 

Strong  

872 

770 



2-00 
10  ©12- 

14              K 

694 

....     j. 

Redshort  (sulphurous)  basic 
Bessemer  steel  

•IN 

•!>1 

•M 

8. 
•88 

810 

Very  slight  

760 

735 

Moderate  

671 

645 

Accelerations  in  heating  (tempering)  curves  of  hardened  steel. 


d, 

da 

d!.           - 

V. 

w. 

Half-hard     steel     (same     as 

Seating 



345 

Slight  

Hard  steel(same  as  number  K) 

15 

<;so 

Moderate  

3S3  

Strong  

..  aid  ..    ..  Kitaiit  

a  Hardened  steel. 
Italics  and  heavy-faced  typo  refer  to  heating,  i.  e.  to  rising  temperature  :  the  others  to  falling  temperature. 

of  carbon  have  been  detected  at  V  in  cooling  (from  W), 
but  not  in  heating. 

§  257.  THERMAL  PHENOMENA  DURING  HEATING  AND 
COOLING  ;  a  AND  ft  IRON." — Digressing,  let  us  consider  the 
interesting  theories  of  Osmond  and  Werth,  and,  to  that 
end,  note  the  thermal  phenomena  which  occur  when  iron 
is  heated  and  cooled.  These  are  represented  graphically 
in  Figure  71.  If  a  bar  of  unhardened  steel  be  heated  say 
to  500°  C.,  and  be  then  allowed  to  cool  gradually,  losing 
heat  by  radiation,  and  if  we  plot  successive  degrees  of 
temperature  as  abscissse  and  the  intervals  of  time  occu- 
pied in  cooling  from  each  degree  to  the  next  lower  as  or- 
dinates,  we  obtain  smooth  curves,  rising  regularly  as,  with 
nearer  approach  to  the  temperature  of  the  atmosphere, 
radiation  becomes  slower.  Put  like  curves  plotted  for 
cooling  from  higher  temperatures  are  extremely  irregular, 
showing  that  at  certain  temperatures  either  the  specific 
heat  changes  abruptly,  or,  as  seems  more  probable,  some 
change  occurs  within  the  metal,  accompanied  by  absorp- 
tion or  emission  of  heat.  Like  irregularities  occur  dur- 
ing gradual  heating. 

w»nt  rhOT  toXi  i  retards  cooling,  raising  the  cooling  curve  locally. 

i  hastens  heating,  lowering  the  heating  curve  locally. 

TTont    v.o    \-**\  j  hastens  cooling,  lowering  the  cooling  curVe  locally. 
30  (  retards  heating,  raising  the  heating  curve  locally. 

Osmond  recognizes  three  chief  irregularities  in  these 
curves.  Those  which  occur  during  heating  he  terms  ac, 
those  during  cooling  ar :  those  which  occur  at  the  lowest 
temperature  he  names  ac  t  and  ar  t :  those  at  the  inter- 
mediate and  highest  temperat  tires  he  names  ac2,  ac3,  ar2 
and  ar3  respectively.  When  he  thinks  that  two  or  all  of 
these  irregularities  coalesce,  he  gives  them  such  names  as 
ac21  and  a,..,.^!. 

a  Ann.  Minos.  8th  Ser.,  VIII.,  p.  5,  1885.  "  Transformations  duFer  et  du  Car- 
bone  dans  les  Fers,  les  Acicrs,  et  les  Fontes  Blanches,"  Osmond,  Pari  ,  1888, 
Stahl  und  Eisen  VI.,  pp.  374,  539,  18SO:  Idem,  VII.,  p.  447,  1887:  Idem,  VIII., 
p.  :«>4,  1888.  Comptes  Rendus,  CIIL,  pp.  743,  1135:  Idem,  CIV.,  p.  985.  Cf. 
Muller,  Stahl  und  Eisen,  VIII.,  p.  391,  1888. 


Under  favorable  conditions  H.  Tomlinson  detects  as 
many  as  seven  recalescences  during  the  cooling  of  iron 
from  whiteness :  two  decided  ones  are  generally  noticed, 
one  between  500°  and  1,000°  C.,  the  other  below  5()U°.b 

In  the  series  of  irons  experimented  on  by  Os  mond,  detailed 


CURVE  OF  TEMPERING  HARDENED  STEEL,    OSMOND, 


inTaWe  87  A,  we  find  that  the  position  of  two  of  these  ele- 
vations, On  and  a^s,  is  tolerably  constant  for  given  condi- 
tions of  heating  and  cooling,  and^  nearly  independent  of 
chemical  composition.  aV^isjia^sed  only  14°  C.  by  increase 
of  carbon  from  0-05  to  f'Sd^,.;  bu£it  is  lowered  about  40° 
by  an  increase  of  manganese  from?  6 -3?  to  1-08$.  The 
higher  the  temperature  which  precedes  cooling  and  the 
more  rapid  the  cooling,  the  lower  is  arl  for  steels  with  0'57 
and  1  -25f0  of  carbon. 

The  statement  that  the  position  of  ar  3  is  nearly  inde- 
pendent of  composition  is  on  my  own  authority,  and 
directly  opposed  to  Osmond's  view.  According  to  him  a,  a 
descends  rapidly  with  increasing  carbon,  merging  in  a,  2 
when  the  carbon  reaches  0'20%.  Here,  however,  he  appears 
to  strain  the  facts  to  fit  his  theory.  The  reader  can  verify 
from  Figure  71  the  existence,  in  eight  out  of  the  nine 
cooling  curves,  of  a  slight  rise  whose  crest  lies  within  the 
narrow  limits  815°  and  872°  C. 

The  height  of  arl  and  perhaps  also  that  of  ar3  varies 
greatly  with  the  composition.  ar  1;  insignificant  in  iron 
with  '05  or  '08$  of  carbon,  increases  constantly  and  very 
greatly  with  rising  carbon  till  this  reaches  1  '25% :  with 
further  increase  to  4'1?£  it  again  decreases.  Increasing 

b  Jour.  Iron  and  Steel  Inst.,  1888, 1.,  p.  355,  from  Trans.  Proc.  Phys.  Soc., 
London,  IX.,  pp.  107-1S3. 


Ifc8 


THE    METALLURGY    OF    STEEL. 


chromium  probably  heightens  it,  as  does  tungsten  (3  '5$, 
±)  in  one  case:  in  another  case  tungsten  shortens  it, 
while  neither  manganese  (changing  from  0  to  1  '08$)  sul- 
phur, phosphorus  nor  silicon  seems  to  affect  it.  20%  of 
manganese,  however,  effaces  it,  and  6  "3$  of  tungsten  prob- 
ably greatly  shortens  it.  The  temperature  assigned  by 
Osmond  to  an  agrees  well  with  Pionchon's  observation 
that  the  specific  heat  of  iron  was  much  higher  in  the 
range  660°  to  720°  C.  than  at  lower  or  at  immediately 
higher  temperatures. 

I  trace  no  simple  relation  between  the  percentage  of 
carbon  and  the  height  of  a^.  Neither  chromium,  silicon, 
sulphur,  silicon,  nor  phosphorus  nor  a  little  manganese 

Fig.  71,    CURVES  OF  COOLING  AND  HEATING,    OSMOND, 


1200' 


IIOOV  1000 


(1  "08$)  seems  to  affect  it,  but  it  is  missing  in  ferro-man- 
ganese,  in  white  cast-iron,  and  in  tungsten  steel. 

In  one  case  only,  that  of  electrolytic  iron,  curve  2,  does 
0,3  reach  a  considerable  height,  and  here  its  height  may 
be  due  not  to  the  relative  freedom  from  carbon,  but  to 
some  individual  peculiarity  of  the  specimen  tested,  for 
RCS  in  this  same  specimen  is  very  short :  further, 
is  short  in  phosphoric  iron,  number  ],  which  has  still  less 
carbon.  Pionchon  noticed  no  absorption  of  heat  in  this 
range,  but  he  found  one  at  a  much  higher  temperature, 
about  1050°  C.,  both  in  very  pure  commercial  iron  and 
in  iron  reduced  by  pure  hydrogen  from  pure  ferric  oxide. 

While  a,  x  and  ar  8  seem  to  be  distinct  entities,  as  much 
cannot  be  said  confidently  of  ar  z.   Those  retardations  which 


are  called  a,.2  vary  so  much  in  position  and  height  in  dif- 
ferent steels  as  to  suggest  that  they  are  not  due  to  the 
same  cause.  Grouping  them  provisionally  as  ar2,  we  note 
that,  with  rising  carbon,  the  temperature  of  this  retarda- 
tion falls  continuously,  from  727°  with  0*05$  of  carbon  to 
695°  with  carbon  U-57$,  now  nearly  merging  in  arl,  which 
seems  to  swallow  it  completely  when  1'25  or  4*1$  of  car- 
bon is  present.  As  manganese  rises  from  0'27  to  1'08$, 

2  falls  some  63°  C.,  of  which  35°  may  be  due  to  the  simul- 
taneous rise  of  carbon.  With  20%  of  manganese  it  is  no 
longer  visible.  Rising  tungsten  in  one  case  raises,  in  another 
almost  effaces  it :  sulphur  perhaps  raises  it :  but  neither 
chromium,  phosphorus  nor  silicon  changes  its  position. 

Its  height  seems  on  the  whole  to  increase  with  rising 
carbon,  but  not  constantly,  and  perhaps  with  rising 
chromium ;  but  it  is  lessened  by  tungsten,  while  rising 
manganese  lessens  and  finally  effaces  it.  Silicon,  sulphur 
and  phosphorus  do  not  seem  to  affect  its  height. 

achas  been  studied  much  less  than  a,.  Only  two  elevations 
can  in  general  be  traced,  and  these  seem  much  less  marked 
than  those  with  falling  temperature.  The  upper  one  is 
slightly  above  a,  3,  and  probably  corresponds  to  it :  and 
hence  may  be  called  ao3  provisionally.  The  second  lies 
between  a,  j  and  a*  2 :  Osmond  calls  it  ac  j  in  some  cases, 
ac2  in  others,  implying  that  it  corresponds  to  arl  in 
the  former  and  to  a^in  the  latter  :  but  this  correspond- 
ence seems  to  be  very  doubtful  except  in  the  case  of 
steel  with  1  -25%  of  carbon,  with  which  a  very  strongly 
marked  elevation  occurs  at  705°  C.,  31°  higher  than  a,i : 
this  may  well  be  called  ac  r. 

When  hardened  steel  is  reheated,  three  if  not  four  de- 
pressions occur  between  the  common  temperature  and 
680°  C.  (V).  We  may  name  the  lowest  of  these  di,  the 
others  d2,  ds,  etc. 

§  257A.  DISCUSSION.  Of  these  flexures,  two  only,  a*,  and 
an,  seem  to  have  definite  positions.  ar2  indeed  seems  to 
vary  with  some  regularity :  but  beyond  these  we  find  two, 
three  or  even  more  flexures.  In  the  cooling-curve  of  elec- 
trolytic iron  eight  distinct  flexures  exist.  Osmond  often 
classes  two  distinct  elevations  as  one,  e.  g.  that  marked 
a^  and  the  one  at  its  right  in  the  cooling  curve  of  electro- 
lytic iron  (3) :  in  other  cases  he  asssumes  that  one  eleva- 
tion really  consists  of  two  or  even  three,  e.  g.  the  great 
elevation  in  the  cooling-curve  (]  1)  of  steel  with  l'25$of 
carbon,  which  he  terms  ari23.  For  the  assumptions,  ap- 
parently deemed  essential  to  his  theory,  I  see  little  war- 
rant. 

art  is  probably  a  phenomenon  of  the  after-glow,  of  the 
rapid  change  from  hardening  to  cement  carbon  (this  Os- 
mond admits)  and  from  hard  to  soft  steel.  This  is  indi- 
cated by  its  absolute  position,  700°  C.,  (1,300°  P.,  a  dull 
red),  and  by  the  fact  that  its  height  is  roughly  propor- 
tional to  the  intensity  of  these  changes.  Let  H  =  the 
ratio  of  the  hardness  in  the  quenched  to  that  of  the  slowly 
cooled  state,  or  the  intensity  of  the  hardness-change,  I  = 
the  intensity  of  the  after-glow,  and  J  =  the  height  of  a,*. 

As  carbon  increases  from  0-05$  to  1'2,%  H,  I  and  J  in- 
crease apparently  continuously  and  roughly  proportion- 
ally, from  insignificant  to  most  striking  phenomena:  before 
the  carbon  rises  high  enough  to  form  white  cast-iron, 
however,  both  H  and  J  have  diminished  somewhat.  A 
moderate  quantity,  say  \%  of  manganese  apparently 
affects  neither  H,  I  nor  J  seriously,  and  the  same  may  be 


OSMOND'S    THEORY. 


257. 


189 


true  of  a  little  chromium:11  alarge  proportion  of  manganese, 
as  in  ferro-manganese  and  Hadfield's  steel,  greatly 
diminishes  or  effaces  all  three."  In  regard  to  tungsten 
alone  have  we  even  an  apparent  anomaly.  A  large  pro- 
portion, say  6$,  of  tungsten  greatly  diminishes  if  it  does 
not  efface  H  and  I :  while  in  curves  8  and  9  3  Al%  in  one 
case  lessens,  in  another  enormously  increases  an.  Our 
data  are  too  scanty  for  analysis :  but  it  may  be  doubted 
whether  this  small  proportion  of  tungsten  would  greatly 
diminish  H  and  I ;  and,  further,  the  great  retardation  in 
curve  9  lies  so  much  below  the  temperature  of  arl  in  all  the 
other  curves,  that  we  may  reasonably  doubt  whether  it 
really  is  arl :  it  may  well  represent  some  other  change 
within  the  metal. 

As  sudden  cooling  prevents  the  heat-yielding  change 
from  hardening  to  cement  carbon,  it  is  natural  that  when 
hardened  steel  is  reheated,  and  while  its  carbon  is  gradu- 
ally changing  to  cement,  heat  should  be  evolved,  causing 
the  depressions  dx,  etc.,  in  the  heating-curve  number  15  of 
Figure  71. 

dt  seems  to  occur  at  the  same  temperature  as  the 
temporary  weakening  of  hardened  steel  noted  in  §  255. 
It  will  be  interesting  to  see  whether  a  second  weakening 
occurs  at  353°,  corresponding  to  d2. 

The  meaning  of  ar8  and  a^  is  not  clear.  The  constant 
position  of  aT3  suggests  that  this  point  is  the  W  of  Brin- 
nell  and  the  b  of  Chernoff :  but  the  temperature,  810°  to 
900°  C.,  which  Osmond  assigns  it,  seems  rather  lower  than 
that  of  W  and  b,  while  the  range  of  temperature  1,000  to 
1,050°,  in  which  Pionchon  found  his  second  absorption  of 
heat,  and  which  we  may  call  Pionchon' s  as,  seems  very 
near  W  and  b. 

The  reason  why  raising  the  initial  temperature  and  in- 
creasing the  rapidity  of  cooling  cause  a^  to  occur  at  a 
lower  temperature,  may  be  that  at  the  higher  tempera- 
ture the  crystalline  form  becomes  more  firmly  fixed,  as  in 
the  burning  of  iron,  §  263,  and  so  resists  more  strongly  the 
tendency  to  change  on  cooling  past  the  critical  point :  and 
that,  as  we  have  already  seen,  the  change  from  hardening 
to  cement  carbon  is  always  a  slow  one. 

We  have  so  few  facts  concerning  ac  that  speculation 
were  premature.  One  naturally  asks  whether  retardations 
of  heating,  corresponding  to  and  a  little  higher  than  arl, 
a,^  and  ar3  respectively,  exist,  indicating  that  the  changes 
which  occur  in  cooling  are  each  reversed  at  a  little  higher0 
temperature  iu  heating.  In  few  if  any  cases  is  such  a 
correspondence  clear.  Indeed,  it  seems  evident  that  the 
lower  elevation  in  heating,  which  we  call  aci,  is  not  due  to 
a  change  the  reverse  of  that  which  causes  arl. 

Thus,  while  arl  seems  directly  connected  with  the 
change  of  carbon  from  hardening  to  cement,  acl  does  not 


a  "Manganese,"  R.  A.  Hadfield,  p.  77:  Excerpt  Min.  Proc.  Inst.  Civ.  Eng., 
XCIII.,  1887-8. 

b  I  find  a  surprising  if  accidental  correspondence  between  my  observations  and 
Osmond's.  When  I  first  tried  chrome  steels  I  failed  to  note  the  after-glow :  on 
repeating  the  experiment  I  found  to  my  surprise  a  very  marked  after-glow.  I 
attributed  my  failure  to  notice  it  the  first  time  to  malobservation :  but  I  now  find 
from  Osmond's  experiments  that,  if  the  initial  temperature  is  low,  say  800°  C-, 
chrome  steel  shows  but  an  arrest  of  cooling  at  arl :  while,  if  slowly  cooled  from 
1100'  C.,  a  very  marked  rise  of  temperature  occurs  at  arl:  thus  my  failure  was 
probably  dui  to  not  heating  high  enough  initially. 

c  At  a  slightly  higher  point,  because,  if  crystalline  tendency  or  chemical 
affinity  changes  at  a  certain  point,  we  may  suppose  that  at  that  point  itself 
equilibrium  between  the  two  crystalline  tendencies  or  between  the  two  chemical 
affinities  exists.  In  heating  or  cooling  we  must  pass  an  appreciable  distance  be- 
yond that  point  before  departing  far  enough  from  exact  equilibrium  to  overcome 
chemical  inertia. 


seem  to  represent  the  reverse  change  :  for  it  appears  to  be 
well  marked  in  Pionchon' s  carbonless  iron.  Moreover,  a^ 
occurs  between  690°  and  705°  C.:  while  the  chief  change  of 
carbon  from  cement  to  hardening,  and  of  stet'l  from  soft  to 
hard,  occurs  only  at  a  much  higher  temperature,  a  low 
yellow,  say  1000  to  1100°.  Whether  its  intensity,  like  that 
of  arl,  is  proportional  to  the  percentage  of  carbon  is  un- 
certain. No  increase  can  be  traced  confidently  with  carbon 
rising  from  0'05  to  0-16$,  in  unhardened  steel.  In 
hardened  steel  of  1-25$  of  carbon  acl  is  very  strong,  but 
whether  because  of  the  high  carbon  or  of  the  hardening  is 
not  clear.  If  of  the  hardening,  acl  might  correspond  to 
the  change  of  fracture  from  F  and  D  to  H  at  about  700°  C., 
which  has  no  analogue  in  case  of  unhardened  steel.  We 
do  not  refer  it  to  change  from  hardening  to  cement  carbon, 
which  probably  continues  to  take  place  at  700°,  as  this 
should  liberate  heat  and  depress  the  heating  curve,  while 
atl  is  in  this  case  a  sharp  elevation. 

The  study  of  fracture  and  of  polished  sections  shows 
tha*;  changes  of  crystallization  and  of  mineral  species  oc- 
cur during  heating  and  cooling.  Some  of  these  have  been 
definitely  located  at  V,  and  W.  Others  seem  to  occur 
progressively,  but  not  necessarily  at  constant  rate,  when 
hardened  steel  is  heated  from  the  cold  towards  W.  The 
position  of  others,  e.  g.  that  from  F  to  E  and  from  E  to 
D,  the  formation  of  ferrite,  cementite  and  pearlyte  from 
the  probably  obsidian-like  hardenite,  is  yet  only  roughly 
known.  To  these  known  and  apparently  sufficient  causes 
it  seems  not  unnatural  to  ascribe  the  flexures  other  than 
a,!  and  ar3.  Indeed,  in  case  of  ferro-manganese,  Osmond 
does  refer  the  series  of  perturbations  which  occurs  be- 
tween 900°  and  the  melting  point,  to  such  changes,  or,  as 
he  puts  it,  to  liquation. 

These  evolutions  of  heat  are  not  confined  to  iron.  Per- 
son found  that  the  alloy,  bismuth  8  parts,  lead  5,  and  tin 
3,  after  solidifying  at  96  to  94°  C.,  cooled  regularly  till  it 
reached  57° :  its  temperature  then  rose  one  or  two  de- 
grees, with  marked  expansion.  If  the  molten  alloy  be 
quenched,  so  as  to  prevent  the  molecular  change  which 
evolves  heat,  after  removal  from  the  water  it  grows  so  hot 
as  to  burn  the  fingers,  evidently  because  the  heat-yielding 
change  which  was  prevented  by  quenching  now  occurs.11 

Osmond's  Theory.* — The  resemblance  between  the  ef- 
fects of  quenching  and  of  cold-working  on  iron  and  steel 
appears  to  Osmond  so  close  as  to  indicate  that  these  oper- 
ations act  through  causing  a  common  chemical  change. 
As  cold-working  does  not  change  the  condition  of  carbon, 
an  allotropic  change  in  the  iron  itself  is  invoked.  He  im- 
agines two  allotropic  modifications, 

a  iron,  which  predominates  in  annealed  metal,  soft  and 
malleable,  and 

ft  iron,  hard,  strong,  and  brittle,  which  characterizes 
quenched  and  cold-worked  iron,  in  which  it  is  mixed 
with  more  or  less  a  iron,  according  to  the  intensity  of  the 
causes  which  have  formed  it. 

«  iron  is  changed  to  ft,  I,  by  cold- working,  II,  by  raising 
the  temperature  past  a  certain  critical  point  or  range,  ft 
iron  changes  to  a  at  temperatures  which,  though  high,  are 


d  Comptes  Rendus,  XXV.,  p.  444:  also  Ledebur,  Stahl  und  Eisen,  VII.,  p.  450, 
1887. 

e  Osmond,  op.  cit. :  also  Ann.  Mines,  8th  ser.,  VIII.,  pp.  42,  65  :  Comptes  Ren- 
dus, CIII.,  pp.  743,  1135  ;  CIV.,  p.  985.  Cf.  Ledebur,  Stahl  und  Eisen,  VI.,  p. 
374,  1886  ;  VII.,  p.  447,  1887  ;  VIII.,  p.  364,  1888  ;  also  Miiller,  idem.,  VIII., 
p.  S9'.,  1888. 


100 


THE    METALLURGY    OF    STEEL. 


below  this  critical  point,  freely  if  carbon  be  absent,  slowly 
if  it  be  present,  carbon  acting  as  a  brake.  Hence  both 
cold- worked  iron  and  steel  and  hardened  steel  are  soft- 
ened by  reheating,  ft  changing  to  a.  High-carbon  steel  is 
hard  after  quenching,  because  its  carbon  has  impeded  the 
change  from  p  to  «  iron,  soft  after  slow  cooling  because 
change  from  ft  to  a  has  had  time  to  occur  in  spite  of  the 
retarding  effect  of  the  carbon.  Carbonless  iron  is  not 
hardened  by  quenching,  because  this  change  has  not  been 
checked ;  while  with  intermediate  percentages  of  carbon 
quenching  produces  intermediate  degrees  of  hardness  by 
impeding  this  change  more  or  less. 

Discussion. — Osmond's  theory  implies  three  distinct 
propositions,  (1)  that  the  wonderful  difference  in  hardness, 
ductility,  coercive  force,  etc.,  between  suddenly  and  slowly 
cooled  steel  is  a  feature  of  an  allotropic  change,  call  it  the 
a  ft  change,  which  occurs  spontaneously  with  certain 
changes  of  temperature  :  (2)  that  the  a  ft  change  is  distinct 
from  though  influenced  by  the  change  in  carbon-condition  : 
(3)  that  distortion  in  the  cold  (as  in  cold-rolling)  pro- 
duces the  aft  change.  Here  we  have  three  known  changes, 
that  in  hardness,  strength,  ductility,  coercive  force,  etc., 
which  we  may  call  the  hardness-change :  that  in  carbon- 
condition,  the  carbon-change:  and  that  due  to  cold-work- 
ing, the  cold-work  change  :  and  one  hypothetical  change, 
the  a  ft  change.  Experiments  which  I  will  describe 
later  go  to  show  that  the  only  direct  evidence  of  the  ex- 
istence of  a  separate  «  ft  change  during  heating  and  cool- 
ing is  untrustworthy. 

In  a  later  section,  treating  of  cold- working,  finding  that 
the  ulterior  and  tangible  effects  of  cold-working  iron  and 
steel  resemble  those  of  cold- working  the  other  metals  as 
much  if  not  more  than  those  of  heating  and  quenching 
steel,  I  infer  that  the  proximate  effects  of  cold-working 
iron  are  classed  more  reasonably  as  like  in  nature  to  those 
of  the  like  process  of  cold-working  the  other  metals  (which 
hardly  creates  ft  brass,  bronze,  German  silver,  etc.),  than 
as  like  in  nature  to  those  of  the  unlike  process  of  quench- 
ing. If  I  am  right  here,  Osmond's  theory  is  superfluous. 

Turning  now  to  the  first  two  propositions,  as  suddenly 
and  slowly  cooled  steel  are  so  unlike  that  one  would  hard- 
ly suspect  from  mere  physical  examination  that  they  were 
different  forms  of  the  same  material,  we  would  not  quarrel 
with  Osmond  for  terming  the  change  from  one  to  the  other 
allotropic.  The  word  may  be  applied  legitimately  to  less 
striking  changes. 

Next,  if  we  divide  the  phenomena  which  occur  during 
rising  temperature  provisionally  into  those  noted  at  V  (a 
sudden  absorption  of  heat,  a  sudden  loss  of  magnetism,  a 
sudden  change  in  thermo-electric  power),  and  those  ob- 
served at  W  (the  change  in  carbon- condition,  in  fracture 
and  probably  in  appearance  of  polished  sections,  the  sud- 
den accession  of  the  hardening  power,  the  momentary  loss 
of  elastic  limit,  the  surprising  welding  noted  by  Coffin),  or 
into  the  V  and  the  W  groups,  we  may  admit  that  the  V 
ygrpup  is  distinct  from  the  carbon  change,  for  two  reasons. 
'  First,  the  carbon  change  as  shown  by  nitric  acid  spotting 
does  not  occur  till  the  temperature  rises  above  V,  nearly 
or  quite  to  W  ;  the  force  of  this  is  lessened  by  the  fact 
that  we  are  not  absolutely  certain  that  the  nitric  acid  test 
gives  sure  indications  of  the  carbon-condition.  Second, 
because  at  least  one  member  of  the  V  group  has  been  de- 
tected by  Pionchon  in  wholly  carbonless  iron,  reduced  by 


hydrogen  from  pure  ferric  oxide.  In  this  a  sudden  ab- 
sorption of  heat  was  indicated  in  the  following  way.  The 
iron  was  heated  and  at  once  cooled  siiddenly  in  a  calorim- 
eter, and  the  operation  was  repeated  at  a  gradually  ris- 
ing series  of  temperatures.  The  total  heat  of  cooling  in- 
creased regularly  up  to  about  660°  C.  ;  but  between  this 
point  and  720°  C.  it  increased  suddenly  and  greatly,  show- 
ing that  in  cooling  from  this  range,  which  includes  V,  some 
change  occurs  which  evolves  heat,  and  which  does  not 
occur  in  cooling  from  below  Y.  This  indicates  that  a  cor- 
responding absorption  of  heat  occurs  in  heating  past  V.a 

Further,  he  detected  the  loss  of  the  magnetic  properties 
simultaneously  with  the  absorption  of  heat,  apparently 
either  in  this  same  iron,  or  in  another  containing  only 
traces  of  carbon  and  silicon,  in  which  the  absorption  of 
heat  was  practically  identical  with  that  in  the  absolutely 
carbonless  iron.b 

But  the  fact  that  the  V  group  is  distinct  from  the  carbon 
change  does  not  help  Osmond's  theory,  for  the  carbon 
change  and  the  hardness  change  are  both  members  of  the 
W  group. 

The  question  then  arises,  are  the  members  of  the  W 
group  simultaneous  effects  of  a  single  change,  or  have  we 
here  two  or  more  essentially  distinct  changes,  one  of  car- 
bon-condition, the  other  from  soft  to  hard  steel  ?  During 
cooling  the  changes  of  this  group,  while  probably  most 
marked  at  V,  seem  to  be  spread  out  over  a  greater  range  of 
temperature  than  during  heating :  and  if  the  group  really 
consists  of  two  distinct  changes  we  might  expect  them  to 
occur  at  different  periods  during  cooling  if  anywhere. 

We  have  seen  that  the  position  and  intensity  of  ari  indi- 
cate that  it  represents  the  carbon- change.  Can  we  go 
further  and  identify  the  other  retardations,  saying  that 
arl  represents  only  the  carbon  change,  the  other  changes 
of  the  W  group  being  represented  by  this  other  retarda- 
tion, the  V  group  by  that  ?  Osmond  attempts  this,  but  I 
think  that  one  cannot  do  it  confidently  without  either 
more  data  or  a  more  searching  and  much  more  impartial 
analysis  of  our  present  data  than  he  gives  us.  In  fact,  I 
see  no  strong  evidence  that  these  retardations  do  not 
represent  simply  successive  similar  steps  of  one  great 
change,  including  both  the  V  and  the  W  groups,  arl  being 
a  vast  stride,  a^  and  ar3  timid  fumblings. 

Admitting  that  ari  represents  the  carbon  change,  beholds 
that  ara  and  ars  represent  the  hypothetical  a  ft  change. 
Were  this  true,  then  since  the  intensity  of  the  hardness- 
change  seems  roughly  proportional  to  the  size  of  arl  (§  258), 
but  without  clear  relation  to  that  of  ar2  and  a,.3,  one  would 
still  regard  the  hardness-change  as  a  feature  of  the  carbon- 
change  and  not  of  the  a  ft  change. 

Thus  a.,3  is  slight  in  the  non-hardening  iron  with 
0'05$  of  carbon  and  in  the  intensely  hardening  high-car- 
bon steel,  while  extremely  high  in  the  non-hardening 
electrolytic  iron  (curves  1, 11  and  3). 


a  Pionchon  proved  that  this  absorption  of  heat  was  not  due  to  experimental 
error,  by  showing  that  it  did  not  occur  with  other  metals. 

b  A  striking  feature  of  this  V  group  is  that  it  does  not  seem  to  include  a  sudden 
change  of  tensile  strength,  elastic  limit  or  ductility  :  these  properties  seem  to 
change  gradually  as  V  is  passed,  though  it  is  possible  that  a  momentary  weaken- 
ing in  passing  V  may  be  detected  hereafter,  like  that  in  rising  past  W  and  in 
falling  past  V.  This  reminds  us  that,  tremendous  as  are  the  changes  caused  by 
sudden  cooling,  this  operation  does  not  affect  the  modulus  of  elasticity  greatly. 
Whether  we  regard  the  hardening  changes  as  the  result  of  mechanical,  physical, 
crystalline  or  chemical  changes,  the  relative  constancy  of  this  property  while 
the  others  are  revolutionized  is  at  first  sight  mo4  surprising. 


OSMOND'S    THEOKY.      §  257. 


191 


The  position  of  ar3  indeed  bears  some  relation  to  the 
intensity  of  the  hardness-change,  for  the  temperature  at 
which  it  occurs  descends  as  the  carbon  rises.  Its  inten- 
sitt/,  however,  not  its  position,  should  be  but  is  not  pro- 
portional to  that  of  the  hardness-change.  Most  marked 
in  the  but  slightly  hardening  steel  with  '20$  of  carbon, 
and  in  the  well  hardening  chrome  steel,  it  is  slight  or 
absent  in  the  slightly  hardening  steel  with  OM6$of  car- 
bon, in  the  non-hardening  ferro-manganese,  and  in  the 
intensely  hardening  high-carbon  steel.  In  the  latter  in- 
deed it  is  perhaps  swallowed  up  in  arl.  It  is  more  marked 
with  0'05  and  0'08$  than  with  0-16$  of  carbon,  more 
marked  with  '20$  than  with  -51%  of  carbon  if  we  may 
judge  by  its  steepness  in  the  curve  for  the  latter. 

The  crucial  test,  however,  is  to  quench  at  some  point 
below  ars  and  a,.3  but  above  arl:  when,  on  Osmond's  theory, 
the  steel  should  be  soft  while  the  carbon  is  hardening:  on 
the  carbon  theory,  which  regards  a^  as  identical  with 
Brinnell's  V,  and  ar3  as  probably  identical  with  his  W, 
the  metal  should  be  partly  softened  and  should  have  part 
of  its  carbon  in  the  hardening,  part  in  the  cement  state. 
From  this  test  neither  Osmond  nor  I  have  shrunk.  He 
reports  that  when  steel  of  0'57  of  carbon  is  quenched  from 

A,  curve  7,  it  is  hard  and  the  carbon  hardening :  while  if 
quenched  from  B  it  is  soft,  the  carbon  still  being  harden- 
ing.a    This  is,  I  believe,  the  only  direct  evidence  of  the  ex- 
istence of  a  distinct  a  ft  change ;  it  therefore  merits  atten- 
tion. 

'  In  view  of  what  follows,  it  is  perhaps  superfluous  to  point 
Out  that  these  results  agree  poorly  with  his  theory.  Steel 
quenched  from  the  crest  of  a^,  should  be  already  partly 
softened,  having  passed  all  of  ar3  and  half  of  ar2 :  yet  he 
reports  it  as  hardened  unqualifiedly.  Steel  quenched  from 

B,  on  the  cooler  slope  of  arl,  should  have  part  if  not  most 
of  its  carbon  in  the  cement  state,  yet  he  reports  "harden- 
ing carbon"  without  qualification. 

Lacking  time  for  an  elaborate  investigation,  I  have  made 
the  following  tests,  which  indicate  either  that  the 
steel  on  which  Osmond  experimented  differed  strangely 
from  all  those  which  I  have  tested,  or,  as  seems  more  prob- 
able, that  he  is  simply  mistaken.  The  right-hand  end  of 
a  copper  box,  Figure  72,  12"  X  0'44"  X  0'88"  inside,  with 
walls  0'44"  thick,  was  placed  within  a  muffle  furnace  heated 
to  a  light  yellow,  the  left-hand  end  projecting  into  the 
outer  air.  Thanks  to  the  high  thermal  conductivity  of 
copper,  the  temperature  descended  very  slowly  and  regu- 
larly in  passing  from  right  to  left.  Within  this  after  it 
was  thoroughly  heated  I  placed  two  bars  of  steel  cut  from 
the  same  piece,  containing  about  0-50$  of  carbon,  0'375 
inch  square,  previously  nicked  hot  on  one  side  at  points 
.05  inch  apart,  and  polished  on  the  opposite  face.  After 
1  i  minutes  I  began  drawing  bar  I  back,  a  little  at  a  time, 
till  after  25  minutes  more  I  had  drawn  it  back  3 '5  inch, 
in  18  small  movements  of  about  0'2  inch,  each  I  then 
drew  and  quenched  each  bar.  Bar  I  was  re-polished,  its 
carbon  condition  determined  by  nitric  acid  spotting,  its 


» "  19e  chauffage  (rapide)  &  7708;  refroidissement  a.  1'air  jusqu'  &  697-8; 
tremp<5  &  697'8  ;  me'tal  tremp<5 ;  carbone  de  trempe.  SOe  chauffage  (rapide)  & 
784-1 ;  refroidissement  &  1'air  jusqu'  &  658  ;  trempe'  &  658 ;  me'tal  doux  ;  carbone 
de  trempe."  Trans,  du  Fer,  etc.,  p.  87  "  Essayons  enfln  les  e'chantillons  ainsi 
pr^par^s,  &  la  lime,  pour  juger  de  leur  duret(5  et  &  la  touche  par  1'acide  azotique, 
pour  verifier  I'e'tat  du  carbone."  Idem,  p.  38.  However  untrustworthy  thesis 
methods  may  be,  they  may  properly  be  used  in  rebuttal  of  Osmond's  representa- 
tions of  what  they  themselves  show  :  and  in  this  way  I  use  them  in  the  experi 
ments  which  I  am  about  to  describe. 


hardness  by  drawing  the  same  edge  of  the  same  file,  at  as 
nearly  constant  speed  and  pressure  as  I  could,  across  its 
edge  twenty  times  at  each  of  many  points,  care  being  taken 
to  choose  the  order  of  these  points  so  that  the  gradual 
dulling  of  the  file's  edge  might  not  mislead  me  :  the  depth 
of  the  file  mark  gave  a  rough  measure  of  hardness.  The 
carbon  condition  and  the  hardness  of  bar  I  and  the  hard- 
ness of  bar  II  were  noted  independently. 

We  have  in  bar  I  a  series  of  points  each  of  which  be- 
fore quenching  had  cooled  from  above  W  to  a  little  lower 
point  than  its  neighbor.  While  we  have  no  absolute 
measure  of  these  temperatures,  we  here  have  evidence  of 
the  relative  positions  of  the  carbon-change  and  the  haid- 
ness  change  during  cooling.  Instead  of  finding,  as  Os- 
mond' s  statements  imply,  a  sudden  change  in  hardness  at 
one  point,  and  then  a  sudden  change  of  carbon-condition 
at  a  point  which  had  been  cooler,  I  found,  as  Brinneirs 
results  confirmed  by  Coffin  would  lead  us  to  expect,  that 
these  changes  cover  a  long  region  and  are  apparently  sim- 
ultaneous. The  carbon-change  could  indeed  be  ti«ced 
over  a  longer  space  than  the  hardness-change,  probably 
because  slight  carbon-changes  are  recognized  by  the  eye 
more  easily  than  equally  slight  hardness-changes  are  by 
the  file.  I  have  repeated  this  experiment  many  times  with 
Bessemer  rail-steel  of  about  0-40$  of  carbon,  Bessemer 
steel  of  about  0  50%  of  carbon,  and  crucible  tool  steel  of 
several  grades,  always  with  the  same  result." 


SECTIONAL  PLAN.. 

DULL  RED        ___^_ 


" 


LEGEND:  „ 


* *•  HARDNESS  CHANGING. 

'CARBON  CHANGING. 


7®  Hi. 


STEEL  OF  AB1 


r  0.50'?,.  CARBON*-* 


Thus  there  seems  to  be  no  reason  to  doubt,  but  every 
reason  to  believe,   that  the  hardness-change  is  simul- 


t>  it  will  be  noticed  that  the  change  from  hard  to  sofc  in  bar  I  which  was 
gradually  cooling  when  quenched  appears  to  occur  at  a  somewhat  lower  temper- 
ature and  to  extend  over  a  longer  space  than  in  the  reverse  change  from  soft  to 
hard,  in  both  resoects  agreeing  fairly  with  Brinnell's  results  showing  that  the 
Change  from  hardening  to  cr ment  carbon  occurs  gradually  in  the  range  W-V 
while  the  reverse  change  occurs  rapidly  at  W.  In  this  particular  case  the  differ- 
ence between  the  length  and  position  of  change  from  hard  to  soft  was  much  less 
marked  than  in  most  of  my  other  experiments,  and  I  am  inclined  to  thiuk  that  in 
drawing  back  bar  I  the  temperature  of  bar  II  must  have  been  temporarily 
raised  and  then  again  lowered :  for  in  another  experiment  (Figure  7:!  b)  in  which 
both  bars  were  drawn  and  quenched  immediately  after  heating  for  16  minutes  in 
this  box,  the  change  of  hardness  covered  a  length  of  only  0'25  inch.  In  this 
case  one  bar  was  from  the  same  piece  as  those  shown  in  Figure  72,  the  other  of 
hard  crucible  tool  steel :  yet  the  range  covered  by  the  change  from  soft  to  hard 
had  almost  exactly  the  same  position  in  both  bars.  The  slight  difference  was  prob- 
ably due  wholly  to  experimental  error,  since  the  change  occurred  if  anything  at  a 
lower  temperature  in  the  low  than  in  the  high-carbon  steel.  The  agreement  is  as 
close  as  could  be  expected  with  such  rough  tests :  it  tends  to  confirm  Coffin's  be- 
lief that  the  position  of  W  is  independent  of  the  proportion  of  carbon  (§  245, 
p.  175). 

In  all  these  experiments  I  found  that  the  change  from  soft  to  hard  steel  and 
back  occurred  simultaneously  with  the  change  of  carbon  as  shown  by  nitric  acid 
spotting,  though  naturally  their  limits  did  not  coincide  exactly,  as  is  inevitable 
with  two  such  rough  tests.  Further,  the  change  from  soft  to  hard  coincided  with 
the  change  from  coarse  fracture  (Brinnell's  B)  to  fine  (Brinnell's  F).  While  the 
change  from  soft  to  hard  was  always  more  sudden  than  the  reverse  change,  the 
difference  between  the  suddenness  of  these  two  changes  seemed  to  me  less  marked 
than  one  would  infer  from  Brinnell's  results.  I  hope  to  present  in  an  appendix  more 
trustworthy  results  as  to  the  change  in  hardness,  obtained  by  scratching  with  the 
diamond  or  by  indentation.  These  methods  may  not,  indeed,  give  like  results,  one 
telling  the  hardness  of  the  very  skin,  the  other  that  of  skin  and  relatively  deep 
subcutaneous  layers,  whose  hardness  may  vary  at  a  different  rate  from  that  of 
the  skin. 


192 


THE     METALLURGY    OF     STEEL 


taneous  during  both  heating  and  cooling  with  the  carbon- 
change,  and  is  a  direct  result  of  it.  This  admitted,  it 
becomes  relatively  unimportant  whether  any  phenomena 
of  the  W  group  be  independent  of  the  carbon-change  and 
liable  to  occur  separately  from  it.  We  may  note,  how- 
ever, that  Pionchon  found  indications  of  a  change  at  W 
in  perfectly  carbonless  iron,  whose  specific  heat  seemed 
to  change  at  this  point.  This  change  may  be  wholly  in- 
dependent of  the  carbon-change,  occurring  whether  carbon 
be  present  or  not ;  it  may  precipitate  the  carbon- change, 
which  in  turn  introduces  practically  wholly  new  phe- 
nomena, the  hardness-change,  of  which  not  more  than  the 
germ  (if  even  that)  occurs  in  carbonless  iron. 

A  possible  simple  explanation  of  the  discrepancy 
between  Osmond's  results  and  mine  is  that  he  judged  the 
hardness  in  the  usual  way,  simply  by  the  feeling  of  the 
file,  and  not  by  the  depth  of  the  indentation  produced  by 
a  fixed  number  of  like  strokes.  The  feeling  readily 
detects  the  slight  difference  between  that  degree  of 
hardness  which  just  forbids  and  that  which  permits  the 
file  to  bite,  but  not  slight  differences  between  this  and 
slightly  lower  degrees  of  hardness.  It  exaggerates 
greatly  the  first  slight  decline  in  hardness.  Judging  from 
my  results,  in  the  steel  which  he  pronounced  soft  though 
with  hardening  carbon  both  carbon  and  hardness  had 
begun  to  change.  When  compared  with  that  of  a  fully 
annealed  piece  the  carbon-tint  indeed  seems  wholly  harden- 
ing :  while  judged  simply  by  the  feeling  the  steel  seems 
soft :  blacksmiths  to  whom  I  have  submitted  steel  in  this 
condition  have  always  pronounced  it  soft.  Yet  careful 
comparison  of  carbon-tint  and  depth  of  indentation  with 
those  of  like  steel  quenched  from  slightly  higher  and 
slightly  lower  temperatures  seems  to  show  clearly  that 
both  hardness  and  carbon-tint  have  changed,  and  appar- 
ently in  not  unlike  degree. 

Let  us  now  consider  Osmond's  allotropic  theory  as  ap- 
plied to  the  phenomena  of  tempering,  turning  to  curve 
15.  He  holds  that  dt  and  di  represent  the  change  from 
hardening  to  cement,  and  hence  that  d4  can  only  represent 
that  from  ft  to  a  iron,  because  he  found  by  Weyl's  method 
that  the  carbon  was  cement  in  steel  which  had  been  held 
for  thirty  minutes  in  molten  lead  at  about  400°  C. 

But  Weyl's  method  could  hardly  give  trustworthy  in- 
formation as  to  the  completeness  of  the  change  from  hard- 
ening to  cement,  as  Osmond  admits* :  but,  accepting  it,  it 
does  not  justify  his  inference,  for  in  curve  15  only  two 
minutes  and  a  few  seconds  were  occupied  in  passing  from 
98°  to  520°  C.,  or  far  past  dt  and  d2.  That  these  two  de- 
pressions do  not  represent  the  whole  change  from  harden- 
ing to  cement,  and  hence  that  d4  may  be  regarded  as  due 
to  the  continuation  of  that  change,  is  shown  by  Abel's 
discovery  that  less  than  half  the  carbon  of  hardened  steel 
became  cement  during  six  hours  exposure  to  say  a  blue 
heat,  say  300°  C.,b  and  that  this  change  occurred  gradually 
at  both  a  blue  and  a  straw  heat ;  and  is  further  indicated 
by  the  results  of  Barus  and  Strouhal,c  who  found  that  the 
thermo-electric  power  of  hardened  steel  increased  con- 
tinuously with  rising  tempering-temperature,  and  was  far 
from  reaching  a  maximum  at  330°  C. 

Again,  Coffin  finds  that  the  proportion  of  the  carbon 


a  Ann.  Mines,  8th  ser.,  VIII.,  p.  30, 1885. 

b  Table  2,  p.  12. 

c  Bulletin  14,  U.  S,  Geological  Survey,  pp.  54-5,  1885, 


which  is  in  the  hardening  state  (as  indicated  by  nitric  acid 
spotting)  diminishes  continuously,  as  the  temperature  at 
which  hardened  steel  is  subsequently  tempered  is  raised 
from  the  cold  up  to  redness,  say  900°  C.d  As  the  hardness 
diminishes  continuously  and  gradually,  we  more  naturally 
attribute  its  change  to  the  change  of  carbon  known  to  be 
simultaneous,  gradual  and  continuous,  rather  than  to  two 
distinct  causes  operating  jerkily,  change  of  carbon  falsely 
supposed  to  be  confined  to  lower  temperatures,  imagined 
allotropic  change  of  iron  unwarrantably  supposed  to  occur 
at  d4. 

Finally,  undaunted  by  the  fact  that  hardened  steel  is 
actually  softened  by  heating  past  d^  and  still  more  if 
heated  to  d2,  though  his  theory  holds  that  /j  changes  to 
«  only  when  the  temperature  reaches  d4,  Osmond  explains 
that  this  softening  is  not  due  to  the  simultaneous  change 
from  hardening  to  cement  carbon,  but  to  ths  fact  that  this 
change  causes  some  of  the  iron  to  leave  the  /j  state  in  order 
to  form  a  carbide  (cementite)  with  the  now- forming  cement 
carbon.  Unfortunately,  Muller  has  proved  that  this 
cementite  is  extremely  hard  and  brittle,  scratching  glass  : 
Sorby  was  convinced  that  it  was  extremely  hard.  Now 
the  change  from  brittle  p  iron  to  a  mixture  of  part  ft  iron 
and  part  glass-hard  carbide,  does  not  explain  the  soften- 
ing and  toughening  which  occurs  when  hardened  steel  is 
tempered :  while  the  carbon-theory,  holding  that  in 
tempering  a  harder  compound  of  all  the  iron  with  harden- 
ing carbon  (hardenite)  is  gradually  and  progressively 
changed  to  a  mixture  of  uncombined  soft  iron  and  hard 
carbide,  ferrite  and  cementite,  explains  the  softening  clearly 
and  in  accordance  with  the  known  facts. 

To  sum  up,  Osmond's  theory  accords  neither  with  our 
old  nor  his  new  facts:  while  the  latter  like  the  former  har- 
monize well  with  the  carbon-theory.  The  carbon-change 
being  a  fact,  the  «  p  allotropic  change  of  iron  as  yet  wholly 
unproved,  the  balance  of  present  probability  is  readily  seen. 

§  258.  RECRYSTALLIZATION  AT  HIGH  TEMPERATURES 
AFTER  FORGING. — The  microscope  shows,  as  we  should 
expect,  that  cold-working  distorts  the  crystals  which 
compose  iron  ;  and  further,  as  we  might  not  expect,  that 
this  distortion  is  effaced  when  the  metal  is  reheated ;  and 
that  the  distortion  of  the  grains  which  doubtless  occurs 
during  hot  working  is  effaced  before  the  metal  grows  cold, 
the  ultimate  grains  in  both  cases  becoming  nearly  or  quite 
equiaxed.  If  this  occurred  through  each  crystal's  draw- 
ing together  and  resuming  its  initial  shape  while  retain- 
ing all  its  original  particles,  the  bar  as  a  whole  would  re- 
gain its  initial  shape,  like  a  stretched  bar  of  India-rubber. 
A  cold  rolled  bar,  however,  changes  shape  so  little  on  re- 
heating as  to  show  that  a  rearrangement  of  particles  occurs, 
and  that  practically  new  crystals  arise. 


a  Trans.  Am.  Soc.  Civ.  Engineers,  XV  ,  p.  322,  1887.  Twelve  pieces  from  tha 
same  bar  of  tool  steel  were  similarly  hardened,  numbered,  tempered  at  tempera- 
tures rising  gradually  from  the  cold  to  full  redness,  repolished,  touched  with  nit- 
ric acid  on  the  unnumbered  side  for  45  seconds,  washed,  and  arranged  in  the  or- 
der of  their  color,  numbered  side  down.  Turning  the  numbered  sides  up,  their 
order  was  found  to  agree  exactly  with  their  numbering,  and  hence  with  their 
tempering  temperature.  The  differences  between  the  two  coolest  (untempered  and 
very  faint  straw-tempered)  and  between  the  three  hottest  (ash-grey  to  full  red) 
was  recognized  with  difficulty.  We  have,  indeed,  no  conclusive  evidence  that 
these  changes  of  color  are  due  to  increasing  proportion  of  cement  carbon  though 
this  is  extremely  probable:  but  their  progressive  change  indicates  that  they  are 
due  to  some  change  which  goes  on  continuously  in  tempering,  from  the  cold  to  red- 
ness. Tempering  a  hardened  steel  bar  in  the  copper  box  already  described,  the 
tempering-temperature  rising  so  gradually  that  the  change  from  a  grey  tint  to 
purple  occupied  twelve  inches,  I  found  that  the  hardness  measured  by  abrasion 
decreased  gradually  and  continuously,  and  not  by  jerks. 


RECRYSTALLIZATION     AT     UK;  II     TKMPKKATUKKS     AFTER    F()H(iIN(i.       §258. 


19? 


A.  Distortion  in  Gold  Working. — -Sbr£»^Bdrew  out  :i  bai 
of  weld-iron,  1 '8  inches  square,  to  about  53 '25  times  its  orig- 
inal length  by  cold-forging:  the  microscope  showed  that  the 
grains  were  broken  down,  and  twice  or  thrice  as  long  in  the 
line  of  the  length  of  the  bar  as  transversely.  On  exposure  to 
redness  during  80  hours,  crystals  again  became  equiaxed. 

Martens*  hammered  cubes  of  rail-steel  on  one  face, 
till  they  began  to  crack,  then  nicked  and  split  them. 
Their  fractures,  Figures  73-4,  indicate  that  the  grains 
were  flattened  into  sheets  parallel  with  the  hammered  face. 


Fractures  of  cold-hammered  cube  of  rail-steel. 

Figure  73.  Fracture  on  section  per-  Figure  74,  Fracture  on  section  parallel 

ficndicular  to  hammered  face.  to  hammered  face. 


Figure  75.  -Steel  bar  cold-hammered  OB 
«*jt  all  four  faces.    Etched  section. 


Schistosity  of  Bent  Wrought-iron.    (Sorhy .1 
Figure  76,  Somewhat  hent.  Figure  77,  Much  bent. 

Osmond  and  Werth,c  etching  (with  nitric  acid,  36°B.) 
steel  which  had  been  hammered  cold  on  all  four  sides, 
lind  a  St.  Andrew's -cross,  Figure  75,  coinciding  with 
Tresca's  zones  of  transmission  of  force.  In  the  most 
fatigued  parts  the  simple  cells  (pearlyte  ?)  are  lengthened 
along  the  planes  of  movement,  in  which  their  relatively 
brittle  shells  (cementite  ?)  are  shattered,  in  such  a  way  as 
to  recall  the  schistosity  of  rocks. 

B  The  Distortion  in  Hot  Forging  which  evidently 
must  occur,  is  illustrated  by  Figures  55,  (p.  165),  76  and  77, 
the  first  showing  the  rodlike  or  fibrous  arrangement  of  the 
slag  in  rolled  bars,  the  second  arrangement  of  the  slag 
and  metal  at  the  concave  side  of  a  wrought- iron  bar  bent 
somewhat  at  redness,  the  third  that  in  such  a  bar  bent  so 
much  as  to  cause  great  squeezing,  the  structure-lines  be- 
ing here  normal  to  the  surface  of  the  bar.  This  structure 
shows  why,  when  a  bar  thus  bent  is  again  opened,  rupture 
readily  occurs  in  planes  perpendicular  to  the  surface  d 

» Journ.  Iron  and  Steel  Inst.,  1887,  I.,  p.  263. 

bStabluud  Eisen,  VII.,  p.  339,1887. 

c  Comptes  Rendus,  C.,  p.  453,  1885:  Ann.  Mines,  8th  Ser.,  VIII.,  p.  15,  1885. 

d  Figures  70-7,  originally  intended  to  illustrate  the  schistosity  of  rocks,  show 
the  structure  of  hot- bent  wrought-iron  almost  exactly,  accordiag  to  Sorby. 
(Jourii.  Iron  and  St.  lust.,  1887,  I.,  p.  369.) 


Tlie  Grain  of  Hot-Forged  Iron  Equiaxed.—  Sorby  found 
that  the  ultimate  crystals  of  ferrite,  cementite  and  pearl  ytc 
in  bars  of  ingot-steel  and  of  weld-iron,  the  former  drawn 
out  to  6-25  times  its  initial  length  by  hot  forging,  were 
but  little  if  at  all  longer  in  the  direction  of  the  length  of 
the  bar  than  transversely.  A  bar  about  one-inch  square, 
forged  from  a  Bessemer  ingot,  showed  traces  of  the  original 
ferrite  network,  disturbed  and  drawn  out:  apait  from 
this  network,  some  only  of  the  crystals  of  ferrite  a  IK  I 
pearlyte  remained  distorted  by  the  elongation ;  and 
even  these  probably  owed  their  distortion  to  forging  pro- 
longed till  the  metal  was  too  cold  to  recrystallize  fully. 

The  large  patches  in  Figure  54,  p.  165,  some  light,  some 
dark,  may  be  the  traces  of  large  crystals  distorted  by 
forging,  surviving  the  recrystallization  which  has  given 
rise  to  the  small  nearly  equiaxed  grains  which  now  com- 
pose them. 

The  slag  of  weld-iron  remains  for  the  most  part  drawn 
out  into  long  fibres.  A  moderate  quantity  of  slag  does 
not  prevent  the  neighboring  metallic  grains  from 
recrystallizing  equiaxially.  Figure  55  contrasts  the 
fibre  of  the  slag  with  the  equiaxed  grains  of  the  metal 
itself.  But  when  the  proportion  of  slag  is  excessive,  the 
iron  itself  "might be  said  to  have  a  sort  of  fibre,"6  even 
after  hot  forging.  I  understand  that  this  "  sort  of  fibre  " 
is  more  apparent  than  real,  the  grains  themselves  being 
equiaxed,  yet  separated  into  quasi  fibres  by  layers  of 
slag,  like  a  mass  of  minute  cubes  of  iron  very  highly 
magnetized,  divided  up  into  rows  by  thin  strips  of  glass, 
the  strength  and  ductility  of  the  whole  being  due  to  the 
magnetization  of  the  iron  cubes,  and  being  merely  lessened 
by  the  glass.  Such  iron  may  be  likened  to  a  gneiss,  the 
crystals  of  felspar  and  quartz  with  their  axes  in  all 
azimuths,  the  plates  cf  mica  lying  parallel  and  causing 
cleavage.  In  this  view  wrought-iron  may  indeed  be 
said  to  have  fibre  :  but  the  fibre  as  such  should  weaken, 
not  toughen. 

The  grains  of  hot- worked  ingot-iron  and  steel  examined 
by  Wedding l  and  by  Osmond  and  Werth  also  appear  to 
be  equiaxed. 

Slag,  though  retaining  the  shape  acquired  in  forging 
much  more  tenaciously  than  metal,  under  favorable  con- 
ditions seems  to  draw  together.  Sorby  finds  it  in  almost 
perfect  spheres  within  crystals  of  wrought-iron,  very  long 
heated.* 

D.  Lengthwise  m.  Crosswise  Properties. — Table  £8 
shows  that,  as  we  should  expect,  the  strength  and  duc- 
tility of  wrought-iron  are  much  higher  along  than  across 
the  direction  of  rolling,  the  difference  being  probably  due 
to  the  presence  of  longitudinal  threads,  sheets,  etc.,  of 
slag.  There  is  a  general  belief  that  a  like  but  less  marked 
difference  exists  in  case  of  ingot-metal.  The  data  in  Table 
i:  8  indicate  that  this  difference,  if  it  exists  at  all,  is  very  . 
slight ;  but  those  on  which  Table  88A  is  based  have  been 
bought  to  indicate  that  it  is  very  great  even  in  case  of 
ingot-metal. 

The  value  of  the  evidence  in  Table  88  is  somewhat 
essened  by  the  fact  that,  in  most  cases,  we  are  not  per- 
fectly sure  that  the  rolling  has  been  chiefly  lengthwise  of 
he  plate.  But,  in  a  great  group  of  cases  given  by  Riley, 


e  Idem,  p.  363. 

t  Idem,  1885.  I.,  p.  Plate  III. 

tlderu.,  1887,  I.,  p.  S63. 


194 


THE    METALLURGY    OF    STEEL. 


TABLE  88. — INFLUENCE  OF  TUB  DIRECTION  OF  ROLLING. 
The  properties  of  test  pieces  cut.  from  plates  of  weld  iron,  ingot  iron  and  Ingot  steel  parallel  with  the  length  of  the  plate,  compared  with  those  of  similar  test  pieces  cut  perpendicularly  to  it. 


Number. 

Observer. 

General  description. 

Thickness. 
Inches. 

Number  of  groups 
in  which  the  maxi- 
mum crosswise 
tensile  strength  ex- 
ceeds or  equals 
minimum  lenpth- 
w  i  8  e  tensile 
strength. 

Total    num- 
ber    o  1 
groups  or 
cases. 

s, 

&        S 

Number  of  groups    in  which  the 
average  crosswise  properties  arc 
less  than  the  lengthwise. 

Deficit  (  —  )  or  excess  (-J-)  of  the  cross- 
wise over  the  lengthwise  properties, 
measured  in  percentages  of  the  length- 
wise properties. 

Tensile 
strength 

Elastic 
limit. 

Final 
eloiiga- 

timi. 

Kuduc- 
lion  of 
area. 

Tensile 
strength 

*. 
+0-52 

4-o-i 

+0'1 
-0  45 

o- 

—II  70 
-fO'2 
t'19 

Elastic 
limit. 

Final 
elonga- 
tion. 

Final  reduc- 
tion of  area. 

I.. 

2.. 
2A 

I'll 

*c 

8-. 
4.. 
5.. 
6.. 
T. 
8.. 
9.. 
10.. 
11.. 
12.. 

Kirkaldy  . 
J.  Kiley  . 

Gatewood  . 
Burba    ..  . 
A.  E.  Hunt 
Kirkaldy  ... 

•187®  875 
•25@1'00 
1  00 
•60 
•25 
•50 

4 

4           40 

56          432 
20 
16 
20 

2              8 
8            28 
17 

1 

29 
11 
8 
10 
2 

2 
4C 
15 
13 
18 
2 

1 
511 
18 
14 
18 
1 

*. 

-fr-5 

—0-60 
-7'9 

7-77 

%• 
+25-4 
-16-07 
-12-06 
-  17  11 
-16-63 
-  4-27 

-11  27 

-:l*  14 
—4*  -01 

The  1  inch  thick  plates  of  Number  2  

2 

—7  82 
-12  -If 
-3-lil 
+14  C 

—35  68 
-44-46 

i>        it        it 

l-ob 

•75 
•BO 

25 
•12@  81 
•19®  -94 

n        t(        ii 

48 

-0-3 
ll 
—1-4 
—1-0 
+1-3 
-14  91 
—  3-92 

0 
—0-7 
—13 
-  0-C 
+05 

The  1  inch  plates  of  Number  6  

8 

21 

6           87 

'.'6          325 

25 

e 

25 

5 
25 

Wrought-iron  plates  . 

mad 


all  cut  from   the  same  plate,  apparently 
enty-eight 
18  were 


e  parallel  with  and  4  across  the  direction  of  rolling. 

6  to  1O.  Kirkaldy,  Gatewood,  Kept.  U.  8.  Naval  Advisory  Bd.  on  mild  steel,  1886,  p.  133,  from  Parliamentary  Paper,  €,  2897,  London,  1881. 

11.  Kirkaldy,  Expts.  on  Wrought-iron  and  Steel,  p.  145     Of  the  87  tests,  20  were  made  lengthwise,  17  crosswise. 

12.  Idem,  p.  150.    Of  the  325  tests,  163  are  lengthwise,  162  crosswise. 


and  included  in  Number  2  of  Table  88,  all  the  rolling  was 
lengthwise  of  the  plate,  and  here  the  lengthwise  and  cross- 
wise properties  are  practically  identical. 

From  a  study  of  the  first  nine  lines  of  Table  88 A,  which 
all  refer  to  the  same  material,  we  cannot  say  confidently 
that  the  forging  has  improved  the  properties  of  test-pieces 
taken  lengthwise  more  than  those  of  test-pieces  taken 
transversely.  In  seven  cases  the  ratio  of  the  lengthwise 
to  the  transverse  properties  is  greater,  in  five  it  is  less, 
after  than  before  forging.  P'rom  such  contradictory  data 
no  safe  conclusion  can  be  drawn. 

The  last  nine  lines  at  first  seem  to  indicate  that  forging 
benefits  the  metal  more  along  than  across  the  direction  of 
forging  ;  for  in  every  case  the  ratio  of  the  lengthwise  to 
the  transverse  properties  is  greater  after  than  before  forg- 
ing. But  two  facts  raise  our  suspicion,  and  tempt  us  to 
look  beneath  the  surface.  First,  if  this  action  is  due  to 
setting  up  a  sort  of  fibre  parallel  with  the  direction  of 
forging,  how  comes  it  to  be  as  strong  in  the  oil-hardened 
as  in  the  unhardened  test-pieces  ? 

If  the  metal  was  reheated  for  oil-hardening  after  forging 
ceased,  the  reheating  should  according  to  Sorby  at  least 
tend  to  efface  the  grain,  and  so  to  equalize  the  lengthwise 
and  crosswise  properties.  Again,  how  is  it  that  the  cross- 
wise properties  of  the  original  ingot  are  so  much  better 
than  the  lengthwise  ?  Does  not  this  suggest  another  ex- 
planation, also  competent  to  explain  the  slight  excess  of 
the  lengthwise  over  the  transverse  properties  in  case  of 
ingot-metal,  shown  in  Table  88  ?a  In  our  ingot  the  blow- 
holes, even  the  minute  ones  which  might  escape  notice  in 
the  test-piece,  lie  radially,  presenting  their  ends  to  trans- 
verse, their  sides  to  longitudinal  stress.  This  should 
make  the  transverse  test-pieces  cut  from  the  unforged 
metal  stronger  than  the  longitudinal  ones  ;  and  so  we  find 
them  in  lines  13  to  15  of  Table  88A.  Flattening  the  ingot 
cheese-wise  should  exaggerate  this  excess  of  the  radial 
over  the  axial  properties,  and  so  it  does  in  lines  16  to  18. 
But  drawing  the  ingot  out  lengthwise  should  draw  the 
blowholes  and  similar  cavities  out  lengthwise  of  the  ingot, 
so  that  they  will  present  their  ends  to  longitudinal  and 


•  Cf.  J.  Head,  Journ.  Iron  and  Steel  Inst.,  1886,  I.,  p.  100. 


their  sides  to  transverse  stress,  and  the  longitudinal  test- 
pieces  should  be  somewhat  stronger  than  the  transverse, 
and  so  they  are  in  lines  19  to  21  of  Table  88A,  and  so  they 
may  be  to  a  slight  extent  in  Table  88  taken  as  a  whole. 

Three  facts  go  to  show  that  any  excess  of  the  longitu- 
dinal over  the  transverse  properties  is  not  due  directly  to 
the  formation  of  fibre  parallel  with  the  length  of  the  plate, 
owing  to  rolling  at  so  low  a  temperature  during  the  last 
passes  that  the  elongated  grains  cannot  thereafter  become 
equiaxed.  1,  The  excess  in  question  is  as  great  in  annealed 
as  in  unannealed  ingot-metal,  while  annealing  removes 
the  effects  of  cold-working  nearly  or  quite  completely,  in- 
cluding the  distortion  of  the  grains.  2,  The  excess  is 
nearly  and  perhaps  quite  as  great  in  thick  as  in  thin  and 
hence  cooler  finished  plates.  3,  Cold-rolling  seems  to  in- 
crease the  strength  as  much  in  one  direction  as  in  another. 

To  sum  up,  the  properties  of  ingot-metal  are  probably 
in  general  nearly  independent  of  the  direction  of  rolling  or 
hammering  as  such :  any  slight  difference  between  the 
lengthwise  and  the  transverse  properties  may  be  due  in 
part,  and  perhaps  wholly,  not  to  the  existence  of  a  defi- 
nite direction  of  grain  or  fibre  such  as  exists  in  wood,  but 
to  the  longitudinal  drawing-out  oi  cavities,  often  minute 
or  even  microscopic. 

§  259.  CHANGE  OF  CKYSTALLIZATION  IN  THE  COLD. — Do 
shock,  vibration,  flexure,  etc.,  change  the  crystallization 
of  iron  at  the  ordinary  temperature  ?  Do  they  make 
tough  fibrous  iron  brittle  and  crystalline  ?  Iron  is  sold 
me  as  tough  and  fibrous :  after  long  vibration  it  breaks 
with  a  crystalline  fracture:  have  I  a  prima  facie  case  against 
the  seller  ?  May  the  properties  and  crystallization  of  the 
metal  while  at  rest  change  in  the  cold  ?  Before  answer- 
ing, let  us  consider  the  nature  of  crystalline  and  fibrous 
iron. 

Fibre  in  Iron  and  Steel. — Whether  the  metal  yields 
a  fibrous,  a  silky,  or  a  crystalline  fracture  depends  (1)  on 
the  properties  of  the  metal  itself,  and  (•>,)  on  the  mode  of 
rupture.  Certain  tough  irons  yield  a  fibrous  fracture 
under  favorable  conditions,  e.  g.  when  nicked  on  one  side 
and  bent  slowly  away  from  the  nick,  but  a  crystalline  one 
under  others,  e.  g.  when  nicked  all  around  and  broken 


FIBRE    IN 


AND    STEEL.      §  259. 


Tuu  88  &.— IimmnoB    0»   IMKECTION  OK  FOBOINO,   FEOM  MAITLAND'S   DAT*.    (EICESSES  +,   DEFICITS—.) 


Dwcriptton, 

Tensile  strength,  Ibs.  pcrsq.  in. 

Elastic  limit,  Ibs.  per  sq.  in. 

Elongation,  %  in  2  inches. 

Work    of  rupture,   inch-tuna  per 
cubic  inch. 

Test  pieces  taken. 

Unhardened. 

Oil  hanU-tird. 

Unhardened  . 

Oil  hardened. 

ITnhardened. 

Oil  hardened. 

Unhanlfiird. 

Oil  hardened. 

1. 

2. 
3. 
4. 
5. 
6. 

B! 
i 

18. 

14. 
15. 
16. 
IT. 

IS. 
19. 
20... 
21... 

Jllnforged,  heated  oiu-i'. 
Heated    twice,    forged 
once.  .. 

Lengthwise  

72,800 
711.5114 
—  8-JB 
71,008 
69,828 
—2-86 
74,816 
70448 
—5-84 
62,608 
09,21« 
+10-55 
78,084 
61,152 
—  16-2C 
74,868 
66,080 
—11-15 

99,126 
100,240 
+1-13 
99,904 
90,888 
—9-02 
92.612 
93,072 

77,723 
75,483 
—2-88 
97216 
91,892 
—5-99 
87,696 
74,256 
—15-83 

35,892 
84.8S4 

2'85 

21  '5 

14'S7ft 
—80-79 
27-1) 
2026 
—26-0 
80-0 
25-5 
—15-0 
9-26 
15-55 
-fllS-11 
26-0 
8-25 
—  88-*l 
M-0 
17-7.-> 
—38-79 

725 
7-875 
+8-54 
16-75 
10-875 
—85-07 
24-75 
1975 
—20-20 
9-25 
11-5 
+24-88 
18-75 
6-75 
—64-00 
24-25 
11-0 
-54-64 

6-75 
8-90 
-32-17 
6-97 
5-12 
—  M-M 
9-07 
6-12 
—8258 

Crn>suisc  

!<  deficit  of  No.  '2  

Li-Mirthwise  

82.256 
81,752 

Crosswise  

54,482 

Heated      four      times, 

53,530 
48.466 

—18  88 

M',948 

58,464 
—1-88 

9-IHI 

5-85 

-40-51) 

(  'rossuise  

Itound  ingot,  unforged. 

£  deficit  of  No.  8  
Axiallv  

Kadi:dH-  

<  deficit  of  No.  14... 

Kadiallv    . 

88,870 
80,464 
—  8-78 
89,200 
80,683 
—21-72 

56,000 

6-94 
1-87 
—78-05 
8-10 
5-50 
—32-10 

Round  ingot,lengthened 

;<  deficit  of  No.  IT... 

Axiallv       

54,448 

8-50 
6-90 

—18-82 

IJadiallv  

%  deficit  of  No.  ail  

1  to  9,  two  ]»i,-ivs  \VITI-  rut  from  Hie  sume  ingot  "  so  as  to  be  of  i-iiual  quality."  One  was  forged  successively  from  the  section  10"  X  10"  to  7"  X  7",  to  5"  X  5"  and  to  5"  X  2-5",  each  reduction 
owutTiiig  at  one  heating.  The  other  piece  was  heated  together  with  the  first,  but  not  forged.  1  to  3  gives  the  properties  of  the  second  piece  heated  once  but  not  forged  ;  4  to  6  tbose  of  the  first 
piece  heated  twice  ami  fnrirfd  <>n<-<',  fn>m  lit"  X  1""  to  7"  X  7":  7  to  9  those  of  the  first  piece  heated  tour  times  and  t'nrired  thrice,  the  total  reduction  being  from  10"  X  10"  to  6"  X  2-5". 

13  to  21.  From  the  upper  part  of  a  circular  Jngot  longitudinal  and  transverse  test  pieces  were  cut,  numbers  13  to  15.  A  part  of  the  same  ingot  was  then  flattened  down  into  a  cheese,  and 
test  pieces  were  taken  transversely  and  axiallv,  16  to  18.  A  third  piece  was  drawn  out  parallel  with  the  length  of  the  ingot,  19  to  21. 

Maitlaiid,  "The  Treatment  "I '( inn  -Steel,""  excerpt  1'nic.   Inst.  Civ.  Kng.,  Ixxxil,  18S7. 


with  a  sharp  blow.ab  Again,  good  fibrous  wrought-iron 
armor-plates  struck  by  shot  shatter  like  glass,  and  with  a 
crystalline  fracture.*  The  usual  explanation  is  that  dur- 
ing slow  rupture  the  individual  grains  are  drawn  out  into 
fibres,  while  in  sudden  rupture  there  is  not  time  for  this 
elongation,  and  accordingly  rupture  strikes  across  the 
piece,  between  the  crystal  faces:  perhaps  rather  a  re-state- 
ment than  an  explanation. 

Thick  pieces  of  soft  steel  which  fail  in  the  bending  test 
usually  show  a  crystalline  fracture,  though  tensile  rupture 
produces  in  them  a  silky  one.c  Again,  not  only  do  guns, 
whether  cast-iron,  wrought-iron  or  steel,  whether  of  brittle 
or  ductile  material,  on  bursting  invariably  show  a  short 
granular  fracture,  but  Maitland  has  found  that  this  same 
fracture  invariably  arises  when  steel  tubes  are  burst  by 
pressure  from  within,  whether  this  pressure  be  suddenly 
or  gradually  applied,  whether  the  metal  elongates  much 
or  little  On  the  other  hand,  rods  torn  in  two  tensilely  by 
explosion  of  gun-powder  or  even  gun-cotton  invariably 
yield  a  silky  fibrous  fracture. d  In  explanation  it  is  pointed 
out  that,  under  tensile  test  of  a  rod  or  common  test-piece, 
the  rupturing  stress  is  in  a  single  direction,  and  tends  to 
elongate  the  metal' s  crystals  :  that  when  a  tube  is  burst 
these  crystals  are  exposed  to  forces  acting  simultaneously 
at  right  angles,  a  longitudinal  and  a  tangential  stress8 :  the 
crystal  cannot  so  readily  elongate  in  two  directions  at 
once,  the  tangential  stress  opposes  the  tendency  of  each 
crystal  to  elongate  lengthwise  of  the  tube,  and  vice-versa  : 
hence,  although  the  tube  as  a  whole  may  elongate  greatly, 
its  individual  crystals  elongate  but  little.  Do  they  then 
slide  past  each  other  ? 

Further,  a  punched  steel  bar  yields  a  crystalline  frac- 
ture: ream  but  a  knife-blade  thickness  from  the  sides  of 
the  punch-hole  and  it  yields  a  silky  fracture,  rupture  in 
one  case  apparently  starting  at  the  hole's  edge  and  rip- 
ping thence — as  a  ton-strong  canvass-roll  once  notched  is 
ripped  by  a  boy — in  the  other  all  parts  of  the  section  pull 
jointly.  The  change,  in  the  regions  apart  from  the  hole, 


a  Percy,  Iron  and  Steel,  pp.  10,  1 1 .  I  havfi  verified  this.  Thurston  vouches 
for  this  effect  on  armor-plate.  Matls.  of  Engineering,  II.,  p.  593. 

bCf.  Bayles,  Trans.  Am.  Soc.  Mech.  Eng.,  VII.,  p.  270. 

c  J.  Riley :  paper  2336,  "  The  Treatment  of  Gun-Steel,"  Proc.  Inst.  Civ.  Eng., 
LXXXIX.,p.  187,  1887. 

d  Maitland,  do.,  p.  130-1. 

e  Barlow,  idem.,  p.  203.  I  would  point  out  that  in  the  bending  test  we  have 
these  same  conditions,  tangential  and  radial  stress  acting  simultaneously.  A 
fragment  of  the  Pittsburgh  six-inch  steel  cast  gun  which  I  have  shows  this  short 
granular  fracture 


Wrought-iron. 

Steel. 

Tensile  strength, 
Ibs.  per  sq.  in. 

LOBS* 

Tensile  strength, 
Ibs.  per  sq.  in. 

Loss  f. 

52,640 

55,828:" 

72,800 

87.656b 
70,886 

24."  48b 
2-6 

50,400 

4-2 

c  "  The  Working  of  Steel,"  Proc.  Inst.  Civ.  Eng.,  LXXXIV.,  p    164,  1886.  aWhen  held  In  the 
usual  way.    b  When  held  by  a  pin  . 

is  probably  due  to  changed  approach  of  stress  rather  than 
changed  condition  before  stress. 

Though  the  effect  of  a  crack  in  steel  is  like  in  kind  to 
that  of  a  notcli  in  cloth  or  India-rubber,  it  is  much  less  in 
degree,  as  the  following  experiments  show.  Pine  saw-cuts 
were  made  sometimes  on  one,  sometimes  on  both  edges  of 
steel  and  of  wrought-iron  test-pieces:  they  were  then  closed 
at  a  heat  which  though  high  was  below  the  welding  heat, 
thus  practically  making  artificial  cracks.  These  reduced 
the  tensile  strength  of  the  remaining  section  as  follows  : 

TABLE  88  AA.— EFFECT    OP  CBACKS   ON  TUB   TENSILE  STBENGTII  OF  THE  REMAINING  SECTION. 

BAKEH'S  DATA.O 


A  fine  knife-cut  on  each  edge  of  a  strip  of  India-rubber 
reduced  the  strength  of  the  remaining  section  by  from  60 
to  70  per  cent. 

To  arrest  the  development  of  cracks,  Metcalf  recommends 
drilling  holes  at  their  ends.*  A  rounded  notch  or  a  drilled 
hole  increases  the  strength  of  a  common  test-piece  per  unit 
of  remaining  section,  at  the  expense  of  the  elongation. 

A  fibrous  fracture  is  most  readily  developed 

A,  in  tough  irons,  hence  those  with  little  carbon,  phos- 
phorus, etc. :  and  probably  those  which,  by  proper  heat- 
treatment,  have  acquired  a  fine  crystalline  structure  (e.  g. 
those  which,  since  last  exposed  to  an  excessively  high 
temperature,  have  been  forged,  or  reheated  to  about  W): 
those  in  which  the  stress  due  to  quenching  to  below  V  has 
been  avoided,  etc. 

It  is  natural  that  the  grains  of  tough  iron  should,  during 
rupture,  be  drawn  out  into  fibres  more  readily  than  those 
of  brittle  iron. 

B,  in  slag-bearing,  i.  e.  weld-iron  ;  and,  so  it  is  said, 
more  readily  in  weld-iron  with  much  than  in  that  with 
little  slag,  and  in  rolled  than  in  hammered  weld-iron,  as 
the  rolling  draws  the  slag  more  into  longitudinal  rods  and 
strips.     We  can  understand  that  longitudinal  threads  or 
blades  of  slag  between  the  equiaxed  grains  of  metal, 
(Figure  55)  like  blades  of  mica  among  highly  magnetized 
cubes  of  iron,  should  tend  to  promote  fibrousness  of  frac- 


t  Trans.  Eng.  Club,  W.  Penn.,  1887,  p.  133.     Jour.  Iron  and  Steel  Inst.,  1887, 
II.,  p.  852. 


196 


THE    METALLURGY    OF     STEEL. 


ture,  though  the  metal  before  rupture  may  have  no  true 
fibre  in  itself. 

To  this  action  of  the  blades  of  slag  may  be  ascribed  the 
phenomena  of  "barking,  ""shown  by  tough,  much-worked 
wrought-iron.  When  a  nicked  bar  is  broken  by  bending 
under  impact,  the  skin  at  the  convex  side  soon  separates, 
like  the  bark  and  outer  fibres  of  a  bough  thus  broken, 
from  the  main  body  of  the  piece,  which  bends  much 
farther  before  breaking. a 

Though  toughness  may  produce  fibre  during  strain  and 
rapture,  we  do  not  know  that  fibre  existing  before  strain 
produces  toughness.  Indeed,  we  have  seen  that  the  grains 
of  cold-worked  and  hence  brittle  iron  are  fibrous,  or  at 
least  elongated,  while  those  of  tough  hot- worked  iron  are 
equiaxed.  Moreover,  it  is  not  clear  that  the  fact  that  the 
former  are  not  equiaxed  has  any  important  direct  effect 
on  the  properties  of  the  metal,  for  the  strength  of  cold- 
worked  iron  seems  as  high  across  as  along  the  grain. 

Again  because  toughness  and  slag  both  produce  fibre, 
some  befogged  ones  infer  that  slag  produces  toughness. 
Health,  rouge  and  intemperance  redden  the  cheeks :  do 
rouge  and  rum  give  health  ? 

These  fallacies  pricked,  let  us  examine  (I.)  the  reasons 
to  expect  that  slag  should  toughen  iron,  and  (II.)  the  evi- 
dence that  it  does. 

I.  Blag  may  affect  iron  (a)  chemically  and  (b)  mechanic- 
ally. Chemically,  the  slag  of  weld-iron  may  toughen  the 
metal  by  oxidizing  carbon  and  silicon,  for  the  basic  iron 
silicates  of  which  it  consists  are  energetic  carriers  of 
oxygen.  In  ingot-metal  this  action  is  less  important, 
since  the  carbon  and  silicon  are  better  removed  otherwise, 
and  since,  at  least  in  acid  ingot-metal,  the  acid  slag  has 
little  oxidizing  power. 

No  relation  between  the  percentage  of  slag  and  that  of 
carbon  in  weld  metal  can,  however,  be  traced  in  the  results 
of  the  United  States  Board,  Table  83,  p.  169. 

Mechanically,  slag  (a)  breaks  up  continuity,  (b)  brings 
the  metal  a  step  towards  the  condition  of  a  wire  rope  or 
the  leaves  of  a  book,  and  (c)  hinders  rupture  from  strik- 
ing straight  across  the  piece 

The  first  action  weakens  and  makes  brittle. 

The  second  may  promote  flexibility,  but  hardly  tough- 
ness as  measured  by  final  elongation  under  tensile 
stress :  I  do  not  know  that  a  wire  rope  excels  in  eion- 
gation  a  solid  bar  of  equal  net  sectional  area.  Moreover, 
it  must  lower  the  transverse  strength  and  ductility  as 
much  if  not  more  than  it  increases  the  longitudinal  flexi- 
bility.. The  transverse  strength  of  a  wire  rope  is  practi- 
cally nil.  And  that  it  does  lower  the  transverse  properties 
we  learn  from  Table  88,  which,  representing  nearly  900 
cases,  shows  that  the  tensile  strength  of  weld-iron  plates 
is  decidedly  and  its  ductility  very  much  (about  40$)  less 
crosswise  than  lengthwise,  while  the  properties  of  ingot- 
metal  are  nearly  independent  of  the  direction  of  rolling. 

The  third  might  be  important  were  the  toughness  of 
slag  comparable  to  that  of  iron :  hair  toughens  mortar. 
But  we  cannot  confidently  expect  the  brittle  feeble  rods 
of  slag  to  obstruct  the  path  of  rupture  materially. 

That  they  do  not  is  indicated  by  Baker's  experiment 
in  Table  87  A,  in  which  an  artificial  crack  weakens 
wrought-iron  as  much  as  steel.  But,  on  the  other  hand, 

aThis  is  admirably  illustrated  in  Rept.  U.  8.  B'd.  on  testing  iron,  steel,  etc.,  I., 
D.  125. 


the  behavior  of  tough  wrought-iron  when  b:oken  by  nick- 
ing and  bending  seems  to  indicate  that,  Tinder  these  con- 
ditions, rupture  is  prevented  from  striking  across  the 
piece,  but  probably  less  by  the  resistance  of  the  slag  itself 
than  by  the  lack  of  continuity  due  to  the  presence  of  slag. 
In  this  view  slag-bearing  iron,  like  wire-rope,  should  excel 
in  flexibility  rather  than  ductility  as  measured  by  elonga- 
tion and  contraction  under  tensile  rupture. 

II.  For  evidence  of  the  toughening  effect  of  slag  we 
have  (a)  the  toughness  of  certain  Swedish  and  other  weld- 
iron.  Surprisingly  tough  they  certainly  are  :  but  it  does 
not  yet  S33rn  clearly  shown  that  ingot-iron  as  free  from 
carbon,  silicon,  manganese  and  especially  from  unoxidized 
phosphorus  is  less  tough. 

(&).  The  toughness  and  fibrousness  of  A  vesta  Bessemer 
ingot-iron,  into  which  slag  was  said  to  be  poured  intention- 
ally. But  the  trifling  quantity  of  probably  irregularly 
distributed  slag  in  Avesta  metal,  reported  to  be  as  low  at 
times  as  0'05$,  seems  a  wholly  inadequate  cause.  Indeed, 
after  this  practice,  probably  as  useless  as  it  seemed  sense- 
less, was  abandoned,  the  fibrousness  and  toughness  of 
the  metal  remained  unimpaired.  A  cynic  might  regard 
the  claim  that  the  -  vesta  metal  excelled  because  it  con- 
tained slag,  as  an  attempt  to  make  a  virtue  of  necessity, 
on  the  part  of  steel-makers  whose  crude  plant  permitted 
slag  to  run  into  the  ingot-moulds  nolens  volens.  It  would, 
indeed,  seem  about  as  easy  to  mix  slag  and  steel  effectively, 
as  corks  and  water.6 

The  scanty  data  of  the  United  States  test  board,  Table 
83,  while  suggesting  that  slag  weakens  wrought-iron 
tensilely,  give  no  weighty  indications  as  to  its  effect  on 
toughness. 

The  Terre  Noire  engineers  believed  that  a  minute  quan- 
tity of  slag  made  ingot  metal  weak  and  even  red-short.e 

In  brief,  while  we  see  no  strong  reason  why  slag  should 
benefit  iron  in  any  way.  and  while  we  have  no  strong  evi- 
dence that  it  does,  yet  our  knowledge  of  the  role  which  it 
plays  in  wrought-iron  is  too  crude  to  warrant  our  holding 
confidently  that  it  does  not  toughen  the  metal  in  certain 
ill-defined  ways. 

The  prevalent  belief  that  wrought-iron  is  tougher  than 
ingot-iron  of  like  composition  certainly  implies  that,  un- 
der certain  conditions,  slag  does  toughen  iron.  The 
foundations  of  this  belief,  however,  do  not  seem  to  be  of 
the  firmest. 

As  fibre  appears  to  be  due  to  the  drawing  out  of  the 
previously  equiaxed  grains  of  iron  by  favorable  mode  of 

rupture,  we  may  define   j  crystalline  '   ir°n  &S  ^^  wll°Se 

grains  |  are       ,  j-  readily  drawn   out  into  fibres   during 
(  are  not  j 

rupture,  or  that  which  j  ^^      ^  I   be    readily    made    to 

yield  a  fibrous  fracture. 

§260.  INFLUENCE  OF  VIBRATION,  ETC. — The  question  left 
now  resolves  itself  into  two  :  (1)  Do  vibration,  etc.,  induce 
coarser  crystallization  ;  and  (2)  do  they,  without  altering 
the  shape  or  size  of  the  crystals,  increase  the  tendency  to 
yield  a  crystalline  fracture  ? 


b  Fischer,  Oest.  Zeitschrift,  XXXIV.,  p.  244,  1886.  Goedicke,  Idem,  p.  536. 
Drown,  Proc.  Soc.  Arts,  Mass  Inst.  Technology,  1885-6,  p.  150.  Raymond, 
Howe,  Eng.  and  Mining  Jl.,  XLII..  pp.  181,  219  :  1886. 

oGautier,  Journ.  Iron  and  Steel  Inst.,  1877,  I.,  pp.  43-4.  Also  Holley, 
Metallurg.  Review,  II.,  p.  213,  "Th3  interposed  slag  must  necessarily  decrease 
(its)  strength  and  ductility." 


INFLUENCE    OF    VIBRATION    AND     SHOCK    ON    STRUCTURE.      §  260. 


107 


1.  Regarding  iron  as  a  viscous  liquid,  it  is  not  intrinsic 
ally  improbable  that  the  size  of  its  crystals  should  change 
at  the  ordinary  temperature,  eminent  but  dogmatic  engi- 
neers to  the  contrary  notwithstanding.     The  crystals  of 
native  silver  and  of  "mo-s  copper"  are  credibly  reported  as 
changing  their  shape  somewhat  rapidly  in  mineralogical 
cabinets."    Given  such  a  tendency,  vibration  might  well 
increase  it.     Agitation  precipitates  the  crystallization  of 
water  tranquilly  cooled  below  0°  C.     Instances  of  impor- 
tant changes  in  iron  at  relatively  low  temperatures  are  that 
of  density  at  100°  C.  observed  by  Laugley,  of  stress  at  60°  by 
Barns  and  fctrouhal,  of  carbon  at  a  brown  tint  by  Brinnell, 
of  flexibility  by  Coffin  at  a  straw  tint. 

2.  It  is,  however,  easier,  and  for  most  purposes  enough, 
to  answer  the  second  question.     We  can  readily  under- 
stand that  vibration  should  increase  the  tendency  to  break 
with  a  crystalline  fracture.  First,  every  variation  of  stress 
alters  the  shape  of  the  metal :  and  all  vibration  and  shock 
must  cause  variation  of  stress.  Now,  if  the  metal  is  a  com- 
posite mass  of  crystals  of  different  minerals,  say  kernels 
of  pearl  yte  imbedded  in  a  mesh  work  of  ferrite,  Figure  50, 
p.  1 65,  when  it  is  deformed  these  minerals,  both  on  account 
of  their  different  moduli  of  elasticity  and  of  their  different 
sh:;pes,   may  receive  stress   and  resist  deformation  un- 
equally :  the  thin  meshes  of  ferrite  may  be  strained  far 
more  than  the  kernels  ef  pearlyte,  or  vice  versa.     Differ- 
ently deformed,  the  harder  may  gradually  wear  into  the 
softer,  the  more  brittle  be  gradually  disintegrated  by  ex- 
cessive stress  on  its  most  burdened  saliences.     Again,  re- 
peated deformation  may  weaken  the  cement  between  the 
large  crystals  of  the  first  order  more  than  that  between  the 
smaller  secondary  crystals  (Figure  54).     These  are  not  of- 
fered as  the  true   condition  of  affairs,  but  as  instances  of 
the  numberless  ways  in  which  indefinitely  repeated  defor- 
mation may  gradually  alter  the  strength  of  the  metal,  the  j 
path  of  least  resistance  and  of  rupture,  so  that  rupture 
may  develop  a  crystalline    where    it  would  once  have 
yielded  a  fibrous  fracture.     A  given  degree  of  deformation 
may  thus  have  little  effect,  a  but  slightly  greater  one  pro- 
found influence.     Vibration  may  be  harmless  if  longitud- 
inal, injurious  if  transverse  and  so  flexure-causing ;  the 
flexure  the  immediate,  the  vibration  an  indirect  cause. 
That  which  would  eventually  destroy  a  mass  composed  of 
a  given  group  of  minerals  might  be  impotent  were  the  pro- 
portions, shape,  size  or  mode  of  arrangement  of  the  min- 
erals altered,     lleheated,  the  disintegrated  minerals  may 
reunite.     In  this  view,  cases  in  which  prolonged  vibration 
or  repeated  shock  or  flexure  are  known  to  change  the  frac- 
ture from  fibrous  to  crystalline,  show  the  existence  of  al- 
ready reasonably  suspected  tendencies  :  those  in  which  no 
such   change  occurs  merely  argue  relative  power  to  resist 
these  tendencies.*" 

Again,  if  stress  be  applied  to  iron  by  some  vibrating 
body  whose  vibrations  are  synchronous  with  the  natural 

a- Not  only  do  long  delicate  filamen's  of  silver,  evidently  not  due  to  mechanical 
pr'smre,  form  below  the  melting  point  of  this  metal  when  finely  divided  silver 
sulphide  is  heated  In  hydrogen  (Percy,  Metallurgy,  I.,  p.  359),  aud  growths  of 
this  metal  sprout  from  silver  sulphide  below  328°C.,  440°F.,  (Liversidge,  Chem. 
News,  XXXV.,  p.  68, 1877* :  but  moss  copper  has  formed  visibly  within  a  few  min- 
utes on  fresh  surfaces  of  copper  matte  cool  enough  to  be  held  in  the  band,  (W.  H. 
Hutchings,  idem,  p.  117),  and  very  considerable  growth  of  moss  copper  aud  silver  ; 
in  the  cold,  in  one  case  within  a  few  weeks,  in  others  in  periods  of  about  a  year, 
are  quite  credibly  reported  by  T.  A.  Readwin  and  J.  H.  Collins,  (Idem,  pp.  144, 
154). 

*>Cf.  Percy,  Jour.  Iron  and  Steel  Inst,  1885,  I  ,  p.   17;  Metealf,  Trans.  Am. 
lust.  Civ.  Eng..  XV.,  p.  290,  1887:  Hill,  Mechanics,  1882. 


vibration  of  the  metal  itself,  then  each  vibration  of  that 
body  creates  a  stress  which  tends  to  increase  the  ampli- 
tude of  the  metal's  vibration,  and  we  can  conceive  that 
this  might  go  on  till  we  reached  an  amplitude  so  great  as 
to  cause  rupture,  as  in  the  fabled  attempt  to  fiddle  a 
bridge  down.  As  an  only  slightly  different  rate  of  vibra- 
tion, even  if  more  rapid,  would  not  act  in  this  special 
way,  numberless-  cases  in  which  iron  resists  vibration 
successfully  would  merely  show  that  the  liability  to  fail- 
ure in  this  way  was  small,  not  that  it  did  not  exist. 

The  path  of  least  resistance  in  this  type  of  rupture  might 
well  differ  greatly  from  that  under  static  stress,  yielding 
a  granular  fracture  in  metal  which  would  usually  show  a 
fibrous  fracture. 

A  difficulty  in  the  way  of  this  explanation  of  failures 
under  vibration  is  that,  if  the  piece  has  approximately 
uniform  sectional  area  for  a  considerable  distance,  we 
would  expect  that  it  would  undergo  a  great  permanent 
elongation  long  before  the  amplitude  of  vibration  became 
so  great  as  to  cause  rupture,  and  that  this  very  elonga- 
tion would  change  the  metal' s  natural  rate  of  vibration, 
and  so  remove  the  cause  of  danger. 

Vibration  is  said  to  change  the  structure  of  some  alloys 
greatly,  making  them  extraordinarily  brittle.' 

Here  are  a  few  of  the  many  instances  in  which  long  ex- 
posure to  vibration  has  produced  no  noticeable  injury. 
Thurston  vouches  for  a  great  and  unmistakable  improve- 
ment in  the  quality  of  wrought-iron  rails,  originally  brittle, 
during  prolonged  use  in  the  track.d  Bauschinger  reports 
two  cases  in  which  he  could  detect  no  loss  of  strength  or 
change  of  structure  after  prolonged  exposure  to  vibration. 
The  first  is  that  of  iron  in  use  in  a  chain  bridge  during  49 
years,  and  compared  wich  a  reserve  chain  made  by  the 
same  firm  and  at  the  same  place,  and  carefully  kept  for 
comparison.  In  the  second  case  he  applied  to  bolts  from 
another  bridge,  tests  to  which  they  had  been  subjected 
twenty-five  years  before.6 

Long  searching,  Percy  failed  to  find  conclusive  evidence 
that  vibration  makes  iron  crystalline.  R.  :  tephenson  tells 
of  the  beam  of  a  Corliss  engine,  apparently  uninjured  after 
receiving  a  shock  equal  to  about  f>0  tons  8  or  10  times  a 
minute  for  20  years,  and  of  a  locomotive  connecting-rod, 
which  showed  no  change  after  receiving  ^5,000,000  blows, 
at  the  rate  of  eight  per  second.' 

The  fracture  of  a  wrought-iron  bolt,  thought  to  be  of 
Ulster  iron,  which  had  held  down  the  anvil  of  a  trip-ham- 
mer for  twenty  years,  was  highly  fibrous,  and  like  that  of 
unused  Ulster  iron.  So,  too,  with  a  hammer-head.8 

Kennedy  reports  many  pieces  of  wrought-iron  and  steel, 
all  long  used,  some  broken  in  use  ;  in  none  of  them  did 
he  find  distinct  indications  of  fatigue.  Baker  finds  that, 
when  fiat  bars  of  soft  steel  and  wrought-iron  are  bent 
laterally  repeatedly  Wohler-wise  till  they  break  off  short, 
their  broken  halves,  even  at  points  where  they  had  been 
subjected  to  90$  of  the  stress  which  existed  at  the  rup- 

o  Percy,  Iron  and  Steel,  p.  11 .  Also  "Metallurgy,"  Vol.  I.,  p.  621.  "Somekiuds 
of  brass  wire  become  extremely  brittle  in  the  course  of  time,  especially  if  subjected 
to  vibration.  I  have  seen  thick  brass  wire  become  almost  a.i  brittle  as  glass  in  the 
course  of  a  few  weeks,  after  having  been  kept  extendid  and  subjected  to  vibra- 
tion." 

dMat'ls  of  Engineering,  II.,  p.  577. 

e Journ.  Franklin  Inst.,  CIX.,  p.  417:  Journ.  Iron  and  Steel  Inst.,  1880,  I.,  p. 
347,  f r.  Dingler's  Polytcchnisches  Journal. 

f  Treatise  on  the  Resistance  of  Mails.,  Wood,  p.  212. 

gG.  E.  Whitehead,  Sup'c  Rhode  Island  Tool  Co.,  Providence,  R.  I.,  private 
communication,  Aug.  8th,  1888. 


THE    METALLURGY    OF    STEEL. 


tured  section,  can  invariably  be  bent  double  without  rup- 
ture.* 

The  wrought-iron  side  and  main  driving  rods  of  loco- 
motive engines  have  been  found  fibrous  and  tough  after 
prolonged  use.  Some  examples  follow. 


Condition  of  service. 

Results  of  tensile  tests. 

Length  of  service. 

Mileage. 

Tensile 
strength. 

Elastic  limit. 

Elongation 
f. 

In. 

Contraction 
of  area,  %, 

Passen. 

Freight. 

Total. 

Side  rod.. 

"  '{ 

Main  rod.. 

12  vr. 
12'" 

Tr.  Mo. 

28      8 

6  vr. 

0 
0 

lylL, 
gen.  service 

82  yr.  8  mo 

12  yr. 
12  " 

Tr.  Mo 

29  8 

37  8 

43,410 
56,550 

47,320 
41,180 

24,450 

19- 
81- 

86- 
88- 

1C 

r 

5" 
!• 

Fibrous. 

Fibrous  and 
granular. 

Fibrous, 
spongy. 

1910,080 
860,000  cst 

14-2 
»J 

80-8J 

20,200 

Kept.  Tests  Metals,  Watertown  Arsenal,  1885,  p.  1,044,  1888. 

But,  though  the  fragments  of  Wohler-broken  bars 
show  no  fatigue,  some  change  has  occurred  in  them,  for  a 
comparatively  few  repetitions  of  stress  would  now  break 
them.  Does  this  change  increase  the  tendency  to  break 
with  a  crystalline  fracture  ?  Our  evidence  does  not  permit 
a  certain  answer.  Whole  bars  tested  after  Wohler-treat- 
ment  which  has  not  been  carried  to  rupture  show  a  tremen- 
dous loss  of  tensile  strength  and  elongation,  but  probably 
because  cracks  which  would  eventually  lead  to  rupture 
have  already  formed.  For  instance,  18,140  bendings  re- 
duced the  tensile  strength  and  elongation  of  a  bar,  whose 
companion  had  broken  under  this  number  of  bendings, 
from  70, 000  to  48,000  pounds  per  square  inch  and  from  20 
to  2 '6%.  Bauschinger,  indeed,  finds  that  the  strength  of 
Wohler- treated  bars,  when  subsequently  tested  with  quies- 
cent load,  is  not  lower  than  initially,  but  rather  higher." 

Railway  axles  and  bars  broken  by  Coffin  and  others  by 
prolonged  rotation  while  slightly  bent,  seem  to  fail  by  the 
gradual  creeping  inwards  of  a  thin  crack.  After  this  has 
penetrated  a  certain  distance,  the  remaining  metal  gives 
way  suddenly.  The  fracture  of  this  last  broken  part 
does  not  differ  strikingly  from  that  of  similar  material 
broken  in  the  natural  state.  In  the  case  of  railway  axles, 
while  often  fibrous,0  it  seems  on  the  whole  more  inclined 


a  Trans.  Am.  Soc.  Mech.  Eng.,  VIII.,  p.  163,  1887.  Baker's  statement  has  been 
incorrectly  interpreted  as  meaning  that  a  bar,  subjected  repeatedly  to  90$  of  the 
stress  a  single  application  of  which  would  suffice  to  break  it,  may  show  no  sign 
of  change  :  he  means  that  it  may  show  no  injury  when  bent  a  certain  number  of 
times  under  90$  of  that  stress  which  applied  the  same  num  ber  of  times  would 
break  it:  (Idem,  p.  174).  This  is  true,  the  other  absurd.  The  court  may  be  as- 
sumed to  know  some  law. 

b  Mittheil  aus  dem  Mech-Tech.  Lab.  in  Miinchen,  XV. ,  p.  42,  1886. 

cCf.  Rankine,  Civil  Engineering,  1870,  p.  506.  On  the  Pennsylvania  Rail- 
road the  fracture  of  wrought-iron  axles  is  usually  more  or  less  fibrous,  that  of 
steel  axles  granular:  but  as  a  whole  there  seems  to  be  a  tendency,  stronger  in  steel 
than  in  wrought-iron,  towards  a  crystalline  fracture  (Dr.  C.  B.  Dudley,  private 
communications.  May  9tb,  Sept.  18th,  1888). 

Railway  axles  and  the  bars  experimented  on  by  Coffin  and  others  break  "in  de- 
tail" as  it  is  called.  The  fracture  shows  two  very  sharply  separated  parts:  an  inner, 
slightly  excentric,  sub-circular  region,  occupying  perhaps  one  quarter  of  the  total 
area,  with  a  fresh  fracture,  much  like  that  of  a  bar  broken  in  the  usual  way, 
e.  g.  by  nicking  and  bending.  The  remainder  of  the  bar  has  a  nearly  smooth 
fracture,  not  unlike  that  of  Etruscan  gold,  and  suggesting  that  it  has  been  long 
broken,  and  that  the  opposite  faces  have  worn  each  other  smooth.  The  abrupt- 
ness of  the  transition  is  not  very  readily  understood.  Railway  crank-axles  are 
sometime  run  till  an  incipient  crack  appears,  then  hooped  :  marine  shafts  are 
used  for  a  further  definite  time  after  a  flaw  first  appears.  (Baker,  Trans.  Am.  Soc 
Mech.  Eng.,  VIII.,  p.  163,  1887.) 

Baker  states  that,  though  the  crank  and  straight  driving  axles  of  locomotives  bend 
but  S12  and  „'.,  inch  respectively  under  the  heaviest  stress  to  which  they  are  subject, 
yet  in  1883  one  iron  axle  in  fifty  broke  in  running,  and  one  in  fifteen  was  renewed 
on  account  of  defects  :  further,  that  during  the  preceding  three  years  (1882-4?( 
no  less  than  228  ocean  steamers  were  disabled  by  broken  shafts,  whose  average 
safe  life  is  put  at  about  three  or  four  years.  (Rept.  British  Ass.,  1885,  pp. 
1185-6.) 


to  break  with  a  crystalline  fracture,  and  this  inclination 
is  perhaps  stronger  than  in  case  of  unused  axles  :  but  of 
this  we  cannot  be  sure. 

W.  Parker,  Chief  Engineer- Survey  or  of  Lloyd's  Reg- 
ister, after  prolonged  consideration  of  the  breakages  of 
marine  shafts,  finds  no  reason  to  believe  that  the  vibration 
to  which  they  are  exposed  makes  wrought-iron  shafts 
crystalline,  or  steel  shafts  more  coarsely  crystalline."1 

On  the  other  hand,  passing  by  Fairbairn1  s  famous  as- 
sertion that  "  we  know  that  in  some  cases  wrought-iron 
subjected  to  continuous  vibration  assumes  a  crystalline 
structure,"  we  have  the  following  experiment  by  Sorby." 
He  attached  a  bar  of  iron  to  a  tilt-hammer  so  that  it 
vibrated  up  and  down  continuously :  after  fifteen  hours 
it  broke  with  a  crystalline  fracture.  An  examination  of 
a  longitudinal  section  of  the  broken  end  showed  that  the 
ultimate  structure  was  no  more  crystalline  than  that  of 
similar  iron  in  its  natural  state  :  yet  some  of  the  crystals 
appeared  to  be  slightly  separated  from  each  other,  instead 
of  being  as  usual  in  exact  apposition. 

Again,  Martens  invariably  finds  that  the  fracture  of  the 
tension  side  of  a  bar  broken  by  oft-repeated  slight  flexure, 
as  in  Wohler' s  experiments,  is  much  finer  than  that  of  the 
compression  side :  the  change  is  very  abrupt,  occurring 
along  a  line  which,  in  round  bars,  is  nearly  straight  and 
perpendicular  to  the  line  of  bending,  but  is  curved  and 
sometimes  nearly  a  half -oval  in  square  bars.'  On  the  pol- 
ished section  he  could  find  no  trace  of  this  line  with  the 
microscope:  the  ultimate  structure  seemed  uniform 
throughout  the  region  where  this  line  occurs.  The  change 
then  appears  to  be,  not  in  the  size  or  arrangement  of  the 
crystals,  but  in  their  adhesion  or  in  the  path  of  rupture. 

These  changes  in  the  path  of  least  resistance  are  prob- 
ably due,  not  to  the  last  application  of  stress,  but  to  the 
accumulated  effect  of  repeated  stresses.  Here  then  stresses 
long  antecedent  to  rupture  appear  to  affect  the  fracture. 
But  Bauschinger  finds  that,  while  rupture  by  repeated 
stress  produces  these  markings  in  the  fracture,  if  a  frag- 
ment of  a  Wohler-broken  bar  be  again  broken  in  the 
normal  way,  the  fracture  now  obtained  is  exactly  like 
that  of  similar  bars  which  have  not  been  subjected  to 
Wohler-treatment.  So  with  bars  which  have  been  long 
subjected  to  Wohler-treatment  without  actual  rupture. 
Hence  he  concludes  that  stress  applied  to  iron  and 
steel  millions  of  times  does  not  affect  the  structure.11 

Again,  it  is  the  conviction  of  the  users  of  trip-hammers 
and  of  rock-drills  that  the  head-bolts  of  the  former  and 
certain  parts,  e.  g.  the  rocker-pins,  of  the  latter  become 
crystalline,  i.  e.  that  metal  which  before  use  would  yield 
a  fibrous  after  use  shows  a  crystalline  fracture. g 

The  fracture  of  a  40-year-old  five-inch  connecting-bar  of 
the  300-ton  Washington  Navy  Yard  testing  machine, 
which  broke  under  a  load  of  about  100  tons  (its  original 
strength  should  have  been  some  400  tons)  was  for  most 
part  distinctly  crystalline,  with  some  large  well-defined 


d  Private  communication,  Feb.  5th,  1889. 

e  Jour.  Iron  and  Steel  Inst,  1887,  I.,  p.  265. 

f  Stahlund  Eisen,  VII.,  238,  1887.  He  speaks  of  these  lines  as  ellipses,  but, 
judging  from  his  illustrations  it  is  improbable  that  they  are  parts  of  true  ellipses. 
He  describes  them,  certain  rays  normal  to  and  crossing  them,  and  attendant  phe- 
nomena, minutely. 

8G.  R.  Stetson,  Trans.  Am.  Soc.  Mech.  Eng.,  VII.,  p.  267,  1886:  Rand  Drill 
Company,  private  communications,  Aug.  2d,  1888.  Cf.  Wood,  •'  Treatise  on 
Resistance  of  Mat'ls,"  p.  314. 

nLoc.cit. 


CHANGE    OF    CRYSTALLIZATION    DURING    REST. 


261. 


199 


crystals  "bright  as  mica,"  whose  diameter  must  have 
reached  0'5  inch  to  judge  from  Thurston' s  illustration. 
Purposely  broken  about  one  foot  from  the  original  break, 
it  showed  the  same  fracture.  As  it  was  carefully  made 
from  excellent  material,  Beardslee  regards  it  as  an  "un- 
mistakable instance  of  crystallization,  which  was  proba- 
bly produced  by  alternations  of  severe  stress,  sudden 
strains,  recoils,  and  rest."* 

A  20-foot  porter-bar  at  the  Morgan  Iron  Works  broke 
under  the  jar  of  the  hammer,  at  a  point  where  its  diameter 
was  about  15  inches,  and  where  it  was  unstrained  by  the 
load,  with  a  fracture  in  large  part  crystalline,  one  crystal 
having  faces  0'5  inch  square.1"  We  are  not  informed 
whether  its  temperature  may  not  often  have  been  high 
enough  to  greatly  promote  crystallization  ;  i.  e.  whether 
the  crystallization  was  due  to  jar  in  the  cold,  or  to  heat 
jointly  with  jar. 

Now  I  find  nothing  here  which  indicates  strongly  that 
any  change  in  crystallization  occurs  under  vibration  or 
shock.  The  cases  of  the  Washington  testing  machine  and 
of  the  Morgan  Iron  Works  porter  bar  may  well  be  due  to 
over-heating  during  manufacture.  Finding  the  users  of 
trip-hammers  very  positive  in  their  assurances  that  their 
bolts  became  crystalline,  I  made  some  bolts  for  certain 
trip-hammers,  using  for  one  hammer  an  iron  like,  if  not 
the  same  as  ihat  habitually  used  for  its  bolts,  and  reserv- 
ing part  of  the  iron  for  comparison.  The  most  striking 
result,  unfortunately  a  psychological  not  a  metallurgical 
one,  was  that  the  bolts  actually  lasted  not  merely  longer, 
but  incomparably  longer  than  I  was,  at  least  in  one  case, 
assured  that  they  could.  They  have  alreaeky  run  over 
four  months,  and  only  one  has  failed.  The  fracture,  is 
closely  like  that  of  bars  broken  "in  detail,' '  Wohler-wise, 
by  prolonged  rotation  while  slightly  bent,  already  de- 
scribed. The  sub-circular,  somewhat  eccentric  part  last 
broken  resembled  closely  the  fracture  of  the  reserved 
part  of  the  same  bar  broken  by  nicking  and  bending.  I 
could  find  no  suggestion  of  granulation  in  the  fracture, 
either  where  the  bolt  had  broken  in  use  in  the  trip-ham- 
mer, or  where  subsequently  nicked  and  broken  with  a 
sledge,  or  where  pulled  apart  in  the  testing  machine.  The 
properties  of  the  bolt  broken  in  use  were  practically  identi- 
cal with  those  of  the  iron  reserved  for  comparison. 


Tensile  strength, 
Lbs.  per  sq.  in. 

Breaking  load, 
Lbs.  per  sq.  in. 

Elonga- 
tion* 
in  Jtn. 

Contrac- 
tion of 
area  *. 

Fracture. 

57,867 

49,845 

43-4 

45-8 

KKX  fibrous. 

Piece  reserved  for  comparison. 

57,168 

50,461 

43-4 

47-8 

100^  fibrous. 

Nor  in  Bessemer  steel  trip-hammer  bolts  broken  in  use 
do  I  find  any  indication  of  granulation.  Nearly  the  whole 
fracture  is  of  the  fine,  apparently  smooth-worn  type,  the 
sub-central  crystalline  part  being  very  small.  Nicking 
and  breaking  the  fragments  with  a  sledge,  we  get  a  perfectly 
normal  fracture. 

To  sum  up,  while  vibration  and  shock  often  cause  rup- 
ture under  light  stress,  and  while  it  is  proverbially  difficult 
to  prove  a  negative,  we  have,  I  think,  every  reason  to 
believe  that  the  granulation  and  crystallization  of  iron 
under  vibration  and  shock  is  a  myth. 

Touching  the  relative  power  of  low-  and  of  high -carbon 


steel  to  resist  vibration  and  shock  we  have  the  follow  in;; 
evidence. 

Metcalf  found  that  steam-hammer  piston-rods  made  from 
steel  with  O'CO^of  carbon  lasted  over  two  years,  while  under 
like  conditions  those  of  mild  steel  lasted  but  six  and  those 
of  wrought-iron  but  three  months  ;  and  that  the  endurance 
of  rapidly  reciprocating  pitmans  increased  with  their  per- 
centage of  carbon,  at  least  till  this  reached  0 '84$. c  The 
feed-rollers  in  blooming  mills  receive  extremely  severe 
blows  from  the  bloom,  which  of  ten  butts  against  them  like 
a  tremendous  battering-ram.  At  first  these  rollers  were 
made  of  soft  steel,  in  the  belief  that  a  tough  material  was 
needed  to  resist  these  shocks :  but  experience  shows  that 
they  endure  much  longer  when  made  of  hard  steel. 

From  such  facts  it  has  been  inferred  that  hard  steel  is 
better  fitted  to  resist  shock  and  vibration  than  soft  steel : 
the  inference  is  hardly  justified.  Here  pieces  of  soft 
steel  are  compared  with  enormously  stronger  ones  of  hard 
steel,  which  endured  longer  probably  simply  because  the 
bending  which  they  underwent  was  so  much  farther  below 
that  corresponding  to  their  elastic  limit.  The  hammer- 
rods,  pitmans  and  rollers  of  soft  steel  might  well  have  out- 
lasted those  of  hard,  if  so  proportioned  as  to  have  as  great 
transverse  elastic  limit. d 

In  harmony  with  this  view  are  Baker's  results  given  in 
Table  88  B.  Here  hard  steel  indeed  endures  repeated 
bending  under  given  absolute  stress  better  than  wrought- 
iron  and  soft  steel,  yet  excels  these  classes  in  this  form  of 
endurance  much  less  than  in  tensile  and  compressive 
strength  and  elastic  limit. 

Comparing  cases  in  which  the  stress  on  each  variety 
is  a  given  percentage  of  its  ultimate  tensile  strength  under 
single  load,  hard  steel  breaks  down  much  the  earliest. 

TABLE  88  B. — PATIENCE  OF  IRON  UNDER  REPEATED  BENDING.     BAKER. 


Factor  A. 

Hard  Steel. 

Soft  Steel.     % 

Wrought-iron. 

Thousands 
of  revs. 

Stress,  Ibs.  per 
eq.  in. 

Thousands 
of  revs. 

Stress,  Ihs. 
per  so,,  in. 

Thousands 
of  revs. 

Stress,     His. 
piTKq.  In. 

1'66@1'75 

40'5@60'2 
68'4@155 

3(1.11(10 
84,000 

108@142 
389(3421 

•llKOTl-1 

:;:<,/•;!  I«HI 
82,1X10 
81@30,000 

1-"5@1'90  

5-8 
7'6 
l.fCvj:W-4 
26-1 
157-S 
4725 

67,000 
65,000 
.V),f>oo@Sl,000 
46.500 
10,500 
44,000 

1'9.3@2'0 

14,676 

26,000 

Rotating  spindles,  usually  1  inch  diameter,  and  projecting  10  inches  from  the  shaft  in  which  they 
are  fixed,  revolve  day  and  night,  weighted  at  the  unsupported  end,  so  that  each  fibre  is  alter- 
nately In  tension  and  compression.  "  Thousands  of  revolutions  "  refers  to  the  number  of  revolu- 
tions endured  before  rupture.  Factor  A  is  the  ratio  of  the  ultimate  tensile  strength  to  the 
calculated  tensile  stress  on  the  outer  fibres  doe  to  the  weight. 

The  hard  steel  is  an  excellent  drift-stool,  tensile  strength  about  120,000  Ihs.,  elongation  about 
14i  in  8  inches  Soft  steel  Is  fine  rivet-steel,  tensile  strength  about  CO.  (HHlll.s.,  i-l.  mention  K$. 
WroughMron  is  the  best  rivet-iron,  tensile  strength  about  60,000  Ibs.,  elongation  Ii0j«  in  b'.  Trans. 
Am.  Soc.  Mech.  Eng.,  VIII.,  p.  160, 1887.  


§  261.  CHANGE  OF  CRYSTALLIZATION  AND  OP  PKOPEE- 
TIES  IN  THE  COLD  WHILE  AT  REST.— There  is  a  common 
belief  that  iron  of  various  classes  (wrought-iron,  steel  tools, 
etc.),  is  improved  by  long  rest  and  exposure  to  the 
weather.6  Ledebur  shows  that  the  latter  may  lead  to  seri- 
ous injury  through  absorption  of  nascent  hydrogen/ 
We  shall  see  in  §  269  that  the  tensile  strength  and  elas- 
tic limit  of  iron  which  has  been  distorted  beyond  its  elastic 
limit  do  increase  for  a  long  time,  probably  for  many  years, 
at  an  ever  retarded  rate.  Further,  internal  stress  induced 
by  irregular  cooling  or  by  cold-working  may  be  gradually 
relieved  during  rest,  to  the  benefit  of  the  metal,  especially 


a  Kept.  U.  S.  Bd.,  to  test  iron,  etc.,  I.,  p.  136:  Thurston,  Mat'ls  of  Engineering, 
II.,  p.  578. 
t>  Thurston,  Mat'ls  of  Engineering,  II.,  p.  580. 


c  Metallurgical  Review,  I.,  p.  400.  Cf.  Kent.  Trans.  Am.  Inst.  Mining  Engi 
neers,  VIII.,  p.  76,  1880. 

A  Cf  Lindenthal,  Trans.  Am.  Soc.  Civ.  Engrs.,  XV.,  p.  376-7,  1887. 

e  Thurston,  Matls.  of  Engineering,  II.,  p.  576  :  W.  Hewitt,  Trans.  Am.  Soe. 
Mech.  Eng.,  IX.,  p.  47,  1888. 

f  Cf.  §  178,  p.  114, 


200 


THE    METALLURGY    OF    STEEL. 


Endurance. 

72  fires. 
2,582      " 
800      " 


if  the  temperature  be  raised.  Here  then  we  have  two 
reasonable  explanations  of  this  belief. 

We  have  seen  that  the  thermo-electric  power,  thought 
to  be  a  true  index  of  stress,  changes  rapidly  when  steel  is 
heated  to  66°  C.  (151°F.)a:  iron  might  easily  reach  this 
temperature  in  our  climate  when  exposed  to  the  summer 
sun:  tools  left  in  boilers  are  of  course  continuously  exposed 
to  far  higher  temperatures,  and  they  are  especially  prized. 

An  improvement  so  great  that  we  hesitate  to  ascribe  it 
to  differences  in  the  conditions  of  manufacture  or  of  trial, 
is  reported  in  Rodman  cast-iron  guns  during  rest :  it  is  as 
follows. 

TABLE  89. — EFFECT  OF  BEST  CN  CAST-IRON  GUNS. a 

Tensile  strength. 

Cast  in  1851  and  tested  soon  after 87,811  Ibs. 

Castin'lSWnnd  tested  In  1852 29,42;)    " 

Cast  In  1846  and  tested  in  1852     22,989    " 

aThurston.  Matls.  of  Engineering,  II.,  p.  589,  fr.  Rodman.  Kept.  Expts.  on  Strength  and 
Other  Properties  of  Metal  for  Cannon,  Rand,  p.  217,  1856. 

But  Mr.  Wm.  P.  Hunt  informs  me  that,  in  the  case  of 
discs  cut  from  the  muzzles  of  Rodman  cast-iron  guns,  the 
initial  stress  due  to  casting  around  a  water  cooled  core  did 
not  diminish  materially  during  some  ten  years'  rest.b 

Both  the  galvanized  and  the  ungalvani  zed  wire  supplied 
for  the  East  River  Bridge  often  gained  strength  by  simple 
rest,  the  ungalvanized  often  gaining  five  per  cent,  in  a 
week  or  two." 

Examining  12  groups  of  specimens  from  102  heats  of 
structural  open-hearth  steel,  under  uniform  conditions  of 
working  and  testing,  and  collectively  embracing  446  tests, 
E.  C.  Felton  found  those  tested  more  than  twenty-four 
hours  after  rolling  slightly  but  fairly  constantly  stronger 
and  more  ductile  than  those  tested  within  twenty -four 
hours.  The  elastic  limit  was  less  constantly  affected.  In 
eight  out  of  the  twelve  groups  it  was  lower;  in  the  four 
others  it  was  greater  in  the  late  than  in  the  early  tested 
pieces.  In  other  words,  the  repose  appeared  to  increase 
the  tensile  strength  and  ductility  slightly,  but  to  have  no 
constant  effect  on  the  elastic  limit."  His  results  are  con- 
densed in  Table  91. 

TABLK  91. — EFFECT    OF   REPOSE   ON   THE   PROPERTIES  OF    12  GROUPS  OF  STEEL  SPECIMENS. 

FELTON. 


Increase  (-f-)  or  Decrease  (  —  ). 

Tensile 
strength. 

Elastic  limit. 

Elongation  . 

Reduction  of 
area. 

4-0-15* 
+0-07* 

11 

—  0-8* 
-0-6* 

4 

4-2-4 
+1-4 

10 

4-6-2 
-1-2-1 

13 

Number  of  groups   in    which    an  increase 

From  the  foregoing  we  see  that  the  strength  of  iron  in 

Fig.78 


aBarus  and  Strouhal,  Bull.  U.  S.  Geol.  Survey,  14,  pp.  54-5:  Cf.  §§  53-4,  this 
work. 

l>  Private  communication,  April  12th,  1888.  Wm.  P.  Hunt,  Pres- 
ident of  the  South  Boston  Iron  Company.  Discs  one  inch  or  more  in 
thickness  were  cut  from  the  muzzles  of  the  Rodman  guns  cast  at  the 
South  Boston  Iron  Works,  and  the  initial  stress  was  roughly  deter- 
mined by  cutting  a  slot  (AA  Fig,  78)  across  them  in  a  planing  ma- 
chine. When  this  slot  had  been  cut  to  within  about  a  quarter  of  an  inch  of  the 
bottom  the  stress  would  tear  the  remaining  metal  apart,  and  the  thickness  of  this 
metal  indicated  Ihe  amount  of  stress.  Mr.  Hunt  found  that  the  stress  thus  deter- 
mined was  substantially  the  same  in  two  discs  cut  from  the  same  gun,  one  tested 
at  the  time  of  casting,  the  other  some  ten  years  later. 

c  Collingwood,  Trans.  Am.  Soc.  Civ.  Eng.,  IX.,  p.  171,  1880.  He  refers  the 
gain  to  "  the  accommodation  of  strain  induced  by  the  drawing." 

d  Trans.  Am.  Soc.  Mech.  Engineers,  IX.,  1888.  It  is  true  that,  as  Mr.  Felton 
says,  on  an  average  the  elastic  limit  is  lowered  by  the  repose.  But  the  number  of 
cases  in  which  the  reverse  is  true  is  so  great  that  this  result  should,  I  think,  carry 
little  weight.  So  too  Mr.  Felton  endeavors  to  explain  the  fact  that  the  re- 
pose affects  the  ductility  and  elasticity  of  the  hands  round  more  but  their  tensile 
strength  less  on  an  average  than  those  of  the  comparatively  hotrolled  guide 
rounds.  Here,  too,  the  exceptions  are  so  very  numerous  as  to  suggest  that  this 
fact  represents  no  general  law  except,  perhaps,  as  regards  tensile  strength,  but  is 
simply  such  an  accidental  result  as  may  always  be  looked  for.  Averages  of  the 
heights  of  20  blue  and  20  brown-eyed  men  would  give  one  set,  say  the  brown- 
eyed,  as  slightly  taller  than  the  other  :  from  which  no  oae  would  deduce  a  rela- 
tion between  eye-color  and  height, 


certain  cases  increases  with  rest  immediately  after  stress, 
and  after  forging. 

§261A.  PERSISTENCE  OF  CRYSTALLINE  FORM  after  the 
mineral  which  caused  it  has  ceased  to  exist,  is  illustrated, 
1st  by  hardened  Bessemer  steel  (apparently  of  0'49$  of 
carbon),  which,  though  apparently  wholly  converted  into 
hardenite,  yet  shows  traces  of  the  network  structure  which 
had  initially  existed  between  the  primary  prismatic  crys- 
tals, conspicuous  on  fracture:  2nd  by  malleable  castings, 
whose  interior  shows  the  laminar  structure  of  pearlyte, 
though  analysis  indicates  that  it  has  not  enough  carbon 
to  form  pearlyte. 

One  would  expect  the  ferrite,  of  which  these  castings 
probably  consist,  to  crystallize  as  usual  in  its  characteristic 
interfering  grains  :  but  it  seems  to  remain  as  a  pseudomorph 
after  pearlyte,  in  unexpected  crystalline  equilibrium  ° 

H.  Stein  found  that  the  Maltese  cross*  of  comparatively 
soft  material  (pearlyte  ?)  and  the  diagonals  of  harder 
material  (cementite  ?)  which  etching  developed  in  square 
ingots  of  drill  steel,  persisted  when  these  ingots  were 
forged  into  rectangles,  squares,  and  octagons  successively, 
and  could  be  developed  by  etching  in  the  round  drill-rods. 
If  the  drill-bit  came  wholly  within  the  Maltese  cross,  all 
was  well;  but  if  it  crossed  into  the  parting  diagonals  (or 
St.  Andrew' s  cross)  the  different  parts  could  not  be  har- 
dened alike,  the  diagonals  becoming  harder  than  the  cross. 
On  using  round  instead  of  square  ingots  the  trouble 
ceased. g  Here  we  may  surmise  that  the  cementite 
which,  according  to  Sorby,  the  primary  pearlyte  crys- 
tals expel,  and  which  is  distributed  as  a  network  between 
them,  is  bj»the  same  action  concentrated  in  these  diag- 
onals to  such  a  degree  that  quenching  and  repeated  forg- 
ing fail  to  redistribute  it.  I  have  often  seen  this  cross  in 
the  fracture  of  f-inch  square  bars  forged  from  two-inch- 
square  test-ingots  of  Bessemer  rail-steel. 

§262.  OVERHEATING  AND  BURNING. — A.  Phenomena. 
The  burning  of  iron  and  steel  is  probably  another  instance 
of  persistence  of  crystalline  form.h 

We  have  seen  that  the  coarse  crystalline  structure  A 
and  D  of  iron1  which  has  been  exposed  to  a  very  high 
temperature  may  be  removed  by  reheating,  preferably  to 
W,  and  also  by  careful  forging.  The  accompanying 
brittleness  and  weakness  are  simultaneously  greatly  di- 
minished, but  it  is  doubtful  if  they  can  ever  be  completely 
effaced.3  Such  iron  is  said  to  have  been  overheated.  By 
excessively  long  or  strong  overheating  the  iron  may  be- 
come burnt,  and  the  coarseness  and  brittleness  due  to 
burning  are  removed  with  greater  difficulty  and  much  less 
completely  than  those  due  to  overheating,  yet  in  quite 
the  same  manner  and  by  the  same  expedients. 

Burnt  iron  is  cold-short  and  brittle,  can  be  forged  and 


e  Sorby,  Journ.  Iron  and  Steel  Inst.,  1887,  I.,  p.  283. 

t  Such  a  Maltese  cross  is  represented  by  the  shaded  portion  of  Figure  28,  §  228, 
the  light  portions  representing  the  diagonal,  probably  of  cementite. 

K  Iron  Age,  June  30th,  1887,  p.  15. 

hAs  far  ai  my  observation  goes,  "  burnt "  as  applied  to  iron  is  used  far  more 
frequently  to  indicate  the  possession  of  the  peculiar  properties  shortly  to  be  point- 
ed out,  than  to  indicate  that  it  is  oxidized.  As  it  is  not  desirable  that  a  class-name 
should  be  based  on  the  possession  of  either  of  two  different  and  apparently  inde- 
pendent properties,  we  should  select  the  former  as  the  better  established,  regret- 
ting that  this  word  "burnt,"  whose  usual  meaniug  is  so  nearly  synonymous  with 
"  oxidized,"  should  here  have  a  confusingly  different  meaning. 

1  In  this  section  I  use  the  word  generically  to  include  all  malleable  iron  and 
steel. 

J  "  For  '  burned  steel,'  which  is  oxidized  steel,  there  is  only  one  way  of  resto- 
ration, and  that  is  through  the  knobbling  flre  or  the  blast  furnace.  "Overheating" 
"  is  always  injurious."  Metcalf,  Treatment  of  Steel,  p.  5Q, 


OVERHEATING    AND    BURNING.      §  262. 


201 


welded  only  with  care,  and  has  low  tensile  strength. 
Its  fracture,  which  is  illustrated  in  Figure  79,  is  coarse 
and  even  flaky  crystalline,  with  brilliant  and,  according 
to  M.  W.  AVilliams,"  rounded  or  conchoidal  facets.  But, 
under  a  strong  lens,  its  facets  appear  to  me  quite  plane. 
Ingot-metal  is  thought  to  burn  more  readily  than  the  corre- 
sponding varieties  of  weld-metal.  The  presence  of  phos- 
.  phorus  and  carbon  increase  the  tendency  to  burn,  that  of 
manganese  is  thought  to  oppose  it. 

The  degree  to  which  burning  occurs  during  high  heating, 
while  mainly  dependent  on  the  length  and  strength  of  the 


Fig.  79. 

Fracture  of  Burnt  Steel.    Martens. 

heating,  may  further  depend  on  conditions  as  yet  un- 
known. W.  Garrett  describes  a  case  in  which  ingot-steel 
of  0*74$  of  carbon  was  heated  so  highly  that  it  became 
badly  deformed,  and  could  hardly  be  introduced  into  the 
rolls  :  yet  it  rolled  well,  and  behaved  normally  under  phys- 
ical tests.  This  and  similar  cases  led  him  to  assert  that 
neither  open-hearth  nor  Bessemer  steel  is  made  brittle  by 
overheating. b  A  more  accurate  statement  would  be  that 
they  are  not  always  made  seriously  brittle.  There  is 
little  doubt  that  such  exposure  is  very  likely  to  injure 
steel,  though  the  injury  might  not  be  noticed  in  rough  test- 
ing, especially  as  forging  tends  to  efface  it.  The  belief  that 
steel  cannot  be  burnt  has  no  doubt  gained  ground  from 
the  fact  that  prolonged  overheating  aud  even  burning  do 
not  necessarily  remove  any  of  the  carbon.  The  carbon  re- 

TABLE  92.— BURNING  AND  OXIDATION.    (LEDEBUB.) 


Composition. 

Excess  (+)  or  de- 
ficit (—  )  of  oxy- 
gen in  the  burnt 
over  that  in  the 
unburnt  steel. 

Carbon. 

Silicon. 

Man- 
ganese. 

Phos- 
phorus. 

Sul- 
phur. 

Copper, 
nickel, 
cobalt. 

Oxygen. 

Weld  steel. 

Bloomary       J  Sound 
steel  |  Burnt 
Puddled        j  Sound 
steel  |  Burnt 
Shear  (g:irb).  I  Sound 
eteel  |  Uurnt 

IP--U7 
0-726 
0-882 
0-863 
0-827 
0-728 

9-028 

o-o-JG 
0-113 

o-osi 

0-0*3 
0-OS3 

0-101 
0-098 
0-1*7 
0126 
0010 
0010 

O-lllO 
0-024 
0081 
0  04* 

O-l  127 
tr. 

0003 
0007 
0007 
0-004 
0-004 
O'OOS 

0-045 
0-028 
0-045 
0-026 
0-053 
0-058 

0-05S 
0-089 
0060 
0-054 
0-087 
0-043 

[  .  -0-019 
I  —0-006 
[  +0-006 

Ingot  st-;el. 

Bessemer      /  Sound 
steel  1  Burnt 
Crucible        /Sound 
steel  \  Burnt 

0-673 
0-J81 

0-917 
0916 

0207 
0-209 
0098 
0-098 

0-478 
0-473 

o-i!>5 

0-150 

lrlil-,11, 
0070 
0-025 
0-025 

0-010 
0-015 
0005 
0-0(18 

0-045 
0-084 
0-187 
0  136 

0-007 

0-024 
0-045 
0068 

I  +  o-on 

|  +0-016 

One  end  of  a  bar  of  each  kind  of  steel,  about 
fusion  fur  about  four  minutes,  in  :i  charcoal  fire  :  ( 
latloiu  of  burnt  steel.     After  filing  off  the   outer 
unburnt  ends,  by  means  of  sharp  files  prt-vinuslv  i 
buch  fur  Bert;-  und  lluttenwesen  im  Konigreich  !• 

6  inches  (40  cm  .)  long,  was  heated  to  Incipient 
n  removal  aH  showed  the  characteristic  scintil- 
"kln.  samples  were  taken  from  the  burnt  and 
eaned  with  ether  and  alcohol.    Ledebur,  Jahr- 
achsen,  1883.  p.  25. 

a  Jour.  Chem.  Soc.,  New  Ser.,  IX.,  Part  II.,  p.  790,  1871. 
t>  Trans,  Am.  Inst.  Mining  Engineers,  XIV.,  p.  793,  1886, 

mained  constant  in  the  above  and  another  instance  de- 
scribed by  Garrett  ;  in  the  reported  experiments  of 
Leeds  ;  and  in  three  out  of  Ledebur's  five  experiments  on 
burning,  recorded  in  Table  92.  If,  however,  burning  be 
simply  a  structural  change,  there  is  no  reason  why  it  should 
expel  carbon. 

B.  The  Rationale  of  Burning.  Is  burning  due  to  oxi- 
dation, or  is  it  solely  a  structural  change,  an  exaggera- 
tion of  the  effects  of  overheating,  consisting  essentially  in 
the  formation  of  coarse,  feebly  adhering  crystals,  an  exag- 
geration often  accompanied  by  oxidation,  but  independ- 
ent of  it  ?  ° 

It  is  natural  to  attribute  burning  to  oxidation,  1st, 
because  if  the  exposure  be  sufficiently  prolonged,  for 
months  for  instance,  the  metal  evidently  becomes  oxi- 
dized :  2d,  because  iron  is  often  exposed  to  oxidizing  con- 
ditions while  burning :  3d,  because  the  burning  of  most 
substances  is  known  to  be  oxidation  ;  hence,  by  a  shallow 
fallacy,  the  burning  of  iron  is  assumed  to  be  oxidation  : 
4th,  because  oxygen  has  long  been  the  common  scape- 
goat for  most  of  the  mischief  which  the  iron-worker  can 
lay  to  no  other  culprit. 

Of  late  this  belief  has  received  seeming  confirmation 
from  the  supposed  experiments  of  Leeds,  who  according 
to  rumor  found  that,  during  intentional  burning,  steel 
lost  no  carbon  but  took  up  much  oxygen  :  that  if  the 
oxygen  thus  taken  up  was  removed  the  steel  was  com- 
pletely restored  :  and  that,  if  enclosed  in  a  tightly  luted 
box,  steel  can  be  heated  and  cooled  indefinitely  without 
injury.  These  statements  seemed  to  me  in  some  respects 
improbable  and  unlike  Professor  Leeds'  usual  utterances. 
That  steel  should  take  up  much  oxygen  at  the  high  tem- 
perature at  which  burning  occurs,  without  losing  any  of 
its  carbon,  is  opposed  to  all  experience.  On  asking  Pro- 
fessor Leeds  to  describe  the  conditions  of  his  experiments, 

c  We  have  seen  that,  during  long  exposure  t«  a  bigh  temperature,  as  when  an 
ingot  of  steel  cools  slowly,  the  dominant  minerals  tend  to  form  large  crystals, 
expelling  the  other  minerals,  which  form  a  network  between  the  dominant  crys- 
tals. When  steel  is  re-heated  to  W  the  secondary  minerals  appear  to  recombine 
with  the  dominant  ones  to  form  a  nearly  homogeneous  whole  :  at  least  when  steel 
is  quenched  after  heating  to  W  only  extremely  minute  and  apparently  uniform 
crystals  can  be  seen.  This  suggests  to  me  two  possible  explanations  of  the  phe- 
nomena of  burning. 

I.  In  ordinary  overheating  moderately  large  crystals  of  the  dominant  minerals 
form.  The  secondary  minerals  are  distributed  in  relatively  thick  layers  between 
the  faces  of  the  dominant  ones,  forming  planes  of  weakness.  Now  the  longer  the 
over-heating  the  larger  should  these  dominant  crystals  become,  and  the  farther 
apart  should  ie  the  meshes  which  the  secondary  minerals  form.  Overheated  steel 
can  be  restored,  because  the  meshes  of  the  secondary  minerals  are  still  so  near  to- 
gether that  the  recrystallization  which  occurs  at  W  is  able  to  cause  their  re-absorp- 
tion and  incorporation  with  the  materials  of  the  dominant  minerals  :  burnt  steel 
cannot,  because  the  meshes  have  become  so  far  separated  that  their  material  can- 
not be  completely  redistributed  on  recrystallizati-m,  but  remains,  forming  a  mesh- 
work  of  weakness. 

Two  objections,  neither  of  them  conclusive,  suggest  themselves.  (A)  If  it  is 
simply  a  question  of  long  exposure  to  a  high  temperature,  how  is  it  that  a  slowly 
cooled  Ingot,  necessarily  exposed  during  and  immediately  after  solidification  to  a 
very  high  temperature,  is  easily  restored,  while  a  forged  bar  when  exposed  to  a 
necessarily  lower  temperature  becomes  permanently  injured  ?  In  the  first  place 
this  objection  weighs  as  heavily  against  the  oxidation  as  against  the  crystallization 
theory.  In  the  second  place  the  crystalline  changes  which  occur  with  falling 
temperature,  as  in  the  case  of  the  ingot,  should  differ  from  those  induced  by 
rising  temperature,  as  in  the  bar  which  is  burning. 

B.  If  burning  is  due  to  a  separation  of  the  secondary  minerals,  how  is  it  that 
pure  iron,  which  consists  wholly  of  ferrite  with  no  secondary  minerals,  bums ! 
We  do  not  know  that  such  iron  would  burn.  But  it  is  true  that  the  less  carbon 
iron  contains,  i.  e.  the  less  of  the  common  secondary  minerals,  cementile,  pearl- 
lyte,  etc.,  it  contains,  the  less  liable  it  is  to  burn. 

(2).  A  slightly  different  view  is  that  in  burnt  steel  the  coarse  crystalline  struc- 
ture has  become  so  firmly  fixed  and  persistent  through  the  long  exposure  to  high 
temperature,  its  polarity  has  become  so  powerful,  that  it  defies  the  tendency  to 
recrystallization  which  arises  when  the  temperature  rises  to  W,  but  that  in  merely 
overheated  steel  this  polarity  has  not  twcome  so  powerful. 


202 


THE     METALLURGY     OF     STEEL 


I  learned  that  these  statements  either  are  a  hoax,  or  else 
have  been  attributed  to  the  wrong  person." 

In  contrast  with  these  inconclusive  reasons,  witness  the 
following. 

I.  Burning  may  Occur    without  Oxidation. — In  two 
out  of  the  five  cases  in  Table  92  the  burnt  ends  of  the 
bars  have  less  oxygen  than  the  unburnt  ends  :    in  the 
three  other  cases  the  gain  of  oxygen  is  too  slight  to  indi- 
cate that  it  is  connected  with  the  change  in  the  metal's 
properties. 

Nor  is  the  loss  of  carbon,  silicon  or  manganese  suffi- 
ciently constant  here  to  indicate  that  it  is  a  real  character- 
istic of  burning.  M.  W.  Williams  indeed  found  that, 
after  long  exposure,  burnt  wrought-iron  always  contained 
iron  oxide,  but  that  burnt  steel  did  not :  the  burning  in 
case  of  steel  was  always  accompanied  by  loss  of  carbon, 
which  is  hardly  surprising,  as  his  exposures  lasted  from  a 
few  hours  to  four  days.b 

II.  Oxidation  may  Occur  without  Burning. — Ledebur 
describes  three  specimens  of  after-blown  basic  metal  (num- 
bers 1  to  3  of  Table  43)  which  contained  from  0'171  to 
0'244$  of  oxygen,  or  from  2 -7  to  3-9  times  as  much  as  the 
most  highly  oxygenated  of  the  burnt  steels  of  Table  92, 
and  which  had  much  finer  structure  than  the  burnt  weld- 
iron  with  which  he  compared  it,  and  lacked  the  character- 
istic brilliant  fracture.  °  However  much  we  may  distrust  our 
methods  for  determining  oxygen,  we  can  hardly  doubt  that 
after-blown  basic  metal  is  well  saturated  with  this  element. 

While  overblown  Bessemer  metal  and  burnt  iron  are 
alike  in  being  difficultly  forgeable,  yet  the  overblown  and 
the  burnt  iron  which  I  have  examined  seem,  on  careful 
comparison,  very  unlike.  Overblown  metal  I  find  lacks  the 
brilliant  fracture  of  burnt  iron,  and  is  fairly  tough  when 
cold :  where  solid,  thin  pieces  can  be  bent  double,  and 
the  bend  hammered  flat  without  cracking.  The  metal  can 
be  forged  with  care  at  and  above  a  light  yellow,  but  is 
extremely  yellow-short  and  red-short.  I  do  not  find  that 
it  is  greatly  improved  by  forging :  a  piece  which  I  forged 
with  great  difficulty  into  a  bar  about  i"  square  broke  on 
bending  cold  about  30° :  it  was  here  very  unsound,  and 
rupture  was  doubtless  hastened  by  the  cracks  due  to  red- 
shortness.  Allowing  for  this,  however,  and  making  many 
bends  on  many  different  small  and  large  pieces,  I  could 
not  assure  myself  that  forging  increased  the  cold-ductility. 

Taking  now  some  f"  round  wrought-iron,  which  bent 
170°  to  a  radius  of  about  £"  before  rupture,  and  "barked" d 
like  other  tough  wrought-irons,  with  a  very  fibrous  frac- 
ture, I  burnt  and  then  slowly  cooled  it.  It  now  broke 
short  without  appreciable  bending,  showing  the  character- 
istic brilliant  fracture.  Heated  to  gentle  whiteness  and 
bent  slightly,  it  began  to  crumble.  Forged  with  care  and 


a  Jour.  Iron  and  Steel  Inst.,  1880,  II.,  p.  717 :  "  Prof.  Albert  R.  Leeds,  of 
Steveus  Institute,"  is  distinctly  credited  with  these  statements.  Ledebur,  Jahrbuch 
fur  das  Berg-  und  Huttenwesen  im  Konigreieh  Sachsen,  1883,  refers  to  him  as 
"Prof.  Leeds  "simply.  The  Oesterrelchische  Zeitschrift  fur  Berg- und  Hutten- 
wesen, XXIX.,  p.  375,  1881,  credits  "Professor  A.  R.  Leeds"  with  these  experi- 
ments. The  Berg- und  Hiittenmannisches  Zeitung,  XL.,  p.  122, 1881,  credits  them 
to  "Leeds."  Here  my  patience  failed.  1'rofessor  Albert  R.  Leeds,  of  Stevens 
Institute,  Hoboken,  New  Jers?y,  writes  me  on  receipt  of  the  abstract  of  his  paper 
[rom  the  Journal  of  the  Iron  and  Steel  Institute,  "I  never  tried  such  experiments 
as  I  am  credited  with,"  "  and  the  slip  you  send  me  is  the  first  time  I  have  seen 
myself  alluded  to  in  connection  with  the  subject"  (Private  Communications, 
March  30th  and  April  3d,  1888). 

b  Van  Nostrand'a  Eng.  Mag.,  V.,  p.  51,1871:  Journ.  Chem.  Soc.,  New  Ser., 
IX.,  part  II.,  p.  790,  1871. 

"  Op.  cit.,  p.  23. 

4  Cf.  Rept.  U.  S.  Bd.  on  Testing  Iron,  etc.,  I.,  p.  125,  1881, 


gently  upset,  it  bent  to  about  120°  at  very  dull  redness  (a 
most  trying  heat)  before  rupture.  Cooled,  a  piece  about 
i"  square  bent  45°  before  rupture,  yielding  an  only  moder- 
ately bright  fracture,  partly  silky,  partly  crystalline  with 
facets  of  moderate  size. 

In  short,  these  pieces  of  overblown  iron  differ  from  those 
of  burnt  iron  with  which  they  were  compared,  in  fracture, 
in  being  initially  only  yellow  and  red-short  instead  of  gen- 
erally hot-short :  in  being  fairly  malleable  when  cold  in- 
stead of  extremely  cold-short :  in  being  benefited  slightly 
instead  of  very  greatly  by  forging.  No  certain  inference 
can  be  drawn  from  such  isolated  cases  :  but,  indicating  that 
oxygenated  metal  is  unlike  burnt  iron,  they  certainly  tally 
with  the  rest  of  our  evidence. 

Over-blown  acid  Bessemer  steel  was  cast  in  a  wronght- 
iron  box,  and  rolled  to  a  round  bar  1*1 2  inches  in  diameter. 
The  skin  of  wrought-iron  was  turned  off  in  a  lathe.  After 
nicking  and  breaking  I  found  the  fracture  extremely 
silky.  At  bright  whiteness  the  metal  forged  well  with  but 
slight  care,  but  became  brittle  at  a  moderate  yellow  heat. 
I  could  see  no  strong  resemblance  to  burnt  iron  in  its 
behavior  or  fracture. 

III.  Burning  is  Apparently  Cured  without  Removal  of 
Oxygen. — The  characteristics  of  burnt  iron  can  be  removed 
in  very  great  part  by  careful  forging,  which  certainly 
appears  to  acthere  directly  on  the  structure,  physical!}', 
as  it  does  in  case  of  overheated  iron,  and  not  by  expelling 
oxygen.  By  careful  hammering,  burnt  wrought-iron  with 
a  galena-like,  flaky,  crystalline  fracture,  may  be  made  to 
yield  a  thoroughly  fibrous  one." 

In  a  bar  of  burnt  steel  Boker  found  that  part  of  the 
silicon  existed  as  such,  and  part  as  silica.  He  reheated 
one  end  of  the  bar  in  a  reducing  fire  and  forged  it  lightly, 
so  as.  to  restore  it ;  the  proportion  of  silica  was  still  the 
same  as  in  the  unrestored  part.f  The  value  of  his  evi- 
dence is  lessened  by  the  fact  that  the  two  parts  of  his  bar 
which  these  analyses  represent  had  not  initially  under- 
gone the  same  amount  of  burning,  and  hence  may  not  have 
had  the  same  proportion  of  silica  initially. 

TABLE  93. — SILICON   AND   SILICA   IN  DIFKKKKNT  PAUTS   OF  A  BURNT   Cuucnti.K-sTEKL   BAH 


Silicon  as  such  (difference) . 
Silicon  ag  silica  .. 


(BiiKEB). 

In  the  burnt  bar 
without  farther 
treatment. 

0-136* 

O'OGo* 


Aft<-r  re- 
storing. 
0  184* 
0'OC7;« 


On  further  burning 
undor  oxidizing 
conditions. 

0-024^ 

(TUT* 


V.  Finally  carbon  and  phosphorus,  which  should  pro- 
tect iron  from  oxidation,  greatly  increase  the  tendency  to 
burn :  for  the  more  highly  carburetted  and  the  more 
highly  phosphoretted  the  iron  the  more  readily  does  it 
burn. 

This  cumulative  evidence  strongly  indicates  that  burn- 
ing is  not  oxidation,  but  the  result  of  a  structural  change 
not  dependent  on  oxidation,  though  possibly  favored  by 
it.  For  positive  proof,  heating  with  complete  exclusion 
of  oxygen  seems  necessary. 

SEGREGATION." 

§264.  That  cast-iron  is  sometimes  heterogeneous  has  long 
been  knowoi.  Abel  found  the  last-solidifying  part  of  phos- 
phoric cast-iron  abnormally  rich  in  phosphorus  :h  and, 


e  Percy,  Iron  and  Steel,  p.  7. 

'  Stahl  und  Eisen,  VI.,  p.  634,  1886.     Wedding  here  describes  the  microscopic 
appearance  of  burnt  and  of  restored  steel. 

•  R  Segregation  in  steel  ingots,  cf.  Stahl  und  Eisen,  IV.,  p.  646,  VI.,  p.  143: 
Journ.  Iron  and  St.  Inst.,  1881,  pp.  199,  379.  In  cast-iron,  cf.  Stahl  und  Eisen, 
IV.,  p.  634,  VI.,  pp.  143,  244  :  VII.,  p.  170  :  VIII.,  p.  23. 

ii  Percy,  Iron  and  Steel,  p.  664,  A.  D.  1864. 


SEGREGATION.      8  264. 


203 


more  than  thirty-three  years  ago,  he  found  wart-like  ex- 
crescences of  nearly  pure  sulphide  of  iron  on  the  surface 
of  spherical  shot  made  from  very  sulphurous  cast-iron." 
These  phenomena  were  properly  ascribed  to  segregation 
and  liquation"  during  solidification :  and  Lawrow  and 
Ivnlakoutsky  seem  to  have  noted  segregation  in  steel  ingots 
as  early  as  If- 67.°  Nevertheless,  much  as  segregation  in 
cast-iron  and  in  very  many  of  the  well-kuown  allows,  e.  g 
those  of  copper-tin  (bronzes)  and  of  copper-lead,  shoulc 
lead  us  to  expect  it,  segregation  in  steel  ingots  seems  to 
have  been  generally  overlooked  until  comparatively  lately. 

It  was  observed  by  Porsyth11  in  1879  and  described  in 
1881  by  Stubbs0  and  (later)  by  Snelus.'  Hard  spots  hac 
indeed  been  noted  in  steel,  but  had  been  ascribed  appar- 
ently with  perfect  confidence  to  imperfect  mixing  of  the 
recarburizing  additions  with  the  mass  of  .the  metal.  *  In- 
deed, even  so  broad-minded  and  intelligent  a  man  as  Snelu 
received  Stubbs'  announcement  of  segregation  in  stee] 
ingots  most  incredulously  :  "he  could  not  conceive  that 
there  could  be"  such  "interchange  of  elements"  "in  the 
time  allowed  for  it." 

It  is  doubtless  possible  to  introduce  a  quantity  of  cold 
recarburizing  metal  just  before  teeming  in  such  a  way 
ihat  part  of  it  may  not  melt  in  time  to  become  thoroughly 
diffused :  but  such  evidence  as  I  can  find  goes  to  show 
that  the  hard  centres  and  other  irregularities  now  so  well 
known  are  in  the  main  due  to  segregation. 

First,  we  find  that  some  molten  metals  diffuse  in  others 
with  extraordinary  rapidity.  Thus  Roberts  found  that 
the  diffusion-rate  of  silver  and  of  gold  in  lead  was  about 
one  foot  in  five  minutes,  or  not  much  less  than  that  of 
oxygen  in  hydrogen,  or  than  the  rate  of  transmission  of 
heat  through  iron.  The  result  reached  in  forty  minutes 
with  gold  and  lead  would  require  at  least  twenty  years 
were  these  metals  replaced  by  salt  and  water.  In  other 
cases,  however,  such  as  copper-antimony,  diffusion  is 
comparatively  slow.h  But,  clearly,  it  is  not  intrinsically 
improbable  that  the  recarburizer  should  become  uniformly 


a  Journ.  Iron  and  Steel  Inst.,  1881,  II.,  p.  392. 

b  For  convenience  I  use  segregation  to  designate  a  concentration  inwards,  and 
liquation  to  designate  an  expulsion  of  matter  outwards  from  the  exterior  of  the 
mass,  but  without  insisting  on  tho  propriety  of  this  terminology.  The  metal 
othir  than  the  segregation  is  known  as  the  "mother  metal:"  it  is  not  closely  anal- 
ogous to  "mother-liquor,"  for  it  is  in  general  the  first-crystallized  and  purer  sub- 
stance, the  segregation  being  the  residue  left  from  its  crystallization :  while  mother- 
liquor  is  the  impure  residue  left  by  the  early-formed  relatively  pure  crystals. 

c  Cbernoff,  Rev.  Univ.,  2J  Ser.,  VII.,  p.  140,  in  a  paper  read  in  1878,  states 
that  t'jese  gentlemen  remarked  and  proved  liquation  >a  steel  ingots,  referring  to 
tho  "Journal  d'artillerio  de  1868  et  1807."  I  have  been  unable  to  nnd any  further 
reference  to  them  or  to  thtir  discovery  in  the  metallurgical  and  chemical  publica- 
tions of  that  period. 

<1  In  February,  1879,  Forsyth  found  a  hard  spot  in  the  head  of  a  bt-okpn  Besse- 
mer steel  rail,  near  the  junction  of  head  and  web.  Analyzing  it,  he  found  very 
marked  segregation.  He  then  examined  many  others,  wi'.h  results  given  in  Table 
06.  Many  of  these  examinations  were  made  for  the  Chicago,  Burlington  & 
Quincy  Railroad,  and  I  have  to  thank  Mr.  Stone  of  that  road,  cs  well  as  Mr. 
Forsyth,  for  permission  to  publish  these  results. 

e  Journ.  Iron  and  St.  Inst.,  1881,  I.,  p.  199. 

f  Idem.,  II.,  p.  379. 

ft  Bessemer  (Journ.  Iron  and  St.  Inst.,  1881,  It.,  p.  395),  admits  finding,  in  t'ae 
early  days  of  tte  Bessemer  proce-s  (i.  e.  sometime  alter  1-1154),  a  vein  in  aBes;emer 
steel  hydraulic  cylinder  so  hard  that  tho  to-.l  wcu'.d  cot  rut  it:  but  he  apparently 

attributes  it  to  imperfect  mixing.     In  his  famous  Cheltenham  paper  ho  fays:  "To    mar^e(J     ^y     a  peculiar  structure.      Figure     81     sllOWSa 
persons  conversant  with  tho  manufacture  of  iron,  it  will  bo  at  once  apparent  that  *  * 

the  ingots  of  malleable  metal  which  i  have  described  w,n  have  no  hard  or  steely  relatively  slight  concentration  of  several  elements  in  the 
parts,  such  as  is  found  in  puiidk-d  iron,"  etc.   (Jeans,  steel,  p.  5i.)  j  Upper  part  of  a  very  large  ingot.    Figure  82  probably  indi- 

Dudley  (Trans.  A:n.  Inst.  Min.  Ens.,  IX  ,  p.  588,  1881),  says,  "Come   where  | 
steel  is  being  cut  and  shaped,  and  I  will  show  you  (hat  it  is  often  cccessary  to  stop 
the  lathe  or  planer  and  take  a  coM-rhisel  to  cut  out  a  hard  spot"— which — "is 
firnply  a  part  of  the  ppiegel  w'oirh  vas  r.ot  thoroughly  mixed  with  the  mass." 


distributed,  especially  when  we  remember  how  the 
mobile  metal  is  mixed  as  it  pours  from  converter  or  fur- 
nace to  ladle,  and  from  ladle  to  mould. 

Next,  manganese,  so  abundant  in  the  recarburizer  but 
almost  wholly  absent  from  the  unrecarburized  metal,  is 
probably  on  the  whole  much  more  uniformly  distributed 
that  any  other  of  the  non-ferrous1  substances  present. 

Next,  if  heterogeneousness  were  chiefly  due  to  imper- 
fect mixing,  we  would  expect  differences  between  differ- 
ent ingots  of  a  single  heat  at  least  as  marked  as  between 
different  parts  of  a  single  ingot :  but  so  far  as  my  obser- 
vation goes  the  composition  of  the  different  ingots  of  a 
heat  is  remarkably  constant.  Witness  the  case  in  Table 
94. 

TABLE  94.— SIMILARITY  or  COMPOSITION  OF  DIFFERENT  PARTS  OP  A  HEAT  or  STEEL. 

First  test-Iadleful ..-10            -005           '8?'          -m  '086 

Second"          '      -JQ            -005           -gj           .022  -noa 

i,hml.   '  '      '10  -005  -88  -025 

Fourth"          '      , -10            -005           -86           -028  ^, 

Cold  ferromanpineso  was  added  to  an  open-hearth  charge  three  or  four  minutes  lieforo 
tapping.  Four  test-ladlefnls  were  taken  from  the  beginning,  middle  and  end  of  the  cast  during 
teeming.  K.  O'C.  Acker,  private  communication,  Oct.  28,  1888. 

At  an  American  Bessemer  works  crop  ends  from  each  of 
the  three  ingots  of  each  of  about  fifteen  heats  were 
analyzed  for  manganese :  the  variation  was  within  the 
limits  of  analytical  error.  These  heats  were  recarburized 
by  adding  red-hot  crushed  ferromanganese  in  the  ladle.1 

Two  tests  from  each  of  twelve  ingots  of  one  open-hearth 
steel  heat,  and  two  from  each  of  seven  ingots  of  another 
were  pulled.  The  tensile  strength  and  elongation  lay 
between  the  following  limits. 

TABLE  95.— UNIFORMITY  IN  OPEN-HEARTH  STEEL.    H.  H.  CAMPBELL. 


•081 


Heat. 

Number  of  In-  1 
pots  tested. 

Tensile  strength.    Lbs.  per  eq.  in. 

%  C.  correspond- 
ing to  this 
variation. 

Elongation,  a  In  8". 

Maximum. 

Minimum. 

Variation. 

Maximum. 

Minimum. 

Variation. 

4533 
4536 

10 
T 

IU.640 
79,050 

80,800 
74,180 

8,840 
4,870 

•059 
•075 

25-7 
27 

22 
28-9 

8-7 
8-1 

If  we  assume  that  the  variation  in  tensile  strength  was 
lere  due  wholly  to  varying  carbon-content,  the  tensile 

ion  of  carbon,  we  have  a  variation  of  0'059$  of  carbon 
Between  the  strongest  and  weakest  test-piece  of  the  first 
leat,  and  of  0'075$  between  those  of  the  other. 

Two  test-ingots  were  taken,  one  during  the  first  and  one 
during  the  last  third  of  the  teeming,  from  each  of  twelve 
'pen-hearth  steel  heats.  The  greatest  difference  in  tensile 
strength  between  the  two  tests  of  any  one  heat  was  2,960 
rounds  per  square  inch,  implying  on  the  assumptions  just 
made  a  variation  of  carbon  of  0'045$.  The  greatest  varia- 
tion in  elongation  was  from  21 '5  to  25$  in  eight  inches. k 

Finally,  the  shape  and  position  of  the  parts  which  have 
abnormal  composition  is  far  more  readily  referred  to 
segregation  than  to  imperfect  mixing.  The  segregation 
usually  occurs  near  the  top  of  the  ingot.  Figure  80  shows 
how  the  carbon  gradually  concentrates  in  a  pear-shaped 
mass  near  the  ingot-top.  In  broken  rail-ingots  I  have  seen 
what  appeared  to  be  this  pear-shaped  mass  very  strongly 


hRept.   British   Ass.,  1883,    p.   404:    Engineering,    XXXVI.,   p.    308,    1883. 
W.  Chandler  Roberts,  Fir  William  Thomson. 


I  It  is  customary  to  speak  of  the  segregated  substances  as  "metalloids":  but 
this  leaves  out  manganese,  to  say  nothing  of  copper,  slag,  arsenic  and  antimony. 

i  E.  F.  Wo  d,  private  communication,  Jan.  26th,  1889. 

k  H.  H.  Campbell,  Trans.  Am.  lust.  Mining  Eng.,  XIV. ,  p.  358,  1886.  The 
open-hearth  fur  nace  was  stationary. 


204 


THE     METALLURGY    OF     STEEL. 


cates  the  true  nature  of  the  concentration,  and  suggests 
that  it  should  be  studied  by  analyzing  small  borings 
taken  discriminatingly  from  etched  polished  sections. 

F.  A.  Emmerton  finds  that  if  an  ingot  be  overturned 
when  partly  solidified,  the  segregation  will  now  be  found 
at  the  point  indicated  in  Figure  84. a  This  shows  that  the 
position  of  the  segregation  is  due  at  least  in  part  to  gravi- 
tation. 

It  is  stated  that  the  segregation  occurs  at  a  lower  point 
in  bottom-  than  in  top-poured  ingots,  which  would  indicate 
that  it  tends  to  move  to  the  last-freezing  point. 


usually  implies  heterogeneous  strength  and  ductility :  and 
the  strength  of  a  heterogeneous  substance  is  usually 
nearer  the  strength  of  the  weakest  component  or  part 
than  the  average  of  all  the  parts :  the  piece  tends  to  break 
down  piecemeal.  So  with  ductility. 

§  2(5.  THE  CAUSES  OF  SEGREGATION  IN  STF.EL  INGOTS. 
—The  same  forces  which  lead  to  the  differentiation  of  cool- 
ing steel  into  the  minerals  already  described  (§  237,  p. 
163)  and  of  solidifying  rock-magmas  into  the  complex 
crystalline  granite,  doleryte,  etc. ,  are  probably  the  cause 
of  the  segregation  in  cast-iron,  in  steel,  and  in  alloys  in 

TOP  OF  INGOT. 


P. 


C. 


Mn. 


\ 


\ 


TOP  OF 


BOTTOM  OF 


INGOT 


INGOT 


0.1  0.2  0.3 

PERCENTAGE   OF   NON-FERROUS   ELEMENTS. 

ITiS.  81 
SEGREGATION  IN  A  13-TON  INGOT.    ACKER. 

The  top-poured  ingot  number  43,  Table  96,  weighing  about  26,000  pounds,  and  about  30"  X  48" 
X  6',  was  rolled  down  to  a  sl.ib  about  8"  X  40":  it  was  then  sheared  into  ten  slabs,  and  drillings 
from  each  sheared  face  of  each  slab  were  analyzed.  The  abscissas  represent  the  composition  at 
each  shearing-plane,  the  ordinates  the  height  above  the  bottom  of  the  ingot.  The  investigation 
was  made,  and  the  data  arc  furnished  by  E.  O'C.  Acker,  private  communication,  188S. 

The  results  given  in  Table  96,  most  of  them  here  pub- 
lished for  the  first  time,  show  how  serious  the  irregularity 
of  composition  may  be.  W.  ltichardsb  states  that,  with 
carefully  checked  analyses,  the  carbon  in  his  large 
ingots  varies  by  from  O'lO  to  0'15$ :  while  J.  Rileyc  states 
that  the  variation  of  carbon  is  not  infrequently  nearly 
0'50$  in  one  and  the  same  ingot. 

While  segregation  may  occasionally  be  harmless  or 
even  beneficial,  e.  g.  by  concentrating  the  impurities  in 
the  neutral  axis  of  the  piece  where  little  or  no  strength  is 
needed,  or  by  concentrating  them  in  the  ingot-top,  which 
is  subsequently  cut  off  as  in  case  of  gun-ingots,  it  is 
doubtless  usually  injurious.  Heterogenous  composition 


O  •  ®  O  ® 

.27          .30          .28  .23  .28 

•  •  •  0  © 

,M  ,.60  .57  .88  .27 

,30  .39  .61  .78          ^49  .42  -.30 

f f ttf  ft 

3s          ^S  ZSS  ..43          Jt  ^8  .33 

f    ft    ft    ft 

ft ttf tt 

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iQQQQQ t 
f Qoggof 

to  o  o  ®  ®  • 
.25  JZS  .2T  .28  .28  .30 

f ft  ft  ft 


Figure  80. 

Percentage  of  carbon  at  different  points  in  the  vertical  section  ofalarfrelngot.     Maitland,  the 

Treatment  of  Gun-Steel,  Excerpt  Proc.  Inst.  Civ.  Eng.,  LXXXIX.,  p".  12,  1887.    The 

depth  of  shading  of  the  spots  is  roughly  proportional  to  the  proportion  of  carbon. 


Fig.  83. 

No.  62,  Table  96.    Segregation  in  Sheffield  steel,  developed  by  etching.    H.  Eocles,  Journ. 
Iron  and  St.  Inst.,  1888, 1.,  p.  70. 


0.1 


TOP 


"  Private  communicatiou,  Januarv,  1886. 

b  Journ.  Iron  and  Steel  Inst.,  1886,  I.,  pp.  113-114. 


Fig.  84. 

Position  of  Segregation  In  Overturned  Ingot. 

general.  There  is  the  struggle  between  crystalline  force 
and  surface  tension  aided  by  gravity,  on  the  one  hand, 
tending  towards  differentiation,  and  of  diffusion  on  the 
other,  tending  towards  uniformity. 

As  the  temperature  sinks  towards  the  freezing-point, 
surface  tension  probably  increases,  the  different  compon- 
ents tend  less  powerfully  to  diffuse  among  each  other  and 
more  to  draw  apart  in  drops,  as  oil  separates  from  water, 
the  lighter  to  rise,  the  denser  to  sink.  Further,  as  the  com- 
plex molten  mass  cools  past  the  freezing-point  of  a  certain 
potentially  present  compound,  into  which  certain  elements 
might  group  themselves,  this  compound  tends  to  form, 
to  solidify,  to  crystallize,  to  expel  the  more  fusible  resi- 
due, as  a  salt  crystallizing  from  an  aqueous  solution 


SEGREGATION.      §  265. 


205 


expels  the  mother  liquor,  which  is  gradually  driven  in- 
wards towards  the  last-freezing  region. 

Now  time  is  required  to  effect  a  considerable  separation 
and  segregation  in  either  of  these  ways  :  whether  to  enable 
the  lighter  separated  bodies  to  coalesce  into  masses  of  such 
size  that  they  may  rise  readily  by  gravity,  or  to  en- 
able the  first-freezing  compounds  to  select  and  reject  the 
more  fusible  ones,  and  to  push  them  thus  into  the  still 
molten  interior  :  hence  we  infer  that  here,  as  in  the  solidi- 
fication of  other  alloys,  and  in  the  crystallization  of  salts 
from  aqueous  solutions,  slow  cooling  favors  separation. 

The  masses  which  separate  or  segregate  should  be  1, 
compounds  which  differ  much  in  fusibility  from  the  rest, 
of  the  inass :  2,  compounds  whose  components  have  a 
strong  affinity  for  each  other,  and  which  hence  tend 
strongly  to  form  during  cooling  :  3,  compounds  which 
differ  greatly  in  density  from  the  rest  of  the  mass.  Now 
slight  differences  in  the  composition  or  rate  of  cooling  or 
of  pressure  may  greatly  change  the  resultant  of  the  sepa- 


Fig.  82. 

Segregation  in  a  Rail  Ingot. 

The  rails  made  from  a  single  ingot  are  planed  at  points  corresponding  to  the  bottom,  middle 
and  top  of  the  ingot :  these  sections  are  etched  with  acid,  and  nature-prints  obtained.  F.  A. 
Kinmerton,  private  communication,  January,  1886. 

rating  forces.  Here  one  set  of  substances  tends  to  form, 
and  of  this  set  one  is  light,  fusible,  and  highly  phosphoric  ; 
phosphorus  segregrates  markedly  :  there,  the  proportion 
of  phosphorus  remaining  the  same  and  that  of  some  other 
element,  say  manganese,  changing ;  or,  the  composition 
being  constant,  some  change  in  crystallizing  conditions 
tending  to  establish  a  different  set  of  compounds,  our 
light,  fusible,  phosphoric  compound  no  longer  forms,  no 
segregation  of  phosphorus  occurs.  (Cf.  p.  2,  2nd  col.) 
Hence,  while  we  confidently  anticipate  that  a  given  ele- 
ment, say  phosphorus,  will  tend  most  strongly  to  segre- 
gate when  abundantly  present,  we  may  expect  perplexing 
exceptions  and  contradictions. 

The  strong  affinity  of  carbon,  phosphorus  and  sulphur, 
as  compared  with  that  of  manganese,  for  iron,  and  the 
greater  fusibility  and  lower  density  of  carbides,  phos- 
phides and  sulphides  than  of  manganese-iron  alloys, 
should  favor  the  segregation  of  carbon,  phosphorus  and 
sulphur  as  compared  with  manganese,  and  compensate 
more  or  less  for  the  fact  that  the  often  much  larger  per- 
centage of  manganese  than  of  these  metalloids  should 
favor  the  segregation  of  this  metal. 

With  our  present  scanty  information  it  were  quackery 
to  attempt  a  complete  explanation  of  the  instances  of 
segregation  at  hand.  A  glance  at  Figure  82  shows  that 
borings  taken  from  immediately  adjoining  points  might 
give  widely  different  compositions.  As  borings  have  almost 
necessarily  been  taken  very  blindly,  we  have  here  still 
another  reason  to  anticipate  very  discordant  results.  In 
Figure  82  at  least  two  different  compounds  seem  to  have 


segregated.  Now,  should  one  of  these  be  highly  phosphoric 
and  the  other  not,  our  borings,  should  they  penetrate  only 
the  non-phosphoric  bunches,  might  falsely  say  that  there 
was  no  segregation  of  phosphorus,  nay,  even  that  this 
element  was  chiefly  concentrated  in  the  mother-metal. 

Again,  while  phosphorus  increases  the  fusibility  of  iron 
greatly,  it  does  not  at  all  follow  that  when  the  mass  splits 
up  into  a  more  and  a  less  fusible  part,  the  more  fusib'c 
will  always  hold  more  phosphorus  than  the  other.  Tli;- 
elements  group  themselves  in  accordance  witli  their  Hirmi- 
cal  affinities,  and  it  may  often  happen  that  the  more  phos- 
phoric of  two  compounds  may  be  the  less  fusible,  the 
influence  of  its  excess  of  phosphorus  being  outweighed  by 
that  of  its  deficit,  say,  of  carbon.  So  with  the  other  ele- 
ments. 

But,  though  our  results  are  as  discordant  as  we  could 
well  expect,  certain  of  their  features  deserve  notice. 

§266.  WHAT  ELEMENTS  SEGREGATE  MOST? — Of  cast- 
iron  we  have  hardly  enough  cases  to  justify  generaliz- 
ation :  let  us  therefore  confine  our  attention  to  the  steels, 
Table  96. 

Phosphorus  segregates  in  a  greater  proportion  of  cases 
than  any  other  element,  and,  sparingly  as  it  is  present, 
it  segregates  on  an  algebraic  average  to  a  greater  extent 
than  any  other  element  except  carbon.  As  the  influ- 
ence of  a  given  absolute  quantity  of  phosphorus  is  so 
much  greater  than  that  of  the  other  elements,  so  is  its 
segregation  much  more  important  than  theirs.  Still,  in 
no  less  than  13  out  of  the  59  cases  the  segregation  contains 
less  phosphorus  than  the  mother  metal,  but  in  no  case 
very  decidedly  less,  its  greatest  deficit  being  less  than 
0'02$.  In  each  of  the  four  cases  in  which  the  phosphorus 
in  the  segregation  exceeds  that  in  the  mother-metal  by 
more  than  0'11$  there  is  also  a  very  heavy  segregation  of 
carbon,  in  two  of  them  a  heavy  segregation  of  manganese 
and  in  two  a  heavy  segregation  of  sulphur.  The  segre- 
gation-excess of  phosphorus  amounts  to  0'05$  or  more  in 
17  out  of  the  59  cases  given. 

Sulphur. — The  segregation  of  sulphur  probably  comes 
next  in  importance,  though  the  greatest  excess,  ()'192$,  is 
much  less  important  than  the  maximum  phosphorus  ex- 
cess, 0'277$.  Out  of  the  ten  cases  in  which  the  segrega- 
tion-excess of  sulphur  is  0'05$  or  more,  there  is  a  very 
considerable  segregation  of  phosphorus  in  7,  of  carbon  in 
5,  of  manganese  in  only  one.  This  suggests  that  sulphur 
and  phosphorus  tend  to  segregate  together.  We  may  not 
infer,  however,  that  this  is  untrue  of  sulphur  and  man- 
ganese. In  nearly  every  case  in  which  manganese  segre- 
gates, a  larger  and  usually  a  very  much  larger  proportion 
of  the  sulphur  present  segregates  along  with  it :  and  in 
very  many  cases  the  segregation-excess "  of  sulphur  is 
larger  absolutely  than  that  of  manganese,  in  spite  of  the 
relatively  small  proportion  of  sulphur  present.  As  far  as 
this  goes,  it  harmonizes  with  the  evidence  in  §81,  p.  43, 
showing  that  manganese  tends  to  drag  sulphur  off. 

Carbon. — The  average  segregation-excess  of  carbon  is 
greater  than  that  of  any  other  element,  and  in  five  cases 
it  exceeds  0-44$.  The  segregation  of  carbon  when  severe 
is  usually  accompanied  by  a  severe  segregation  of  some 
other  element ;  but  of  now  one,  now  another,  without 


a  By  the  "  segregation-excess "  of  a  given  element,  I  mean  the  excess  of  the 
percentage  of  that  element  in  the  segregation  over  that  in  the  mother-metal.  So 
with  "  segiegation-deficit." 


208 


THE    METALLURGY    OF    STEEL. 


TABLE  t>6.— -SEGREGATION  IN  STEEL  AND  CAST-IRON. 


Carbon. 

Silicon. 

Manganese. 

Phosphorus. 

Sulphur. 

Copper 

Slag. 

A. 

B. 

B  —  A. 

A. 

B. 

B  —  A. 

A. 

B. 

B  —  A. 

A. 

B. 

B  —  A. 

A. 

B. 

B-  A. 

A. 

B. 

B—  A. 

A. 

B. 

B  —  A. 

Description. 

1 

§ 

X! 

S 

g 

1 
I 

1 

1 

B 

§ 

i 

0 

c 
o 
•3 

1 
3 

a 

c 
S 

1 

a 
i 

i 

i 

J3 

1 

1 

1 

a 

S 

i 

1 

If 

1 

0) 

1 

M 

B) 

^ 

H 

• 

^ 

M 

y 

M 

E 

a 

a 

o5 

a 

cfi 

a 

» 

a 

CO 

s 

& 

s 

» 

STEEL. 


1. 

2. 
8. 

4. 

5. 
6. 

7. 

8. 
9. 
10. 
11. 

12. 

18. 

14. 

15. 
16. 
17. 
18. 
19. 
20. 
21. 
22. 
23. 
44. 

25. 

20. 

27. 
28. 
29. 
80. 
81. 

82. 
88. 
84. 
85. 
36. 
87. 

88. 
89 
41 
42 
48 

45 

46 
47 
48 
49 
50 
51 
52 
58 
54 
65 
56 
57 
68 
59 
60 

61 

62 

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•022 
•030 

•030 

•03', 
•020 
•OK 

•074 
•028 

•044 

•138 
•034 

•040 

•024 
•056 

•028 
•076 

•08! 

•024 

•082 
•080 
•084 

•063 
•162 

•034 
•032 

•030 

•036 
•020 
•050 
•032 
•044 

•044 

+     -108 

—         -020 

+         -018 

+         -002 

+         -030 
•004 
+         '024 

n 

+         -008 

-          -012 
-f          -O.V2 

—      -ooc 

+         -006 
+    -142 

-1-         -012 
4         "002 

0 

+         -006 
0 
4-        -022 
—        -042 
4-        -016 

0 

Good  rail-  1 
wore  well  f 

Good  rail-  \ 
wore  w*rll  / 
Bad  rail.... 

Broke     in  \ 
testing..  / 

•028 
•107 

•050 
•029 
•U85 
•028 
•058 
•049 
•036 
•1)84 
•062 

•022 
•099 

•114 

•048 
•042 
•028 
•068 
•126 
•036 
•081 
•048 

—        -001 
-         -008 

+    '064 

4         "019 
+         '007 
•000 
-f         -005 
f   -07  T 

+      -ooi 

—         '003 
—        -014 

Good  rail-\ 
wore  well  / 

•007 
•OS6 
•016 
•006 
•105 
•036 

•056 

•186 
•013 
•848 
•049 
•014 

•028 
•224 

+         -002 
—         '007 
+         -003 
0 
—         -001 

—       -ooi 

_          '009 

+     '014 

4-       -00-2 
L    -024 
0 
-    .022 

+    -017 

•oio 

Bad  rail.... 

Bad  rail.... 

Broke     i'n'Y 
testing..  / 
Good  rail-  \ 
wore  well  / 

•475 

•019 
•008 
•022 
•016 
•010 

•089 
•025 

•455 

•019 
•009 
•029 
•012 
•018 

•089 

•087 

—        -020 
•000 

+      -coi 

+        -007 
-        -004 
+        -008 

•000 
+        '012 

Bad  rail  

Bad  rail.... 

•818 
•188 

•600 
•178 

Failed    in  \ 
track.../ 

ssemer  Ingot 
re  steel  

IBoilei  plate 
Boiler  plate 
13-ton  Ingot 

•090 
•520 

•no 

•100 
•590 

+         -010 
+        -070 

•018 
•020 

•015 
•070 

4-        -002 
+    -050 

•500 
•890 

•870 
•410 

-    -ISO 

4-         -020 

•052 
•089 
•040 

•270 
•16 
•18 
•056 
•04 

•07 

.._,.( 

•072 
•155 
•08 

•023 
•00 

•17 

•150 

•180 

+        -080 

•690 

•720 

4-        -080 

O 
O 

a 
•*t 

!" 
in 

>:', 

! 
i 

Bi 

Ingot,  
>el  rail 

•190 

•270 

•870 
•440 
190 
•420 
•6SO 
•116 
•105 
•115 
•150 
•452 
•28 
•20 
•294 
•77 

•85 
•30  ± 
•09 

•300 

•410 

•920 
•770 
•210 
•420 
1-200 
•160 
•155 
•185 
•240 
•898 
•24 
•20 
•25 
•726 

1-02 

•780 
20C 

+  -no 

+    -14O 
+    -650 
4-    -33O 

4        -020 
•000 
+    -520 

4        -045 

+      -oso 

•020 
•090 
4-    '446 

—         '045 
•000 
—         -042 
-         -050 

+    -168 
4    -480 
4    '105 

•015 
•006 
»  

•860 
•498 
•514 
•360 
•788 
•690 
•576 
576 
•518 
•648 
•69t 
1-100 
•594 
M5 
425 

•44 
•33 

5ot.  90"  long 
jot,  7'  long.. 

'  steel  roll  .  . 

Bteel  plates,! 
Ecclea  "j 

'  thaft  

•043 

4-         -087 

•585 
•558 
342 
•755 
840 
•590 
•65.' 
518 
•614 
•818 
1-216 
•618 
•509 
•306 

•425 
•871 

+        -08" 
+        -044 
—        -018 

4-      -on 

+    -15O 

4     -014 

4-         -079 
0 
—        -034 
+    -128 
4-    -118 

4     -01 

—         -03 
—    -119 

—         -02 
4-         -040 

0 
tr 
•410 
tr 
tr 
tr 
•010 
•106 
•864 
•805 
•252 
•078 

•180 

0 
tr 
•410 
tr 
tr 
tr 
•010 
•128 
•944 
•821 
•240 
•028 

•195 

0 
0 
0 
0 
0 
0 

•ooo 

4-         017 
h    '080 
4-        "016 
-         012 
—    '055 

+    -065 

Bcssemei       i 
steel       J. 

tyres.  1 

r    of    Krupp 

steel            .  . 

4-         -005 
4-         -141 

Lividia  hollers. 

SUMMARY  OF  SEGREGATIONS  IN  STEEL. 


84 

28 

82 

44 

82 

12 

15 

17 

12 

20 

18 

IB 

18 

4 

ii      o       n 

8 

11 

1 

2 

0 

4 

4 

Maximum   + 

4-        -660 

+        '221 

4        -250 

4-       -2772 

4-        -192 

4-         '024 

4-        '142 

Maximum   — 

—        '065 

—        -055 

—        'ISO 

—        -019 

—        -015 

—        '022 

•042 

+        "080 

+        '018 

4-        -029 

4-         '038 

4-        -082 

4-      '0009 

+        "016 

Arithuictr.  av'ge 

•100 

•019 

•055 

•048 

•086 

•0058 

•023 

CAST-IRON. 


101. 
102. 
10*. 
104. 
105. 
106. 
107. 

irs. 

109. 
110. 

Gruson  armor.. 
Chilled  

3-810 
8-270 
3-975 
8-764 
8-000 
4-391 
4-876 
4-288 
8-202 
2-980 

3-030 
3-060 
8-409 
2-864 
1-750 
4-808 
4-768 
4-627 

[    2-940 

-    -280 
—        -210 
-    -566 
-    -9OO 
-1-250 
4-        '417 
4-         -892 
+         -344 

4-      -010 

8 
6 

+       -417 
—      1-250 

•260 
•910 
8.668 
8-140 
1-630 
•895 
•521 
•318 
•640 

•700 
1-010 
3-679 
V153 
•790 
•260 
•229 
•101 

•760 

+  -44O 

4-  -wo 

4  '026 
4-  "018 
-  -840 
-  -135 
-  -292 
-  -212 

+  -120 

5 
4 

1-080 
1-640 
1-580 
•852 
•855 
6-120 
6-008 
5-872 

1-080 
1010 
1-820 
•931 
•288 
6-570 
6-970 
6-880 

4-        -050 
-    -63O 
-    -260 

4-        -079 
—        -067 
4-    -45O 
+    -962 
4    '5O8 

•018 
•885 
1-530 
•525 
•591 
•561 
1-818 

•005 
•826 
0-840 
•171 
•878 
•27-2 

1-346 

—        -013 
—        -059 
+  5-310 
-    -354 
-    -213 
—    -289 

4-        -028 
2 
5 

+      5-810 
—       -854 

•027 
•010 
•120 

•199 

•019 
•018 
•060 

•007 

—        -008 
4-        -008 
—        -060 

—        -192 
1 

4-      -cos 

•192 

•087 
•058 

•027 
•051 

—        -010 
—        '007 

Arsenic. 
•06401     -184 

Slag. 
1-4«°     -920 

+    -070 

—        '540 

1 
1 

-4-        '070 
—        -540 

Cleveland  iron.. 
VSpiegeleisen  i 

[  6-ton  block..  J 

5 
8 

4-        -902 
•680 

0 

2 

M  a  x  i  m  n  in   + 
case  

4-  -440 
—  -840 

Maximum  — 
case  

-010 

Liquations. 


115. 
116. 
117. 
118. 

8-411 

8-069 

—  -347 

2-O44 

1-685 

—  -409 

0-430 

0-420 

—  010 

0-440 

•823 

IfKl 
2-466 

4-  1-544 
4-  1-643 

O-OSCi 

•056 

•050 

0-052 

•228 

•050 

—        -084, 

+        '167 
0 

0-028 

0-012 

—         -016 

Siegen  cast-Iron. 

8-468 

::  f.!in 

8-818 
4020 

+  -355 

-I-  .430 

2-196 
1  790 

1-869 
8-150 

—  -827 
+  1-36 

2-620 
•680 

b-iss 

•870 

+  2-568 
+  -240 

•620 

2-180 

+  1.51O 

1  to  35.     B;  Forsyth  private  communication.  .Ian.  27tn    188C. 

36.  1!.  W.  (  lucv.  r,  Trail*.  Am.  Inst.  Min.  Eng.,  XIII.,  p.  167.     Bessemer-steel  ingot  18"  X  13"  X  4'  6".     Mother-metal  =  point  at  outside :  segregation  =  axis  2'  6"  from  bottom. 

37.  Borlnp.i  from  niotal  oncrinally  at  the  outsirtu  (mother-metal)  and  originally  at  the  center  (segregation)  of  a  550  Ib.   open-hearth  steel  tyre-Ingot.    Zetsche,  Stahl  und  Elsen,   IV.,    p.  646, 
1SS4.     Also  .Io,,r.  Inm  and  Steel  Inst,  1884,  II.,  p.  672. 

38  to  43.    E.  O'C.  Acki-r,  private  communication,  1888. 

38.  S-lnch  boiler-plato  rolled  from  10"  X  18"  InRot :  mother-metal  =  bottom-end  of  plate,  segregation  =  middle.      39.   Bottom-end  and  middle  of  another  boiler-plate.     40.  Test-Ingot  of 
heat,  and  point  near  top  of  a  boiler-plate  infrot  10"  X  IS"  X  30". 

42.  Open  hearth  ingot,  10"  x  18"  X  80"  top-cast :  mother-metal  =  points  at  outside  :  segregation  =  4"  from  top,  in  axis  of  ingot. 

43.  26,0on-lh.  im;,it,  cf.  Figure  81.      Mother-metal  =  test  inirot  of  heat :  segregation  =  a  point  in  the  axis  near  the  tup  of  the  Ingnt. 

46.  F.  Stubbs,  .Ic.nrn.  Iron  and  St.  Inst.,  1881,  I.,  p.  199.     Ingot  7'  C"  long :  mother-metal  =  2'  6"  from  bottom  :  segregation  =  1'  11"  from  top. 

47.  Snelus,  Journ,  Iron  and  St.  Inst.,  1881,  II.,  p.  879.    After  recarburizlng  with  spicgeleisen  the  Bessemer  converter  was  turned  up  and  the  blast  sont  through  the  metal   for  nearly  a  min- 


SPECIAL    FEATURES    OF    SEGREGATION       §  267. 


207 


apparent  rule.  In  63$  of  the  cases  there  is  a  greater  or 
less  segregation-excess  of  carbon  :  and  in  only  4  out  of 
54  is  there  a  segregation-deficit  of  as  much  as  O'O.^. 
When  we  turn  to  the  cast-irons,  however,  the  segregation- 
deficit  of  carbon  is  usually  very  severe.  There  is  a  segre- 
gation-deficit in  every  case  except  103  to  108,  and  here  we 
have  reason  to  believe  that  what  appears  to  be  a  seg 
regation  is  really  the  first-solidified  part,  spanning  sub- 
sequently-formed vugs 

Ledebur  suggests  plausibly  that  the  segregation-deficit 
of  carbon  in  case  of  cast-iron  may  arise  because  an  increase 
of  carbon  beyond  a  certain  point,  say  3%,  actually  de- 
creases fusibility  :  so  that  here  the  less  carburetted  com- 
pound is  the  more  fusible,  and  hence  segregates. 

Manganese  and  Silicon. — In  the  cases  here  presented 
the  segregation  of  manganese  and  of  silicon  is  in  general 
much  less  important  than  that  of  carbon,  phosphorus  and 
sulphur,  in  the  case  of  silicon  perhaps  because  little  sili- 
con is  usually  present,  and  in  case  of  manganese  for  the 
reasons  already  given.  Still,  the  segregation-excess  of 
manganese  reaches  0128$  in  eight  cases  and  0-22$in 
three.  We  have  only  one  very  severe  segregration- ex- 
cess of  silicon,  0'221$  in  Number  4. 

Perhaps  the  worst  cases  are  Numbers  12,  the  end  of  a 
rail  rolled  at  Chicago  in  1879,  broken  in  testing,  and  show- 
ing a  hard  spot  on  head  and  web,  with  segregation-excess 
of  0'45$  of  carbon,  0'25$  of  manganese,  and  0'217%  of 
phosphorus  :  Number  46,  a  very  large  ingot  reported  by 
Stubbs,  with  a  segregation-excess  of  0-55%  of  carbon :  and 
Number  .r)0,  a  33-inch  steel  roll  with  a  segregation  excess 
of  0'52$  of  carbon. 

§  267.  SPECIAL  FEATUKES  OF  SEGREGATION. — By  apply- 
ing severe  pressure  to  partly  solidified  cast-iron,  Stead 
caused  the  molten  interior,  into  which  much  phosphorus  had 
already  segregated,  to  burst  the  still  tender  walls  and  gush 
out."  The  ejected  matter  contained  6'84$  of  phosphorus, 
while  the  cast-iron  treated  held  b  it  1'53$  (No.  10.5,  Table 
94).  Now  in  a  like  way  the  pressure  which  the  rapidly 
cooling  and  contracting  walls  exert  on  the  interior  during 
the  early  part  of  the  solidification  may  squeeze  drops 
of  the  still  molten  metal  through  the  walls,  as  mercury 
is  squeezed  through  chamois.  Riley's  pea-like  drops,  con- 
taining over  4$  of  phosphorus,  occurring  on  phosphoric 

a  In  1883  I  proposed  concentrating  the  phosphorus  of  phosphoric  cast-iron  by 
casting  the  metal  in  large  blocks  as  it  ran  from  the  blast-furnace,  and  bleeding 
them  when  partly  solidified,  thus  obtaining  relatively  pure  shells. 


cast-iron,b  are  doubtless  instances  oZ  this  action  ;  others 
are  given  in  Numbers  1 15  to  118  of  Table  96. 

The  excess  of  contraction  of  the  interior  over  that 
of  the  exterior  after  the  period  when  the  shell  has  become 
rigid,  causes  internal  cavities  :  and  in  and  around  these 
cavities  we  may  expect  to  find  the  last-freezing  part  of  the 
metal,  and  the  segregation  if  any  there  be.  Occasionally 
it  shoots  out  in  little  pine-tree  crystals  into  these  vugs. 

But  we  may  find  in  the  vugs  not  the  last-  but  the  first- 
freezing  part  of  the  metal.  Thus,  if  in  a  narrow  casting, 
such  as  a  pig  of  spiegeleisen,  early  forming  crystals  shoot 
completely  across  the  mass,  these  crystals  may  be  found 
stretching  across  the  vug  which  forms  by  contraction  later. 
Of  this  we  seem  to  have  an  example  in  Numbers  106-108 
of  Table  96,  for  the  composition  of  the  vug-crystals  indi- 
cates that  they  ara  less  fusible  than  the  mother-metal. 

In  exceptional  cases  the  segregated  matter  is  found  as  a 
kidney-shaped  mass  within  the  central  vugs,  as  in  Number 
101,  Table  96,  sometimes  wholly  detached,  in  other  cases 
attached  to  the  mother-metal  at  few  points.  Ledebur 
plausibly  supposes  that  the  segregation  separates  from  the 
mother-metal  because  its  coefficient  of  expansion  is  higher, 
i.  e.  it  shvinks  away  from  surrounding  metal.  Possibly, 
however,  the  segregation  while  molten  refuses  to  wet  the 
mother-metal,  lying  like  mercury  on  glass,  or  oil  in 
water :  later,  when  the  excess  of  contraction  of  interior 
over  shell  causes  a  vug  to  form,  parting  occurs  more  readily 
at  the  junction  of  the  mutually  repellent  segregation  and 
mother-metal,  than  through  the  mother-metal  proper,  i,  e. 
the  mother-metal  shrinks  away  from  the  segregation. 

The  microscope  tells  us  that  iron  and  unhardened  steel 
are  never  homogeneous,  microscopically  speaking:  we 
may  regard  the  microscopic  minerals  described  in  §  § 
237-8,  pp.  I63etseq.,  as  microscopic  segregations.  But 
it  is  probable  that  much  iron  and  steel  contains  segrega- 
tions intermediate  between  these  microscopic  ones  and  the 
very  serious  ones  shown  in  Figure  82.  It  may  well  happen 
that  the  comparatively  large  quantities  of  metal  which 
we  take  in  common  sampling  may  include  several  small 
segregations  and  several  small  lots  of  mother-metal,  and 
that  these  may  balance  each  other  so  that  borings  in 
different  spots  may  have  like  average  compositions.  But 
T.  T.  Morrell  finds  that  when  very  small  borings  are 
made,  say  of  50  mg  each,  the  quantity  of  carbon  at 


b  E.  Riley,  Journ.  Iron  and  St.  last.,  1881,  II.,  p.  393. 


ute.     Cooled  very  slowly  in  moulding  sand,  so  that  though  cast  on  Saturday  it  was  not  cold  on  Monday, 
centre  of  a  slice  jut  21"  from  the  top.    (Manganese  from  slices  near  bottom  and  near  top.) 


Ingot  7'  X  19"  X  19".    Mother-metal  =  average  composition  at  outside.    Segregation  = 


48.  Idem.    Open-hearth  steei  ingot  8'  6"  X  21"  X  17".    Mother-metal  =  slice  4"  from  bottom  :  segregation  =  slice  10"  from  top. 

49.  Idem.    Bessemer  rail  ingot,  4'  X  13"  X  13"  at  bottom.    Mother-metal  =  slice  3J"  from  bottom,  segregation  =  slice  12"  from  top. 

50.  A  broken  steel  roll,  3S"  in  diameter.    Mother-metal  =  chippings  from  exterior,  segregation  =  clippings  from  centre.    Source  withheld. 

51  to  54.    H.  Kccles,  Journ.  Iron  and  St.  Inst.,  1438.  I.,  p.  70.    Steel  plates.    Mothei-metal  =  planings  from  outside  of  plate  :  segregation  =  cuttings  from  inside  of  plate. 
55.    Forged  steel  shaft,  about  19  in  diameter.    Mother-metal  =  large  end  of  shaft,  segregation  =  small  end.    Source  withheld.  ™,T,niri*on 

56  to  58:    Bessemer  steel  tyres,  Ledebur,  Stahl  uud  Bison,  VI..  p.  147,  183  i.      li  >rings,  obtained  with  a  slowly  moving  dull  drill,  were  sifted  through  a  very  n 
with  the  other  results  here  collected,  the  coarser  borings,  representing  the  tougher  material,  are  here  classed  as  mother-m-tal,  the  finer  and  more  brittle  ones  as  segregation,  th 
come  within  the  legitimate  use  of  these  words.  a       r«     i?  -    YV     «  vz*  I«QT 

59.  An  ingot  weighing  seveia!  tons  was  drill.il  at  top  and  bottom.    Mother-metal  =  bottom.    Segregation  =  top.     W.  Metcalf,  Trans.  Am  Soc.  Civ.  bng.,  i.V.,  p.  i5b,  i^s,. 

60.  A  large  bar  of  steel  made  for  rolls  by  Krupp.    Mother-metal  =  outer  turnings  :  segregation  =  inner  borings     Idem.  »_,->„,      MafMaml  The  Treitment  of  Oon- 

61.  A  sound  In.'ot.     Mother-metal  =  appi-oxim  He  average  composition  of  outside,  segregation    =  spot  near  the  top  containing  the  maximum  of  carbon.    J 

iU"  02:T:!urW,n'^,'re,d!V{.mhr-inSi*^v'ere  ptSfromone  of  the  Lividia's  boiler-plates.      Mothcr-meU.  is  the  average  of  the  two  outer  layers :  segregation  i,  the  layer  richest  in  carbon, 
phosphorus  and  sulphur.     The  manganese  varied  only  between  the  limits  0  2:57  toO'410*.     W.  Parker,  Trans.  Inst   Nav.  Arch  ,  XXII.,  p   a>,  Issl. 

101.  Crust  and  inner  part  of  (iruson  chilled  cast  iron  armor.    Ledebur,  Stahl  und  Eisen,  IV.,  p.  635,  ISSt. 

102.  Ditto,  ditto,  lor  a  chilled  cast-iron  tread-wheel.     Idem. 

1041  V^^&k^^^^^«  /segregation,  light  gray,  fine-grained,  kidncy-shaped  mass  contained  in  a  vug,  and  .In  some  cases  wholly  detached  _fro,n  UiewaiK  Idem. 


104.  Mother  meta  ,  dark  gray,  eoarse-grained  pig-iron:  segregation,  llgntgray,  nn  ne.i,  Kuiney-si  ,h     Vii   „      »„  int«nil norr  .•ushed  out  •  it  is  lure  given  as 

105.  About  100  Ibs  of  Cleveland  cast-iron  wasrast  in  a  mould,  an«l  when  it  had  become  pasty,  was  subjected  to  severe  pressure  :    the  still  molten  intern  jl  part  MShui  out  Jew  !-  vu,  as 
egation.     -Mother-metal  =  the  composition  of  the  cast-iron  used.     A  second  experiment  gave  like  results.      J.  t   Stead,  Dingier  s  Polytech   Journ.  GCXXX.,  p.  II 


segregati( 

'  IOC  to  lO8i  Mother-metal  =  a  fine-grained  spiegeleisen,  yielding  when  attacked  by  acids  a  brown  residue  of  carbon,  silica    a 
crossing,  leafy  crystals  stretching  across  the  vugs  :  perhaps  0  004"  (0/1.  mm.)  thick  In  their  middle,  thicker  where  attached  to  the 


and  iron.      Segregation  =  smoolh.  mirror-liki-.  parallel  or  acutely 
ills  of  the  vugs  :  quickly  aaiuuln;,'  in  the  air  a  thin,  deep-blue, 


208 


THE    METALLURGY    OF    STEEL. 


neighboring  points  in  the  same  piece   of  steel    usually 
varies  through  a  range  of  about  ()-()6  or  0  07$. a 

In  this  view  such  admirable  uniformity  of  composition 
as  is  indicated  in  Table  97  may  be  more  apparent  than  real. 


s. 

0-03 
0-08 
0-04 


Manganese  % 
2-818^ 
2-714  I  15  basic 

—  f 
+  -099,1 
2-971 
2-688 


TABLE  97.— COMPOSITION  OF  PENNSYLVANIA  STEEL  KAIL. 

C.                     Si.                    Mn.  P. 

Head                                              0-89                    0-01                    O-.M  0-099 

Web                                            ,..  0-81»                 0-61                 0-51  0-100 

Flange'/. '. 0-89                  O'Ol                  0'51  0-098 

A  rail  rolled  at  the  Pennsylvania  Steel  Works  in  1869,  and  in  use  on  the  Pennsylvania  Railroad 
until  1887.    F.  W.  Wood,  private  communication.  June  29th,  1888 

A  separation,  which  however  appears  in  some  cases  to 
be  rather  a  stratification  than  a  segregation,  may  occur 
while  the  metal  is  molten.  Beside  the  drop-like  particles 
which  occasionally  swim  on  the  surf  ace  of  molten  iron,  we 
have  the  observations  given  in  Table  98.  Here  the  top  of 
pigs  of  basic  cast-iron  has  more  phosphorus  in  17  out  of 
20  cases  and  more  manganese  in  12  out  of  1 5  cases  than 
the  centre.  Further,  comparing  the  middle  pigs  of  each 
of  ten  beds  from  the  same  casting  of  basic  cast-iron,  the 
proportion  of  manganese  increased  continuously  from  the 
first  to  the  last  bed  (except  that  it  was  alike  in  the  t  th  and 
9th  beds),  but  here  the  behavior  of  phosphorus  is  very  ir- 
regular. These  observations  suggest  that  manganese  tends 
to  rise  by  gravity  in  the  molten  mass : 

TABLE  98.— STRATIFICATION  OF  PHOSPHORUS  AND  MANOANKSK,  (Reinhardt).b 

Phosphorus  % 

Average  of  top 2-6575^ 

'•        bottom 2-2676  I  20  basic 

[     P'68- 

Difference -f  -SSW) 

Middle  pigs  of  last  five  beds 2-806 

Middle  pigs  of  first  five  beds 2  840 

Difference —  0-034 

The  difference  between  the  composition  of  the  early  and 
late  beds  clearly  cannot  be  referred  to  segregation  during 
solidification.  Nor  is  it  probable  that  the  difference  be- 
tween the  top  and  centre  of  the  individual  pigs  is  chiefly 
due  to  segregation :  for  two  of  these  pigs  were  examined  at 
several  different  points,  and,  excluding  the  top,  phosphorus 
and  manganese  seem  to  be  rather  higher  in  the  middle 
than  at  the  outside. 

So,  too,  J.  W.  Thomas  found  that  the  proportion  of 
silicon  in  the  pigs  of  two  casts  fell  greatly  between  the 
first  and  third  beds,  but  thereafter  remained  nearly  con 
stant."    His  results  follow : 

Bed.  1.  8.  5.  7.  9.  11.  18. 

1st  set  %  81 8-828        2-058         1'890          1-800         1-884          1-834 

2d  set  f  Si 2021        1'782          1-741          1'765         1-722         1'783          1853 

The  crusts  which  occasionally  form  on  pig-iron  may  be 
due  in  part  to  the  liquation  of  oxidizable  elements,  in 
part  as  Ledebur  suggests  to  the  volatilization  of  sulphide; 
and  cyanides,  which  are  oxidized  by  the  moisture  in  the 
casting-house  sand,  and  condensed  on  the  sides  of  the  pig : 
in  this  view  they  are  condensed  fume.  Examples  are 
given  in  Table  99. 

Figures  80  and  81  show  that  the  proportion  of  carbon  in 
the  very  shell  of  the  ingot  is  higher  than  at  points  slightly 
nearer  the  centre.  In  Figure  81  this  is  shown  by  the  de- 
flection of  the  carbon-line  to  the  left.  It  is  readily  under- 
stood. The  very  skin  freezes  too  fast  to  permit  segrega 
tion,  and  hence  has  approximately  the  average  composition 
of  the  molten  mass.  In  the  more  slowly  cooling  parts 
slightly  within  the  skin  time  is  afforded  for  segregation 
and  the  centripetal  expulsion  of  fusible,  highly  carburet 
ted  compounds. 

§268.  To  PREVENT  HETEROGENEOUSNESS,  in  so  far  as  ii 
is  due  to  segregation,  the  natural  steps  are  to  hasten  cool 


»T.  T.  Morrell,  private  communication,  June,  1888. 
l'  C.  Reinhardt,  Stahl  und  Eisen,  VIII.,  p  22,  1888. 
=  Jour.  Iron  and  Steel  Inst.,  1888,  II.,  p.  241,  from  Jour.  Anal.  Chem.,  II.,  p 
148. 


TABLE  99. — CRUSTS,  ETC.,  ON  CAST-IKON. 


CRUSTS. 


Graphite. 


4-55 


SiOj. 


75-95 


51)86 
2284 


94-87 


Ti02. 


1-12 
5-J!) 
5-77 
4-45 

•95 


Alj03. 


4-90 
3-56 


FeO. 


8-56 


Fe203. 


38-41 
3-2-1 1 
67-00 


MnOi. 


5-75 
4-97 
9-96 
8-80 

•25 


CaO. 


•02 
1-61 
0-10 
0-04 


MgO. 


•40 


K,O. 


SbjO 


1-80 


CRUSTS. 


PaO,s. 


tr. 
•Of, 
•12 


•on 


v,ot 


Cr,03 


1-82 
1-15 


0-15 


CAST-IRON  ACCOMPANYING. 


Carbon. 


3-310 


Si. 


3-27 
0'51@0-S4 


Mn. 


•44 

•375 


P. 


1-132 
•55@-81 


•018 


1    A  yt-Ilowish  white,  readily  detached,  moss-like  mass  of  threads  or  stemlets,  filling  cavities 

n  the  extcri'-r  of  dark-gray,   ctmrse-grained  pig-iron,   which  wt-re  deep,  irregular,  and  clearly 

[brnit-d   by   the  escape  of  gas   during  solidification.      The  iron  which  contained  this  substance 

always  smokt-d  much  in  ca-ting     The  alumina  may  have  come  Irom  the  casting-beds.    Ledubur, 

Stahl  and  Eiyen.  IV.,  p.  638.  1884. 

2.  Crust  on  pig-iron  made  at  Pequest,  N.  J.:  the  vanadic  acid  is  from  a  second  specimen 
examined  by  Oro*  n.  Robertson  and  Kirmstone,  Trans.  Am.  Inst.  Mln.  Kng.,  XII.,  p.  641. 

8.  Like  crusts  from  Glenclon,  Pa.,   Idem. 

4   Crusts  similar  to  No    2.  from  Pequest;  G.  Auchy,  Idem,  p.  644. 

5.  Crusts  from  pi,'-iron  made  at  Kiegelsville,  Pa.  B.  F.  Fackeuthal,  Jr.,  private  communica- 
tion, June  14  1886. 


ing,  by  keeping  the  thickness  of  the  ingots  within  bounds, 
and  by  using  iron  moulds  as  far  as  practicable,  or,  in  case 
sand  moulds  must  be  used,  by  breaking  up  the  mould  soon 
after  the  outside  of  the  mass  has  set,  so  as  to  hasten  the 
solidification  of  the  interior.  But  as  we  have  already 
seen,  rapid  cooling  should  tend  to  increase  the  volume  of 
the  pipe,  and  the  formation  of  both  blowholes  and  cracks. 
(Cf.  pp.  151,  152,  161.)  We  should  therefore  cast  in  in- 
gots of  moderate  size,  and  cool  at  a  moderate  rate.  An 
excessive  casting  temperature  promotes  slow  cooling, 
while  increasing  the  tendency  to  form  cracks  and  blow- 
holes, and  should  thus  on  every  account  be  avoided.  It  is 
the  actual  experience  at  some  American  Bessemer  works 
that  stickers  (ingots  which  do  not  leave  the  mould  readily, 
usually  because  cast  too  hot),  show  excessive  segregation. 

To  make  the  metal  quite  homogeneous  before  teeming, 
in  the  crucible  process  we  have  to  mix  the  contents  of  the 
several  crucibles,  in  the  Bessemer  and  open-hearth  pro- 
cesses to  mix  the  recarburizer  with  the  rest  of  the  metal 
thoroughly.  The  mixing  may  be  done  in  the  casting  ladle 
(in  the  crucible  process,  the  different  crucible-f  uls  may 
to  that  end  be  run  into  a  common  ladle),  e.  g.  by  means  of 
Allen's  agitator,  Figure  85,  or  by  poling,  /.  e.  inserting 
a  pole  of  green  wood  into  the  ladle,  when  steam  and  hy- 
drocarbons distill,  stirring  the  mass  :  or  by  pouring  from 
one  ladle  to  another,  as  is  done  in  Britain. 

In  the  Bessemer  process  we  may  turn  the  converter  up 
for  a  few  seconds  after  adding  the  recarburizer.  In  the 
open-hearth  furnace  the  recarburized  bath  may  be  vigor- 
ously stirred  or  poled  :  or  mixed  by  rotating  the  hearth, 
as  in  the  Pernot  furnace.  Indeed,  greater  uniformity  of 
product  is  claimed  as  an  important  advantage  of  this  fur- 
nace :  but  the  results  given  in  Tables  94  and  95,  and 
immediately  after,  obtained  in  a  stationary  open-hearth 
furnace,  go  to  show  that  uniformity  may  be  attained  with- 
out resorting  to  the  Pernot  furnace. 

Allen's  agitator  has  been  tried  at  several  American 
works,  but  generally  abandoned.  Its  use,  by  postponing 
teeming,  delays  the  pit-men,  a  very  costly  gang,  and  cools 
the  metal,  often  undesirably,  without  fully  compensating 
advantage  as  regards  increased  solidity  or  homogeneous- 
ness.  In  some  American  Bessemer  works  poling  is  still 


PREVENTION     OF     IIETEROGENEOUSNESS.       §  268. 


200 


resorted  to  :  a  pole  is  held  in  the  casting  ladle,  while  the 
steel  is  pouring  into  it  from  the  converter. 

Now  that  it  is  known  that  the  hard  spots  in  steel  are 
usually  due  to  segregation  rather  than  to  imperfect  mix- 
ing, mechanical  agitation  receives  less  attention  than  for- 
merly. But  segregation  may  be  favored  by  imperfect 
mixing:  for,  since  the  tendency  of  a  given  element, 
say  carbon,  to  segregate  appears  to  increase  as  the  pro- 
portion of  that  element  present  increases,  so  in  a  high- 


ingots,  he  obtained  almost  complete  uniformity  :is  ivsrnrds 
carbon  by  pouring  from  one  ladle  to  another. 

But  this  transfer  may  have  hindered  segregation  simply 
by  cooling  the  metal,  so  that  it  solidified  more  rapidly. 

How  muc7i  segregation  is  usual?  From  the  foregoing 
we  see  that  this  question  cannot  be  answered  -with  confi- 
dence till  we  have  the  results  of  a  great  number  of  careful  ly 
studied  cases  :  for  the  examination  of  a  few  spots  at  ran- 
dom may  fail  to  detect  the  segregation.  .  .  The  cases 


Figure  85,  Allen's  Agitator. 

The  ladle  C  C  C,  containing  the  molten  steel,  Is  brought  by  the  casting  crane  beneath  the  propeller-blades  D  D  ofjn» 
agitator,  then  raised  so  as  to  Immerse  the  agitator,  as  shown  in  the  figure.     In  another  arrangement  the  •gnHn'  is  carri< 
by  a  small  crane,  and  is  raised  and  lowered  during  the  whole  period  of  agitation.    The  propeller-blade  and  the  stem  EE  arc 
coated  with  clay. 


carbon  streak  in  the  molten  metal  due  to  imperfect  mix- 
ing, the  tendency  towards  the  segregation  of  high-carbon 
fusible  compounds  may  be  exceptionally  strong.  In  this 
way  we  may  explain  W.  Richards'  statement*  that,  after 
trying  Allen's  agitator,  poling,  and  long  repose  in  the  con- 
yerter  to  overcome  the  irregularity  in  carbon  in  his  large 


»  Journ.  Iron  and  St.  lust.,  1886,  1.,  p.  113. 


in  Table  96  are  as  a  whole  much  worse  than  the  average, 
for  clearly  the  bad  cases  attract  most  attention  :  yet  in  22 
out  of  its  54  cases  the  segregation  of  carbon  is  not  over 
0-03^  arithmetically.  I  can  only  say  that,  while  we  know 
that  segregation  is  liable  to  be  very  serious,  we  believe 
that  with  reasonable  care  it  may  be  kept  within  harmless 
limits  in  ingots  of  moderate  thickness. 


210 


THE     METALLUKGY     OF     STEEL. 


CHAPTER      XIV. 
COLD  WORKING,  HOT  WORKING,  WELDING. 


§  269.  COLD-WORKING  IN  GENERAL. — It  is  probable 
that  all  forms  of  moderate  permanent  distortion  of  iron 
and  steel  in  the  cold,  whether  by  stretching,  compress- 
ing, or  twisting,  by  cold-rolling,  cold-hammering,  wire- 


drawing,   or   otherwise,   increase    the    tensile    strength 
and  hardness  and  still  more  the  elastic  limit,"  while  lower- 


aThe  proportionality  limit  is  indeed   temporarily   lowered  by  stret' bing,  but 
quickly  rises  again.    Cf.  §  270. 


TABLE  100. — INFLUENCE  OF  COLD  WORKING  ON  THE  PROPERTIES  OF  IRON. 


Size. 

Elongation. 

Increase       of       t<-nsil<- 

treneth       unds 

Peduction  of  area 

strength,  etc.,  by  o-tll 

Final. 

square  inch. 

per  8-quare  inch. 

Percentage. 

a  a 

—  o 

Per  cent. 

the    tensile   strength, 
etc.,  before  cold  work- 

0. 

ing. 

s 

0- 

H 

p 

c 

j 

>. 

1 

* 

i 

I 

•a 

! 

i 

i 

1 

P 

-o 

Q 

'•°  1 

1 

i 

|4 

e 

3 

o 

1 

1 

M 

i 

*3 

a 

Hardd 

S 

a 
a 

*S 

1 

l 

"3 

3 

ts 

Annea 

5i  - 
SiS  E 

1 

la 

Hardd 

f 

a 

a 

It 

1 

a 
1 

A  WIRE  DRAWING. 


t; 
i; 

it 

.L 
tl 

M 

T 

A 

A' 

\' 
\' 
\' 
A' 

Win 
Chan 
logo 

_*  >, 

If"1 

•*•*  J- 

a 
•a 

Open 

i-qi 

in 
The* 
dra 
Usua 
wir 

Steel 
h'd 

Mild 
wir 
fro 

7  aiid  8 
14 

u 

< 

•187,165 
•088 

i 

7U@75,000 

1611,000 
102,384 
127  980 

411,000 

80,000+ 

15 

4 
0-80 

12 

15-74 

M 

12-2± 
14± 

+121 
+73 

+100 

—78 

-92 
-92 
-98 
-97 
-4SB 
-74  C 
—  58  B 
—  79  C 
—  28  B 
—  82  C 
-  8B 
-78  C 
-90± 

-91-67 
-88-84 
-88-87 
-95-87 
—98-29 

—  67-49 
-47-19 
—31-86 
—44-88 
—67-68 

0-87 

191,970 

0-91 
0-75 

227,5o2 

52,614 
68,256 
54,086 
52,614 
A127.980 

91,008 
89,586 
85,320 
85,820 
B180.594 
C231.786 
8191,970 
C220,410 
8200,502 
C234.680 
8216,144 
C231.786 
171,760 

178,330 

181.020 
90,000 
100,000 
111,000 

66,817 
61,158 
69,692 
69,692 

9-45 
7-46 
16-79 
16-25 
AC-62 

0-74 
0-62 
0-81 
0-60 
B341 
01-75 
B2-95 
01-47 
B4-70 
Cl-18 

22-00 
22-00 
20-52 
20-60 

+81 

+58 
+62 
+41  B 
+81  C 
+35  B 
+55  C 
+28  B 
+50  C 
•f.Vi  B 
+660 
+145± 

167 

tt       «i 

U             U 



''A  wire-rod,  Bhardened  wire 
C  finished,  D  annealed  wire 
A  wire-rod,  Bhardened  wire 
C  finished,  D  annealed  wire 
A  wire-rod,  Bhardened  wire 

0119,472 
L<126',588 

1)8-00 
i)6"88 

15-74 
15-74 

' 

H 

A142.200 



A7-00 

' 

0-15  sq. 

it 

A156.420 
A139',856  ' 

'ETO.OOO 

F86.790 
60,000 

A6-54 

A  wire-rod,B  hardened  wire 
^C  finished  wire.  , 

A6-17 

Eso-bo' 

F87-45 

B5-67 
01-86 
1-4 

© 
2-6 

1-89 

10 

io6,'doo'± 



•hearth  steel  wire  billets  and 
are  wire  from  them,  drawn 

r 
ii 

2 

E  50 

F  61-89 

92 
& 
85-0 



+  28-61 
+  47-86 
+  88-52 
+126-08 
+  82-86 

nine  annealed  after  the  6th 

properties  of  wrought-iron 
e  

1' 

10 

15 
20 

.  . 

wire  hard-drawn,  apparently 
nd,and  same  slightly  ann'l'd 

steel  wire-rods,  hard-drawn 
e,    and    annealed    wire,  all 
n  the  same  billet.'  

(' 

0-2 

•259 
288 
•208 
•165 
•184 

56,000 
61,588 
67,469 
90,070 
105,997 
85,725 

78,400 

f  S 

284 

•i  288 
I  22 
1,22 

8 
4 
6 
8 
10 

67,939 
64,489 
67,782 
66,170 
66,170 

109,884 
98,762 
101,722 
126,246 
122,085 

60,726 
62,188 
63,750 
59,606 
67,857 

47,846 
45,629 
49,078 
46,888 
46,888 

22-8 
19-8 
21-7 
21-6 
21-6 

1-9 
82 
8-5 
1-0 
0-87 

15-2 
17-5 
28-6 
21-2 
22-4 

8 
8 
8 
3 
8 

59-42 
64-78 
66-40 
68-11 
68-11 

19-82 
34  21 
45-58 
37-88 
22-05 

62-63 
64-32 
66-48 
70-14 
66  17 

+60-93 
-+53-14 
+58-92 
+90-69 

+84-48 

44,58] 

48,702 
42,224 
49,285 

B  COLD  ROLLING,  ETC. 


•24 
•25 
2(i 
•27 
•^ 
'211 
:tfl 
81 
ii'2 

:« 
M 
X, 
:iii 
37 
88 
:«> 

10 
41 
4-2 
48 

W, 
B 
i: 

B 

M 
M 
Wa 
\Va 
F 
T 

71,530 
68,184 
62,882 
66000 
58,000 
55,400 
55,480 
64.076 
57,850 
49,510 
65,760 
50,927 
58,627 
52,500 
46,788 
48,500 
5(1,300 
47,400 
48,167 

86,580 
78,384 
71,008 
67,200 
70,000 
70,420 
81,890 
99,445 
92,623 
66,862 
83.156 
99,298 
88,229 
69.000 
66,100 
66,933 
67,888 
68,167 
73,883 
96,870 

40,744 

78,940 

80 
21-5 

14 
9-7 

2 

+21 
+20 
+13 
+20 
+21 
--27 
--18 

+  94 

—53 
-60 

—74 
-71 

-55 

—82 

-60 
—58 
—90 

-7T 

Pieces  cut  from  Creusot  steel,and 
hammered  cold  till  they  were 

( 

} 

28-5 
85 

6 
10 

\ 

Norway  Steel  and  Iron  Co.,  com- 
pressed steel  (G.  U.  Billings' 

f 

27,000 
26,540 

61,000 
61,100 

+126 
+130 
+178 

J2-08 
12-03 
I  -94 

1-936 
1-808 
•75 

846 

156 
0-75 

5 

20 

42-9 
42'9 
58 

83-6 
16-7 
89 

Jones&  Laugh  lin'scold-rol'diron 
Puddled  iron  '. 

:13,9!>6 

94,554 

88 

--61 
--85 
--49 

--95 
+50 
+81 
+41 
+38 
+85 
+44 
+58 

+  84 
+106 

•75 
•75 
1-00 

37250 
42,489 

68,427 
87,896 

Charcoal  bloom  iron  

20-0  ' 
24-58 
26-25 
24-00 

'  Y-9  ' 
10-42 
2-75 

'  '6-60 

8-05 
4-68 
16-4 



10 
10 



1-07 

Cold-rolled     iron,      Jones    &  I 
Laughlin's,  Lauth's  patent.,  f 

51  600 
46.800 
49,600 
49,500 
50,900 
48,700 

30,000 
28,600 
28,200 
24800 
27.700 
29,200 

59000 
60,300 
57,500 
67,467 
60,867 
68,888 

88.000 
31,400 
SI.  SCO 
31,600 
32.700 
88,600 

25-00 
14-25 
12-50 
9-50 
12-65 
15-80 

10 
10 
10 
10 
10 
10 
5 

--  97 
--111 
--104 

2-56 
2-06 
1-87 
1-06 
•67 

2-44 
2 
1-81 
1 
•68 
2-40 

--136 
-118 

.*        u 

ik        ii 

1935 

--119 

Cold-swaged  steel  

87 

1.  Wire  of  this  quality  was  found  to  be  procurable  in  large  lots  for  the  East  Kiver  Bridge.  The  elastic  limit  was  always  more  than  half  the  ultimate  tensile  strength.  The  "Initial"  bar  here  refer 
to  pieces  of  cross-section  fitted  for  common  bridge  members.  F.  Collingwood,  Trans.  Am.  Soc.  Civ.  Eng.,  IX.,  p.  170, 1880. 

2  to  13.  A.  Bonnaud,  Eev.  Univ.  2d  Ser.,  IX.,  p.  823,  1881.  10  to  13  give  the  properties  A  of  the  wire  rod,  B  of  the  hardened,  f.  e-  quenched,  wire  (fil  trcmpfi  et  revenu),  C  of  the  finished 
wire,  which  has  apparently  undergone  additional  drawing  after  hardening:  and  D  of  the  finished  wire  annealed. 


.      .     . 
sectional  area  by  wire  drawing  was  thus  87'5,  24-7,  32'5  46  and  66&    Horace  Allen,  Excerpt.  Proc.  Inst.  Civ.  Esg.,  XCIV,  p. 

24.  Thoroughly  annealed  steel  had  the  properties  given  under  *'  Initial  "  :  after  cold-hammering  on  only  one  pair  eff 
U.  S.  Naval  Inst.  XIII..  p.  56,  1887,  from  Notes  on  Construction  of  Ordnance,   No.  8,  Washington.  July  20th,  1882. 


resent  the 
are  from 


_____  ^ 

W.  M.  Metcalfe.    The  details  of  the  operations  are  given  'at  great  length 

15.  One  coil  of  the  wire  of  No.  14  was  lightly  annealed  between  the  5th  and  6th  draughts,  which  reduced  the  tensile  strength  greatly,  and  greatly  increased  the  reduction  of  area,  but  without 
increasing  the  elongation. 

16.  Usual  properties  of  wrought-iron  wire,  Thurston.  Mails  of  Engineering,  II.,  p.  201. 

17.  Slight  annealing  greatly  raises  the  elastic  limit  of  thick  and  apparently  hardened  (quenched)  wire.    Sir  W.  Armstrong,  Journ.  Iron  and  Steel  Inst.,  1882,  II.,  p.   701,  from  paper  read 
before  Sect,  G.  British  Ass.  Aug.,  1882.    Thinner  wire  is  simply  softened  without  Increase  of  elastic  limit  by  annealing. 

18  Xo  2O.  A  two-inch  billet  of  mild  steel,  carbon  0-115.  silicon  0*009,  phosphorus  0*072,  were  rolled  hot  to  Numbers  1,  2,  4,  and  5  B.  W.  respectively,  and  the  resulting  rods  were  drawn  at  a 
single  draught  to  Numbers  3,  4,  6,  and  8  B.  W.  G.  The  Number  8  wire  was  further  drawn  to  Number  10  B.  W.  G.  without  annealing,  and  apparently  in  two  additional  draughts.  The  reduction  of 

'        -        '  p.  1888.    The  density  of  these  materials  is  given  in  Table  105. 

effaces  it  had  those  given  under  u  hard  drawn."    Woodbridge,  Birnle,  Proc. 
.    .  ,        .    ,  ngton.  July  20th,  1882. 

25  to  27.  Treatment  of  steel,  Barba,  Holley,  pp.  50  to  54.  Soft  steel  was  hammered  out  cold,  till  its  length  was  increased  by  about  7'5&  The  hard-drawn  results  in  number  25  repr 
mean  obtained  with  six  bars,  and  their  properties  are  compared  with  the  mean  of  similar  but  untreated  pieces.  For  26-7  it  is  probable  but  not  certain  that  the  initial  and  hard-drawn  results 
material  originally  of  the  same  piece. 

28.  Circular  of  the  Norway  Steel  and  Iron  Company.    The  steel  contains  about  0"14£  of  carbon,  0-40^  of  manganese,  and  0-01  of  silicon. 

29-30.  Eng.  and  Mining  J].,  XXXV.,  p.  222,  1883.  From  tests  on  the  Watertown  testing  machine.  A  single  bar  of  hot-lolled  steel  was  cut  into  three  pieces.  The  first  was  tested  without 
further  treatment  (here  given  as  the  "initial"  bar);  the  second  after  a  single  draught,  which  reduced  its  diameter  from  2-03  to  1-936  inches;  the  third  also  after  a  single  but  more  severe  draught, 
which  reduced  its  diameter  from  2'03  to  1  '808  Inches.  The  modulus  of  elasticity  of  the  uncompressed  bar  was  29,000,000:  that  of  the  first  of  the  two  compressed  (hard-drawn)  bars  was  31,000,000. 
In  com  press]  \-o  tests,  the  permanent  set  and  the  compression  was  almost  exactly  the  same  in  the  compressed  as  in  the  uncompressed  steel 

31.  G.  H.  Billings,  private  communication.  May  9th,  1SS8  The  initial  and  the  hard-drawn  pieces  are  from  the  same  bar.  The  initial  was  turned  down  to  |-inch  diameter  in  a  lathe  before  test- 
ing. Modulus  of  elasticity  of  the  uncompressed  (Initial)  bar  29,400,000:  of  the  compressed  (hard-drawn)  36.400,000. 

32-33.  Te  tsby  M"rrick  &  Sons,  Southwark  Fdry.    Thurston,  Kept,  on  O  Id-rolled  Iron.  1887.  D.  12 

34  35.   W.  Wade,  1860:  Idem.  p.  10. 

36.   Win.  Fairbairn,  :  Rankine,  Civil  Engineering,  1870,  p.  XVI.     Also  Thurston,  Op.  Clt.  p.  7. 

37-42.  Thurston,  Op.  Clt.,  pp.  82-8,  109.  In  Nos.  38  to  42  the  "Initial"  and  the  "cold-rolled"  results  each  represent  three  bars.  The  cold-rolled  pieces  were  from  the  same  bars  as  the  "inlU«l" 
or  hot-rolled  ones.  All  were  tested  as  they  came  from  the  rolls,  without  subsequent  redaction  in  the  lathe. 

43.  Mldvale  steel,  cold-swaged  at  Washington  Navy  Yard.  The  elongation  was  8<  on  SO  inches,  and  16'4%  on  the  5  Inches  where  rupture  occurred.  Kept  Tests  on  Strength  of  Struct.  M*U, 
Watertown  Arsenal,  1888,  p.  178, 


COLD    WORKING.      §  269. 


211 


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ive  pulls  the  plec.  usually  un 
pull  of  61,286  Ibs.  per  sq.  In.  a 

n  the  preceding  line,  say  N-1, 

which  the  piece  was  subjected  durin 
chschulc  in  Munchen,  XV..  1886. 
n  diameter,  I.  and  II.  19'6  inches  lo 

Original  numbers,  1850  f, 
:  of  course  an  appreciable 

bers  lying  Immediately  be 


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subjected  to 

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83    s£  >  £-=«<5  o  »  8«~  ; 

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lil  1 


212 


THE    METALLURGY    OP    STEEL. 


ing  the  density :  and  that  the  changes  which  distortion 
induces,  at  least  in  the  case  of  tensile  strength  and  elastic 
limit,  continue  at  an  ever  decreasing  rate  for  years  after 
the  distortion  has  ceased,  and  are  accelerated  and  per- 
haps exaggerated  by  gentle  heating,  but  are  lessened 
or  even  wholly  removed  by  heating  to  redness.  I  do  not 
here  refer  to  AVohler-like  indefinitely  repeated  stresses, 
which,  even  if  below  the  initial  elastic  limit,  may  event- 
ually destroy  the  piece." 

TABLE  302. — INFLUENCE  OF  TWISTING  ON  TENSILE  STRENGTH  OF  WEOUGHT-IKON  AND  SOFT 

STEEL. — Gilmore. 


Number. 

Description  of  test  piece. 

Tensile  strength, 
pounds  per  sq.  in. 

Material. 

Bound  or 
square. 

Thickness, 
inches. 

Length, 
inches. 

Before  twisting. 

1. 
2. 
8. 
4. 

Wronght-iron. 

Steel. 
Wrought-iron. 

Round. 
Square. 
Round. 
Square. 

i 

} 

•76 

8 

8 
12 
12 

64,180 
55,325 
5T.360 
52,545 

Tensile  strength,  pounds  per  square  inch. 

After  twisting. 

i 
turn. 

i 
turn. 

i 

turn. 

1 

turn. 

» 

turns. 

2 
turns. 

2i 
turns. 

3 

turns. 

*t 
turns. 

5i 
turns. 

7 
turns. 

11 
turns. 

13 
turns. 

69,020 
53,050 
68,305 
.',6,265 

68,500 
64,665 

85J285 

04,750 

65.000 
broken 

broken 

broken 

broken 

broke. 

57J65 
58,930 

57,265 
54.765 
58,410 

Lieut.  F.  P.  Gilmore,  IT.  S.  Navy,  Trans.  Tech.  Soc.  Pacific  Coast,  V,  p   100,  1SS8. 


TABLE  103. — EFFECTS  OF  COLD  BUNDING  (RADIUS  8.5")  AND  ANNEALING.     PARKER. 


Ho. 

Tensile 
strength, 
pounds  per 
square  inch. 

Elastic  limit, 
pounds 
per  square 
Inch.a 

Elongation 
jSin  10 
inches. 

Contraction 
of  area,  %. 

Treatment  before  testing. 

1 

60,928 

83,376 

27-3 

BB*< 

Untreated. 

9 

62,160 

22.400 

25-7 

52'fl 

Bent  and  straightened  cold. 

8 

69,888 

29,120 

20-7 

50-5 

Bent  and  straightened  at  a  blue  heat. 

4 

78,248 

20,100 

17-6 

82'0 

Quenched. 

5. 

60,704 

84,272 

29'2 

58-5     | 

Bent  and  straightened  cold  four  times: 
then  annealed. 

1.  A  plain  piece  of  steel  1-5"  X  0-76".  2o  A  similar  piece  of  the  same  material  bent  cold  with 
a  radius  of  8*5  inches,  and  then  straightened.  3.  The  same  as  2,  but  bent  at  a  blue  heat.  4e 
A  similar  piece  heated  and  quenched  in  cold  water.  5o  Bent  in  the  same  way  as  2,  but  four 
times  instead  o" once:  then  heated  to  redness  and  allowed  to  cool.  Parker,  Journ.  Iron  and 
Steel  Inst.,  1887, 1.,  p.  186. 

a  This  is  probably  the  "  proportionality  limit." 


TO,  000 


rOffftBWEB1 


ig.  86.    Parker. 

grams  corresp  mding^to 


Table  IO3, 


10  30  00 

Elongation,  percent  in  10  inches, 

The  jog  shown  in  lines  1  and  5  is  very  common  in  the  strain-diagrams  of  wrought-iron  any 
steel  when  neither  hardened  nor  cold-worl-cd,  but  not  in  those  of  other  metals.  A  not  wholld 
dissimilar  jog  also  occurs  in  the  torsional  strain-diagrams  of  locust  and  hickory  wood. 

The  effect  on  the  modulus  of  elasticity  is  relatively 
slight  (usually  less  than  5%,  sometimes  less  than  1$),  and 
less  constant.  The  modulus  is  usually  lowered  slightly 
but  is  sometimes  raised  by  cold-stretching  and  cold- 
hammering:  (e.  g.,  table  101,  VI.,  3;  VII.,  2;  L,  8; 

a  B.  Baker,  Trans.  Am.  Soc.  Mech.  Eng.,  VIII.,  p.  163,  1884,  gives  an  instance 
in  which  a  rotating  spindlo,  weighted  at  its  free  end  so  as  to  cause  alternate  ten- 
sion and  compression  in  any  given  fibre,  broke  after  472,500  revolutions,  the 
actual  stress  being  only  one  third  of  the  stress  at  transverse  elastic  limit.  On  the 
other  hand  Bauscbinger  concludes  that  5  to  15  million  repetitions  of  tensile  stress, 
whose  lower  limit  is  zero  and  whose  upper  limit  is  near  the  original  proportion- 
ality limit,  do  not  cause  rupture.  (Mittheil  aus  Mech. -Tech.  Lab.  in  Munchen, 
XV.,  p.  37,  1886.) 


and  II.,  8).  During  rest  after  stretching  in  Baus- 
chinger's  experiments  it  seems  usually  to  undergo  a 
change  opposite  in  sign  to  that  noted  immediately  or 
shortly  after  stretching  or  cold-hammering,  and  greater  in 
amount,  and  so  returns  past  and  to  a  point  slightly  above  or 
slightly  below  its  original  value  as  the  case  may  be  (e.  g., 
table  101,  line  6,  cases  L,  II.,  III.,  IV.,  VI.  ;  line  23,  cases 
IX.,  X.,  XI.  ;  line  9,  cases  I.,  IL  ;  exceptions,  line  6, 
cases  V.,  VII).  But  this  can  hardly  be  put  forth  confi- 
dently. 

Similar  changes  occur  in  other  malleable  metals,  and, 
like  those  in  iron  and  steel,  increase  during  rest  after  dis- 
tortion. Thus  Bauschinger  noted  that  if  a  piece  of  zinc 
were  subjected  to  a  stress  S  beyond  its  proportionality 
limit,  and  again  tested  within  a  few  minutes,  the  propor- 
tionality limit  had  now  risen  to  S  :  but  on  allowing  the 
same  piece  of  zinc  to  rest  for  about  a  day  after  the  applica- 
tion of  the  stress  S,  the  proportionality  limit  was  now 
found  to  have  risen  from  S,  which  was  1,393  pounds,  to 
1,508  pounds  per  square  inch.b 

Local  Cold-Wor7cing,  however,  though  its  immediate 
effect  may  be  to  strengthen  the  part  worked,  may  greatly 
weaken  the  piece  as  a  whole.  For  instance,  suppose  that 
we  hammer  the  side  A  of  the  piece  shown  in  Figure  87, 

Fig.  87 


and  thus  strengthen  it  and  raise  its  elastic  limit  without 
changing  the  properties  of  the  side  B,  striking  A  fhst 
crosswise  then  lengthwise  so  as  to  avoid  distorting  the 
piece.  If  we  now  stretch  the  piece  as  a  whole  in  tensile 
test,  all  will  go  on  normally  till  the  stress  per  square  inch 
reaches  the  initial  elastic  limit  of  the  material  °  But 
after  we  pass  this  point  B  stretches  more  under  given  in- 
crement of  stress  than  A.  A,  standing  up  to  its  work, 
bears  an  undue  share  of  the  stress.  The  stress  on  A, 
whose  power  of  elongation  is  less  than  that  of  B,  reaches 
the  ultimate  tensile  strength,  and  A  parts  while  the  stress 
on  B,  which  has  all  the  time  been  stretching  instead  of  re- 
sisting, is  still  relatively  small. 

Once  A  is  broken,  B  has  now  to  bear  the  whole  stress : 
indeed,  as  A  breaks  it  may  start  a  crack  which  will  quick- 
ly rip  across  the  piece. 

This  ultimate  weakening  effect  of  a  local  strengthening 
is  clearly  due  to  heterogeneousness  of  elastic  limit  and  of 
power  of  elongation. 

But  such  local  cold- working  need  not  necessarily  weaken 
the  piece.  If,  for  instance,  it  were  the  side  B  instead  of 
A  that  had  been  cold-worked,  the  cold-worked  and 
the  strengthened  portion  being  thus  the  greater  not  the 
smaller  of  the  two,  its  strength  alone  might  be  decidedly 
greater  than  the  initial  strength  of  the  whole  piece  before 
cold-working :  so  that  even  if  B  had  to  bear  the  whole 
stress  and  received  no  assistance  from  A,  the  piece  as  a 
whole  would  be  stronger  than  before  receiving  the  local 
cold-working.  Hence  local  cold- working  may  strengthen 
or  weaken  the  piece  according  to  the  special  conditions  of 


b  Op.  Cit.,  p.  8. 

c  For  simplicity  I  here  ignore  the  usual  slight  depression  of  the  modulus  of 
elasticity  due  to  cold-distortion.  Lowering  the  modulus  of  A  would  increase. 
raising  it  would  diminish  these  effects, 


EFFECTS    OF    COLD- WORKING    DETAILED.      §  270. 


213 


the  case,  such  as  the  proportion  of  the  whole  which  is 
worked  cold,  the  shape  and  position  of  the  part  worked 
cold,  the  intensity  of  the  cold-working,  etc. 

Moreover,  cold- working  in  genenland  local  cold-work- 
ing in  particular  should  set  up  severe  stress  :  this  may 
tend  to  weaken  the  metal.  While  it  is  in  general  out- 
weighed by  the  direct  strengthening  effect  of  cold-work- 
ing, it  may  tinder  many  conditions  outweigh  the  direct 
strengthening  effect.  Local  cold-working  may,  further, 
directly  cause  local  incipient  rupture. 

Thus  it  is  not  surprising  that  local  or  excessive  or  ill- 
advised  cold- working  weakens  the  metal. 

Apparent  instances  of  the  disastrous  effect  of  hetero- 
geneousness  of  strength  due  to  local  strengthening  are  the 
breakage  of  steel  rails  through  their  punched  bolt-holes, 
the  usual  weakness  of  punched  steel  plates,  and  possibly 
Sweet's  rail-breaking  method,  in  which  a  single  blow 
from  a  sledge  usually  suffices  to  break  a  nicked  rail."  A 
steel  rail  which  untreated  would  endure  the  blow  of  a 
2,000  pound  ram  falling  fifteen  feet,  will  sometimes  if 
punched  break  with  a  fall  of  one  foot.b 

Steel  rails  are  reported  as  breaking  in  the  track  soon 
after  being  struck  by  a  derailed  engine  ;  and,  when  they 
are  broken  in  normal  use,  rupture  is  said  to  occur  usually 
where  the  rail  has  been  pressed  by  the  gag  which  is  used 
in  cold-straightening,  and  which  should  not  be  allowed  to 
touch  the  flange  of  the  rail,  thinner,  less  supported  and 
more  liable  to  severe  deformation  than  the  head. 
The  breikage  of  steel  plates,  angles,  etc.,  which  gave 
serious  alarm  during  the  early  employment  of  steel  for 
structural  purposes,  was  in  many  cases  attributed  to  too 
abrupt  cold-bending.  From  the  foregoing  we  see  the  im- 
portance of  bending  to  curves  of  long  radius,  of  striking 
witb  copper-faced  or  even  wooden  mallets  rather  than  iron 
sledges,  or  applying  bending-pressure  through  wooden 
blocks,  etc.,  to  make  the  bends  less  abrupt 

§  270.  THE  SEVKBAL  PKOPKBTIKS  IN  DETAIL. — The 
Elastic  Limit. A  Stretching  lowers  the  proportionality 
limit. d  often  to  zero,  so  that  that  if  the  piece  be  re-tested 
immediately  after  stretching,  either  no  proportionality 
limit  or  only  a  very  low  one  is  found.  (Table  101,  I.,  2,  8, 
4  ;  V.,  3  ;  VI.,  2,  3  ;  VII.,  2,  4).  But  after  brief  rest  it  is 
found  to  have  risen  beyond  the  original  (idem,  II.,  2). 
Cold-hammering  also  lowers  it,  and  sometimes  it  does  not 
fully  recover  even  after  years  of  rest  (idem). 

In  the  case  of  tensional  stretching  the  stretching  point, 
if  determined  immediately  after  stretching  has  ceased,  has 
become  equal  to  the  tension  which  produced  the  stretch- 
ing :  so  that  if,  while  pulling  the  test-piece  in  the  testing 
machine,  we  interrupt  the  stress  for  a  moment  and  imme- 
diately reapply  it,  we  obtain  diagrams  like  curve  '6  of 


a  Trans.  Am.  Inst.  Mining  Engineers,  II  I. ,  p.  92. 

b  J.  Fritz,  Trans.  Am.  Inst  Mining  Engineers,  III.,  p.  91,  1875. 

e  Holley,  Trans.  Am.  Inst.  Mining  Engineers,  VIII.,  p.  4C4,  1880. 

d  'Twere  foreign  to  the  purpose  of  this  work  to  discuss  the  several  different 
points  selected  by  different  writers  for  the  elastic  limit.  We  may,  however,  note 
two,  "  the  proportionality  limit,"  or  point  at  which  Hcoke's  law  "  ut  tensio  sic 
vis"  ceases  to  be  true,  and  the  "stretching  point"  or  "  breaking  down  point, 
"  Streckgrenze,"  at  which  the  increase  of  extension  becomes  altogether  dispro- 
portionate to  the  increase  of  stress,  and  at  which  in  common  continuous  testing 
the  beam  of  the  testing-machine  drops,  and  the  scale  on  the  surface  of  the  metal 
cracks.  The  second  may  not  be  so  definite  a  point  as  the  first,  but  it  certainly 
seems  a  point  of  much  greater  importance  for  constructional  purposes.  And  after 
all  the  fact  that  a  point  can  be  accurately  defined  and  measured  is  in  general  of 
relatively  little  importance  :  the  chief  thing  is  that  it  should  represent  some  prop 
erty  important  as  regards  the  chief  uses  of  the  material,  and  this  the  stretching 
point  does. 


Figure  88.  The  diagram  OB  is  practically  that  of  a  new 
metal,  with  a  new  and  much  higher  stretching  point  than 
that  of  the  original  diagram  OA. 

If,  however,  the  stress  be  reapplied  not  immediately 
but  after  a  considerable  interval,  the  new  stretching  point 
is  in  many  cases  found  much  higher  than  the  preceding 
maximum  stress,  and  our  new  diagram  is  like  (I  II I  in 
curve  2.  Like  results  are  obtained  if,  instead  of  wholly 
removing  the  stress,  we  hold  it  constant,  as  in  curve  4. 
Indeed,  at  least  in  certain  cases,  we  get  approximately 
the  same  diagram  whether  the  stress  be  wholly  removed 
or  simply  held  constant.  Mr.  G.  W.  Bissell  informs  me 
that  he  has  found  this  true  of  a  specimen  of  brass.6 

In  short,  simple  momentary  interruption  of  stress  pro- 
duces simply  a  crevice  like  ACE  (curve  3)  in  our  diagram, 
whose  shape  but  for  this  is  hardly  altered :  so  that  the 
interruption  simply  reveals  the  elevation  of  the  stretching 
point  which  the  stretching  has  caused,  but  does  not  in 

D 


o  c 


CURVES  1  AND  2. 


CURVES. 


Figut^SS. 


CURVES  4  AND  5, 


CURVE  B. 


Curves  1  and  1.  Torsion-strain  diagrams  from  two  pieces  of  soft  steel  of  about  0'15  to  0-20 
%  of  carbon,  cut  from  adjacent  parts  of  the  same  bar.  In  1  the  stress  was  continuous,  in  2  inter- 
rupted. G.  W.  Bissell,  Private  Commnnica*'jn,  Jan.  15th,  1889. 

Curve  8,  Torsion-strain  diagram  of  very  ...ml  steel  (Jessop's)  used  for  tack  pistes.  At  A  stress 
was  removed  for  two  days;  at  B  the  piece  was  left  under  stress  for  one  day.  Stress  was  then 
interrupted  momentarily.  Immediately  reapplied,  and  carried  to  D.  Here  the  stretching  point 
fails  to  rise  above  the  last  previous  maximum  stress.  Idem.  This  investigation  was  kindly 
made  by  Mr.  Bisaell  for  this  work. 

Curves  4  and  5.  Transverse-strain  diagrams  of  common  wrought-iron,  weighted  with  a 
dead  load.  In  4  the  load  was  increased  intermittently,  In  5  it  was  increased  steadily  so  as  to  give 
as  little  time  for  elevation  of  the  elastic  limit  as  possible.  Thurston,  Mails,  of  Engineering,  II., 

Curve  6.     Interrupted-strain  diagram  of  tool  steel.     Idem,  p.  611. 

itself  change  the  stretching  point,  does  not  materially 
change  the  shape  of  the  diagram  beyond  the  point  E, 
leads  to  no  gain  in  tensile  strength.  But,  during  a  con- 
siderable time  after  the  stretching,  the  stretching  point 
goes  on  rising,  and  with  it  the  tensile  strength,  for  the 
line  HI  in  curve  2  will  lead  to  a  higher  ultimate  tensile 
strength  than  the  line  LF  or  the  line  MN. 

It  is  altogether  probable  that  closer  examination  will 
find  a  similar  state  of  things  in  case  of  other  f  orms  of  cold- 
distortion.  This  strengthening  during  rest  was,  according 
to  Bauschinger,  discovered  by  W6hlerf  ;  Styffe  certainly 
knew  it  by  ]  869*  ;  Thurston  and  Beardsley  rediscovered 

e  Private  communication,  Dec.  24th,  1888. 

'Mittheil.  ante.  cit.  p.  3.  From  Erbkam,  Ztsch't  fur  Bauwesen,  1863,  pp. 
245-6.  Cf.  Bauschinger,  Dingier,  CCXXIV.,  p.  1,  1877:  Uchatius,  Dingier, 
CCy.XIII.,p.  242,  1877. 

g  "Sometimes  we  have  even  found  that  the  limit  of  elasticity  in  stretched  bars 
has  been  perceptibly  raised  by  merely  allowing  the  bar  ti  remain  at  rest  for 
several  days  after  stretching."  Iron  ani  Steel,  Styffe,  Sandberg,  p.  109,  1869. 


214 


THE    METALLURGY    OP    STEEL. 


it  independently  in  1873. a    Some  of  Beardslee's  results 
are  here  given : 

TABLE  1M.— INCREASE  OF  TENSILE  STRENGTH  BY  EEBT.— Beardslec. 

Length  of  rest 1  to  3  min.     1  to  8  hrs.    1  day.    8  days.     8  days.    8  to  42  days.    6  m< 

Increase  of  tensile  stivnjttli      1  H  3-8  8'9  162          17-8  15'8  17' 

Number  of  tests...  5  8  5  10  2  5 


_ios 

17-9 

12 


It  is  not  clear  just  what  conditions  cause  this  increase 
in  tensile  strength  and  elastic  limit  after  distortion  has 
ceased.  The  U.  S.  Test  Board  could  obtain  no  positive 
evidence  that  it  occurred  at  all  in  case  of  weld- steel.  In 
some  wrought-irons  it  occurs  much  more  quickly  than  in 
others.  It  is  probable  that  it  is  less  marked  in  ingot-  than 
in  weld-metal,  and  less  marked  in  high-  than  in  low-carbon 
ingot-metal.  There  seems  to  be  little  doubt  that  it  some- 
times occurs  in  ingot-metal. 

It  is  shown  in  Curves  3  and  6  of  Figure  88,  which 
are  interrupted-strain  diagrams,  the  former  of  Bessemer 
steel  of  0'15  to  0*20^  of  carbon,  the  latter  of  tool- 
steel.  Steel  with  even  as  much  as  \%  of  carbon  under- 
goes a  very  great  elevation  of  the  elastic  limit  when 
stretched  at  about  400°  F.  (205°  C.)  cooled  to  70°  F.,  and 
further  tested." 

Heating  to  500°  C.  (932°  F.,  see  Table  101)  diminishes 
and  if  more  intense  may  wholly  remove  these  effects  of 
cold-distortion  (see  Table  100).  But  heating  to  a  lower 
temperature,  say  200°  to  300°  C.  (392°  to  572°  F.)  has  the 
surprising  effect  of  intensifying  them,  as  rest  does.  Ap- 
parently the  distortion  starts  a  strengthening  change  in 
the  metal :  this  change  once  started  goes  on  and  gradually 
approaches  a  maximum  even  at  the  ordinary  temperature, 
and  is  accelerated  by  moderate  heating,  say  to  300° :  but 
it  is  counteracted  more  or  less  completely  and  even  ef- 
faced by  some  other  change,  be  it  crystalline,  molecular, 
allo  tropic,  or  whatever,  which  becomes  marked  at  500°  C. 
and  very  marked  at  redness.  It  is  of  course  possible  that 
the  gentle  heating  acts  by  relieving  stress. 

W.  H.  Paine  found,  between  1856  and  18tl,  that  draw- 
ing cold-rolled  steel  tape  through  a  bath  of  molten  tin, 
zinc  or  lead  raised  its  transverse  elastic  limit,  and  this 
method  was  used  for  the  wire  of  the  East  River  bridge, 
which  was  thereby  increased  both  in  tensile  strength  and 
elastic  limit.  But  he  found  that,  when  a  bath  of  molten 
zinc  was  used,  it  was  necessary  to  pass  the  tape  through 


very  rapidly,  lest  its  elastic  limit  be  lowered  instead  of 
being  raised.0 

That  the  density  is  diminished  by  stretching  was  shown 
by  Styffe  for  puddled  iron  and  for  weld-  and  ingot-steel.11 
Deering  found  that  the  specific  gravity  of  steel  wire  fell 
from  7'8142  before  stress  to  7-8082  after  rupture.6  H. 
Allen  found  the  specific  gravity  at  the  fractured  end  of  a 
tensile  test  piece  of  unhardened  soft  steel  (carbon  0-115$) 
only  7 '819  against  7-826  for  the  unstrained  end.'  Major 
Wade  found  in  1860  that  cold -rolled  iron  was  lighter  than 
the  same  iron  rolled  hot.g  The  specific  gravity  has  been 
found  to  fall  from  7-828  to  7-817  and  then  to  7-780  on  re- 
peated cold -hammering11 ;  from  about  7-82  in  wrought- 
iron  to  7-78  in  a  punching1  from  it ;  and  from  7-839  to 
to  7.836  and  later  to  7-791  in  wire  drawing.1  H.  Allen, 
finally,  reports  the  changes  of  density  given  in  Table  105  : 
while  hot  rolling  here  seems  to  increase  the  density,  so 
that  annealing  again  lowers  it,  wire-drawing  lowers  it 
greatly,  annealing  now  increasing  it,  and  in  one  case 
bringing  it  back  nearly  to  that  of  the  annealed  wire-rod." 

TABLE  105.— DECREASE  OF  DENSITY  ON  WIRE  DRAWING.    (ALLEN.) 

Diameter,  , Sp.  gr s 

inches.  TJoannealed.  Annealed. 

Billet  (hot  rolled) 2"  sq.  7-826 

Wire  rods  [ 0-30                         7'862  7'SM 

Hot  rolled  f (V2S4                         7'868  8-856 

Wire  drawn  from  rod  03"  in  diameter 0-259                       7  835  7'847 

0-22"          "          0-184                         7815  7'824 

Resilience  and  Stiffness. — As  cold-working  affects  the 
modulus  of  elasticity  relatively  little  (note  the  parallelism 
of  the  elasticity  lines  in  Figures  88,  89  :  note  that,  till  we 
approach  the  elastic  limit,  the  strain  diagrams  of  hot-  and 
cold-rolled  irons  coincide)  while  often  doubling  the  elastic 
limit,  it  increases  the  elastic  resilience  enormously,  trip- 
ling or  even  quadrupling  it.  It  clearly  increases  the 
stiffness  as  measured  by  the  total  amount  of  pressure 
which  the  piece  can  undergo  without  permanent  set :  and 
it  is  generally  but  probably  falsely  thought  to  increase 
the  stiffness  as  measured  by  the  temporary  deflection  pro- 
duced by  a  stress  within  the  elastic  limit.  This,  surely, 
should  be  an  error,  for  this  deflection  should  be  pro- 
portional to  the  modulus  of  elasticity.  So  with  high-  and 
low-carbon  steel :  the  former  is  generally  thought  stiffer 
than  the  latter.  Some  of  our  most  intelligent  engineers 
who  have  given  the  subject  most  thought  habitually 
employ  high-carbon  steel  where  unusual  stiffness  and 
rigidity  are  needed,  admitting  that  its  modulus  is  nearly 


a  Kept.  U.  S.  Bd.  on  Testing  Iron,  Steel,  etc.,  I.,  p.  107:  Thurston,  Atatl's  of 
Engineering,  II.,  p.  600. 

This  growth  of  the  tensile  strength  and  elastic  limit  after  stretching  should  tend 
to  produce  higher  ultimate  tensile  strength  during  slow  than  during  fast  pulling. 
But  other  factors  may  modify  this  effect,  notably  the  greater  opportunity  for 
flow  and  consequent  local  reduction  of  area  during  slow  pulling,  and,  in  case  the 
pulling  is  extremely  rapid,  the  effect  of  vis  viva.  Hence  we  may  expect  that  a 
certain  rate  of  pulling,  varying  w  ith  the  composition,  shape  and  condition  of  the 
test-piece,  will  give  the  maximum  tensile  strength.  Thus  Gatewcod  and  Denny  obtain 
higher,  but  Marshall,  Thurston,  and  I  believe  Kirkaldy,  lower  tensile  strength 
with  fast  than  with  slow  pulling.  (Gatewood,  Kept.  U.  S.  Nav.  Advisory  B'd  on 
Mild  Steel,  1886,  p.  134:  Denny.  Proc.  Inst.  Nav.  Arch.,  1880:  Marshall,  Trans. 
Am.  Inst.  Mining  Engineers,  XIII.,  p.  149.  Thurston,  Mat'ls  of  Engineering, 
II.,  p.  592.) 

The  vastly  greater  elongation  under  violently  than  under  gradually  applied 
tensile  stress  is  probably  due  to  the  fact  that  in  gradual  pulling  the  failure  of  the 
piece  at  a  single  weak  spot  prevents  the  stress  over  the  rest  of  the  bar  from 
reaching  the  point  at  which  rapid  stretching  sets  in.  When  a  bar  is  torn  explo- 
sively its  whole  length  reaches  this  stress  and  stretches  under  it,  though  moment- 
arily: indeed,  Maitland  sometimes  found  that  the  test-piece  broke  in  two  places 
simultaneously.  He  found  that  steel  which  gave  27$  elongation  in  2  inches  under 
static  stress,  when  torn  explosively,  e.  g.  with  gun-cotton,  gave  from  47  to  62$ 
elongation.  ("The  Treatment  of  Gun-Ste"l,"  Exeerpt  Proc.  Inst.  Civ.  Eng., 
LXXXIX.,  p.  9,  1887.)  The  enormous  stretching  power  of  wrought- iron  under 
shock  was  (ascordiiig  to  B.  Baker)  pointed  out  by  Robins  in  1742:  a  musket-barrel 
"ballooned"  to  nearly  double  its  original  diameter. 

b  J.  E.  Howard,  Watertow.i  Arsenal,  priv.  commun.,  Feb.  8th,  1889. 


0  Zinc  melts  at  about  412"  C.  (774°  P.).     Testimony  of  W.  H.  Paine  in  suit  of 
Alanson  Cary  et  al.  vs.  Lowell  Mfg.  Co.,  Lit.,  U.  S.  Circuit  C't  Western  Dist.  of 
Penn. :  Deposition  Oct.  21,  1885. 

Paradoxically  the  gentle  heating  not  only  thus  stiffened  the  tape  where  too  soft, 
but  toughened  it  where  too  brittle,  in  the  latter  case,  we  may  surmise,  by  reliev- 
ing internal  stress  induced  by  locally  excessive  cold-working.  Styffe  noted  that 
a  gentle  heat,  say  150°  C.  (300°  P.),  raised  the  elastic  limit  of  previously  cold- 
worked  iron  (Iron  and  Steel,  p.  37,  108).  Jarolimek  has  lately  rediscovered  this, 
and  published  experiments.  (Dingier,  CCLV.,  p.  1,  1885;  also  Journ.  Iron  and 
St.  Inst.,  1885,  II.,  p.  641.)  Armstrong  noted  that  the  elastic  limit  of  hard-drawn 
steel  wire  was  raised  by  gentle  annealing.  (No.  17,  Table  100.  Cf.  Rept.  British 
Ass.,  1882,  p.  403.) 

d  Iron  and  Steel,  Styffe,  Randberg,  pp.  66,  139,  1869. 

e  Percy,  Jour.  Iron  and  Steel  Inst.  1886, 1.,  p.  63. 

f  "The  Effect  of  Rolling  and  of  Wire-drawing  upon  Mild  Steel."  Excerpt  Proc. 
Inst.  Civ.  Eng.,  XCIV.,  p.  10,  1888. 

e  W.  Metcalf,  Private  communication .  Exact  and  scrupulously  conscientious 
as  his  work  alwaj  s  was,  this  result  surprised  Major  Wade  so  much  that  he  would 
not  accept  it  till  it  had  been  verified  by  his  then  assistant,  Mr.  Metcalf,  who  was, 
meanwhile, ignorant  of  its  nature.  Cf.  also  "Rept.  on  Cold  Rolled-Iron,"  R. H. 
Thurston,  private  print,  p.  12 

h  Langley,  "  The  Treatment  of  Steel,"  Miller,  Metcalf  and  Parkin,  p.  42 

1  Cf.  §  285.    Journ.  Franklin  Inst.,  CV.,  p.  145,  1878. 

1  Osmond  and  Werth,  Annales  des  Mines,  8th  Ser.,  VIII.,  p.  44,  1885. 

k  Escerpt  Proc.  Inst.  Civ.  Eng.,  XCIV.,  1888.  The  properties  of  this  billet 
and  of  these  rods  and  wires  are  given  in  tables  100  and  105.  The  rods  and  wires 
tire  made  from  the  billet  here  given. 


EFFECTS     OF     DIFFERENT    FORMS     OF     COLD- WORKING.       §  271. 


216 


the  same  as  that  of  low-carbon  steel,  and  admitting  the 
anomaly.  It  should  be  more  resilient  than  low-carbon 
steel,  but  not  stiff er  within  the  elastic  limit." 

§  271.  DIFFERENT  FORMS  OF  COLD- WORKING. — Some  of 
the  individual  effects  of  cold-working  have  been  long  and 
widely  known,  but  they  have  in  general  been  referred  to 
this  or  that  special  form  of  cold-distortion,  and  relatively 
few  have  suspected  that  it  is  the  cold-distortion  itself,  and 
not  simply  its  special  form  which  produces  these  effects. 
Few  have  suspected  the  general  law  that  all  forms  of  cold- 
distortion  produce  them.  All  know  the  effects  of  wire- 
drawing and  cold  rolling :  many  who  are  well  informed 
have  even  lately  been  surprised  to  find  that  twisting  and 
bending  produce  these  effects,  and  have  even  then  failed 
to  note  the  resemblance." 

A.  The  effect  of  simple  stretching,  as  in  tensile  testing, 
is  shown  in  lines  1  to  6  of  Table  3  01,  chiefly  as  an  eleva- 
tion of  the  elastic  limit  (stretching  point).     Bauschinger, 
pulling  the  same  bar  of  common  wrought-iron  asunder 
repeatedly,   reducing  its  section  with  a  round  file  each 
time  at  the  point  tested,  found  that,   when  weeks  and 
months  elapsed  between  successive  pullings,  the  tensile 
strength  rose  at  each  experiment,  from  45,513  pounds  per 
square  inch  at  the  first  to  62,580  at  the  seventh.     When 
only  a  few  minutes  elapsed  between  successive  pullings 
the  gain  was  much  less,  but  still  marked ,  successive  de- 
terminations   giving    41,246;    44,091;     46,935;    48,358; 
47,646 :  and  49,069  pounds  per  square  inch.0 

The  effect  of  cold  bending  is  shown  in  Table  103  and 
Figure  86.  The  tensile  strength  is  slightly  raised,  and  the 
ductility  lowered.  A  comparison  of  curves  1  and  5 shows 
how  completely  annealing  removes  the  effects  of  cold- 
bending.  The  elastic  limit  here  given  is  probably  the 
proportionality  limit. 

The  strengthening  effect  of  cold-twisting  is  shown  in 
Table  102. 

B.  Gold-rolling,   cold-drawing  and  wire-drawing  in- 
crease the  ultimate  tensile  strength  greatly,  the  elastic 
limit  still  more  (cold-rolling  and  drawing  usually  double 
it  at  least),  but  usually  with  a  loss  of  ductility  in  inter- 
mediate proportion.     The  density  is  lowered  slightly. 

Thus  in  the  last  four  columns  of  Table  100  the  per- 
centage of  increase  of  elastic  limit  due  to  cold-working  is 
with  few  exceptions  greater  than  that  of  tensile  strength, 
and  in  the  great  majority  of  cases  over  thrice  as  large  : 
the  difference  is  especially  noticeable  in  case  of  cold-draw- 
ing, Numbers  28  to  31.  For  cold-drawing  and  cold-rolling 
the  percentage  of  loss  of  elongation  is  invariably  inter- 
mediate, greater  than  that  of  increase  of  tensile  strength 

»Cf.  Styffe,  Iron  and  Steel,  p.  69  :  also  the  author,  Eng.  and  Mining  Jr.,  XX., 
1875. 

b  T.  Andrews  finds  that,  when  wrought-iron  axles  are  subjected  to  severe  blows, 
as  in  drop-testing,  and  rotated  180"  after  each,  the  later  blows  cause  less  deflec 
tion  than  the  early  ones,  i.  e.,  the  axle's  elastic  limit  rises.  The  progressive  de- 
crease of  deflection  was  very  marked  at  213°  F.  (100°  C.)  and  at  120°  and  100'  F. 
(49°  and  38°  C.),  but  it  could  not  be  traced  when  the  axles  were  at  T  to  10"  F- 
(Excerpt  Proc.  Inst.  Civ.  Engineers,  LXXXVII.,  1886-7.)  Barba  noticed  that 
steel  angle-bars  became  stiffer  and  harder  to  bend  after  they  had  been  partly 
bent:  on  bending  less  abruptly  this  effect  diminished.  This  effect  was  less  marked 
when,  by  the  use  of  blocks,  bends  of  longer  radius  were  made.  (The  Use  of  Steel, 
p.  74.)  Indeed,  I  find  in  conversation  that  many  blacksmiths  and  other  iron 
workers  and  users  realize  that,  in  bending  cold  iron,  the  resistance  increases  for 
a  time,  and  that  somewhat  heavier  blows  are  needed  to  stiaighten  it  after  cold 
bending  than  sufficed  to  bend  it.  In  one  case  the  men  reported  to  their  foreman 
that  certain  crow-bars  were  not  stiff  enough;  he  said,  "straighten  them  when 
they  bend,  and  they  will  soon  be  stiff  enough." 

eDingler's  Polytechnisches  Journal,  CCXXIV.,  p.  I.,  1877, 


and  less  than  that  of  elastic  limit.  In  wire-drawing  the 
loss  of  ductility,  while  often  very  severe,  rising  even  to 
98$,  is  occasionally  much  less  for  given  increase  of  tensile 
strength  than  any  here  recorded  in  case  of  cold-rolling  or 
cold-drawing :  thus  in  Number  12  B  the  loss  of  elongation 
just  equals  and  in  Number  13  B  is  but  one  seventh  of  the 
gain  in  tensile  strength. 


Fig.  89 

Strain  Diagrams  of  Hot-rolled,  of 

Cold-rolled,  and  of  Annealed 

Cold-rolled  Iron.   Thurston. 


25 


000 


JOO 


5 

Elongation,  per  cent  in  20  inches. 


HOTTROU.ED 


Further,  while  the  six  or  seven  draughts  of  each  set  in 
Table  106  increase  the  tensile  strength  by  about  half,  the 
loss  in  elongation  is  much  less,  and  in  two  cases  nil.  The 
comparative  flatness  of  some  of  the  broken  (wire-drawing) 
lines  in  Figure  90  illustrate  the  small  loss  of  ductility  in 
wire-drawing. 

But  in  these  cases  the  initial  elongation  is  small :  when 
initially  high  1he  elongation  falls  as  much  in  wire-drawing 
as  in  cold- rolling  or  cold  drawing.  Hence  I  attribute  the 
cases  of  small  loss  in  wire-drawing  not  to  any  special 
advantage  in  this  process,  but  to  a  supposed  general  prin- 
ciple that  the  smaller  the  percentage  of  elongation  the 
smaller  the  percentage  of  that  percentage  removed  for 
given  percentage  of  increase  of  tensile  strength,  whether 
by  increase  of  carbon  or  by  mechanical  treatment.  In 
other  words,  to  pass  from  great  to  greater  toughness  im- 
plies heavy  loss  of  strength :  to  pass  from  great  strength 
to  greater  does  not  mean  severe  sacrifice  of  toughness. 
We  note  in  figure  90,  as  in  Table  6  A  and  as  seen  by 
comparing  figures  3  and  5  (pp.  14, 16,  17),  that  as  tensile 
strength  increases  elongation  at  first  falls  off  very  rapidly, 
from  say  25  %  to  5  %,  but  thenceforth  slowly,  remaining 
between  1  and  2  %,  even  though  the  tensile  strength  rises 
above  400,000  pounds  per  square  inch. 

As  the  cold-working  in  wire-drawing  is  probably  some- 
what localized,  being  more  intense  on  the  outside  than  in 
the  interior,  so,  as  we  should  anticipate,  it  does  not  always 
strengthen  the  wire  as  a  whole,  the  local  strengthening 
being  outweighed  probably  by  the  heterogeneousness  of 
strength,  or  by  initial  stress,  or  both;  incipient  cracks, 
too,  later  drawn  out,  perhaps  weakening  the  wire.  Thus, 


216 


THE     METALLURGY    OF     STEEL 


in  Figure  100,  the  strength  of  the  tempered  wire  of  Test  II 
falls  at  the  fourth  draught :  the  same  thing  occurred  at 
the  fourth  draught  of  Test  III  of  Table  106.  On  my 
communicating  these  results  to  Mr.  Spilsbury,  he  repeated 
the  tests,  thinking  the  irregularity  accidental :  but  in  a 


fourth  and  fifth  test  the  same  weakening  recurred  at  the 
fourth  draught.     The  cause  is  not  yet  known. 

TABLE  106— THE  EFFECTS  OF  SUCCESSIVE  DRAUGHTS  IN  WIRE  DRAWING. 
(SPILSBURY'S  DATA.    SEE  FICJUKE  100.) 


32 


Diameter. 

Reduction. 

Tensile  strength. 

S 

3 

a 

£ 

«^ 

ts  g 

M 

o 

d 

n. 
S  • 

Q 

f  E 

II 

0. 

c 
K 

1, 

i 

6 

a 

ll 

ST 

o  &j 

S3 
o-3 

B 
I 

.O 

j£ 

-3S 

"tn 

1 

1 

p 

•z 

• 

si 

B 
O 

S^ 

^% 

s 

o 

a 

ri 

S 

i 

3 

C3 

S 

fe 

M 

ri 

•153 

8-71 

152,000 

8-12 

10 

6 

1 

i 

•129 

10-86 

•84 

16 

160,700 

"5   7' 

4-17 

7 

6 

a 

J8 

•no 

11-91 

•85 

15 

172,600 

74 

2-08 

8 

7 

'  4 

•093 

13-17 

•85 

15 

194,300 

12-6 

8-12 

13 

7 

5 

•075 

14-73 

•81 

19 

215,000 

10  7 

2  08 

14 

4 

16 

•060 

16-71 

•80 

20 

235,200 

9-4 

1-56 

18 

5 

£ 

fl 

•158 

8  71 

105,300 

4-17 

27 

9 

v    . 

2 

•129 

10  86 

":84" 

'"it" 

120.900 

14*8 

8-12 

13 

8 

Is 

•110 

11  91 

•85 

15 

126,300 

4-5 

2  08 

9 

10 

I4 

•093 

18  17 

•85 

15 

147,  -'I  in 

16-5 

3-12 

7 

_ 

!s 

•074 

14-82 

•80 

20 

167,400 

18-7 

4-17 

16 

8 

IH 

16 

•060 

16-71 

•81 

19 

178,300 

35 

8-12 

18 

7 

M 

•137 

9-79 

143,100 

3-12 

10 

6 

2 

•118 

11-18 

•86 

14 

156,800 

9-6 

8-12 

20 

6 

J3 

•099 

12-71 

•84 

16 

189,000 

20  5 

2-08 

9 

6 

g 

14 

-080 

14-27 

•81 

19 

187.000 

—1-1 

2-08 

10 

4 

-S 

!  5 

•065 

16'0 

-81 

19 

212,500 

13  6 

2-08 

19 

6 

Cl 

16 

-053 

17  56 

•82 

18 

281,200 

88 

2-08 

21 

7 

J' 

(1 

•137 

9  79 

116,000 

8-12 

27 

8 

,- 

i  2 

•118 

11-18 

":86 

"ii" 

134,000 

"Kb 

2  OS 

12 

9 

13 

•098 

12-79 

•88 

17 

137,900 

2'9 

8-12 

8 

9 

11 

14 

079 

14  36 

•81 

19 

152,000 

10-2 

8-12 

12 

9 

» 

•065 

16  0 

•82 

18 

171,800 

13  0 

2-08 

9 

6 

o> 

U 

•058 

17  56 

•82 

18 

174,500 

1-6 

2-08 

7 

8 

1 

•170 

7'67 

163,000 

3-12 

18 

6 

2 

143 

9-0 

•87 

13 

169,400 

3  9 

2-08 

16 

6 

3 

•126 

10-57 

•85 

15 

198,500 

17  2 

8-12 

16 

1 

g 

-1  4 

110 

11  91 

•87 

13 

197,800 

—0  6 

8'12 

17 

6 

S 

5 

•085 

13-83 

•77 

23 

222,900 

13-0 

2-08 

21 

1 

6 

-078 

14-45 

•92 

8 

285,400 

5-6 

8-12 

19 

9 

17 

063 

16-29 

•SI 

19 

263,000 

11-7 

3-12 

21 

8 

i 

fl 

•170 

7  '67 

148,700 

3  12 

26 

6 

& 

2 

•149 

9-94 

':83" 

"ia" 

113,800 

—  23  :  5' 

2-08 

24 

9 

B 

13 

•127 

10-50 

•85 

15 

128,500 

8-5 

8  12 

10 

10 

**"C 

-110 

11  91 

•87 

18 

156,300 

26-6 

3  12 

16 

8 

M 

5 

•035 

18-88 

•77 

23 

174,500 

11  6 

8-12 

20 

6 

g 

6 

•078 

14  45 

•92 

8 

167,400 

—4-1 

8-12 

19 

10 

<r» 

U 

•063 

16  29 

•81 

19 

192,500 

15-0 

3  12 

11 

9 

a  This  is  the  ratio  of  the  diameter  alter  the  draught  to  that  before  it. 

One  might  suppose  the  effect  of  cold-rolling  much  more 


Strengt 


Fig.  90 


Influence  of  Cold-working  on  Tensi 


"     i 
and  Ductility. 


40  006    '60,000:    «0;000    100,000  120,000    140,000  160,000  TBO,000  "200,000"  "220  OOO   230,OTI3  SCO.OOO'  280,000  300,000    330,000  3iO,OjC)0  300,000  380,000  100,000   420,000    440,000 

TENSfLE  STRENGTH,  POUNDS  PER  SQUA'RE  INCH. 


"  Hard-drawn  wire.    A  Cold-hammered  and  cold-drawn  bars,  etc.     O  Cold-rolled  bars,  etc.    When  two  points  are  connected  by  a  line,  the  upper  represents  the  properties  of  the  metal  bcfor* 
cold-working,  the  lower  after  cold-working,  the  length  and  direction  of  the  connecting  line  indicating  the  degree  and  nature  ol"  " 

Most  of  the  data  are  from  Table  UK),  §  269;  Engineering,  Feb.  1 6,  1877,  p.  135  (wire  for  Brooklyn  Bridge);  Journ.  Iron  an< 
Metals  at  Watertown  U.  8.  Arsenal,  1885,  pp.  657  to  665  (wires  for  wire-wound  guns). 


by  a 

f  the  change  effected  by  the  cold-working. 
and  St.  Inst.  ,  1S86,  I.,  pp.  62,  et  seq.,  Percy,  Maitland;  and  Kept.  Tests  of 


250,1100 

\ 

X 

s 

-1  I.I 

u 

O 

\ 

<> 

„ 

\ 

A, 

\ 

^ 

K\ 

^, 

"* 

i 

01 

^ 

"v 

1(  ),( 

Ml 

T 

e 

S' 

0  .OS  .10 

DIAMETER  OF  WIRE.  INCHES. 


t 


Test 


severe  on  the  skin  than  on  the  interior  of  the  bar :  but  the 
results  in  Table  107  do  not  indicate  any  marked  localiza- 
tion :  the  strength  per  square  inch  of  the  centre  of  the  bar 
is  very  nearly  as  great  as  that  of  the  whole  bar. 

TABLE  107. — ILLUSTRATING  THE  DEPTH  TO  WHICH  THF  KKFECT  OF  COLD-ROLLING  EXTENDS. 

(Thornton). 


Cold  rolled  iron. 

Untreated  iron. 

ter, 

Tensile 

Elastic 

Tensile 

Kl.iatic 

inches. 

strength, 

limit, 

Elonga- 

Reduction 

strength, 

limit. 

Klonga- 

Reduction 

Ibs.  per 
fq  in. 

Ibs.  per 
sq.  in. 

tion. 

of  area. 

Ibs.  per 
sq.  in. 

Ibs.  per 
sq.  in. 

tion. 

of  area. 

2 

66,933 

57,500 

24-s:( 

H 

66,900 

63,900 

6-00 

29M4 

48,790 

S0.900 

80-00 

41-38 

n 

68,500 

M,li(X) 

7-65 

88-80 

HI.BOO 

33,500 

29-70 

40-18 

60,600 

56,700 

6-55 

31-12 

47.900 

26,000 

21-30 

39-14 

; 

65,850 

M.WIll 

11-07 

31-35 

58,450 

28,800 

26-30 

84*88 

65,640 

56,600 

9-00 

29-66 

49,880 

23800 

21-57 

::7-N.r> 

t 

66,660 

55,400 

9-22 

M-fl 

5(1  B40 

24,100 

24-57 

43-!)4 

66,200 

56,00  i 

8'14 

VT'76 

.MI  :IMI 

23,000 

18-57 

40-42 

I 

IH.400 

54.300 

7'29 

2S-89 

5S.MO 

20,800 

20-57 

46-24 

64,660 

50,900 

3-43 

89'M 

42,980 

22,400 

16-93 

47-28 

Fig.  100.— Tensile  strength  of  wire  after  successive  draughts.    Spilsbury  data. 
These  curves  represent  the  tensile  strength  of  nnannealed  wire  after  each  of  severol  successive 
draughts.    E.  G.  Spilsbury,  private  communication,  June,  ISSs, 


a  Two-inch  wruiiglu-ir«n  bars,  some  cold-rolled  some  untreated,  had  their  diameters  reduced 
by  turning  in  a  lathe  to  the  sizes  indicated  in  the  lirst  column,  and  were  then  subjected  to  tensile 
test,  with  the  results  given  in  the  remainiiif,'  columns.  I:  II  Thurston,  Report  on  Cold-Rolled 
Iron,  18T8. 


The  gain  in  elastic  limit  seems  on  the  whole  higher  in 


THE    RATIONALE    OF    THE     EFFECTS    OF    COLD-WORKING. 


272. 


217 


cold-drawing  than  in  cold-rolling,  and— in  the  sole  case  in 
which  the  loss  of  elongation  is  also  given — with  less  than 
corresponding  loss  of  ductility  :  from  which  single  case  no 
inference  should  be  drawn.  The  greater  increase  in  elastic 
limit  I  incline  to  attribute  to  greater  reduction  in  drawing 
than  in  rolling,  and  to  believe  that,  with  heavier  reduction, 
an  equal  increase  could  be  obtained  in  cold-rolling. 

The  modulus  of  elasticity  is  affected  relatively  little. 
Here  it  seems  to  be  lowered"  slightly,  there  to  be  slightly 
raised.  As  the  elastic  limit  is  usually  at  least  doubled, 
the  elastic  resilience  is  enormously  increased,  according  to 
Thurston  by  from  300  to  400$. 

T7te  transverse  strength  and  elastic  limit  seem  to  be  in- 
creased by  cold-rolling  in  about  the  same  proportion  as 
the  tensile,  the  transverse  like  the  tensile  modulus  of 
elasticity  now  rising  now  Calling  on  cold-rolling. 

TorsionaUy,  the  elastic  limit  is  about  doubled  by  cold- 
rolling,  like  the  tensile  and  transverse  elastic  limits, 
while  the  ultimate  strength  is  raised  but  little,  and  the 
modulus  of  elasticity  apparently  lowered. 

Thus  most  of  the  effects  seem  to  be  alike  in  all  directions, 
and  independent  of  the  longitudinal  fibre  set  up  by  cold- 
rolling  (Cf .  §  2r>8,  A.,  p.  193). 

Annealing  probably  completely  removes  the  effects  of 
these  as  of  other  forms  of  cold-working.  In  Table  100 
the  tensile  strength  and  ductility  of  the  annealed  wire  are 
now  somewhat  higher,  now  somewhat  lower  than  those  of 
the  wire-rod.  So  with  cold-rolled  and  annealed  bars  in 
the  same  table.  The  strain  diagrams  of  cold-rolled  and 
annealed  iron,  as  in  Figure  89,  sometimes  coincide  with 
those  of  the  same  metal  hot  rolled.  In  other  cases  the  an- 
nealing fails  to  depress  the  elastic  limit  to  its  original 
position,  probably  because  incomplete. 

Some  who  should  know  better  have  said  that  the  tensile 
strength  elongation,  etc.,  of  cold  rolled  or  wire-drawn  iron 
differed  from  those  of  the  untreated  metal  simply  because 
we  now  reckon  these  properties  on  the  section  reduced  by 
cold-rolling  or  wire-drawing,  and  on  the  length  thus  in- 
creased :  and  that,  if  reckoned  on  the  dimensions  of  the 
metal  before  cold-rolling,  they  would  be  the  same  as  those 
of  the  untreated  metal.  This,  however,  is  manifestly  un- 
true. For  example,  in  number  38  of  Table  100,  the  cold- 
rolling  reduces  one  inch  of  cross-section  of  metal  to  0-9044 
square  inches  :  the  absolute  tensile  strength  and  elastic 
limit  of  the  original  one  square  inch  were  46,733  and 
28,600  pounds  respectively:  those  (not  per  square  inch 
but  absolute)  of  the  0-9044  square  inches  left  from  this 
original  one  square  inch  are  59,780  and  54,530  pound 
respectively  :  the  absolute  elastic  limit  of  the  bar  as  a 
whole  is  nearly  doubled.  So,  too,  one  running  inch  of 
the  original  bar  is  in  the  same  case  drawn  out  in  tensile 
testing  to  1 '2625  inches.  In  cold-rolling  this  one  inch  is 
drawn  out  to  1*106  inches,  and  when  this  elongated  bar  i 
then  tested  tensilely  this  1-106  inches  is  further  drawn 
out  to  only  1-135  inches  before  rupture.  Thu*  the  total 
elongation  in  cold-rolling  plus  tensile  testing  of  the  cold- 


» Thurston  (Kept,  on  Cold  Rollel  Iron  and  Steel.  1878,  private  print,  pp.  80, 
98:  also  Mat'ls  of  Engineering,  I  [.,  p.  617)  found  that  cold-rolling  raised  the 
modulus  from  about  25,000,000  to  about  26,000,000  pounds  per  square  inch  on  an 
average.  In  many  of  his  experiments,  however,  it  actually  lowered  the  modulus 
Hence  it  seems  probable  that  as  Styffe  believed  (Iron  and  Steel,  p.  69),  the  mod 
ulus  is  lowered  temporarily  by  cold  rolling,  rising  during  rest  as  in  Bauschinger's 
stretching  tests,  Table  101,  to  or  beyond  its  initial  value.  It  may  well  be  that  the 
bars  whose  modulus  Thurston  found  lowered  by  cold-rolling  had  been  rolled 
shortly  before  testing,  and  that  later  the  modulus  would  have  been  found  higher. 


rolled  bar  is  only  18-6$,  while  the  elongation  of  the  same 
metal  teusilely  tested  before  cold -roll  in--  \\  ,-is  2<;-2.V,'.  Thus 
the  change  induced  by  cold-rolling  is  not  simply  an  appar- 
ent but  a  real  one.  Indeed,  a  glance  at  curves  2,  4  and  6, 
Figure  88,  should  show  one  how  real  the  change  due  to 
rest  after  cold-stretching  is. 

§  272.  THE  RATIONAL K  OF  THE  EFFECTS  OF  COLD- 
WOKKING  is  uncertain.  It  evidently  produces  in  the 
metal  some  change  or  changes,  which  once  started  appar- 
ently continue  long  after  the  cold-working  has  ceased. 
But  the  nature  of  this  change  seems  to  me  very  obscure 
I  offer  no  theory,  but  consider  two  which  have  been  pro- 
posed and  seem  incompetent. 

As  has  been  already  pointed  out,  Osmond,  apparently 
struck  by  the  c  rtainly  remarkable  resemblance  between 
the  ulterior  effects  of  quenching  and  those  of  cold-work- 
ing on  the  tensile  strength  and  elastic  limit  of  steel, 
believes  that  the  immediate  effects  of  these  two  operations 
are  like  in  kind,  an  allotropic  change  from  to  ft  iron. 

We  have  seen  that  the  phenomena  of  quenching  hard- 
ening can  be  explained  without  calling  in  the  a  ft  change, 
by  other  and  known  causes :  and  we  failed  to  find  any 
marked  indication  that  this  supposed  a  ft  change  had 
any  marked  effect,  or  that  it  even  existed  in  the  case  of 
heating  and  quenching. 

Now,  quenching  and  cold-working  are  utterly  unlike 
not  only  in  their  procedure  but  in  those  of  their  immediate 
chemical  and  structural  effects  which  are  known.  The 
former  changes  the  chemical  condition  of  carbon  and  the 
mineralogical  constitution  of  the  metal  completely :  the 
latter  does  neither,  apparently  simply  mechanically  dis- 
torting the  individual  crystals.1* 

Yet  Osmond  would  persuade  us  that  these  operations 
act  chiefly  through  a  common  hypothetical  immediate 
effect,  the  a  ft  change;  and  that  the  known  tremendous 
immediate  effects  of  quenching  are  relatively  unimpor- 
tant. 

Clearly,  he  must  show  that  the  resemblance  between 
the  ultimate  effects  of  these  two  apparently  unlike  opera- 
tions is  too  close  to  be  accidental,  so  close  as  to  imply  a 
common  immediate  effect.  But  here  we  are  confronted 
with  a  new  difficulty. 

Cold-working  affects  the  other  malleable  metals  much 
as  it  does  iron.  It  will  hardly  be  claimed  that  it  does  so 
by  creating  a  P  copper,  silver,  brass,  bronze,  etc.  It  is 
then  most  natural  to  infer  that  the  like  operations  of 
cold-working  iron  and  steel  on  the  one  hand  and  cold- 
working  the  other  metals  on  the  other,  act  by  producing 
the  same  kind  of  change :  and  we  would  abandon  this 
inference  and  hold  with  Osmond  that  cold-working  pro- 
duces one  kind  of  change  in  the  other  metals  and  a  second 
kind  in  iron  and  steel,  and  that  this  second  kind  is  the 
same  as  that  produced  by  the  unlike  operation  of  quench- 
ing, only  in  case  we  find  that  the  effects  of  cold  working 
iron  and  steel  resemble  those  of  quenching  steel  much 


b  Cf.  §  57,  p.  35-  In  addition  to  Abel's  testimony  that  cold-working  does  not 
change  the  condition  of  carbon,  we  have  that  of  Osmond  and  Werth,  who  obtain 
the  following  proportions  of  carbon  in  the  same  steel  after  different  treatment. 


Rggtrb 
method. 


Untreated 

Hardened  by  quenching 

Hardened  by  quenching,  then  annealed 

Cold-worked 


Boussingault 

method. 

•49 

•89 

•58 


Ann.  Mines,  8th  Ser.,  VIII.,  p.  26. 

The  quantity  of  carbon  found  by  EgKcrte'  method,  while  lessened  by  quenchlng-lmnlemr,,'  ;,.„( 
increased  »S"in  by  annealing  \i  not  dhotod  t.y  »H-worHn«, 


218 


THE    METALLURGY     OF     STEEL. 


-  diminish 


more  closely  than  they  resemble  those  of  cold -working  the 
other  metals. 

Let  us  now  examine  these  resemblances  in  some  detail. 

§  273.  RESEMBLANCE  BETWEEN  THE  EFFECTS  OF 
QUENCHING  AND  OF  COLD- WORK  ING. — Osmond  claims" 
that  when  steel  undergoes  either  operation 

1,  it  absorbs  heat: 

2,  its  malleableness, 

3,  its  density, 

4,  its  thermo-electric  constants,  and 

5,  its  electric  conductivity 

6,  its  coefficient  of  dilatation  increases :  and, 

7,  its  chemical  reactions  become  more  energetic.      To 
these  we  may  add, 

8,  its  hardness,  strength  and  elastic  limit  increase.    He 
further  states  that, 

<J,  the  strain-diagrams  of  brass  and  bronze  are  smooth : 
those  of  soft  iron  and  steel  consist  of  two  smooth  curves, 
united  by  an  abrupt  jog  at  the  stretching  point,  shown  in 
curves  1  acd  2  of  Figure  88.  He  might  add  that  this  jog 
is  absent,  usually  at  least,  from  the  diagrams  of  cold- 
worked  and  hardened  iron  and  steel.  This  suggests  to 
him  that  these  two  curves  represent  two  different  metals, 
a  iron  up  to  the  elastic  limit,  0  iron  above  it,  the  distortion 
which  occitrs  at  this  point,  like  that  of  cold-working,  de- 
termining the  change  from  the  former  to  the  latter.b 

Taking  these  up  in  order,  1,  that  the  change  from  the 
annealed  to  the  hardened  state  is  accompanied  by  absorp- 
tion of  heat,  the  phenomena  of  the  after-glow  and  the 
retardations  of  both  rising  and  falling  temperature  show. 
That  cold-working  causes  a  similar  absorption  of  heat 
Osmond  and  Werth  infer  from  their  calorimetric  studies, 
in  which  they  find  that  cold-forged  like  quenched  steel 
when  dissolved  in  double  chloride  of  copper  and  ammo 
nium  gives  out  more  heat  than  annealed  steel :  the  differ- 
ence in  different  steels  was  far  from  proportional  to  the 
percentage  of  carbon  present.  They  appear  to  have  reached 
closely  agreeing  duplicate  results,  whose  mean  is  given  in 
§  14,  p.  7, 

Cold-worked  copper,  on  the  other  hand,  gave  out  the 
same  quantity  of  ht  at  as  annealed  copper.  The  difference 
in  rise  of  temperature  between  annealed  and  cold- worked 
steel  was,  however,  only  about  0'1°  C.,  while  between 
duplicate  results  from  similar  samples  the  difference  was 
in  one  case  one  third  as  large  as  this.  The  difference, 
moreover,  is  probably  not  proportional  to  the  other  effects 
of  the  cold-working,  being  almost  as  great  in  case  of  steel 
with  0'16$  of  carbon  as  in  that  with  1'17$,  while  it  is 
probable  that  cold-working  affects  the  properties  of  high- 
more  than  those  of  low-carbon  steel.  Such  minute  differ- 
ences in  heat-evolution  seem  less  naturally  ascribed  to 
allotropism  than  to  unnoted  differences  in  conditions 
e.  ff.,  initial  dissimiliarity  of  composition,  due  say  to 
segregation  ;  or  possibly  to  some  effect  of  the  hydrogen 
in  which  the  powder  of  the  annealed  metal  was  an. 
nealed.c  Osmond  calls  in  a  giant  to  do  a  boy's  work. 

a  Annales  des  Mines,  8th  Ser. ,  VIII.,  p.  48,  1885. 

b  Stahl  und  Eisen,  VI.,  p.  640,  1886. 

c  The  cold-working  consisted  in  hammering  bars  0-7888  inches  square  down  to 
0-197  inches  square.  Fearing  that  the  action  of  the  file  used  in  removing  ma- 
terial for  analysis  from  the  annealed  bars  would  be  equivalent  to  slight  cold- 
working,  the  p  wder  filed  from  the  annealed  pieces  was  reheated  and  cooled  in 
hydrogen.  Now  hydrogen  appears  to  have  some  obscure  effect  on  the  condition  of 
carbon.  Steel  which  in  its  natural  state  showed  Q-9\%  of  carbon  by  Eggertz's 
test,  after  heating  in  hydrogen  showed  only  0'45$;  while  c  n  heating  in  vacuo  no 


If,  however,  we  admit  that  cold-working  increases  the 
evolution  of  heat  on  subsequent  solution,  this  merely  im- 
plies that  it  stores  energy  in  some  way,  which  is  not  neces- 
sarily through  the  «  0  change.  The  shattering,  stretching 
or  crumpling  of  resilient  crystals,  the  creation  of  stress, 
macro-  or  micro-,  are  possible  causes.  Further,  theie  is  so 
much  obscurity  about  the  thermal  relations  of  the  com- 
pounds of  iron  and  carbon  that  we  can  draw  no  safe  infer- 
ences from  such  scanty  data.  Indeed,  while  Osmond  and 
Werth  find  that  heat  is  set  free  when  carbon  and  iron  com- 
bine, and  while  the  fact  that  gray  cast-iron,  though  melt- 
ing at  a  higher  temperature  than  white  cast-iron  yet 
according  to  Gruner  has  less  latent  heat  of  fusion,  points 
in  the  same  direction,4  yet  such  eminent  observers  as 
Troost  and  Hautefeuille  found  that  the  combination  of 
iron  and  carbon  was  attended  with  absorption  of  heat. 

2.  Both  operations  diminish  malleableness. 

3  The  loss  of  density  due  to  quenching  is  readily  re- 
ferred, if  not  to  the  stress  born  of  uneven  contraction,  at 
least  to  the  chemical  and  mineralogical  changes  which 
heating  and  quenching  cause.  It  cannot  be  regarded  as  a 
proof  of  allotropic  change  from  «to  /siron,  because  when 
soft  wrought-iron  is  quenched  its  specific  gravity  is  lowered, 
like  that  of  steel:'  yet  on  Osmond's  theory  its  iron  is  a 
even  after  quenching. 

4-5.  I  do  not  see  that  they  offer  any  evidence  that 
quenching  and  cold-working  affect  these  properties  alike. 
Indeed  Barus  and  Strouhal,  to  whom  they  refer,  ttate  that 
the  specific  resistance  is  smaller  in  hard-drawn  and  greater 
in  quenched  wire  than  in  soft  wire.' 

6.  As  regards  the  coefficient  of  dilatation,  my  knowl- 
edge is  so  fragmentary  that  I  can  reach  no  safe  conclusion. 
If  we  confine  ourselves  to  comparing  results  obtained  by 
the  same  observers,  it  seems  that  cold-working  and 
quenching,  while  both  increasing  the  coefficient,  do  so 
in  a  ratio  so  disproportionate  to  that  of  their  effects  on 
the  other  properties  as  to  form  a  serious  discrepancy. 
Thus  the  data  of  Lavoisier  and  Laplace  indicate  that 
quenching  increases  the  coefficient  thirty  times  as  much 
as  wire-drawing.  On  the  other  hand,  Troughton  assigns 
to  the  coefficient  of  iron  wire  a  value  which,  compared 
with  the  results  given  below  would  indicate  that  the  effect 
of  cold- working  exceeded  that  of  quenching. 


TABLE  109.— DILATATION  .    Length  at  100°  C.  of  a  rod  whoso  length  at  0°  C.  Is  1. 


Hard  Soft. 

Steel,  hard  vs.  annealed,  Fizoau 1-001,822  1-001,101 

Steel,  yellow-tempered  vs.    untempored,  Lavoisier  and 

Laplace 1.001,377  1.001,079 

Iron,  wire-drawn  vs.  soft.     Idem 1.001,2.35  1.001,220 

Iron,  wire,  Troughton 1,001,440 


Difference 
(0  000)221 

298 
15 


7.  Osmond  and  Werth  find  that  cold-working  increases 
the  rapidity  of  corrosion  of  steel  in  dilute  hydro- 
chloric, nitric,  sulphuric  and  acetic  acids.g  Quenching, 
however,  probably  produces  the  opposite  effect.  Barns 
and  Strouhal  found  that  as  hardened  steel  was  tempered 
at  successively  higher  temperatures,  the  rate  at  which  it 
dissolved  in  hydrochloric  acid  continually  increased,  and 
that  hardened  steel  was  electro-negative  to  the  same  steel 


such  change  occurred.  The  hydrogen  appears  to  have  caused  some  change. 
It  probably  did  not  expel  carbon,  for  the  loss  of  weight  on  heating  in  hydrogen 
was  found  to  be  only  0'007$. 

d  Juptner,  Jour.  Iron  and  St.  Inst.,  1887,  II.,  p.  332,  fr.  Oest.  Zeit.,'XXXV., 
pp.  12—461—4. 

e  Wrightson,  Journ.  Iron  and  St.,  Inst.,  1879,  II.,  p.  434,  found  the  sp.  gr.  of 
wrought-iron  reduced  from  7'64  to  7'562,  a  loss  of  1'02$,  by  fifty  quenchings. 

I  Bull.  14,  U.  8.  Geological  Survey,  p.220. 

B  Ann.  Mines,  8th  Ser.,  VIII.,  p.  46,  1886. 


RATIONALE     OF    THE    EFFECTS     OF     COLD-WORKING.       §  274. 


219 


annealed,  both  in  distilled  water  and  in  zinc  sulphate.'1 
Further,  Monroe  found  the  hardened  points  of  two  cold- 
chisels  long  immersed  in  sea-water  wholly  uncorroded, 
their  unhardened  bodies  being  deeply  pitted ;  and  he 
learns  of  a  similar  phenomena  in  case  of  a  hammer." 

Osmond  and  Werth,  however,  believe  that  hardening 
like  cold-working  increases  the  solubility,  but  apparently 
on  quite  insufficient  ground  They  rely  on  Gruner  s  find- 
ing in  one  case  that  hardened  steel  dissolved  more  rapidly 
in  acidulated  water  than  annealed  steel,  and  on  analogous 
results  of  their  own  experiments.  It  is  probable  that 
Gruner' s  result  'o  which  they  refer  is  Number  40-1  of 
Table  44,  p.  94,  in  which,  unfortunately,  manganese  steel 
was  tried. 

Its  behavior,  of  course,  throws  no  light  on  that  of  car- 
bon steel,  since  manganese  steel  does  not  undergo  the 
very  change  in  question,  the  change  of  hardness  when 
quenched  from  a  high  temperature.  Osmond  and  Werth 
do  not  give  us  their  own  results.  Actually,  Gruner' s  evi- 
dence appears  to  agree  with  that  of  Barus  and  Strouhal 
and  that  of  Monroe :  in  sea-water  Gruner  found  that  hard- 
ened steel  corroded  less  than  the  same  steels  annealed. 

8.  Both  quenching  and  cold-working  harden  and 
strengthen  steel,  at  the  same  time  raising  its  elastic  limit 
and  making  it  brittle,  usually  without  greatly  affecting 
the  modulus  of  elasticity.  But  the  ratio  of  gain  of 
one  property  to  that  of  another  on  quenching  is  widely 
different  from  that  on  cold- working.  Thus  quenching  in- 
creases the  hardness  enormously,  the  tensile  strength  rel- 
atively little :  indeed  it  occasionally  lowers  the  latter. 
Cold  working  even  when  doubling  the  tensile  strength  in- 
creases the  hardness  but  little.  A  quenching  which  makes 
previously  soft  steel  utterly  unfileable  may  raise  its 
tensile  strength  by  less  than  2f;$  :  while  the  unskilled 
hand  can  hardly  detect  with  the  file  the  hardening  effect 
of  a  cold-working  which  may  nearly  double  the  tensile 
strength.  As  regards  the  ratio  of  increase  of  tensile 
strength  to  that  of  elastic  limit  the  case  is  better,  but  there 
is  still  quite  a  discrepancy.  In  forty-nine  cases  in  Tables 
8,  9  and  10,  pp.  18  to  20,  the  average  increase  of  tensile 
strength  on  quenching  is  only  about  half  as  great  as  that 
of  elastic  limit :  in  12  cases  in  Table  100  the  average  in- 
crease of  tensile  strength  is  nearly  one  third  as  great  as 
that  of  elastic  limit.  These  discrepancies  may  be  ex- 
plained away  later :  indeed,  I  think  it  likely  that  the  for 
mer  discrepancy  is  in  large  part  due  to  difference  in  the 
intensity  and  distribution  of  internal  stress."  While 
then,  the  effects  of  quenching  and  of  cold-working  on 
these  properties  are  not  so  hopelessly  unlike  as  to  dis 
prove  Osmond's  theory,  certainly  they  are  not  yet  shown  to 
be  so  like  as  to  give  it  important  support. 

We  have  seen  that  the  elevation  of  the  elastic 
limit  due  to  cold-working  is  increased  by  gentle  heating 
(to  200°  or  300°,  §  270).  Jarolimek,  applying  to  steel 
springs  hardened  by  quenching  the  same  gentle  heating 
which  he  had  found  to  raise  the  elastic  limit  of  like 

a  Am  Journ.  Sei.,  3d  Ser.,  XXXII.,  p.  276,  1886.  "The  rate  at  which  solu- 
tion takes  place  increases  as  temper  continually  decreases."  "  As  hardness  in- 
creases the  hydro-electric  position  of  steel  moves  continually  in  an  electro- negative 
direction." 

b  Journ.  Franklin  In;t.,  LXXXV. ,  p.  309, 1883,  Prof.  C.  B.  Munroe,  U.  S.  Naval 
Academy.  In  case  of  the  chisels  the  corrosion  was  most  marked  at  the  junction 
of  the  hardened  aud  unhardened  parts:  and  the  sime  was  true  in  the  experiments 
of  Barus  and  Strouhal.  In  the  case  of  the  hammer  it  is  possible  that  the  differ- 
ence in  corrosion  may  have  been  due  to  the  face  being  initially  of  a  harder  steel 
welded  to  softer  metal. 


springs  which  had  been  distorted,  /.  e.  col i- worked,  found 
that  it  did  not  increase  their  elastic  limit.0  Indeed,  the 
general  phenomena  of  tempering  hardened  steel  would 
lead  us  to  expect  that  reheating  to  300°  C.  (572°  F.,  a  blue 
oxide  tint)  would  lower  the  elastic  limit  (Table  II.,  p.  22). 
Should  further  investigation  confirm  Jarolimek' s  results, 
this  would  constitute  a  serious  difference  between  the 
effects  of  quenching  and  those  of  cold  working. 

Further,  the  effect  of  quench  ng  on  tensile  strength 
seems  instantaneous :  while  cold-working,  at  least  cold- 
stretching,  does  not  seem  to  affect  tensile  strength  at  all 
immediately,  the  growth  of  tensile  strength  occurring 
gradually  after  the  stretching  has  occurred. 

The  ninth  point  may  be  dismissed  summarily.  Not 
only  are  the  strain-diagrams  of  soft  iron  often  without 
jog,  but  we  cannot  even  regard  greater  sharpness  of  bend 
at  the  elastic  limit  as  a  constant  characteristic  of  non- 
cold-worked  iron,  distinguishing  it  from  other  materials, 
nor  hence  as  an  indication  of  allo  tropic  change  due  to 
cold-working  at  the  elastic  limit.  Doubtless  on  an  aver- 
age the  bend  is  sharper  for  hot-rolled  weld  iron  than  for 
cold-worked  iron  and  other  metals  :  but  the  reverse  is 
probably  often  true.  Thus  Thurston  gives  cases  in  which 
the  bend  is  apparently  sharper  in  cold-rolled  than  in 
similar  but  hot-rolled  iron.d  Again,  we  find  many 
strain-diagrams  for  steel  of  carbon  varying  from  0'15  to 

32$  which  are  smooth  at  the  elastic  limit,  together  with 
strain-diagrams  for  copper  with  a  sharp  bend. 

Osmond  and  Werth  would  distinguish  highly  carbu- 
rettei  steel  from  ingot-iron  by  the  smoothness  of  its 
strain  diagram.  Yet  it  is  of  the  two  probably  the  more 
influenced  by  cold-distortion,  including  that  at  the  elastic 
limit,  and  should, — if  this  distortion  acts  through  allo- 
tropic  change,  and  if  the  jog  results  from  this  change,— 
show  the  greater  jog  ° 

We  have  seen  that  this  jog  characterizes  locust  and 
hickory  wood.' 

§  274.  RESEMBLANCE  BETWEEN  THE  EFFECTS  OF  COLD- 
WOBKING  IRON  AND  THOSE  OF  COLD- WORKING  OTHER 
METALS. — Time  fails  me  for  an  exhaustive  study  :  I  can 
merely  turn  to  the  readily  accessible  data. 

Under  cold-work  the  other  metals,  like  iron,  become 
harder,  stronger,  more  elastic  and  resilient,  more  brittle  : 
their  strain-diagrams  undergo  changes  like  those  of  iron  : 
their  modulus  of  elasticity,  like  that  of  iron,  seems  to  be 
increased  but  little,  judging  from  the  ela  sticity-lines  of  in- 
terrupted-strain diagrams.  Like  that  of  iron  the  electric 
conductivity  of  some  (e.  g.  platinum  and  German  silver) 
is  increased  by  cold-working,  while  that  of  others  is  less- 


e  Dinglers'  Polytechnisches  Journal,  CCLV.,  p.  3,  1885. 

d  Rept.  on  cold-rolled  iron,  private  print,  Plate  VII. ,  numbers  1 104  A  and  1 105 
A;  Plate  XVI.,  numbers  1,203  A,  1,204  A  and  1,218.  * 

e  Osmond  and  Werth  state  that  this  jog  occurs  in  the  strain-diagrams  of  abso- 
lutely all  classes  of  weld  and  ingot-iron  us  distinguished  from  hard  and  hardened 
sorts,  and  they  give  us  to  understand  that  this  is  an  essential  characteristic  of 
soft  iron  as  distinguished  from  other  materials  in  general.  They  seem  to  be 
wholly  in  error.  Not  to  multiply  cases  needlessly,  jog-less  diagrams  of  ingot-iron 
sometimes  quite  soft,  are  given  by  the  U.  S.  Test  Board  (Nos.  1091  B. ,  1060  D, 
and  1583,  the  former  two  with  0-23  and  0'24  of  carbon,  the  latter  with  still  less, 
judging  from  its  tensile  strength  54,760  Ibs.):  by  Kirkaldy  (Expts.  on  Fagersta 
steel,  Series  D.,  pi.  I.,  No.  1054,  with  0'15  of  carbon),  and  by  Gatewood  (Kept, 
of  U.  S.  Naval  Advisory  Board  on  Mild  Steel,  pi.  XVIII.,  with  0-'.6  of  carbon). 
Further,  jogged  diagrams  of  hard  steel  are  given  by  the  U.  S.  Test  Board  (N'os. 
1053  A.  and  C.,  1056  A.,  B.  and  C.,  and  1058  A.  B.  an  1  C.  with  973,  -994  and 
905$  of  carbon  respectively.  Further,  many  of  the  torsion-diagrams  of  tool-steel 
here  show  decided  jogs. 

I  Matls.  of  Engineering,  II.,  p.  531.  Thurston  regards  the  jog  as  a  sign  of 
heterogeueousness. 


220 


THE    METALLURGY    OF     STEEL. 


ened  (e.  y.  gold,  c  pper,  silver,  zinc) :  probably  like  that 
of  iron  the  coefficient  of  dilation  increases  very  slightly.* 
Cold-working  condenses  the  metal  by  closing  cavities, 
lightens  it  by  some  other  immediate  effect.  In  case  of 
iron  the  lightening  outweighs  the  condensation.  To  judge 
from  published  tables  the  reverse  is  in  general  true  of  the 
other  metals.  But  the  case  is  simpler  if  we  consider  the 
effect  of  annealing  on  the  density  of  cold-worked  metals, 
for  here  the  closing  of  cavities  is  eliminated.  The  density 
of  cold-worked  iron  is  apparently  increased  by  annealing : 
that  of  cold-drawn  copper  and  brass  seems  to  be  very 
slightly  increased,  judging  from  the  following  results  ob- 
tained for  me  in  Drown' s  laboratory. 

Copper.  Brass. 

Sp.  gr.  when  annealed 8'90S  8-fttM 

8p.  gr.  when  unannealed 8-905  b'411'.i 

Difference -f  0-008         +0-004 

In  the  case  of  cold-rolled  coin-silver  my  assistant  ob- 
tained the  following  results,  indicating  that  this  alloy  too 
is  lightened  by  cold-rolling. 

Sp.  gr.  when  annealed. ..  10  1716 

8p.  gr.  when  unannealed 10-1674  (10-1076,  10-1C72) 

4-     -0042 

In  three  series  of  experiments  O'jN'eillb  found  that  the 
cold-hammering  lowered  the  density  of  copper.  I  here 
condense  his  results.  The  numbers  in  each  of  the  first  sets 
are  the  mean  of  ten  results  : 

Uncompressed 8-879  8-898 

The  same  piec-fS  compressed 8-855  8'878 

"      annealed 8-884a 

Gain +0-029 


8-8S5 
8-867 


-fO-018 


a  Annealed  in  red-hot  sand  and  again  cleaned. 

b  Five  of  the  same  pieces   annealed  in  a  charcoal  fire. 

It  is  true  that  Baudrimont  found  that  the  density  of  wires 
of  iron,  silver,  copper  and  other  metals  was  diminished  by 
annealing :  and  that  cold-rolling  increased  the  density  of 
the  annealed  copper  and  iron  wires  enormously,  e.  g.  from 
7-5361  to  7-7334.°  I  can  hardly  credit  his  results.  They 
indeed  agree  with  the  others  here  presented,  in  showing 
that  the  effect  of  cold  working  on  iron  is  like  in  sign  to 
its  effect  on  other  metals. 

The  points  of  similarity  between  the  effects  of  cold- 
working  iron  on  the  one  hand,  and  of  hardening  it  and  of 
cold- working  the  other  metals  on  the  other,  are  here 
summed  up. 

TABLE  110.— EFFECTS,  ETC.,  OF  COLD-WORKING  IRON  COMPARED  WITH  THOSE  OF  HARDENING 
IT  AND  OF  COLD-WORKING  OTHER  METALS. 


'  Malleableness 

Tensile  strength 

Elastic  limit 

Modulus  of  elasticity 

Hardness 

Evolution  of  heat  during  solution 

Klt-ctric  conductivity 

Ik-ut-expausion 

Ohemical  activity 

Density 

Condition  of  carbon 

x  Structural  condition 

llemoval  of  effects  by  heating 

Apparent  nature  of  processes 

Intensity  of  stress 


Hardening  iron,  like  or  un- 
like cold-working  iron. 


Roughly  like  in  kind,  but 
-  very  different  in  propor- 
tion among  themselves. 

Like  (?) 
Opposite 
Doubtful 

Probably  opposite 

Like 

Unlike 

Like  in  part 
Unlike 
Unlike 


Cold-working  other  met- 
als, like  or  unlike  cold- 
working  iron . 


I  Like  in  kind :  not 
V  known  how  like  in 
I  proportion. 

Unlike  for  copper 

Like  for  some  metals 

Like 

Like 

Probably  like 

Like 

Identical 

Probably  like 


Let  each  judge  for  himself  the  closeness  of  these  resem- 
blances. To  me  it  seems  that,  while  the  resemblance 
between  the  effects  of  cold-working  and  those  of  quench- 


»  The  escess  of  the  linear  expansion  between  0°  and  100°  C.  for  the  harder  over 
that  for  the  softer  state  is  as  follows: 

Iron,  wire-drawn  vs.  soft  Lavois.  and  Laplace.... 0*000,01459 

Cold,  standard,  unannealed  vs.  annealed,  idem 3794 

Brass  wire  vs.  cast,  Smeaton   5500 

Zinc,  hammered  vs.  unstated,  Smeaton 6900 

It  is  not  clear  that  the  coefficients  for  the  two  states  of  brass  are  comparable,  as 
the  composition  of  this  alloy  varies  widely. 

b  Manchester  Phil  Soc.,  II. ,  p.  56,  March  5th,  1861.  Also  Percy,  Fuel,  p.  287, 
1861. 

o  Ann.  Chim.  Phys.,  3d  Ser.,  LX.,  p.  78,  1835. 


ing  steel  is  striking  at  first  sight,  on  examination  it  seems 
more  apparent  than  real,  and  not  so  close  that  it  may  not 
well  be  accidental.  •  n  the  whole  it  seems  less  complete 
than  the  resemblance  between  the  effects  of  cold  working 
iron  and  those  of  cold-working  the  other  metals,  though 
unfortunately  our  data  here  are  scanty.  The  former  re- 
semblance is  at  a  disadvantage  as  regards  electric  con- 
ductivity ;  probably  as  regards  the  proportion  between 
the  gain  of  tensile  strength,  etc.,  and  that  of  hardness; 
and  probably  as  regards  the  progressive  nature  of  the 
change  in  tensile  strength  and  elastic  limit. 

In  short,  the  probabilities  seem  strongly  against  Os- 
mond's theory,  and  in  favor  of  the  belief  that  cold-work- 
ing produces  a  special  kind  of  change,  the  cold-ioork 
c?ianye,  roughly  alike  in  the  different  malleable  metals. 

AVhat  the  nature  <  f  this  change  is  I  will  not  attempt  to 
say,  beyond  surmising  that  it  is  essentially  physical.  It 
has  been  thought  to  consist  essentially  in  stress  :  but  this 
seems  wholly  improbable,  for  two  chief  and  two  minor 
reasons. 

1st,  While  there  is  certainly  stress  in  much  cold- 
worked  iron,"1  Thurston's  results  in  Table  107  indicate 
that  it  is  very  mild. 

Here  the  tensile  strength  and  elastic  limit  of  cylinders 
of  progressively  decreasing  diameter,  turned  from  cold- 
rolled  wrought-iron  bars  two  inches  in  diameter,  decrease 
but  slightly  with  the  diameter,  indeed  hardly  more  than 
in  case  of  like  but  hot-rolled  bars.  In  §  54  B.,  p.  32,  I 
showed  that  the  tensile  strength  of  a  hardened  steel  bar 
differed  greatly  from  that  of  small  cylinders  turned  from 
it.  The  difference  clearly  was  not  due  to  the  slower  cool- 
ing of  the  centre,  for  this  was  stronger  than  the  average 
of  the  whole  bar,  but  probably  to  stre-s. 

2d,  Cold- working  in  one  direction  seems  to  affect  the 
properties  of  the  metal  alike  in  all  directions  :  e.  g. 
longitudinal  extension,  as  in  cold-rolling,  seeming  to  in- 
crease the  transverse  and  torsional  as  much  as  the  longi- 
tudinal and  elastic  limit.  The  stress  caused  by  cold- 
rolling  should  not  be  uniform  in  all  directions. 

3d,  It  is  not  easy  to  understandhow  stress,  as  such,  should 
materially  increase  the  hardness  proper,  the  resistance  to 
abrasion  and  indentation. 

4th,  Gentle  heati'g,  which  should  relieve  stress,  inten- 
sifies the  effect  of  cold-working. 


WIRE-DRAWING. 

§  275.  IN  Wi  HE-DRAWING  the  cold  wire,  coated  with  a 
lubricant,  is  drawn  through  a  succession  of  conical  gently 
tapering  holes  in  extremely  hard  steel  or  cast-iron  dies  or 
"  draw-plates,"  each  hole  a  little  smaller  than  the  preced- 
ing and  each  slightly  diminishing  the  diameter  of  the  wire. 
The  metal  gradually  becomes  hard  and  brittle,  and  must 
be  annealed  from  time  to  time,  and  then,  to  remove  the 


d  To  prove  the  existence  of  stress  iu  cold-worked  bars,  I  slit  a  round  steel  bar, 
whose  diameter  had  been  reduced  from  0-8  to  0-7467  inches  by  a  single  cold- 
draught  through  a  die,  for  a  distance  of  4'25  inches  from  one  end,  making  a  crude 
tuning  fork  of  it.  When  released,  the  ends  of  the  tynes  sprang  apart  by  0'0413 
inches:  had  the  bar  been  quenched  instead  of  cold-drawn  its  tyues  would  have 
sprung  towards  each  other. 

Since  then  I  learn  that  Baker  has  shown  the  presence  of  stress  in  cold-bent  iron 
in  two  experiments.  1.  On  planing  off  the  outside  of  a  cold-bent  steel  boiler  plate, 
the  radius  of  curvature  changed.  2d.  An  initially  crooked  steel  bar  11  inches 
wide  and  IS  feet  long  was  straightened,  and  sawed  lengthwise  through  the  middle; 
it  immediately  bent  to  the  theoretically  calculated  curvature.  ("Tba  Use  and 
Testing  of  Open-Hearth  Steel  for  Boiler-Making,"  Eicerpt,  Proc.  Inst.  Civ.  Eng., 
XCII.,  pp.  40-7,  1888.) 


WIRE-DRAWING.       §  277. 


221 


coat  of  oxide  produced  in  annealing,  it  must  be  pickled 
before  further  drawing,  and  then  washed  to  remove  the 
pickling  acid.  The  whole  procedure  may  indeed  be  re- 
garded as  made  up  of  one  or  more  similar  series  of  opera- 
tions, each  series  consisting  of  pickling,  washing,  lubricat- 
ing, several  draughts  and  an  annealing.  We  will  now 
consider  these  several  operations  separately. 

§276.  POINTING  AND  PICKLING. — The  coiled  wire-rod, 
(i.  e.  the  wire  as  it  leaves  the  rolling  mill  and  before  draw- 
ing, covered  with  a  scale  due  to  the  high  temperature  of 
rolling),  rirst  has  one  end  pointed  so  that  it  may  enter  the 
draw-plate  readily.  To  remove  the  scale  which  if  left  on 
would  greatly  increase  the  resistance  and  rapidly  wear 
out  the  die,  the  wire  is  next  pickled  either  in  dilute 
sulphuric  acid,  say  of  from  1  to  3  parts  of  60°  B  acid  to 
100  of  water,  and  at  say  101°  F.  (38°  C.),  the  immersion 
lasting  say  35  to  50  minutes,  or  in  hydrochloric  acid.  It 
is  then  washed,  preferably  with  a  hose. 

The  later  picklings,  which  follow  the  annealing  of  the 
partly  drawn  wire,  are  like  that  of  the  wire-rod :  the  finer 
the  wire  the  more  thoroughly  must  it  be  washed  to  re- 
move the  acid.  Wire  finer  than  No.  14  B.  W.  G-.  is  usu- 
ally "batted"  while  washing,  i.  e.  beaten  vigorously  by 
two  workmen  with  long  wooden  sticks,  say  6'  x  1J"  X  2", 
while  a  hose  plays  on  it. 

The  consumption  of  acid  per  ton  of  wire  is  estimated 
by  Badeker"  for  certain  conditions  at  47'6  to  54  pounds, 
by  Wedding"  at  54  to  65  pounds,  of  which  14  pounds  are 
used  in  pickling  drawn  wire.  At  an  American  wire 
mill  18 '3  pounds  of  acid  were  used  per  ton  of  wire 
rods  on  the  first  pickling,  on  a  test  trial. 

When  its  acid  has  been  so  far  neutralized  that  it  is  no 
longer  efficient,  the  pickling  liquor  is  in  some  mills  run  to 
waste :  in  others  its  ferrous  sulphate  is  crystallized  out  as 
copperas,  the  mother-liquors  are  evaporated  to  dryness, 
and  the  residue  roasted,  yielding  Venetian  red  (ferric- 
oxide,  colcothar).  In  this  country  the  sulphuric  acid 
driven  off  in  roasting  the  residue  is  wholly  lost :  but  it 
might  be  condensed  as  Nordhausen  acid. c 

§  277.  LUBRICATION. — Any  common  lubricant  would  be 
squeezed  out  by  the  pressure  between  wire  and  die,  which 
would  then  abrade  each  other.  Certain  coatings,  such  as 
lime,  flour,  hydrated  iron-oxide,  and  salt,  strangely 
enough  adhere  to  the  wire  tenaciously  and,  instead  of  be- 
ing scraped  off  by  the  die,  seem  to  elongate  as  an  extreme- 
ly thin  apparently  continuous  sheath,  so  that  wire  and 
draw-plate  do  not  touch  each  other. 

According  to  the  mode  of  coating  the  wire  with  lubri- 
cant, wire-drawing  is  divided  into  dry  drawing  and  wet 
drawing.  In  both  cases  the  coating  is  applied  by  immers- 
ing the  hank  of  wire  into  a  solution  containing  the  lubri- 
cating substance.  In  dry  drawing  the  hank  is  removed 
from  the  liquor  and  dried  or  baked  before  drawing  ;  in 
wet  drawing  it  is  drawn  directly  from  the  solution,  in 
which  it  stands  immersed,  wound  upon  a  reel.  In  dry 
drawing  several  draughts  are  given  between  successive 
lubricatings,  the  lubricant  being  applied  say  after  each 
annealing  and  pickling.  In  wet  drawing  the  wire  is  lub- 


agtahl  und  Eisen,  VI.,  p.  183,  1886.    Iron  Age  Apl.  I.,  1886,  p.  25. 

b  Stahl  und  Eisen,  VI.,  p.  14,  1886. 

«  Concerning  the  manufacture  of  Nordhausen  or  fuming  sulphuric  acid  from 
copperas-slate  Cf.  Lunge,  Sulphuric  Acid  and  Alkali,  I.,  p.  631,  1879,  Fr.  Wag- 
ner's Jahresbericbt,  1873,  p.  320,  also  Traitt?  de  Chimie  Technologique  et  Indus- 
trielle,  Knapp,  Merijot  et  Debize,  II.,  p.  403. 


ricated  before  each  draught,  the  hank  of  wire  as  soon  as 
it  has  passed  completely  through  the  die  being  returned  to 
the  tub  which  contains  the  coating  solution,  and  at  once 
undergoing  a  fresh  draught.  In  dry  drawing  ( he  wife  must 
be  well  smeared  with  tallow  outside  the  dry  coat  of  lubri- 
cant :  to  this  end  a  lump  of  tallow  is  placed  against  the 
entering  side  of  the  die  C,  Figure  101,  and  through  it  the 
wire  draws.  In  wet  drawing  no  grease  is  used. 

Coarse  wire  is  almost  always  drawn  dry,  while  in 
case  of  fine  wire  the  earlier  draughts  are  dry,  the 
later  wet,  the  change  from  dry  to  wet  usually  occurring 
not  earlier  than  number  14  and  not  later  than  number  18 
wire-gauge. 

In  many  cases  the  wire  is  drawn  dry  until  the  last 
pickling,  which  usually  comes  immediately  after  the  last 
annealing,  say  at  14  gauge  for  wire  which  is  to  be  drawn 
to  20  gauge,  or  at  19  gauge  for  wire  which  is  to  be  drawn 
finer.  The  grease  of  the  dry  drawing  is  charred  in  an- 
nealing and  removed  in  pickling  :  thereafter  the  wire  is 
drawn  wet.  In  other  works  the  change  from  dry  to  wet 
occurs  at  14  gauge,  while  the  last  annealing  occurs  at  19 
gauge :  but  wire  is  rarely  drawn  dry  after  the  last  pick- 
ling. 

The  more  common  dry  coatings  are  lime,  flour,  and  the 
"water-coating."  The  former  two  are  applied  by  simply 
dipping  the  coil  of  wire  in  thin  lime-water  or  flour  paste, 
and  then  baking  it  in  a  large  oven,  whose  temperature  is 
in  some  cases  so  low  that  one  may  walk  into  it  (say  150° 
P.,  66°  C.),  in  other  cases  as  high  as  630°  F.  (344°  C.).  It 
is  said  that  unless  thus  rapidly  dried  the  lime  or  flour 
coating  does  not  adhere  well :  but  the  baking  probably 
fulfills  another  very  important  office,  to  wit,  hastening  the 
expulsion  of  hydrogen  which  is  absorbed  during  pickling, 
and  which  makes  the  wire  brittle  and  liable  to  break  in 
drawing." 

A  water  coating,  confusingly  enough,  is  a  dry  coating. 
It  apparently  consists  of  hydrated  iron-oxide,  and  is  pro- 
duced by  exposing  the  pickled  and  washed  hank  of  wire 
to  the  air,  sprinkling  it  from  time  to  time  to  hasten  rust- 
ing. The  care  required  in  producing  this  coating  makes  it 
more  expensive  than  the  lime  coating,  but  it  is  more  a  effi- 
cient and  more  persistent  lubricant.  In  some  cases  water- 
coated  wire  is  subsequently  lime-coated  before  drawing. 

A  coating  of  salt,  according  to  Morgan,6  adheres  to 
wire  much  more  tenaciously  than  either  flour  or  lime, 
and  is  therefore  well  fitted  to  resist  the  heavy  pressure  in 
drawing  steel  wire,  especially  in  the  early  draughts  in 
which  the  reduction  is  severe.  So  salt  was  extensively 
used  for  a  time  in  dry  wire-drawing,  sometimes  mixed 
with  lime  :  but  it  induces  rusting  so  much  that  its  use 
has  been  generally  if  not  wholly  abandoned. 

Its  behavior  in  wire-drawing  is  instructive  as  illus- 
trating that  of  dry  coatings  in  general.  Thompson'  found 
that  it  persisted  through  seven  draughts,  the  proportion 
of  salt  per  square  inch  of  surface  diminishing  rapidly 
during  the  first  two  draughts,  suggesting  that  part  of  it 
was  scraped  off,  but  thenceforth  slowly.  After  the  first 
draught  the  salt  was  invisible,  though  readily  tasted. 
Exposed  to  a  pressure  of  192,000  pounds  per  square  inch 


a  Cf.,  §  178  B,  pp.  114,  et  seq.,  especially  p.  117. 

e  C.  H.  Morgan,  Trans.  Am.  Inst.  Mining  Engineers.  IX.,  p.  673.     He  appears 
to  have  originated  the  use  of  salt  in  wire-drawing  in  1878. 
f  Idem.,  p.  300-1. 


222 


THE    METALLURGY    OF     STEEL. 


between  plane  surfaces,  salt  was  converted  into  a  thin 
transparent  wafer.     Some  of  Thompson's  results  follow. 

TARLE  111  —PERSISTENCE  OF  THE  SALT-COATING  IN  WIIIE  DRAWINU  (THOMPSON). 


Initial 

After  1st  draught. 
2d       " 
8d 

4th  '• 
5th  " 
6th  " 
7th  " 
8th  " 


Diameter. 

Inches. 


0-192 

0-164 

0-131 

0-113' 

0-102 

0-092 

0-07S 

0-067 


Salt  per  square  inch. 
Grammes. 


.  B. 


O'OOllO 
0-00060 
0-00044 
0-00040 
0-00039 
0-00039 
Broke 


Wire  C. 


0-01390 
0-00127 
0-00080 
0- oi«l.s:i 
0-00036 
0-00039 
0-00027 
0-00027 
Broke 


Total  salt  per  running 
foot.    Grammes. 


Wire  A. 


o-ooso 

0-0019 
0-0016 
0-0018 
0  0011 
Broke 


Wire  C. 


0-0943 
0-0073 
0-0026 
0-0014 
0-0015 
0-0013 
0-0008 
0-0008 
Broke 


The  most  common  wet  coating  is  that  known  as  "  lees' 
coating.     Examples  of  its  preparation  follow : 

1.  Rye-flour  "lees"  are  made  by  stirring  two  or  threi 
pounds  of  flour  in  a  barrel  of  water. 

2.  Two  parts  "lees"  liquor  are  mixed  with  one  of  milk 
of  lime." 

3.  16-5  pounds  of  wheat-flour  are  boiled  with  9  gallon! 
of  water,  a  little  yeast  is  added  and  fermentation  follows,1 

Lacquer.  Before  wire  is  drawn  wet  it  is  often  lacquered, 
i.  e.,  coated  with  copper  by  immersion  in  a  slightly  acidu- 
lated copper-sulphate  solution,  usually  for  a  few  seconds 
only,  exceptionally  for  even  half  an  hour.  It  is  then 
immersed  in  the  "lees"  liquor  and  drawn.  Should  it  be 
badly  scratched  in  drawing  it  may  be  lacquered  again 
after  one  or  more  draughts  :  otherwise  the  lacquering  is 
not  repeated,  one  wet  draught  following  another  imme- 
diately. At  some  works  a  little  copper-sulphate  is  often 
added  to  the  "lees"  liquor  to  cause  a  slight  deposit  of 
copper  on  the  wire  :  those  who  do  not  follow  this  custom 
of  course  denounce  it  as  useless. 

The  copper  greatly  assists  lubrication  :  but  as  its  color 
persists  through  two  or  three  draughts,  wire  which  is  to 
have  a  bright  finish  should  not  be  lacquered  within  say 
three  draughts  of  the  last. 

The  preparation  of  the  wet  coating  is  in  the  hands  of 
the  individual  wire-drawer  himself,  and  he  guards  it 
jealously :  even  the  superintendent  professes  ignorance  of 
its  composition.  But  the  management  exercises  a  certain 
control :  e.  g.  it  will  not  permit  the  use  of  more  than  a 
certain  quantity  of  copper-sulphate. 

Dry  vs.  Wet  Drawing.  Let  us  consider  the  relative 
advantages  of  these  methods  of  drawing,  especially  seek- 
ing the  reason  why  dry  drawing  is  confined  to  coarse,  wet 
to  fine  wire. 

1 .  Wire-drawers  say  that  in  dry  drawing  the  die  cuts 
less  under  a  heavy  than  under  a  light  draught  or  reduc- 
tion. 

The  following  advantages  are  claimed  for  dry  over  wet 
drawing  : 

2.  The  wire  tends  less  to  rust,  thanks  to  the  grease  coat- 
ing. 

It  is  cheaper  than  wet  drawing : — 

3.  Because,  as  the  dry  coating  is  a  better  lubricant,  the 
draughts  may  be  heavier  than  in  wet  drawing. 

4.  Because  it  requires  a  less  thorough  washing  after 
pickling,  the  lime  partly  neutralizing  the  acid  if  any  re- 
mains. 

fi.  Because  it  requires  slightly  less  floor-room,  the  tubs 
needed  for  wet  drawing  necessarily  occupying  more  room 
than  the  simple  reels  of  dry  drawing 


a  Mertcalfe,  Rep.  Cbf.  Ordnance  U.  S.  A.,  1885,  p.  476. 

b  Fresou,  Revue  Universelle,  3d  Ser.,  XVIII. ,  p.  145.     1885. 


Dry  drawing  is  said  to  labor  under  the  following  dis- 
advantages : 

6.  It  lubricates  less  certainly  than  wet  drawing.     For  if 
the  drawer  be  inattentive  (and  each  drawer  has  several  lots 
of  wire  drawing  under  his  charge  simultaneously),  some 
of  the  wire  may  fail  to  be  coated   with  tallow  :    while 
the  wet  coating  is  necessarily  continuous. 

7.  Its  grease  dulls  the  wire,  and  persists  through  many 
draughts. 

8.  The  dry  coating  cuts  the  die  more  than  the  wet  coat- 
ing does. 

The  third  and  eighth  propositions  at  first  seem  to 
harmonize  poorly.  Their  discordance  appears  to  be  re- 
solved by  the  first  proposition  :  the  probable  explanation 
is  that  the  dry  coating  lubricates  best  for  heavy,  the  wet 
for  light  reductions. 

Of  these  considerations,  the  first  commends  dry  drawing 
for  coarse  rather  than  for  fine  wire,  the  third  gives  it  a 
greater  advantage  for  coarse  than  for  fine  wire,  which, 
owing  to  its  small  sectional  area,  would  break  if  too 
heavy  a  reduction  were  attempted 

The  sixth,  seventh  and  eighth  tend  to  confine  dry  draw- 
ing to  coarse  sizes,  weighing  lightly  against  the  dry  draw- 
ing of  coarse  but  heavily  against  that  of  fine  wire.  The 
sixth  for  this  reason : — annealing  is  especially  undesirable 
in  case  of  fine  wire,  for,  thanks  to  its  greater  surface,  more 
oxidation  occurs  in  annealing,  and  the  pickling  needed  to 
remove  the  oxide  formed  in  annealing  obviously  must 
consume  more  of  both  acid  and  wire  than  in  case  of  coarse 
wire:  washing  the  acid  from  the  pickled  fine  wire  is 
also  difficult  and  costly.  Hence  with  fine  wire  annealing 
must  be  dispensed  with  as  far  as  possible :  i.  e.  fine  wire 
must  undergo  many  draughts  without  annealing.  Be- 
cause it  is  made  brittle  by  these  repeated  draughts  with- 
out annealing  as  well  as  because  of  its  small  sectional  area, 
he  tendency  of  fine  wire  to  break  in  drawing  is  relatively 
great :  hence,  finally,  for  fine  wire,  because  of  its  greater 
iability  to  break,  the  more  certain  lubrication  of  wet 
drawing  is  needed.  The  seventh  because  the  bright  finish 
which  wet  drawing  alone  can  give  is  much  oftener  needed 
n  case  of  fine  than  of  coarse  wire :  this  tends  to  establish 
svet  drawing  as  the  normal  procedure  for  fine  wire. 

The  eighth  because  the  enlargement  of  the  die  must  be 
more  carefully  guarded  against  in  case  of  fine  than  of 
oarse  wire,  (a)  Because  the  coils  of  fine  wire  are  so  much 
onger  than  those  of  coarse,  and  owing  to  the  infrequency 
)f  annealing,  the  fine  wire  is  as  a  whole  harder  than 
oarse  wire :  hence  the  absolute  wear  of  the  die  during 
he  passage  of  a  single  coil  and  the  absolute  difference  in 
iameter  between  the  ends  of  the  coil  are  greater  under 
ike  conditions  for  fine  than  for  coarse  wire,  (b)  Because 
he  finer  the  wire  the  more  objectionable  is  a  given  abso- 
ute  variation  in  diameter. 

Thus  we  see  that  a  variety  of  considerations  all  tend  to 
he  same  result,  some  by  giving  dry  drawing  special  ad- 
antages  in  case  of  coarse  wire,  others  by  giving  it  special 
isadvantages  in  case  of  fine. 

Wet  drawing  was  unsuccessful  in  case  of  the  coarse 
quare  wire  for  the  Woodbridge  gun,  and  was  abandoned 
n  favor  of  dry  drawing. 

278.  DRAWING.— The  hank  of  wire  is  coiled  on  a  reel 
),  Figure  101.  Its  previously  tapered  end  is  men  passed 
hrough  the  draw-plate  C,  grasped  by  grippers,  and  a 


WIKE-DRAWING.      §  278. 


223 


TAULK  112.— BIRMINGHAM   WIKE  OAI-I:K  (K.    W.  O.). 


v>   i;  w  G 

•<IIHK> 

•000 

•Illl 

•ll      I        1 

2 

4 

5 

3 

7 

8 

!t 

10 

11 

12 

13 

14      i      15 

111      1 

Diameter,  inches  

•454 

•425 

•33 

•34    |       -30 

•284 

•259 

•288 

•820 

•203 

•180 

•165 

•148 

•134 

•120 

•109 

oee 

083    |     '072 

•068    | 

IHtlen-iice  in  iliaTii.  inrln-*. 

•m 

9    |     -04 

5    |     -04 

0    1     -040    |     -111 

ll    |     -IP. 

£    1     'OS 

1     |      Ml 

*    I    •<> 

7    |     -0- 

!3    |     •() 

15    |    -0 

7    |     -ii 

4    |     -ii 

14    |     -0 

11    |     -0 

2    |     -Oil    |     -0 

IT    |     -IXI7 

No.  B.  W  G  

17 

18 

19 

20      1      21 

22 

23 

24 

25 

26 

27 

28 

29 

:)0 

81 

89 

H 

34      1      85 

36 

Diameter,  inches  

•058 

IMfl 

•042 

•035    |     '032 

on 

•025 

•022 

•020 

•018 

•1)16 

•014 

•111:! 

•012 

•(110 

•1109 

•008 

•007     |     -IKI5 

•004 

lli!l'-reii<:c  in  <li:tin.,  inehe.s. 


'007    |     '003    |     '004    |     -003    |     '003    |     '002 


"U02    |     '002    |     'OU1    |     '001    |     HHI2    |     '001 


little  of  the  wire  is  drawn  through.  It  is  then  fastened  to 
the  dram  or  "block  "  A,  which  is  now  rotated  by  gearing, 
gradually  drawing  the  wire  completely  through  the  draw- 
plate.  In  wet  drawing  the  reel  stands  in  a  wooden  tub 
which  holds  the  lees  liquor. 

The  tendency  of  modern  practice  is  towards  heavier 
draughts.  Thus  while  some  mills  reduce  from  6  (rod)  to 
12  gauge  in  six  draughts,  the  more  advanced  use  but  three 
or  at  most  four  draughts.  The  reduction  may  be  heavier 
in  the  draught  immediately  following  an  annealing  than 
in  later  ones.  After  wire  has  been  reduced  to  about  1 8  or 
20  gauge,  further  reduction  is  usually  at  the  rate  of  one 
gauge  number  per  draught. 


Figure  101.— Wire-drawing  Machine.    (After  Beckert.) 

A  The  power-driven  drum  or  "  block"  which  draws  the  wire  through  the  draw-plate,  and  on 
which  the  drawn  wire  coils. 
B  The  shaft  which  drives  A. 

<3  The  die  or  draw-plate  through  which  the  wire  is  drawn. 
D  The  reel  on  which  the  wire  to  bo  drawn  is  coiled. 

The  wire  passes  from  J>  through  C  to  A. 

The  resistance  which  the  wire  offers  to  drawing  depends 
on  its  hardness,  on  the  reduction,  and  on  the  taper  of  the 
hole.  In  the  following  table  the  resistance  offered  by  hard 
steel  wire  (No.  III.)  is  over  thrice  that  offered  by  soft 
Swedish  iron  wire  (No.  I)  under  like  conditions. 

TABLE  113.— RESISTANCE  OK  WIKE  TO  DBAWINQ  (MORGAN,  Loc.  CIT). 


Block. 

Reduction. 

Designation. 

Diameter, 
inches. 

B 

& 

>  B 

y 

C  i  r  c  umfer- 
ential  vel- 
ocity, feet 
per  minute. 

Size. 

°1 

ill 
«:3.5 

Initial. 

Final. 

B.  W.G. 

Inches. 
A. 

B.  W.G. 

Inches. 
B. 

26 

22 
22 
22 
22 
22 
22 
22 
16 
16 
16 
16 
8 
8 
8 
8 
8 

45 

45 
45 
60 

806'  3  1 

5 

? 

101 
12 
18 
14 
13 
16 
17 
18 
19 
20 
21 
22 
23 
24 

•22 
•19 
•169 
•148 
•184 
109 
•095 
•088 
•072 
•OC5 
•058 
•049 
•042 
•HI 
•082 
•028 
•025 
•022 

«| 

5l 

If 

13 
14 
15 
1C 
17 
18 
19 
20 
21 
22 
23 
24 
25 

•19 
•18 
•148 
•134 
•12 
-095 
•083 
•072 
•065 
•058 
•049 
•042 
•035 
•082 
•028 
•025 
•022 
•02 

•86 
•95 
•8T 
•90 
•89 
•87 
•87 
•87 
•90 
•89 
•84 
•86 
•88 
•91 
•8T 
•89 
•88 
•91 

12  size  

'845:  6 

16-Inch  blocks  -| 
8-inch  blocks..  .     .  .    -| 

75 

432 

90 

90 

877 

877 

66 
66 
66 
66 

56 

117-3 
117-8 
117-3 
117-8 
117-3 

Where  great  strength  is  sought  the  reduction  may  be 
twice  or  even  two  and  a  half  times  as  great  as  this. 
Draw-Plates,  Figure  102,  examples  of  whose  composi- 
tion are  given  in  Table  115,  are  usually  made  of  intensely 
hard  steel,  sometimes  it  is  said  of  chrome  or  tungsten 
steel.     For  comparison  examples  of  the  composition  of 

Soft  Swedish  iron 


Diameter  before  drawing 

"        alter         "        

Reduction  of  area,  per  cent 

Length  of  taper  of  wire  in  die 

llKSISTANrK,   pounds 

Carbon,  per  cent 

Silicon 

Manganese 

Sulphur 

Phosphorus 


0-224" 
OM91 
27-3 
0"28 
1,060 


•031 


•399 
•006 
•084 


5  gauge 
auge 


II. 

Half-hurd  Besse- 
mer steel  wire. 


5  gaugi- 
6}  gauge 


0-226" 
0  VII 
24-9 


0  29 

8,054 

0'45 


•068 
1-04 
•052 
•144 


III. 


Hard  crucible 
steel  wire. 


0-224" 
0-192 
26-6 
0-84 

8,450 
0-86 

•209 
0-461 

025 

•114 


5   gauge 
6J  gauge 


Diameter  before  drawing 

"        after          ''         

I:I,M>TAM  i:,  pounds 

Carbon,  per  cent 

Silicon 

Manganese 

Sulphur 

Phosphorus . 


H.  ALLEN  (PRoe.  INST.  Civ.  ENG.,  XCIV.,  1888). 

IV.  V.  VI. 

Mild  steel.  Mild  steel.  Mild  steel. 

265  -221  -205 

•220  -183  -155 

2,200  1,850  1,600 


0-115 
0-009 
0-410 
0-068 
0-072 


I.  to  III.,  Morgan,  Trans.  Am.  Inst.  Min.  Eng.,  IX.,p.  672. 
IV.  to  VI.,  II.  Allen,  excerpt  Proc.  Inst,  Civ.  Eng.,  XCIV.,  18SS. 

The  resistance  in  pounds  is  given  by  Morgan  as  1'060,  3-054  and  S'450,  but  the  decimal  jwint  is 
apparently  here  given  by  typographical  error  for  a  comma. 


In  Vavra's  experiments  on  drawing  Bohemian  iron  wire, 
the  speed  of  the  drawn  wire  varied  from  120  feet  per 
minute  for  0-24"  diameter  (4  gauge)  to  399  feet  for  0'7" 


diameter  (15  gauge).8    Badeker  gives  the  usual  speed  as 
from  148  to  180  feet  per  minute." 

The  finer,  i.  e.,  more  flexible,  the  wire  the  smaller  is  the 
diameter  of  the  block  employed.  The  diameter  and  speed 
of  block  and  the  usual  reduction  per  draught  at  a  well- 
known  American  wire-mill  are  given  in  Table  114. 

TABLK  114 — SOME  DETAILS  OF  WIRE-DRAWING  IN  AN  AMERICAN  MILL. 


mint  dies  are  given  : 


TABLE  115.— COMPOSITION  OF  WIKE  AND  MINT  DIES. 


No. 

Au- 
thority. 

Description. 

Car- 
bon. 

Sili- 
con. 

ii 

c  a 
*%  gj 

S3 
Li 
—    O 

*-a 

02  "el, 

H 
3.3 

H" 

1-37 

0-78 

1-70 

0-20 

0'387 

0112 

0-091 

3 

u 

2-S9 

0-14 

0-26 

0-02 

0-031 

4.. 
5 

" 

'*    American,  as  good  aa  No.  3 

2-37 
1-97 

0-20 
0-013 

0-18 
0-396 

0-08 
0-014 

0-091 
0-009 

H 

1-92 

0-119 

0-856 

0-019 

tr. 

8.. 

Roberts. 

Best  mint  dies  

0'S2 
1-07 

0'05 
0-06 

0''0 

o-ia 

"tr°." 

tr. 
tr. 

10.. 

11.. 
1?, 

" 

Mint  dies,  apt  to  crack  in  hardening  
Best  American  mint-dies,  Foster's  steel..  . 

0-79 
1-19 
1-20 

018 
0-29 
0-1T 

0-24 
0-45 
0-22 

0-01 
tr. 

0-004 

0-01 
tr. 
0-029 

Oil. 
0-02 

numbc 

9    the 


y  by  0-00025". 

.a  ^hem.  News,  XLn i.,  p.  £•«',  J*»i  ,  wwui.  *»«n  »u«.  uw^.  *•.**«.,  .™., — .,  ,,.  ™-.    -  — 
r  8  200  000  florins  were  struck,   while   the   normal    output    per  die  is  50,000.     J 
average' output  is  54,000  pieces.     lOand   11  are  apt  to  crack  in  hardening.    Mint  die 
eei  is  so  soft  as  to  take  the  impression  from  a  bronze  piece.    I  have  a  bronze  coin  struck  from  a 
ie  so  prepared.     Under  a  strong  lens  it  is  seen  to  be  less  sharp  than  common  coins,  but  under 
mnl  observation  it  would  probably  pass  unnoticed. 
12     Mint  die  steel  made  by  Alex.  Foster*  Co.,  Philadelphia.    C.  K.  Barber  (Engraver  U.  S. 

Mint  at  Philadelphia,  private  'S^S'S^0^^^^^^^^^^^'^^^ 
"     teel.  ho  introduced  the  use  of  >  ostcr  s  steel  in  1Mb. 


cas 
12 

int 
i.loying  .Tessop's  s 


It  has  proved  superior 


i.oyng  .essops  see,  ie  nroce  . 

to  any  other  giving  us  a  far  greater  average  per  pair  of  dies  than  any  steel  ever  used  in  this  mint, 
and,  so  far  as  I  am  able  to  learn,  our  average  is  better  than  any  of  the  mints  in  Europe        The 
composition  here  given  was  kindly  determined  by  Messrs.  Hunt  and  Clapp,  of  "ttuhurfr,  for  thi 
work.    The  average  output  per  silver-dollar  die  in   1SS7  was  372,307  pieces;  559,140  has  been 
reached  for  an  average  in  making  bronze  one  cent  pieces. 


The  wire-drawer  himself  makes  the  holes  in  his  die, 
punching  or  "pricking"  them:  this  is  said  to  demand 
great  skill,  the  least  inaccuracy  breaking  the  punch  in  the 
hole.  As  the  die  wears  it  is  closed  from  time  to  time,  say 
every  few  hours,  by  hammering  the  metal  together  around 
the  small  end  of  the  hole. 


a  Jour.  Iron  and  St.  Inst.,  1884, 1.,  p.  227.    Oest.  Zeit.  XXXII.,  p.  199. 
*>  Stabt«nd  Eisen  VI.,  p.  182,  1886;  Iron  Age,  April  1,  1886,  p.  85. 


224 


THE     METALLURGY    OF     STEEL, 


Hard  white  cast-iron  dies  also  are  used  for  the  coarser 
sizes  of  wire,  say  Number  9  B.  W.  G.  and  coarser.  It 
might  indeed  be  difficult  to  make  holes  in  this  material 
small  enough  for  the  very  fine  sizes  of  wire :  the  punching 
or  pricking  used  in  case  of  steel  dies  is  hardly  applicable 
to  the  white  cast-iron.  When  the  hole  in  a  cast-iron  die 
wears  unduly  large,  it  can  be  reamed  out  and  used  for  the 
next  larger  size  of  wire. 

The  relative  merit  of  cast-iron  and  steel  dies  for  the 
coarser  sizes  is  in  dispute  ;  each  is  used  in  important  and 
intelligently  conducted  American  mills. 

When  extreme  accuracy  is  sought  a  sectional  steel  die 
may  be  used,  the  play  between  its  sections  being  initially 
too  small  to  cause  a  fin  on  the  wire,  yet  such  that,  by 
gradually  taking  it  up,  the  drawer  can  compensate  for  the 
wear  which  occurs  in  drawing  a  single  long  coil.  Gems 
too  may  be  used  for  accurate  drawing.  Their  use  is  rare 
in  this  country,  but  much  more  common  I  am  told  in 
Britain. 

The  draw-plate  is  in  some  cases  canted  slightly  to  the 


rear,  say  by  from  2n 


to  8°,  to 


'kill"  the  wire,  i.  e.  to  pre- 


vent the  tendency  to  spring  out  into  an  unmanageably . 
large  coil  on  removal  from  the  drum :    experiments  in 
drawing  wire  for  the  Woodbridge  gun  tended  to  show  that 
this  was  not  strictly  necessary. 


Fig. 102 

Drawplste  (Morgan). 

§  279.  ANNEALING. — The  coarser  sizes  of  wire  and  any 
wire-rods  which  may  have  been  rolled  at  so  low  a  tempera- 
ture as  to  render  annealing  desirable,  are  often  annealed 
in  muffles  :8  the  finer  sizes  are  annealed  in  pots  (figure  103), 
which  permit  less  oxidation.  They  are  usually  of  cast- 
iron,  sometimes  of  boiler-plate.  The  covers  are  often 
double,  to  exclude  the  air  more  completely.  The  anneal- 
ing temperature  may  be  about  700°  to  800°  C.  (1292°  to 
1472°  P.),  and  sometimes  as  high  as  982°  C.  (1800°  P.). 
In  certain  cases,  e.  g.  immediately  before  galvanizing, 
wire  may  be  annealed  by  passing  through  pipes,  or  be- 
tween iron  plates,  each  externally  heated.  (Figure  105). 


Fig;  103 
Annealing  Pot. 

I  have  already  pointed  out  that  fine  wire  cannot  well  be 
annealed,  its  enormous  proportion  of  surface  leading  to 
excessive  oxidation  in  annealing  and  excessive  corrosion 
and  consumption  of  acid  in  pickling,  its  fineness  making 
it  hard  to  wash.  In  practice  it  is  rare  to  anneal  wire  finer 
than  19  gauge,  and  in  some  mills  none  finer  than  14  gauge 

a  Ovens  heated  from  vt  ithout,  so  that  the  charge  within  them  is  not  exposed  to 
the  fuel  nor  to  tbe  products  of  its  combustion, 


is  annealed  (save  of  course  the  final  annealing  after  the 
last  draught  in  case  of  wire  which  is  to  be  sold  as  annealed). 
Thus  No.  3:-3  wire  must  usually  undergo  14  and  sometimes 
19  passes  without  annealing  :b  this  is  so  trying  that  only 
the  best,  i.  e.  costliest,  metal  can  be  drawn  to  the  finer 
sizes,  and  even  then  the  loss  by  breakage  is  serious. 

Even  with  coarser  wire  the  loss  of  iron  by  corrosion,  the 
consumption  of  acid  for  pickling,  and  the  pollution  of 
streams  with  the  pickling  liquor,  are  serious  matters  ;  the 
tendency  of  modern  practice  is  towards  less  frequent 
annealing.  In  drawing  from  wire-rod  to  fine  wire  there 
were  formerly  as  many  as  four  annealings,  to-day  only 
two  in  the  best  mills.  Wire-rods  can  now  be  rolled  hot  to 
6  gauge  in  repeating  mills  such  as  Garrett's,  and  at  least 
to  8  gauge  in  continuous  (Bedson)  mills  :  from  the  former 
size  the  wire  can  be  drawn  to  12  or  even  13  gauge,  from 
the  latter  to  14  gauge,  without  annealing. 

The  bad  consequences  of  annealing  just  noticed  are  due 
to  the  oxidation  which  it  entails  :  a  non-oxidizing  anneal- 
ing is  urgently  needed  not  only  that  we  may  avoid  them, 
but  also  for  making  wire  which  is  to  be  at  once  bright  and 
very  tough :  for  many  purposes  a  "  bright  annealed"  wire 
is  in  demand.  Hence  the  many  devices  for  rendering  an- 
nealing non-oxidizing,  and  for  removing  the  oxide  coating 
without  pickling.  Some  of  the  former  have  at  least  sue- 
ceeded  in  diminishing  oxidation  so  far  that  a  much  less 
concentrated  acid  is  needed  for  pickling,  lessening  the  con- 
sumption of  acid  and  loss  of  iron.  Indeed,  Badeker0 
states  that,  when  using  new  double-covered  pots,  many 
wire-drawers  avoid  pickling  middle-sized  wire  (9  to  15 
gauge  ?),  the  fine  wire  drawn  from  it  being  as  bright  as 
that  from  pickled  wire.  Of  these  devices  we  may  note  the 
following. 

1.  Mechanical  devices  for  removing  the  scale. d    In  some 
of  these  the  wire  is  bent  back  and  forth  e.  g.  as  in  Adt's 
apparatus,  Figure  104,  by  passing  between  a  series  of  rolls 
with  parallel  axes  placed  staggeringly,  the  wire  being  bent 
first  vertically  then  horizontally.     In  others  the  wire  is 
stretched  up  to  its  elastic  limit,  when  much  of  the  scale 
falls  off.     Employing  a  set  of  rolls  for  bending  the  wire 
Badeker"  uses  only  6-5  pounds  of  60°  B.  sulphuric  acid 
per  ton  of  wire. 

2.  Devices  for  diminishing  the  quantity  of  void  in  the 
annealing  pots,  e.  g.  by  placing  the  coils  of  wire  in  annu- 
lar spaces,  by  filling  the  voids  with  sand  or  infusorial 
earth,  etc. 

3.  Filling  the  pots  with  non-oxidizing  gases,  carbonic 
oxide,  producer  gas,  gas  distilled  from  coal,  horn,  wood, 
etc.,  gas-yielding  substances  being  sometimes  enclosed  in 
the  pots,  out  of  contact  of  the  wire. 

t>  Though  coarse  wire  is  raised  in  some  cases  to  above  230°  C.  (446° 
F.,  the  melting  point  of  tin)  by  the  friction  in  the  draw  plate,  yet  fine  wire  re- 
mains so  cool  that  it  may  be  grasped  in  the  fingers  as  it  issues  from  the  draw- 
plate  :  its  highest  temperature  in  drawing  may  not  be  above  180°  F.  (82*  C.),  at 
which  no  important  annealing  probably  occurs.  It  is  most  improbable  that  the 
wire  is  materially  hotter  even  at  the  instant  when  it  is  in  the  draw-plate,  for 
we  see  no  path  through  which  heat  can  escape  rapidly  enough  to  account  for  a 
rapid  fall  of  temperature  after  the  wire  has  left  the  plate.  Nor  do  we  notice  a 
very  rapid  rise  of  temperature  as  we  slide  our  fingers  along  the  departing  wire 
towards  the  draw-plate. 

c  Badeker,  loc.  cit.  He  exhibited  coils  of  No.  31  wire  (0'032",  O'Smm.)  which 
had  never  been  pickled,  even  after  leaving  the  rolling-mill,  the  rolling-mill  scale 
probably  having  been  removed  mechanically,  and  serious  oxidation  having  been 
avoided  in  the  subsequent  annealing. 

d  Wedding  describes  and  illustrates  many  of  these  devices  in  Stahl  und  Eisen, 
VI.,  p.  14,  1886,  No.  1. 

e  Idem,  p.  183  :  Iron  Age,  April  1st,  1886,  p.  35, 


WIRE-DRAWING.      §  280. 


225 


Nitrogen  should  be  perfectly  harmless  and  efficient  :* 
hydrogen  and  hydrogen-bearing  gases  might  be  injurious." 
Carbonic  acid  would  oxidize  the  iron  ;  and  even  carbonic 


Adt's  Apparatus  for  KemoYing  Scale  from  Win1. 


oxide  would  oxidize  it  slightly,0  but  perhaps  so  slightly 
that  its  effects  would  be  wholly  removed  in  drawing  :  it 
might  be  generated  in  the  pots  by  enclosing  charcoal  in 
them,  but  this  would  have  to  be  kept  out  of  contact  of  the 
wire  lest  carburization  occur.  It  has  been  proposed  to 
generate  carbonic  oxide  in  the  pots  by  placing  calcite  and 
coke  or  charcoal  within  them.  So  too  the  hot  pipes  used 
for  annealing  wire  maybe  tilled  with  non-oxidizing  gases  : 
but  the  wire  will  still  oxidize  in  cooling  unless  protected, 
e.  g.  by  passing  at  once  into  water. 

4.  Similar  to  the  last  is  the  plan  of  placing  iron  filings 
within  the  pots  to  consume  the  oxygen  present,  leaving 
an  atmosphere  of  nitrogen.     It  is  said  to  have  given  good 
results.*1    I  suggest  the  use  of  iron  sponge  as  a  much  more 
energetic  and  probably  cheaper  absorbent. 

5.  Wrought- iron  or  steel  instead  of  cast-iron  pots,8  pre- 


a  §  172,  p.  106. 
b§  178,  A,  p.  114. 
c§  182,  p.  118. 

d  Icbland,  Stahl  und  Eisen,  VI.,  p.  23,  1886. 

oU.  S.  patent,  377,000,  Jan.  34th,  1888,  J.  Withington  :  Iron  Age,  XLI.,   p. 
274,  1888  :  Beckert,  Leitfaden  zur  Eisenhiittenkunde,  p.  404,  1885. 


ferably  enclosed  in  cast-iron  ones  to  avoid  injury  by  the 
flames. 

0.  By  annealing  in  a  bath  of  lead,  which  melts  at  335° 
C.  (635°  F.)  Wedding1  would  avoid  oxidation.  Badeker8 
assails  the  project  vigorously,  holding  that  the  wire  would 
not  grow  hot  enough  to  be  annealed  if  passed  through  a 
lead  bath  of  reasonable  size  at  the  speed  employed  in 
drawing  :  this  may  be  true  of  wire-rod,  but  I  doubt  if  it 
is  of  wire  of  moderate  size.  Apart  from  this,  the  lead 
would  probably  adhere  to  the  wire  in  spots  :  this  would 
be  disastrous  except  when  the  wire  was  to  be  galvanized. 
Further,  as  iron  acquires  an  oxide  tint  at  220°  C.  and  be- 
comes dark  blue  at  about  316°  C.,  more  or  less  oxidation 
would  certainly  occur  in  cooling,  unless  the  wire  were 
specially  protected  after  leaving  the  lead. 

In  certain  cases  where  extraordinary  strength  is  needed 
steel  wire  is  hardened  by  quenching  before  receiving  the 
final  passes,  but  this  causes  a  great  loss  of  ductility. 
Hence  for  extreme  strength  combined  with  a  moderate 
amount  of  ductility  wire  is  better  hardened  a'ter  it  has 
received  its  last  draught.  Armstrong11  states  that  the 
elastic  limit  of  wire  is  raised  by  careful  annealing,  though 
the  tensile  strength  simultaneously  falls,  as  in  No.  17, 
Table  100,  p.  210. 

§  280.  EXAMPLES  OF  WiBE-D  RAWING. — Table  116  sum- 
marizes the  general  procedure  in  certain  cases. 

The  practice  in  examples  6  to  9  is  much  better  than  that 
in  the  first  five  examples,  while  that  in  Number  10  is  better 
still. 

In  drawing  the  wire  for  the  Woodbridge  wire-wound 
gun,  annealed  half- inch  square  open  hearth  rods  of  0'3l 


'  Stahl  und  Eisen,  VI.,  pp.  14,  183,  1886. 

g  Idem,  pp.  181,  S76.     Iron  Age,  Apl.  1,  1886,  p.  25. 

h  Kept.  British  Ass.,  1882,  p.  403.     Cf.  §  270,  p.  214. 


TABLE  116.— EXAMPLES  or  GFNF.KAL  PROCEDURE  is  WIRK-DRAWIM;. 


Example  1. 

Example  2. 

Example  3. 

Example  4. 

Example  5. 

Description  of  iron. 

Initial  size. 
Procedure  before  first  draught. 

First  sc-t  of  draughts,  Nos.  B.  W.  G. 
Procedure  between  first  anil  second 
sets  of  draughts. 

Second  sets,  of  draughts,  Nos.  B.  \V.  G 
Procedure  between   second  and  third 
sets  of  draughts. 

Third  set  of  draughts,  Nos    P>.  W.  G 
Procedure  between  third  and   fourth 
sets  of  draughts. 
Fourth  set  of  draughts,  Nos.  B  .  W.  G 
Procedure  between   fourth   and   fifth 
sets  of  draughts. 
Fifth  set  of  draughts,  Nos.  B.  W.  G. 

Bessemer  steel  of  (V4;>#  carbon, 
for  pins. 
No.  6  rod. 
Pickle,  wash,  dip  in  flour-water, 
dry. 
8,  9J  (drawn  dry). 
Anneal,  pickle  (?),  wash  (?),  dip 
in  Hour-water,  dry. 

11J,12A  (drawn  dry). 
\nneal.  pickle  (?),  wash  {?),  dip 
in  Hour-water,  dry. 

14,  15*  (drawn  dry). 
\nneal  (?),    pickle,    wash    (?), 
lacquer. 
15J,  1<H  (drawn  wet), 
Anneal,     pickle,      wash,     bat, 
lacquer. 
174,  184,  19,  19$,  20.  21   (drawn 
wet). 

Kessemer  steel  of  0*45^  carbon, 
for  fencing. 
No.  6  rod. 
Pickle,  wash,  dip  in  salt,  dry. 

8*,  1<H,  1H,  12J  (drawn  dry). 
Coat  with  oil  or  zinc. 

Bessemer  steel  of  0-50#  carbon, 
for  coppering. 
No.  5J  rod. 
Pickle,    wash,     lacquer,    coat, 
dry. 
8J,  9J  (drawn  dry). 
Pickle,    wash,     lacquer,    coat, 
dry. 

10J  (drawn  dry). 
Lacquer. 

11  (drawn  wet). 

Charcoal    iron     for    telephone 
wire. 
No.  6  rod. 
Pickle   (?),    wash    (?),    dip   in 
Hour-water  (?). 
Si,  10,  11,  12  (drawn  dry).? 
Anneal,  pickle,  wash,  coat,  with 
flour. 

13,  14  (drawn  dry  *). 

Swedish  iron  for  fine  wire. 

No.  4.  rod. 
Pickle,  wash,  dip  in  hot  water, 
then  in  hot  soda. 
6},  Si,  (drawn  dry). 
Anneal,  pickle,   wash,  dip    In 
flour  and  lime-water,  drain, 
drv. 
I0"i,  Hi,  12J  (drawn  dry). 
Anneal,  pickle,  wash,  dip    in 
flour-  and  lime-water,  drain, 
dry. 
14,  lf>}Mrawndry). 
Anneal,  pickle  (?),  wash,   lao- 
4uer. 
,  174,  18J,  194  (drawn  wet). 
Anneal,  pickle,  wash,  bat,  lac- 

80f.SU,  23J    24},  2T,  28|.  31, 
33,  84,  35,  86  (drawn  wet). 

1 

Example  6. 

Example  7. 

Example  8. 

Example  9. 

Example-  10. 

Description  of  iron. 

Initial  size. 
Procedure  before  first  draught. 

(  Nos.  B.  W.  G. 

First  set  of  draughts-; 
1  Reduction  % 

Swedish      iron     for     Western 
Union  telegraph  wire. 
No  4$  rod. 
I*ickle,  wash,  lime-coat,  bake. 

5,  G  (drawn  dry). 
4,  S. 

Bessemer  steel  of  O'lO^  carbon, 
for  fencing. 
No.  5  rod. 
Pickle,  wash,   lime-coat,  bake 

64,  TJ,  9  (drawn  dry). 
13,  12,  13, 

Hessemer  steel  of  0'10#  carbon, 
for  fencing. 
No,  5  rod. 
Pickle,  wash,   lime-coat   twice, 
bake. 
64,  8,94,  10},  12  (dry). 

Bessemer  steel  of  0'10#  carbon, 
for  harvester  wire. 
No.  5  rod. 
Pickle,  wash,  lime-coat,  bake. 

<H,  7f,  9  (drawn  dry). 
13,  12,  13. 

Swedish  iron  for  fine  wire. 

No.  6  rod. 
Pickle,  wash,   lime-coat,   bake. 

In  3  or  4  draughts  to  No.  12 
(drawn  dry). 

Procedure  between  first  and   second 

Anneal,  pickle,  wash,  lime-coat, 

Muflle,  pickle,  wash,  lime-coat. 

sets  of  draughts. 
(  Nos.  B.  W.  G 

bake. 
7,  8  (drawn  dry). 

bake. 
104,  12  (drawn  dry). 

bake. 
lOj,  12,  13,  14  (drawn  drv). 

bake. 

In   6   draughts    to     No.  19  (2 

Second  set  of  draughts^ 
(  Reduction  % 

1,8. 

14,  14. 

14,  14,  13,  13. 

draughts  dry,   then    lacquer 

Procedure  between   second   and  third 

Anneal,  pickle,  wash,  lime-coat, 

Anneal,  pickle,  wash,  Twit,  stand 

Anneal,  pickle,  wash,  bat. 

sets  of  draughts. 

1  Nos.  B.  W.  G. 

Third  set  of  draughts  < 
(  Redaction  %. 

stand  for  1  to  7  days,  bake, 
galvanize. 



in  water,  immerse  in  "  Ices." 

15,  16,  17,   IS,    li>,   20   (drawn 
wet). 
13   10  11    1<1  14  17. 

20,  21,  22,  23,  24.  25,  26,  27,  28. 
29,  80,  31,  32,  33  (drawn  wet). 
9     11     9     11     7     17 

Each  column  represents  the  procedure  in  some  one  case.  The  numbers  In  each  horizontal  lino  in  a  given  column  represent  the  si/e  of  the  wire  (gauge  number)  on  emerging  from  passes 
which  succeed  each  other  without  intervening1  treatment :  tho  text  Indicates  the  operations  between  tlic  last  p.iss  of  the  preceding  and  the  first  of  the  following  line.  Examples  1  to  5  from, 
Freson,  Rev.  Univ.  2d  Ser.,  XVIII.,  p.  1 1!»(  1885,  "  Les  Treflleries  Americoines."  Examples  6  to  10  from  the  author's  notes. 


226 


THE    METALLURGY     OF    STEEL. 


to  0'32$  of  carbon  were  reduced  to  (V15"  square  wire 
in  ten  draughts  without  annealing,  the  corners  of 
the  wire  being  slightly  rounded.  The  wire  was  coated 
with  lime-flour  paste  and  dried  before  each  draught :  after 
the  second  draught  (and  apparently  after  all  subsequent 
ones)  the  wire  was  lacquered  before  the  lime-flour  coating 
was  applied.  The  speed  of  drawing  varied  from  fifteen 
feet  per  minute  for  the  first  to  twenty-seven  for  the  last 
draught.  The  ratios  of  reduction  and  the  absolute  reduc- 
tions were  as  follows : 

TABLE  117.— EKDI-CTION  IN-  DKAWIM;  Grn-WiRK  (MEDCALFF.). 


No.  of  draught. 

Initial 
size. 

1. 

2. 

8. 

4. 

5. 

8, 

7. 

8. 

9. 

10. 

Assigned  size,  inches 
Reduction,  per  side. 

0  5 

0-4J5 
0-055 

0-394 
0-051 

0-849 
0-045 

0  3111 
0-039 

0  274 
0  036 

(i  •>;": 
0  031 

(1  215 

II  02S 

0-191 
9-024 

OMP9 
0  022 

0-150 
0  (119 

•89 

•ass 

•8S6 

•sss 

884 

•887 

885 

•8S4 

•885 

•8S8 

The  dies  were  1  "75  inches.thick :  the  holes  were  tapered, 
about  1  in  5,  at  the  outside  face,  but  square  and  straight 
through  the  inner  half  of  the  plates  thickness. 

Though  the  wire  was  of  admirable  material,  there  were 
so  many  breakages  that  the  scrap  and  defective  wire  were 
estimated  at  fully  ten  per  cent,  of  the  total  weight :  hence 
the  conclusion  that  this  is  about  as  severe  treatment  as 
iron  can  successfully  endure.  (The  scrap  appears  to  have 
been  chiefly  pieces  weighing  less  than  twenty  pounds)." 

§  281 .  PROTECTIVE  COATINGS. — A  copper  coating  is  given 
by  dipping  the  coiled  wire  in  acid,  washing  this  off  in  water, 
then  immersing  the  wire  for  a  few  seconds  in  a  copper- 
sulphate  solution  acidulated  with  sulphuric  acid,  when 
copper  precipitates  on  the  iron.  The  wire  is  then  drawn 
to  brighten  it.  It  is  then  sometimes  again  copper-coated 
and  further  drawn. 

For  galvanizing  the  wire  is  usually  first  annealed,  e. 
g.,  by  passing  through  an  iron  muffle  as  at  A,  in  Figure 
105. 

It  passes  thence  immediately  into  a  bath  B  of  say 
hydrochloric  acid,  and  thence  through  a  bath  of  molten 
zinc  in  an  iron  kettle"  D,  thence  through  a  notch 


finally  to  a  power-driven  drum  F,  on  which  it  is 
coiled.  The  scraping  pincers  may  readily  be  opened,  to 
allow  the  joint  between  successive  coils  of  wire  to  pass. 
In  practice  several  wires  side  by  side,  each  guided  by  its 
own  set  of  sheaves,  G,  II,  and  coiling  on  its  own  drum  F, 
pass  through  these  baths  simultaneously. 

Tinning  is  usually  applied  to  finer  wire  which  does  not 
need  annealing :  otherwise  the  procedure  is  much  the  same 
as  in  galvanizing.  The  wire  is  passed  through  a  bath  of 
acid,  thence  directly  into  one  of  molten  tin,  thence  through 
pincers  which  scrape  off  the  excess  of  tin,  thence  through 
a  bath  of  castile-soap  water,  thence  to  the  drum  on  which 
it  is  coiled.  The  soap  coating  is  to  prevent  the  wire  from 
turning  black.  The  wire  is  often  further  drawn  after 
tinning,  to  give  it  a  bright  coat. 

§  282.  TESTS  FOR  WIRK. — Besides  the  usual  tensile  tests, 
wire  for  rope  and  many  other  purposes  is  tested  for  flexi- 
bility. This  property  is  usually  gauged  by  the  number  of 
times  the  wire  can  be  kinked,  as  in  Figure  107,  and 
straightened.  This  very  crude  test  evidently  offers  great 
temptation  for  trickery,  and  must  give  way  to  more  trust- 
worthy methods,  such  as  that  of  bending  back  and  forth 
180°  between  round- cornered  iron  cheek-pieces  (Figure  108) 
which  grasp  the  wire  firmly,  so  that  successive  bendings 


Fig.  107.— Kink-test  for  Wire 


Fig.  103.— Bonding  test  for 
Wire. 


must  occur  at  the  same  spot.  The  free  end  of  the  wire 
is  held  in  pincers,  so  that  rotation  of  the  wire  around  its 
own  axis  may  be  prevented.  Table  118  gives  the  number 
of  bends  required  by  the  German  government  in  case  of 
rope  wire. 


Figure  105.  -Galvanizing  Plant  (Becker*). 


•122 
11 
6(37 
4@6 

•11 
12 
7<as 
5@7 

•098 
12J 
8@9 
5@7 

•079 
14] 
12(3)14 
IO8 

•1170 

IN 

14®  15 
7(g.S 

•002 
161 

l.VK! 
S®9 

•055 
171 
1C@17 
10@12 

•(  1:1:1 
19* 
17@18 
l-A-'M 

Size  of  wire,  B.  W.  G,  ±  

required         1  for  ingot  and  weld-iron 

'Communicated  by  Mr.    E.   Gibbon  Spilsbury    Managing   Director  of  the  Trenton  Iron 
Company. 

Fig.  106.— Pincers  for  Scraping  ofl  Excess  of  Zinc  (Beckert). 


in  a  pair  of  pincers  E  (Figure  105  and  Figure    106) 
in    which   the  excess    of    zinc    is    scraped    off :    thence 


"  Medcalfe,  Kept.  Chief  Ordnance,  1885,  pp.  436,  473. 

b  Concerning  the  zinc-iron  alloy  which  collects  m  this  kettle  C  P,  §  145,  p.  84. 
As  the  alloy  collects  at  the  bottom,  the  kettle  is  heated  on  its  sides  but  not  from 
beneath. 


TABLE  118.— BENDINGS  (FIGURE  108)  REQUIRED  BY  THIS  GERMAN  GOVERNMENT  FOR  UOPE  WIKF.* 


COLD-ROLLING  AND  COLD-DRAWING. 
§  283.  IN  COLD-ROLLINGC  the  previously  pickled  bar  is 
passed  repeatedly  between  highly  polished  chilled  cast- 
iron  rollers,  the  reduction  being  controlled  by  frequent 
calipering.  The  general  disposition  of  the  roll-train  is 
the  same  as  for  hot-rolling,  but  permits  umisually  accu- 
rate adjustment  of  the  rolls.  Round  bars  are  rolled  over 
and  over  in  the  same  groove,  and  rotated  slightly  between 
passes,  for  of  course  only  a  short  arc  at  the  top  and 
bottom  of  the  groove  can  conform  accurately  to  the  sec- 


c  Bernard  Lauth,  U.  S.  patent  31,546,  Feb.  26th,  1861. 


COLD-DRAWING.       |  284. 


227 


tion  aimed  at.  Thus,  at  one  mill,  round  bars  receive  on  an 
average  from  30  to  40  passes  each,  with  a  total  reduction  in 
diameter  of  about  ^  inch  when  less  than  three  inches  in 
diameter,  and  about  -^  inch  when  larger."  The  output 
from  each  stand  is  evidently  chiefly  dependent  on  the 
circumferential  velocity  of  the  rolls,  and  on  the  accuracy  of 
section  aimed  at,  for  great  accuracy  demands  not  only  very 
careful  calipering  but  very  many  passes,  with  very  slight 
rotation  between  each  pass  and  the  following.  In  prac- 
tice extreme  accuracy  is  generally  needed,  for  the  round 
bar  must  generally  be  in  "  wring  fit,"  i.  e.,  it  must  fit  the 
coupling  or  other  piece  which  is  to  receive  it  so  closely 
that,  while  it  cannot  be  readily  slid  or  pushed  on,  it 
can  be  wrung  on.  With  section  accurate  to  within  T^¥ 
inch,  this  mill  turns  out  about  1000  running  feet,  or  say 
50  bars,  per  train  of  rolls  per  shift. 

Fresonb  gives  the  following  details  of  practice  at  an 
American  mill.  After  pickling  in  liquor  composed  of  ten 
parts  of  water  and  on9  of  sulphuric  acid  of  60°  B,  the  bars 
are  dipped  in  lime-water,  dried,  and  rolled  repeatedly 
through  a  single  groove,  with  reductions  of  from  ^JV  to 
-ifor"  at  a  pass  There  are  three  roll-trains  of  the  follow- 
ing dimensions: 

TAHI.K  119.— TRAINS  FOR  COLD-ROLLING  AT  AN  AMERICAN  MILL. 


with  an  angle  of  93°,  and  a  fillet  of  0-3"  radius.  After 
rolling  five  24-foot  bars  with  a  reduction  of  109  per  inch, 
the  upper  roll  cracked  in  two  through  the  bottom  of  the 
groove  with  very  little  warning,  showing  a  chill  5"  to  G" 
deep  :  the  failure  was  attributed  to  excessive  depth  of  chill. 
A  third  set  of  rolls,  apparently  like  the  second,  but  with 
a  guaranteed  chill  of  two  inches,  rolled  seven  24-foot  bars 
without  mishap  or  apparent  injury,  reducing  at  the  rate 
of  from  132  to  140  passes  to  the  inch.  These  results  are 
here  condensed. 


Average  men  X  minutes  =  4S'5  or  24'25  cents  per  bar,  assuming  that  eight  effective  hours 
wutk  cn.st 


The  degree  to  which  cold-rolling  may  be  carried  is  indi- 
cated by  the  results  of  the  following  experiments."  Thor- 
oughly annealed  open-hearth  steel  bars,  apparently  con- 
taining 0'31  to  0'82$  of  carbon*  and  4  '5  inches  square, 
were  to  be  reduced  to  3  43  inches  square  in  the  fewest 
possible  passes.  Rolls  22  inches  in  diameter  and  18  inches 
long  were  employed.  The  first  pair  of  rolls  tried  had  a 
single  groove  2  42"  deep  (the  semi-diagonal  of  3'43")  in 
each  roll,  with  an  angle  of-  91  °,  and  closed  with  a  fillet  of 
0'17"  radius.  The  lower  roll  broke  through  the  bottom  of 
the  groove  after  24  passes  on  a  12  foot  bar,  reducing  at  the 
rate  of  82  passes  per  inch  (i.  e.  such  that  82  passes  would 
reduce  the  side  of  the  square  by  1")  and  6  passes  at  the 
rate  of  120  per  inch.  The  failure  was  attributed  chiefly  to 
the  sharpness  of  the  corners  of  the  bar,  which  cut  into  the 
roll,  and  this  sharpness  in  turn  (A)  to  the  depth  of  groove, 
which  increased  the  drag  of  the  bar  on  the  bottom  of  the 
groove,  (B)  to  the  short  radius  of  the  fillet,  and  (C)  to  the 
small  angle  (91°)  of  the  groove. 

The  second  pair  of  rolls  had  two  grooves  1\  9"  deep, 

»  Private  communication  frem  the  management,  Juno  27th,  1SS8. 
u  Revue  UniverseHe,  2d  ser.,  XVIII.,  p.  338,  1835. 
c  Medoalfe,  Kept.  Chf.  Ordnance.  U.  S.  Army,  1885,  p.  469. 
«  Idem,  1884.  pp.  432-3. 


TABLE  121.  —  EXPERIMENTS  IN  COLD-ROLLING 


STEEL  BABS. 


y, 

^. 
* 
— 

1. 

2. 
B. 

Description  of  rolls. 

Performance. 

Grooves. 

Depth 
of 
Chill. 

PMMI 

per  1" 
reduction. 

Result. 

No. 

1. 

2. 
tJlfi 

Depth. 

Angle. 

Fillet 
radius. 

2-42" 

1-59" 
1-6" 

91° 

93° 
93°(?) 

0-17" 

0-30" 
0.30"(») 

lb«r]+2Jl'a!fcs- 
6  24'  bars. 
.       T  24'  bars. 

52 
120 
109 
132  ®  140 

[  Roll  broke. 

Uoll  broke. 
No     accident: 
roll  intact. 

5"  @  6" 
2"  estimate. 

Number  of 
stands. 

Distance      lie- 
tuvrn  centre's. 
inches. 

Revolutions 
per  minute. 

Circumferen- 
tial velocity, 
feet  per 
minute. 

Product. 

1st  train  

4   stands  +  1 
pollsbiiifrstand 

2 

i  ; 

IS" 
12" 
10" 
12" 

40®45 
40®  45 
60®  60 
50®  60 

1SS'  @  212' 
126'  ©  141' 
131'  ®  157' 
157'  ®  188' 

Hounds,   Ij"  @  4f 
diameter. 
Rounds,  J"   ©  H" 
dhimeter.c 
Rounds,    i"    ®  J" 
diameter. 
Flats  and  squares. 

2(1  train  

8d  train  

c  Given  as  5-4"  ©IJ"  in  tUe  original,  but  probably  by  typographical  error. 

Some  c 

Diameter  of  ba 
Diunii'ter  of  bi 
lUMuetioli  nf  d 

Number  "1*  ji;is 
Tiiiu-  occupied 

>f  the  details  of  rolling  are  as  follows 

I'Alil.K   120.—  COLU-UOLLINU   AT  AN   A.MEB1CAN   MILL,    CONC 

r,  initial,  inches  2-ft6 
r   final                                       .           2-8(1 

: 

LUDE 

•5 
1-38 
8* 
80 
18 
3 

39 

3. 

0-75 
063 
16* 
81 
15 
1,  +  1  boy 

22-5 

ies                                           4S 

minutes  28 

(Freson's  data  end  here) 
Men  X  minutes.  .  .                                                                          .      &4 

§  284.  COLD-DRAWING. — Previously  pickled  steel  and 
iron  bars,  round,  square,  hexagonal,  etc.,  are  drawn  cold 
through  a  die  to  strengthen  them,  raise  their  elastic  limit, 
polish  them,  and  give  them  accurately  uniform  section. 
The  bar  in  emerging  from  the  die  tends  strongly  to  warp, 
and  to  lessen  this  tendency  Billings'  self-centring  appar- 
atus6 is  devised.  As  ithis  is  the  best-known  apparatus,  let 
it  suffice  as  an  example  of  the  general  procedure. 

The  end  of  the  rod  R,  having  been  hammered  down  so 
that  it  may  pass  through  the  die  S,  is  grasped  by  the 
clutch  a,  which  is  shown  in  transverse  section  in  Figure 
110,  and  is  practically  a  pair  of  wedges  like  those  of  com- 
mon iron-testing  machines,  with  semi-cylindrical  toothed 
recesses  for  grasping  the  rod.  The  draw-bar  E,  moved  by 
a  hydraulic  cylinder,  then  pulls  the  clutch  to  the  right, 
drawing  the  bar  through  the  die.  In  the  device  shown 
the  die-seat  f  rests  on  four  rollers  e,  and  is  tipped  so  as  to 
centre  the  die  by  four  set-screws  m  m,  of  which  only  two 
are  here  shown.  In  another  arrangement  the  die-seat  is 
hung  in  gimbals  on  knife-edges,  and  in  still  another  the 
spherical  ended  die-seat  rests  in  a  spherical  recess  in  the 
draw-bench,  forming  a  ball-joint.  In  both  cases  the  die 
may  be  centered  by  set-screws  as  in  Figure  109,  or  may  be 
allowed  to  centre  itself. 


Figs.  109-110.— Billing's  Cold-drawing  Apparatus. 


In  spite  of  these  expedients  the  bar  usually  becomes 
slightly  bent  in  drawing,  the  camber  in  many  bars  which 
I  have  seen  varying  from  nothing  to  1  •£»  inches  in  20  feet, 
estimated  by  the  eye.  The  bar  is  next  straightened  by 
passing  it  between  three  horizontal  rollers. 

e  U.S.  patents  130,465,  G.  H.  Billings,  Feb.  36th,  1872:  395,898,  C.  C.  Bil- 
lings, April  1st,  1884.  Engineering  an!  Mining  Jl.,  XXXV.,  p.  222,  1883. 
Revue  Universelle,  2nd  ser.,  XVIII.,  p.  351,  1885;  Stahl  und  Eisen,  VI  ,  p.  177, 
1886. 


228 


THE    METALLUKGY    OF     STEEL. 


On  an  output  of  six  tons  about  ten  men  are  employed  : 
this  includes 


Two  at  each  drawing  press 
Two  straightencrs 
Machinist 


1 


.............................................................. 

Pickling  ....................................................................  2 

Other  .......................................................................  1 


Total  ..................................................................  10 

Details.  —  At  an  American  mill  bars  from  f  to  3  inches  in 
diameter  are  thus  drawn,  of  round,  square,  and  other  simple 
sections.  The  usual  reduction  is  about  1-16  inch,  but  oc- 
casionally as  much  as  3-1  6  inch  per  draught  The  total 
reduction  is  usually  effected  in  one,  but  occasionally  in 
two  draughts.  There  are  two  drawing  benches,  with  hy- 
draulic cylinders  15  inches  and  8  inches  in  diameter  re- 
spectively, with  a  stroke  of  about  23  feet,  and  with  hy- 
draulic pressure  of  about  600  pounds  per  square  inch. 
Their  capacity,  which  greatly  exceeds  that  of  the  rest  of 
the  'department,  is  estimated  roughly  at  20  tens  per  shift, 
or  rather  more  if  running  chiefly  on  the  larger  sizes.  The 
engine  which  furnishes  the  power  is  so  small  that  about 
2  min.  30  sec.  are  required  to  draw  bars  of  the  larger  sizes,  , 
and  the  return  stroke  takes  1  min.  30  sec.  :  add  20  sec.  for 
attaching  the  clutch,  and  we  have  a  total  of  4  min.  20  sec. 
Mr.  Billings  assures  me,  however,  that  there  is  no  diffi- 
culty in  drawing  at  the  rate  of  1  min.  or  even  less  per 
draught.  The  dies  are  made  of  hard  carbon-steel,  which 
has  proved  more  suitable  than  Mushet's.  In  drawing 
about  2,000  running  feet,  or  100  bars,  the  diameter  of 
the  die  becomes  enlarged  by  about  O'OOl  inch.  It  is  then 
slightly  closed  by  heating  and  hammering,  and  dressed 
on  a  conical  emery  wheel  to  the  exact  size  desired.  The 
cost  of  hammering  and  dressing  each  die  is  estimated  at 
ten  cents,  or  at  O'l  cent  per  bar  drawn. 

Cold-Rolling  and  Cold-Drawing  Compared.  —  The  fol- 
lowing very  rough  calculation,  necessarily  based  in  large 
part  on  estimate,  aims  solely  to  compare  these  two  pro- 
cesses, and  does  not  take  into  account  items  of  cost  which 
are  substantially  the  same  in  each,  such  as  pickling, 
straightening,  and  cutting  to  length. 

I  have  no  direct  means  of  comparing  the  cost  for  power, 
repairs  and  interest,  but  from  general  knowledge  of  the 
two  processes  I  believe  that  it  is  much  higher  for  rolling 
than  for  drawing.  Still,  let  us  assume  that  they  are 
equal,  and  further  let  us  take  the  actual  time  of  drawing 
with  the  present  somewhat  tentatively  constructed  plant 
and  with  insufficient  power,  assuming,  however,  that 
operations  are  on  a  large  scale,  so  that  the  time  of  the 
men  who  hammer  down  the  ends  of  the  bars  and  cut  off 
the  ends  in  lathes  is  fully  employed. 

The  waste  is  greater  in  cold-drawing  than  in  rolling, 
because  the  end  which  is  hammered  down  to  enable  it  to 
enter  the  die  must  be  cut  off  at  any  rate.  Taking  this 
excess  at  1-5  pounds  per  bar,  and  charging  ^  J  cents  per 
pound  for  the  difference  between  the  value  of  scrap  and 
of  the  bar  ready  for  drawing,  we  arrive  at  1  "87  cents  per 
bar  as  the  amount  chargeable  to  cold-drawing. 

Debit  of  cold-drawing,  per  bar.  Cents. 

Excess  of  waste  ..................................................     1  *87 

Min. 
Hammering  down  theend  of  the  bar,  1  man  2  minutes  ........     2 

Drawing,  2  men  4'5  minutes  ................................     9 

Cutting  oil'  the  end  of  the  bar,  1  man  2  minutes  ...............    2 

Total,  minutes  ............................................  18 

18  minutes  at  $2.40  per  8  effective  hours  work  =05  cts.  per  minute-    6'  50 
Cost  of  dressing  die,  10  -*-  100  .....................................     O'lO 

Totaldebit  ..................................................     8-47 

Credit,  outlay  of  labor  in  cold-rolling,  48-5  minutes,  at  0'5  cts  ............  24'25 

Balance  to  credit  of  cold-drawing,  cents  per  bar  ....................  1.V78 

So  heavy  a  balance  as  this  can  hardly  be  outweighed  by 


other  unknown  differences.  Indeed,  leaving  all  estimates 
aside,  it  is  hard  to  believe  that,  with  equally  careful  man- 
agement, the  cost  of  a  single  draught  can  equal  that  of 
many  passes  through  rolls,  increased  by  the  necessity  of 
frequently  calipering  the  bar.  Freson  seems  to  think  cold- 
drawing  more  expensive  than  cold-rolling  a  :  I  think  he  is 
mistaken. 


PUNCHING  AND  SHEARING. 

§  285.  PUNCHING  produces  in  iron  a  veritable  flow,  the 
particles  of  metal  moving  away  from  the  approaching 
punch  in  their  paths  of  least  resistance.  The  Tipper  sur- 
face is  drawn  down  somewhat  like  the  surface  of  water 
over  a  submerged  outlet,  as  shown  in  Figure  111.  Of  the 
metal  initially  in  the  path  of  the  punch  a  part,  whose  pro- 
portion to  the  whole  seems  to  vary  directly  as  the  thick- 
ness of  the  bar  and  inversely  as  the  diameter  of  the  hole, 
and  which  sometimes  amounts  to  69#  of  the  whole,  is  forced 
laterally,  bulging  the  piece,  while  the  rest  is  driven 
directly  before  the  face  of  the  punch  as  a  core.  The  flow 
and  the  small  proportion  which  the  rejected  core  bears  to 
the  volume  of  the  hole  are  illustrated  in  Figure  112.  The 
natural  supposition  that  the  pressure  gives  the  ejected 
core  a  density  greater  than  that  of  the  mother-block  is 
incorrect.  Indeed,  D.  Townsend  found  the  density  of  core 
and  block  7'78  and  7 '82  respectively,  a  difference  far  beyond 
the  limits  of  experimental  error  in  careful  work." 


Figure  111. — Flow  of  Metal  in  Punching. 


Figure  112.— Flow  ot'iletal  In 
Punching. 


Punching  usually  lowers  the  strength  and  ductility  of 
the  mother-metal,  the  loss,  at  least  in  case  of  tensile 
strength,  increasing 

1,  with  the  distance  of  the  hole  from  the  edge  of  the 
piece,  at  least  in  case  of  soft  steel ; 

2,  probably  with  the  proportion  of  carbon  ; 

3,  probably  also  with  the  initial  hardness  of  the  piece, 
however  caused ; 

4,  with  the  thickness  of  the  piece  ;  and, 

5,  as  the  clearance  between  punch  and  die  decreases. 
The  influence  of  clearance-size  seems  to  decrease  with 

the  ratio  of  width  to  thickness  of  bar. 

Supporting  evidence  will  be  offered  shortly. 

We  can  usually  remove  these  effects  completely  either 
by  heating  (whether  with  fast"  or  slow  cooling),  or  by 
reaming  or  countersinking  the  hole :  and  perhaps  par- 
tially, at  least  in  case  of  thin  plates,  by  hot-riveting,  the 
heat  of  the  rivet  causing  a  partial  annealing.  But  rivet- 


•  Op.  Cit.,  p.  353.  "  Les  Chiffres  de  la  main-d'oeuvre  et  de  1'entretien  ont  line 
part  plus  considerable  dans  le  prix  de  revient,"  in  cold-drawing  than  in  cold- 
rolling. 

b  Journal  Franklin  Inst.,  CV.,  p.  145,  1878. 

c  Needless  to  say,  fast  cooling  sets  up  new  conditions,  which,  however,  are 
nearly  if  not  quite  independent  of  the  previous  punching,  whose  effects  are 
effaced  in  heating. 


THE  EFFECTS  OF  PUNCHING.     §  sss. 


229 


TAHI.K  121A. — Pus  CUING:  ITS  )  i 


Number.  |l 

Authority. 

I.  Description  of 

punched  test-pi.  •,•,•. 

Punching 
condition!*. 

II.  Original 
untreated 
metal. 

III.  Drilled  metal,  unpunched. 

IV.  Punched  metal  not 

treated  furttu  r. 

V.  Punched  Metal  reamed. 

VI.  Punched  Ilieta 

Jtnnealrd. 

3im'nsmns 
Inches. 

I 

Dhirnsions, 
Inches. 

Ten  slle  strength, 
].mimls  per 
square  inch. 

Elon- 
gation. 

Diameter  of 
drilled  hole,  In. 

Dim 
of  d 
test- 
inc 

a 

nsions 
rilled 
>ieces, 
hes. 

Thick 

Tensile 
strength 
pounds 
per 
square 
inch. 

Elongation  %. 

|{| 

Tensile 
strength 
pouinU 
per 
square 
inch. 

Elongation  %. 

Percent's 
(4)  or  I 
)1  tensile 
relatl 

Solid 
metal. 

'e  of  gain 

Thickness  of 
reaming, 
inches. 

Tensile 
strength 
pounds 
per 
sq  uare 
inch. 

a 

I 
3 
M 

Percent'^ 
(+)  or  1 

uftensiK- 
n-lati 

e  of  gain 

Diameter  «t 
reamed  hole 
inches. 

Tensile 
strength 
pounds 
per 

square 
inch. 

Elongation  %. 

111 

C   °  J2-3 

alii 

"=  £-2 

•3 
£ 

Thickness 

c  3 

21 

Clearance. 

strength 
v&  to 

strength 
'e  to 

f 

H 

£is" 

Drilled 
metal. 

Solid 
in  etui. 

Drilled 

i 

5 

i 

li 
1 
12 
13 
15 
ll 
1" 
1 
21 
2 

Ha, 

K. 

O. 
Be. 
B. 

W. 

Ba. 

Be. 

T. 

i-'.i:> 

1-75 
2-34 
T9.' 
2.34 

2.34 
2-00 

•66 
•68 
0-66 

•66 

•02 

67,994 

•039 
•035 
•04 

72,195 
67.648 
76,205 

•788 

0-70 
0-66 
1 

96,925 
hard'n'd 
M,080 

74,794 
hanl'li'il 
65,710 
53,450 
50,470 
61,840 
60,040 

66,080 

107311 
64,960 
75,712 
71,680 
64,915 

71,080 

57,930 
61,130 
68,730 
64,440 

10-3 
14-6 
18-1 
19-3 
20-7 

4-95 
0-88 
6- 
3- 
4- 

—  3-09 
—  2'00 
—  IMS 

+0-98 

—  0-79 

—  8-4 

4-0-5 
4-8-5 
4-6-2 
4-1-7 

—  4. 

0-31 

•70 
•66 

•6(1 

2-34 
1-75 

0-81 
•46 

69,933 
77,616 

99,770 

-    8-37 
—    1-82 

62,227 

-  19-84 

67,222 

54,858 

18-39 

1 

61,802 

49,034 

-  20-66 

J 

1 
I 

i 

> 

•66 

•77 
•77 
•77 
•77 
•77 

•K 
"7* 

rw 

•5 
•5 

•75 
•62 
•875 
1-12 
1-1 
1- 
(  1-09 
"I  I'OS 

•74 
•75 

•66 

77,190 

•129 

•25( 
•881 
•495 

•m 

•510 

•1 
•1 
•1 
•1 
•1 

.1 

74,915 
60,4*0 
51,45f 
55  803 

10-S 
gg.g 

86-1 
86-4 

10 
11 

11 
II 

'77 
•77 
•7t 

•77 

81.050 
66,961 
57,280 
63.121 
59,0* 

5-7 
14-1 
I7'2 

urn 

8-2 

11-3 
13-1 
11  5 

72.470 
59,871 
51,680 
44,221 
88,tT< 
53,000 

3-2 
9-6 
13-5 

1-9 

—    8-39 
—    I'OI 
4-0-40 

—  20'7.r 
—  26-35 

—  14  'S3 

6-5 

—  10-59 

—    9'7£ 

-29  95 
83  -9S 





'. 

62  .'.CM 
64,200 

87-2 
25-15 

U 

"77 

J 

•03® 
•IS 
•06 

65,560 

4-2-12 
45'9 

•75 

... 

f  £J 

8. 
1.  1 
l-'l 

•812 

•625  i 
•36 
•26 

..... 

•3®' 

62.720 

ro9 

•5 
•5 

8- 
1- 
1- 

•812 
J:625 

till  21< 

47,:i70 

-  24  47 

-  12  '24 
—  40  72 

—  31-55 

—    9-47 
-  26-95 

•03 
•12 
•17 
•04 
•08 

86.88! 

121,856 
59,360 
72,128 
66,528 
60,592 
62,474 
62,474 

59,136 

24-88 

13-50 
22- 
20-5 
23-5 

s 
S 

( 

8 

I  &I.37I 
(9S,8'J(, 

0-7f 

—  8-05 
—  18-84 

67,366 
72.240 
61,600 

2-v- 
0-311 

•06 
•06 
•10 

66,259 
105,571 
72,800 

4  SS 
0-64 
4- 

—  13-86 

4-   4-6 
4-   6-8 

61.601 

r*,** 

61,841 

1- 

2- 

•12 
•12 
•14 

•12 

(  -04 
1  -08 
•06 
•04 
•04 
•04 
•04 

72  240 
64.534 
57,546 

63,168 

85,526 
8S.52S 
66,627 
5S.3SO 
61.990 
64.740 
65,170 

4' 

•>: 
2 
25 

27 

80 

81 

». 
8! 

8! 
30 

37 
88 

2-34 

•7     ± 
•7 
•7 

•75 



1-12 

.075 

64,355 

—    17'S 

1-12 
1-15 

1-12 

•74 

•74 
•78 
•85 

•51 
•67 
•S3 

64,791 
47,131 

12  3 





—    7-9 
4-    6-8 

—    24T> 

|  —24-2 

•74 

87,946 

56,582 

|  44.801 
*(  41,866 

83264 

—  12  34 
—  22-68 

54,970 
59.820 
60,830 
61,550 

•75 

4-  2-9 
4-  8-0 
+  6-6 
4-  11-9 
4-  9-3 
+  8-2 

-  4'0 
—  3- 

43.747 

51.301 
52,890 
64,480 

—20-5 
—19-6 

43. 
-3-S 
4-2  1 

+7-4 

4-s-i 

4-1-50 

4o-io 

3 
1 

•31 
•47 
•68 

•78 



.. 

•31 
•47 
•63 

69,240 
65,020 
69.070 



—  15'7 

—14-1 

60,690 

•• 

•78 

67.630 

_ 

15-2 

P. 

•76  ± 

•74 



: 

I 

1-08 
I'l 

1  -05 
i  -08 
j  'OS 
i  -11 

44,62j 
52,237 

1M4 

42,806 
50,557 

1  35,616 
i  34,922 
j  40,746 
|  42,403 

j-20 

(-22 

,-is-s 

(  —  b'b 



•13 

47,421 

—9-2 



1-16 

42,851 

1-13 

.74 

1  to  7.  Barba.  Ihilley.  I'.se  of  Steel;  1  to  5,  Terre  Noire  Bessemer  steel  plates;  6  and  7,  LaCreusot  opcn-heaith  steel  plates. 

8  to   12,  Kii-k:ildy,  Experiments  on  Fagersta  Steel,  Scries  2.     Bar  12'5  inches  wide  had  three  rows  of  fiveO'77-inch  holes  punched  across  them,  thus  removing  .30"S<  of  the  width  of  the  piece. 

a  Thepercertage  of  loss  for  column  VI.  is  obtained  by  comparing  the  punched-annealed  with  the  solid  annealed  metal,  because  the  metal,  which  was  uuannealed  when  punched,  is  weakened 
greatly  by  annealing 

To  avoid  complicating  the  Table,  I  omit  the  properties  of  the  dnlted-annealed  metal. 

13,Gatewood,  Kept.  U.  S.  Naval  Advisory  Bl.  on  Mild  Steel,  1886,  p.  170.  The  results  under  punched  metal  reamed  refer  to  punched  metal  countersunk  through.  When  the  countersinking  was 
•topped. 

15.  P.  D.  Bennett.  -Tonrn.  Iron  and  St   Inst.,  1886  I  ,  p.  373,  from  Proc.  Inst.  Mech.  Eng.,  1886,  pp.  44-C1. 

16,  Boyd,  Jeans  "Steel,"  from  Proc.  Inst.  Mech.  Eng.,  1878. 

175  18,Beck-Guerhard  "On  the  Influence  of  Punching  Holes  in  Soft  Steel,"  1884  Russian  Mining ,11.     My  statements  »re  based  on  a  translation  sent  Mr.  T.  Cooper  by  the  author.     Journ. 
Iron  and  Steel  Inst.,  1884,  I.,  p.  290,  has  an  abstract,  with  many  incorrect  numbers.    No.  17  is  the  mean  of  six  sets  of  results,  No.  Is  of  two  sets. 
2O  to  22,  Basic  Bessemer  steel:  White,  ••  On  some  Recent  Experiments  with  Basic  Steel,"  Excerpt  Trana.  Inst.  Nav.  Arch  ,  1887,  p  15. 
23  to  27,  Parker,  Trans.  Inst.  Nav.  Arch.,  XXVII.,  p.  418,  1886.    From  Kept,  for  Lloyds  Register,  March  20th,  1878.   23-5,  Cammell's  Steel;  27  Bolton  Steel: 

30,  Barba,  Op.  at.,  p.  45.  \Vrought-Iron  Plates. 

31,  Bennett,  Luc.  Cit,,  Wrought-lron. 

32-5,  I.»wmoi>r  Wrought-iron  Plates,  Tetmajer,  Stahl  und  Elsen,  VI.,  p.  173,  1886.    All  exceept  the  drilled  specimens  were  out  from  the  same  plate.     The  gain  of  tensile  strength  due  to  drilling 
is  obtained  by  comparing  the  drilled  pieces  with  untreated  pieces  from  tho  same  plate,  whose  properties  1  do  not  give. 
37j  38,  Parker,  Loc.  Cit.,  37,  Seaward's  best  best  iron  boiler-plates;  3S,  CamrnelPs  best  bestiron  plates. 

TABLE  122.  — ] IFKEOTS  OF  PVNCUINU. 


J.. 

2.. 
8.. 
4.. 
5.. 
6.. 
7.. 
8 

Dimensions  of  test-pieces, 
etc. 

Conditions  of  punching. 

Tensile  strength,  pounds  per  square  inch. 

%  loss  of  tensile  strength  on  punching 
relative  to 

Width,  inches. 

Thick- 
ness, 
inches. 

Diameter,  inches 

Of  untreated  metal. 

Of  drilled  test-piece. 

Of  punched  test-piece. 

Solid  piece. 

Drilled  piece. 

Of 
punch. 

Of  die. 

Conical 
punching. 

Cylindrical 
punching. 

Conical 
punching 

Cylin- 
drical 
punching. 

Conical 
punching. 

Cylin- 
drical 
punching. 

8-94 
067 
1-96 

Conicai.   [Cylindrical 

1 

ta 

•a 
q 

s 

f        1-24 
1-95 
2-65 
8-85 
4-05 
4-75 
6-24 

0  27 

0-66 

0-82 
0-82 
0-82 
0-82 
0-82 
0-82 
•74 
•94 
I'll 
1-1 
0-87 

0-76 
0-76 
0  76 
0-76 
0-76 
0-76 

71,075 
63,285 
53,845 
49,974 
61,813 
53,155 
66,035 
53,894 
47,891 
43,887 
72,867 

60.4*11 
57,994 
66,560 
56,786 
54275 
51,722 

+    2-4 
-    8-9 
15-3 

—  12-9 
—  16-48 
—  18-55 
—  26-94 
—  21-84 
—  25-52 

f  ' 
—  3 
—  1 
—  1 

69,440 
estimated 

—  28-0 
—  26-1 
—  23-4 
8-1 
187 
26-2 
83-8 

•25 
•375 
•47  ± 
•593 
0-5 

•69 
•89 
•28 
•45 

•69 

•84 
•97 
•96 
0-69 

1-12 
•69 
•59 

•875 

0-66 

71,887 
66,292 
64,915 
66,192 

1 

s  -i 

10.. 
11 

•— 

3 

0-75 

58,240 

V 

M 

61,876 
67,200 
67.424 

,  *.  „ 
40,544 
60,032 
59,860 
63,213 

13 
14.. 
15 

1 
1-2 

•70 
•70 

02,922 
39,715 

41,620  ± 

—    5-2 
—    5-9 
—  14-S 
—  17-0 
-  16-6 
-    9-     ± 

—  16-0  ± 

1C.. 
17.. 
18.. 
19.. 
20 
21.. 
22. 
23 
24.. 
25.. 

1 

5  " 

M 

1 
f 

f        1-24 
1-95 
2-62 
3-35 
4-05 
5-26 
1-27 
1-02 
•89 
k          '77 

0-81 

37,854 
87,886 
33,824 
32,973 
88,180 
37,878 
111 
60 
64 
71 

). 

—   9           —16-0 
4-14-40 
4-   5-60 
4-11-20 

4-  13-50 



:::::::....:::::: 

1-16  ± 
•875 
•WO 

•C25 
•C25 

1-12 
•52 
•52 
•52 

•52 

1-37 

1-25 
•52 
•52 
•62 
•52 

41,62(1 
97.761' 
57.020 
57.650 
60,580 

84,956 
800 
190 
100 

soo 



sao 


THE    METALLURGY    OF    STEEL. 


ing  may  be  expected  in  some  cases  to  increase  rather  than 
lessen  the  effects  of  punching  (§  288).  The  results  of 
many  experiments  are  summarized  in  Tables  121A  to  123. 

TABLE    123  — EFFECT     OF    PUNCHING    AND    SritSEQfENT    UKAMING    ON    SOFT    INGOT-STEEL. 

HILL. 


Tensile  strength  in  pounds  per  square  inch,  and  %  of  elongation  in  18  inches. 

[tiece,  inches. 

With  a  holeO^Sin.in  diameter  punched,  or  punched  andreamed. 

•02"  radius 

•03"    radius  '04"    rfulins 

"05"  radius 

Unreamed. 

reamed. 

reamed. 

reamed. 

reamed. 

1 

'fl 

g 

4 

c 

A 

o 

4 

1 

j 

o 

4 

c 

0 

01 

=   tB 

i 

"  bo 

•3 

^  ^ 

3 

~  tc 

•^  i* 

.3 

a 

c  n 

11 

ti 

C    S 

1 

& 

c  § 

B 

' 

-  H 

o-  t 

R 

c 

i 

3 

EH  ^£ 

o 

EH  to 

a 

0 

EH  ^ 

J 

EH  to 

0 

P 

H 

W 

'•^ 

W 

w 

W 

W 

•80 

2  in. 

•25 

79,200 

20-2 

62,400 

50 

SO.  600 

19  0 

•87 

88,800 

19'(l 

60,800 

5-0 

85,000 

17-9 

•50 

88,400 

17-3 

59,100 

47 

88,200 

11-2 

88,900 

10-0 

-.11 

•25 

82,900 

18-5 

66.100 

51 

84,100 

18-6 

•87 

86,500 

15  9 

64,800 

4-9 

79.800 

11-8 

87,200 

18-0 

•60 

89,800 

13-0 

61,800 

4-0 

65,100 

4-3 

77,400 

6'(i 

90,800 

11-7 

•    i 

•26 

83,700 

14-7 

74,900 

54 

76,1(10 

5-3 

83,900 

18'9 

•87 

88,500 

13-1 

71,200 

8*0 

74,100 

4-1 

79,900 

8-7 

88,800 

11  -y 

•50 

91,800 

11-4 

69,800 

2-5 

70,900 

2'0 

78,700 

8-0 

81,400 

4'7 

92,800  10*0 

Trans.  Am.  Inst,  Mining  Engineers,  XI.,  p.  259,  1883. 


From  around  the  holes  in  steel  plates,  some  punched, 
some  drilled,  Barba  cut  rings  about  0*19  inches  thick, 
Figure  113.  Those  from  drilled  holes  A,  B,  C,  could  be 
completely  flattened  without  cracking,  and  only  cracked 
when  partly  reopened.  They  were  no  harder  than  the 
mother-metal.  Those  from  punched  holes  cracked  and 
broke  when  bent,  as  shown  at  D  and  E  respectively,  were 
harder  under  the  file, and  scratched  their  mother-metal.  But 
if  the  punched  hole  first  had  0'039  inches  reamed  from  its 
sides,  the  ring  now  obtained  could  be  completely  flattened 
and  brought  back  to  the  shape  of  Figure  G  before  crack- 
ing. Again,  rings  cut  from  unreamed  punched  holes 
could,  after  annealing,  be  flattened  and  brought  back  to 
the  shape  of  figure  I  before  cracking ;  in  other  cases  they 
were  cut  on  a  generating  line,  completely  developed,  and 
bent  back  as  in  Figure  J  so  as  to  extend  the  original  in- 
terior, without  perceptible  crack,  though  with  further 
deformation  cracks  appeared. 

But  punching  maybe  harmless  or  even  beneficial.  Thus 
Guerhard  found  that,  under  given  trans  verse  load,  fourteen 
punched  soft-steel  fish-plates  deflected  2 '8$  less  tempo- 
rarily and  8'1$  less  permanently  than  fourteen  similar 


Hing  from  drilled  hole. 


King  from  punched  hole. 


Cracks  only  after  complete  flattening  and 
partly  opening  again. 


Cracks  after  slight 
flattening. 

^Int;  cut  from  punched  hole,  then  annealed. 


King  from  punched  and  reamed  hole. 


"Cracks  only  after  complete  flattening 
and  partly  opening  again. 


Cracks  only  after  complete  flatten- 
ing and  partly  opening  again. 


Cut  «nd  devel- 
oped, it  cracks 
only  when  bent 
back  thus. 

Figure  113. — Mallenbleness  of  Kings  Cut  from  Around  Punched,  Drilled,  and  Reamed  Holes. 
Barba.     Three-fourths  natural  size. 

drilled  plates.  Thurston  found  the  stripping  and  burst- 
ing strength  of  many  cold-punched  wrought-iron  nuts 
much  greater  than  those  of  similar  but  hot-pressed  nuts, 
the  former  excelling  the  latter  in  bursting  strength  on  an 
average  by  44 %  when  blank  and  by  22%  when  tapped."  In 
Table  122,  numbers  22  to  25  are  reported  to  gain  strength 

a  Hoopes  and  Townsend,  private  print. 


on  punching.11  Cooper  found  that  the  punched  holes  in 
soft  steel  and  wrought-iron  plates  endured  as  much  dis- 
tortion by  drifting  as  similar  punched  and  reamed  holes. 
As  reaming  removes  the  effects  of  punching  one  might 
infer  that  punching  had  not  lessened  the  ductility  of 
the  metal  around  the  holes.  But  a  quite  different  ex- 
planation is  offered  in  §  288.'  His  results  follow. 

TABLE  124. — PERCENTAGE  OF  ELONGATION  OF  HOLES  WREN  DRIFTED  TILL  TOE  METAL  BEGINS 
TO  CRACK. — (CoopEU). 


%"  steel  plates. 

%"  iron  plates. 

%"  stool  angles. 

%"  iron  angles 

Max. 

Min. 

Avge. 

Max 

Min. 

Avgo. 

Max. 

Min. 

Avge. 

Max. 

Min. 

Avge. 

Punched 

123 

54 

97 

54 

M 

54 

115 

K 

100 

86 

86 

36 

Punched   and 

reamed  

100 

93 

IOC 

46 

46 

40 

100 

33 

73 

24 

24 

24 

The  steel  was  very  soft,  its  tensile  strength  being  55.000  Ibs.  per  s<|.  in.  The  holes  were  en- 
larged by  forcing  a  long  tapered  drift  into  them  by  sledging.  Theodore,  Cooper,  private  communi- 
cation, Sept.  7th,  1SSS. 


Thousands  of  punched  steel  boiler-plates  have  been  long 
in  use,  with  relatively  few  mishaps.  The  boiler-plates  of 
the  United  States  vessels  Boston,  Atlanta  and  Dolphin 
were  punched,  those  of  the  Chicago  drilled :  up  to  Sep- 
tember 1st,  1884,  only  seven  failures  had  occurred  among 
the  tirst  three  collectively,  against  eight  among  the  last.S 

§  286.  SHEARING  produces  effects  similar  to  those  of 
punching,  and  doubtless  acts  in  similar  way.  Barbad 
found  that  soft  steel  strips,  with  one  edge  punched,  the 
other  sheared,  when  bent  cracked  at  both  edges  under 
the  same  degree  of  distortion.  The  tendency  to  crack  on 
the  sheared  as  well  as  on  the  punched  edge  was  removed 
by  heating,  whether  with  slow  or  quick  cooling.  Goodall 
found  the  metal  lying  within  0'03  inches  (?V")  of  the 
sheared  edge  of  a  steel  plate  as  malleable  as  that  of  the 
unsheared  plate;  thus  the  effects  of  shearing,  like  those  of 
punching,  are  restricted  to  a  very  thin  shell.6 

The  effects  of  shearing  and  their  removal  are  illustrated 
in  Tables  16,  p.  27,  and  125. 

TABLE  125.— EFFECT  OF  SHEARING  AND  COLT>-HAMMEEING  AND  OF  SUBSEQUENT  ANNEALING  ON 

SOFT  INGOT-STEEL.     HILL. 


Preparation  of  test  piece. 
(All  pieces  %"  X  2"  X  18".) 

•3*  C. 

•4*  c. 

•5*  C. 

•3*  C. 

•4*  C. 

•5*  C. 

•3*  C. 

•4*  0. 

•5*  C. 

Tensile  strength, 
pounds  per  square 
inch. 

Elastic  limit, 
pounds  per  square, 
inch. 

Elongation 
%  in  18  inches 

Cut  in  planer  

86.720 
69,376 
84,950 
85,380 
82,970 

89,880 
75,400 
86,32(1 
87,560 
85,890 

1)  ',210  45,170 
S'2,930  31,290 
112,560  44,880 
91,810  63,720 
90,020  46,300 

53,640 
41.250 
51,470 
64,180 
51,710 

62,070 
49.960 
59.81PO 
71,680 
05120 

19-1 
11-3 
20-2 
8-4 
16-8 

10-4 
8-3 
16  7 
2'3 
14-1 

11  4 
6-1 

12-0 
•7 
8-1 

Sheared  out  

Hammered  cold  
Hammered  cold,  then  annealed.  . 

Trans.  Am.  Inst.  Mining  Engineers,  XI.,  p.  259,  1883. 

§287.  DISCUSSION.— Now  for  evidence  of  the  influence 
of  the  five  variables  noted  at  the  beginning  of  §  285. 

That  of  the  first  is  shown  in  numbers  I  to  6  and  16  to 
20  of  Table  122.  In  each  of  these  sets,  width  alone  vary- 
ing, the  loss  of  strength  on  punching  increases  with  it. 
Barba  found  this  true  not  only  of  steel  but  of  wrought- 
iron  :  of  the  latter  Barnaby'  found  the  reverse  true,  while 
agreeing  with  the  other  observers  as  regards  steel. 

That  of  the  second  is  shown  by  the  smaller  percentage 
of  loss  in  case  of  wrought-iron  than  of  ingot-metal.  But 


b  I  deem  it  proper  to  state  that  these  results  are  published  by  interested  persons, 
and  that  the  tests  are  not  descrioed  so  fully  as  to  indicate  whether  full  precautions 
were  taken  to  make  them  comparable.    Personally  I  believe  that  they  are  true. 
Gatewood,  Kept.  TJ.  S.  Naval  Adv.  Bd.  Mild  Steel,  1886.,  pp.  77-8. 

.  cit.pp.  36-8. 

H.  Goodall:  Excerpt  Proc.  Inst.   Civ.  Eng.,  XCII.,  p.  13,  1888.    Also  Iron 
Age,  XLI.,  p.   196,   1888.      The  malleableness  was  estimated  by  the  distance 
through  which  a  given  drift-pin  could  be  driven  at  fixed  speed  through  washers 
cut  from  the  steel  plates,  before  splitting  them. 
t  Jour.  Iron  and  Steel  Inst.,  1879, 1.,  p.  49. 


THE    EFFECTS    OF    PUNCHING,     DISCUSSION.      §  287. 


231 


in  case  of  ingot  metal  of  different  percentages  of  carbon, 
though  the  results  of  general  experience  seem  to  support 
my  statement,  it  is  not  readily  verified  from  the  evidence  I 
offer.  Of  numbers  17  and  18  in  Table  121  A,  the  latter,  the 
richer  in  carbon,  is  also  the  more  injured  :  but  in  Table 
12:j  the  reverse  is  true.  It  is  uncertain  whether  this  is 
due  to  some  unnoted  variable  (different  proportions  of 
manganese,  silicon,  phosphorus,  different  previous  heat- 
treatment,  or  what  not),  or  whether  the  injury,  increasing 
as  the  carbon  rises  from  -1()  to  "30%  decreases  with  further 
rise  of  carbon  from  -30  to  '50$.  While  further  investi- 
gation alone  can  decide,  I  incline  to  the  former  as  the  more 
probable  explanation. 

The  third  is  offered  as  a  matter  of  general  experience, 
not  supported  by  direct  experimental  evidence.  Indeed, 
number  20  of  Table  122  suffers  slightly  more  than  number 
19,  from  which  it  seems  to  differ  only  in  being  annealed 
before  punching. 

That  of  the  fourth  is  shown  by  numbers  8  to  12  of  Table 
121A,  among  which  the  injury  increases  with  the  thick- 
ness, which  is  the  only  variable.  Parker,  too,  found  that, 
as  the  thickness  of  the  plates  rose  from  '375  to  -5  and  -625 
inches  (-§•",  £"  and  $•"  respectively),  the  loss  of  tensile 
strength  on  punching  rose  from  18$  to  26  and  33$. a 

That  of  the  fifth  is  shown  by  numbers  1  to  6,  11  and 
21  of  Table  122.  In  each  of  these  cases  we  have  two  ex- 
periments, differing  only  on  the  width  of  die  or  bolster  : 
in  all  but  two  cases  the  wider  die  gives  the  smaller  loss. 

The  influence  of  the  greater  clearance  diminishes  in 
numbers  1  to  6  with  ratio  of  thickness  to  width,  appar- 
ently disappearing  when  a  width  of  3  35  inches  is  reached. 
In  number  21  this  influence  is  again  seen,  though  the  bar 
is  5 '26  inches  wide,  the  greater  thickness  here  apparently 
compensating  for  the  increased  width. 

Turning  now  to  the  removal  of  the  effects  of  punching, 
first  note  that  in  numbers  8  to  12,  15,  16,  31,  and  32  to  5 
of  Table  121 A  the  drilled  piece  is  stronger  than  the  un- 
treated metal.  This  seems  to  fall  under  the  general  law 
that,  for  given  section,  the  tensile  strength  of  very  short 
and  especially  of  grooved  pieces  exceeds  that  of  long 
ones,b  in  turn  due  to  the  more  favorable  disposition  of  the 
material  in  the  grooved  piece  with  regard  to  the  lines  of 
stress,  rather  than  to  the  smaller  chance  of  flaws  existing 
in  the  short  piece,  for  after  the  length  increases  beyond  a 
certain  point  the  decrease  of  tensile  strength  is  less 
marked.  Hence,  in  weighing  the  relative  advantages  of 
punching  and  drilling  for  most  purposes,  the  properties  of 
punched  should  be  compared  with  those  of  drilled  rather 
than  of  solid  metal.  Why  the  drilled  is  weaker  than  the 
solid  metal  in  number  17  18,  37  and  38  of  Table  121 A  is 
not  clear. 

The  Influence  of  Heating  is  shown  in  column  VI.  of  Table 
121A.  In  every  case  in  this  column  the  punched  metal, 
after  heating,  nearly  or  quite  (as  in  17  and  18)  equals  the 
drilled.  In  numbers  8  to  12  the  properties  of  the  annealed 
punched  metal  are  compared  with  those  of  drilled  and 
annealed  metal,  for  the  annealing  itself  greatly  lowers 
these  as  well  as  those  of  the  solid  metal.  In  4  and  7  the 
metal  is  quenched,  in  the  other  cases  slowly  cooled. 
Clearly  it  is  the  heating,  not  the  rate  of  cooling,  that  re- 
stores the  lost  strength. 


a  Proc.  Inst.  Naval  Architects,  1878.    Also  Jeans,  "  Steel,"  p.  734. 
b  Compare  Kept.  U.  S.  Board  on  testing  iron,  steel,  etc  ,  I.,  p.  91  et  seq. 


After  Reaming  (Col.  V.,  Table  121  A)  the  strength  of  the 
punched  piece  usually  nearly  equals  or  even  excels  that 
of  both  solid  and  drilled  metal.  Even  when,  as  in  num- 
bers 2  and  32  to  35  only  0'03  to  (V04  inches  is  reamed  from 
the  sides  of  the  punched  holes,  the  restoration  is  nearly  or 
even  quite  complete.  But  in  Table  1 23  it  appears  that 
the  thickness  which  must  be  reamed  to  remove  the  injury 
increases  with  the  proportion  of  carbon  and  with  the 
thickness  of  the  plate,  so  that  while  a  J-inch  plate  con- 
taining 0-30%  of  carbon  is  completely  restored  by  reaming 
•02  inches,  to  restore  a  £-inch  plate  containing  0'50$  of 
carbon  '05  inches  must  be  removed.  Gatewood  found  that 
countersinking,  even  if  carried  through  only  three-quar- 
ters of  the  thickness  of  the  plates,  removed  about  three- 
quarters  of  the  injury  due  to  punching. 

In  harmony  with  the  effect  of  reaming  punched  plates 
is  that  of  tapping  cold-punched  nuts,  which  removes  about 
half  the  effect  of  the  punching.  (§  287.) 

The  local  nature  of  the  injury  is  also  shown  by  experi- 
ments by  Barbac  and  by  Beck-Guerhard,d  in  which  they 
punched  holes  in  steel  plates,  and  then  cut  and  tested 
strips  from  these  plates,  some  in  close  proximity  to  the 
punched  holes,  others  farther  away :  both  found  the 
metal's  tensile  strength  and  elongation  as  great  near  the 
hole  as  far  from  it.  Indeed,  certain  features  of  Guerhard' s 
results  suggest  that  the  metal  around  the  hole  was  some- 
what strengthened. 

TABLE  126.— PROPERTIES  OF  STRIPS  FROM  PREVIOUSLY  PUNCIIKD  STEEL  PLATES,  THE  STRIPS  CUT 
AT  VARIOUS  DISTANCES  FROM  THE  PUNCHED  UOLE. 

B  =  Barba.  G  =  Guerhard. 


J 

*j 

g 

2 

L, 

Li 

• 

Position  regarding  hole. 

| 

I 

S 

3' 

1 

3 

1 

1 

f, 

to 

5 

fc 

£ 

N 

& 

Tensile  strength,  pounds  peri  B... 

69,661 
00,435 

70,582 
57080 

68,768 
60,928 

68,970 
61,443 

61,958 

01  981 

57,494 

63,213 

1  R 

Elongation  %                       •  •  •  1  3" 

21 
22-7 

21-5 
19-0 

21 
WO 

21 
23'0 

20-4 

26-8 

19  S4 

19-09 

In  Burba's  pxperiuieuts,  one  edge  of  the  strip  nearest  the  hole  lay  only  0*09  inches  from  the 

edge  of  the  hole. 

Doubtless,  a  certain  flow  occurs  at  considerable  distances 
from  the  hole.  On  the  surface  of  plates  highly  polished 
before  punching,  Guerhard  noticed  gently  curving,  eye- 
lash-like lines,  convex,  felt  by  the  fingers,  running  outwards 
for  nearly  two  inches  from  the  edge  of  the  hole,  making  an 
angle  of  45°  with  tangents  drawn  through  their  points  of 
departure,  and  readily  removed  by  acid.  Cooper  had  pre- 
viously described  similar  lines  in  the  scale  surrounding 
holes  punched  in  iron."  Again,  punching  bulges  the  neigh- 
boring edges  of  plates,  etc  ,  though  they  lie  at  some  dis- 
tance from  the  edge  of  the  punched  hole.  But  the  evidence 
already  given  shows  that  the  action  which  causes  this  far- 
reaching  flow  does  no  considerable  injury  beyond  a 
narrow  ring. 

Riveting,  in  Parker's  experiments,  increased  the 
strength  of  punched  steel  plates  ^-inch  thick  by  about 
4000  pounds  per  square  inch,  or  say  6%,  but  it  did  not  im- 
prove punched  £  -inch  plates 

In  Bennett's  experiments,  parallel  with  numbers  15  and 
31  of  Table  311,  riveting  reduced  the  loss  of  strength  due 
to  punching  from  20^  to  10$  in  case  of  wrought-iron,  but 
did  not  benefit  steel. 

In   Snelus'    experiments,  punched  unannealed  riveted 


c  Op.  clt.  in  note  to  No.  17,  Table  131. 

d  Op.  cit. 

e  Trai's.  Am.  Soc.  Civ.  Bag.,  VII  ,  p.  174,  1878. 


THE    METALLURGY    OF     STEEL. 


joints  were  much  weaker  than  the  punched  and  annealed 
and  than  the  drilled  joints.8 

The  following  experiment  of  Baker's"  shows  so  serious 
a  loss  of  strength  in  riveted  punched  plates  that,  though 
the  strength  of  the  unriveted  punched  plate  is  not  given, 
it  is  probable  that  riveting  annealed  but  slightly. 


TABLE  127. — KEBTOBATION  BY  RIVETING.     BAKER. 


Description  of  piece.          Solid. 

Tensile  strength 73.158 

Elongation  in  S  in ...     22 


Punched  and 
riveted. 

j 68.033 


Drilled  and 

riveted. 

77213 

6-2 


Punched  and 

annealed. 

79.228 

6-2 


J.  Ward  reports  the  following  results:0 


Elongation. 
Inches. 
0'15 
0-24 
0'15 
0-15 
0-09 
0-11 


Tensile  strength. 
Pounds  per  s<j.  in. 

Untreated  plate 66,801 

Drilled  plate. ..  71,232 

Punched  plate 62,720 

Punched  and  riveted  plate 69.440 

Punched  and  galvanized  plate 62  048 

Punched,  galvanized  and  riveted  plate 65520 

These  results,  collectively,  give  little  reason  to  believe 
that  riveting  removes  materially  the  effects  of  punching. 

Clearly,  the  available  heat  offered  by  the  rivet,  both 
heads  included,  bears  a  higher  ratio  to  the  volume  of  the 
ring  to  be  annealed  in  thin  than  in  thick  plates. 

§  288.  RATIONALE  OF  THE  EFFECTS  OF  PUNCHING  AND 
OF  THEIR  REMOVAL. — The  complete  restoration  of  punched 
plates  by  annealing,  and  the  extreme  endurance  of  distor- 
tion and  the  malleableness  conferred  by  annealing  on  the 
initially  brittle  rings  cut  from  around  punched  holes,  show 
that  punching  does  not  usually  act  chiefly  through  caus- 
ing incipient  cracks.  The  restoration  by  reaming  and 
other  evidence  indicates  that  the  serious  direct  injury  is 
confined  to  a  very  small  ring.  Evidently  the  metal  in  this 
ring  is  distorted  and  subjected  to  great  pressure  in  punch- 
ing :  these  are  the  essential  conditions  of  cold-working : 
after  punching  it  shows  the  usual  characteristics  of  cold- 
worked  iron,  hardness,  extreme  brittleness,  and,  if  we  may 
judge  from  the  lightness  of  the  punched  core,  lower  density 
than  the  hot-worked  metal.  That  the  tensile  strength 
of  this  ring  is  also  very  high,  like  that  of  other  cold- 
worked  iron  we  infer  from  the  much  greater  stripping  and 
bursting  strength  of  cold-punched  than  of  hot-pressed 
nuts,  the  stress  in  both  stripping  and  bursting  falling  in 
undue  proportion  on  the  metal  within  this  ring :  and  fur- 
ther from  the  fact  that  the  excess  of  bursting  strength  of 
the  cold-punched  over  the  hot-pressed  nuts  is  far  greater 
when  they  are  blank  than  when  tapped,  the  tapping  re- 
moving a  part  of  this  strong  ring. 

We  may  thus  conjecture  that  punching  acts  directly 
through  cold-working  this  narrow  ring,  giving  it  much 
higher  tensile  strength  and  elastic  limit  but  much  lower 
ductility  than  the  surrounding  metal,  which  is  probably 
affected  in  the  same  way  but  to  a  much  lower  degree. 
Punching  in  this  view  increases  the  average  strength  of 
the  different  layers  taken  individually,  giving,  however,  a 
heterogeneousness  of  strength,  elastic  limit  and  ductility, 
which  may  be  a  source  of  strength  or  weakness,  according 
to  the  conditions  of  stress,  as  pointed  out  in  §  269. 

In  complete  harmony  with  this  view  are  the  following 
observations  of  J.  Ward."  In  each  of  fourteen  pairs  of 
tests,  apparently  representing  seven  mild  steel  plates, 
(tensile  strength  about  Ct5,000  Ibs.,  elongation  about  25% 
in  8")  the  elongation  of  the  test-piece  cut  from  between 
rows  of  punched  holes  as  in  Figure  114  fell  below  that  of 


~t)^A_ 

O 

B 

0 

c      JS~ 

"j?T" 

f 

4' 

1 

3C^ 

Cf 

o 

.50" 

.an' 

o 

.606' 

THICKNESS    .«3" 

.48" 

similar  test-pieces  from  untreated  parts  of  the  same  plates, 
by  from  1  to  B%  of  the  initial  length  (eight  inches),  the 
average  difference  being  3 '2$.  But  in  only  six  out  of 
the  fourteen  pairs  was  tensile  strength  of  the  test-piece 
from  between  holes  greater  than  that  of  the  untreated 
metal.  In  three  cut  of  four  cases  like  test-pieces  cut  from 
between  drilled  holes,  had  less  elongation  than  those  from 
the  untreated  metal :  this,  however,  seems  to  be  an  acci- 
dental variation. 

In  short,  the  strips  cut  from  between  punched  holes  had 
the  same  strength  as  the  untreated  metal,  but  stretched  less. 

Now,  a  glance  at  Figure  114  makes  this  clear.  The 
metal  near  where  the  punched  holes  have  been  stretches 
less  than  the  rest,  presumably  because  its  elastic  limit  has 
been  raised  by  the  cold-distortion  during  punching.  Thus 
the  elongation  of  the  test-piece  as  a  whole  is  lessened : 
but  its  tensile  strength  is  not  affected :  for  the  tensile 
strength  of  the  test-piece  is  that  of  its  weakest  section,  to 
wit,  the  non-cold-worked  parts  A,  B  and  C. 

Fig.  114 


Local  Elevation  of  the  Elastic  Limit  by  Punching.    Ward. 

Further  corroborative  of  this  view  are  the  results  of  ex- 
periments of  Barba'  sin  which  steel  strips  0-46"  thick,  Figure 
114  A,  were  punched  partly  through  at  A,  the  punch  being 
arrested  when  it  had  penetrated  0'39",  and  so  that  0'07 
inches  thickness  remained.  ' '  No  hole  was  completely 
taken  out."  The  strips  "dressed  on  their  whole  surface" 
when  pulled  yielded  least  in  the  region  partly  punched, 
rupture  occurring  at  B  where  the  punch  had  not  acted.8 
Here  the  strengthening  effect  of  the  cold-working  out- 
weighs the  weakening  effect  of  heterogeneousness. 

Fig,  114  A 


Strengthening  Effect  of  Interrupted  Punching.    Barba. 

But  on  drilling  a  hole  in  the  middle  of  the  partly 
punched  region  and  thus  removing  its  very  strongest 
part,  this  balance  was  reversed,  and  the  strength  of  the 
remaining  section  was  found  to  be  less  than  that  of  the 
untreated  metal. 

If  it  be  true  that  the  injury  caused  by  punching  is  due 
to  heterogeneity  of  strength,  etc  ,  due  in  turn  to  the  cold- 
working  of  this  ring,  restoration  by  reaming  becomes  a 
matter  of  course,  and  by  annealing  a  natural  consequence, 
since  annealing,  if  thorough,  removes  the  effects  of  all 
forms  of  cold-working,  solution  of  continuity  of  course 
excepted. 

Regarding  iron  as  a  viscous  liquid,  the  normal  pressure 
EF  of  the  punch  is  communicated  in  all  directions,  but 
more  and  more  feebly  as  the  direction  departs  from  that  of 
EF.  In  conical  punching  the  direction  of  the  pressure  which 


aKirkaldy,  Snelus,  Journ.  Iron  and  Steel  Inst.     1879.  II.,  pp.  642-3. 

b  Tha  Use  and  Testing  of  Open-hearth  Steel,  etc.,  Excerpt  Proc.  Inst  Civ.  Eng. 
XCII.,  p.  47.  1888. 

c  Traus.  Inst.  Nav.  Arch.  XXVII.,  1886,  p.  181.  Each  number  is  the  mean  Of 
six  results. 

d  J.  Ward,  Trans.  Inst.  Nav.  Arch.,  XXVII.,  pp.  106-114,  1886. 


e  The  Use  of  Steel,  Barba,  Holley,  p.  55.  I  understand  that  this  dressing  on 
the  whole  surface  was  carried  so  far  as  to  remove  all  visible  distortion,  whether 
depression,  spreading,  or  otherwise,  due  to  the  punching,  leaving  the  test  piece  of 
uniform  cross-section.  Holley's  translation  to  which  alone  have  I  had  access, 
states  that  the  strips  were  0  46"  wide,  and  the  punch  0  74"  in  diameter:  but 
judging  from  the  figure  and  description,  it  must  mean  0'46"  thick. 


PRACTICE    AS    TO     PUNCHING.       §  283A. 


233 


falls  on  AB  and  CD  is  farther  removed  from  that  of  EF 
than  in  cylindrical  punching :  clearly  the  tendency  to  force 
the  metal  from  the  block  ABCD  into  the  surrounding 
metal,  and  hence  the  pressure  against  AB  and  CD  are  less 
in  Figure  116  than  in  Figure  115.  In  a  thick  plate  the 


FIGURE  116. 


total  pressiire  on  AC,  and  hence  the  resulting  pressure  on 
AB  and  CD,  must  be  greater  than  in  a  thin  plate.  In  a 
narrow  plate  the  horizontal  component  of  the  pressure  is 
readily  relieved  by  the  horizontal  bulging  of  the  strip  as 
a  whole,  and  the  pressure  on  AB  and  CD  thus  lessened. 
Hence  the  greater  injury  in  cylindrical  than  in  conical 
punching,  to  thick  than  to  thin,  and  to  wide  than  to  narrow 
plates.  For  the  latter  a  further  reason  :  as  pointed  out  in 
§  269,  p.  212,  the  strengthening  of  the  cold-worked  part 
should  weigh  the  more  heavily  against  the  weakening  due 
to  heterogeneousness  of  strength,  the  larger  the  propor- 
tion of  the  whole  sectional  area  which  is  cold- worked. 

There  is  general  and  natural  surprise  that,  in  spite  of 
the  well-known  injury  which  it  does  the  testing-machine 
properties  punching  without  reaming  or  annealing  is 
habitually,  successfully,  and  apparently  safely  used  for 
both  steel  and  iron  boilers  and  many  other  important  pur- 
poses. Not  less  surprising  are  Cooper's  results,  showing 
how  greatly  punched  holes  may  be  elongated  by  drifting 
before  the  metal  cracks.  The  explanation  of  this  last  fact 
I  know  not :  possibly  the  first  blows  on  the  drift  set  up  a 
condition  closely  like  that  induced  by  punching,  cold- 
working  the  ring  immediately  around  the  hole,  and  so 
quickly  remove  the  initial  advantage  which  the  drilled 
holes  had  over  the  punched  ones. 

Of  the  apparent  practical  harmlessness  of  punching 
vaiious  explanations  are  offered,  none  of  which  seem 
wholly  satisfactory. 

The  explanation  that  the  structural  and  boiler  plate 
steel  now  used  is  more  ductile  than  that  formerly  made 
is  beside  the  point :  it  will  hardly  be  claimed  that  it  is 
habitually  more  ductile  than  the  most  ductile  steels  of 
Tables  121A  and  122,  and  it  is  in  these  that  the  injury  to 
the  testing-machine  properties  has  been  abundantly 
shown.  Note  the  ductility  of  numbers  8  to  13  and  17  in 
Table  121.  Numbers  8  to  13  in  the  latter  table  are  from 
material  which  when  unannealed  gave  44  '7$  of  elongation 
in  4*5  inches,  61 -7  %  contraction  of  area,  with  52,475 
pound  stensile  strength  and  28,300  pounds  elastic  limit. 

The  annealing  effect  of  the  heat  imparted  to  the  ring 
around  the  punched  hole  by  the  rivet  is  a  possible  but  not 
a  satisfactory  explanation.  In  the  first  place,  in  the  ex- 
periments recorded  riveting  does  not  seem  to  benefit  thick 
pieces  appreciably,  and  it  is  precisely  these  whose  testing- 
machine  properties  are  most  injivred  by  punching  and 
which,  therefore,  we  should  expect  to  be  especially  treach- 
erous in  use.  In  the  second  place,  we  have  seen  in  §  270,  p. 
214,  that  gentle  heating,  say  to  300°  C.  (572°  F.,  a  blue  ox- 
ide-tint), increases  or  at  least  accelerates  the  effects  of  cold- 
working,  and  should,  if  my  explanation  is  true,  still  far- 
ther raise  the  elastic  limit  of  the  cold- worked  ring  around 
the  punched  hole,  the  heterogeneousness  of  elastic  limit, 


and  the  bad  effects  of  punching  :  and  it  may  be  doubted  if 
any  importart  part  of  the  metal  around  the  punched  hole 
rises  above  this  temperature  in  riveting.  Baker  found 
that  the  heat  imparted  by  the  rivet  did  not  suffice  to  melt 
lead,  nor  even  to  evaporate  water,  in  some  small  holes  in  a 
plate  near  the  edge  of  the  rivet-hole. a 

Were  we  to  contend  that  certain  parts  of  certain  plates 
in  our  boilers  occasionally  reach  an  annealing  tempera- 
ture, the  apparent  safety  of  the  other  plates  not  exposed 
to  the  heat  and  of  punched  structures  (bridges,  ships), 
etc.,  which  never  grow  warm,  would  still  confront  us. 
Further  explanations,  neither  of  them  satisfactory,  are 
the  excessive  factor  of  safety  (actually  of  ignorance)  used, 
and  that  the  properties  which  the  metal  is  actually  called 
on  in  practice  to  display  are  less  injured  by  punching 
than  the  testing- machine  properties. 

Special  Forms  of  Puncli. — That  the  punch  may  attack 
the  metal  gradually,  its  face,  instead  of  being  plane,  is 
sometimes  made  in  steps,  is  sometimes  helical  (Kennedy' s 
and  others)  and  sometimes  concave-cylindrical,  formed  by 
the  intersection  of  a  cylinder  of  large  radius  with  axis 
perpendicular  to  that  of  the  punch.  Adopted  primarily 
to  lessen  the  stress  on  the  punching  machine,  these  ex- 
pedients doubtless  favor  the  metal  as  well.  Webb  re 
ported  the  average  strength  of  certain  steel  plates  as 
58,579  pounds  per  square  inch  when  punched  with 
common  punches,  but  as  63,929  pounds  when  punched 
with  Kennedy' s,  a  difference  of  eight  per  cent,  in  favor  of 
the  latter.1"  The  step  punch,  employed  for  many  years  in 
punching  steel  rails  at  the  Troy  Bessemer  Works,  gave 
surprisingly  good  results,  but  was  abandoned  years  ago  in 
favor  of  drilling." 

Smith's  Dynamometer  Puncfi,  recording  the  press- 
ure required  in  punching,  aims  to  determine  quickly  and 
cheaply  the  hardness  of  the  metal,  and  thus  its  fitness 
for  its  intended  use.  It  has  not  come  into  use.d 

§  2S8A.  PRACTICE  AS  TO  PUNCHING. — A.  Structural 
Work. — Many  of  our  best  bridge-engineers  require  all 
punched  work  to  be  reamed,  say  -fa  inch  all  around.  Others 
permit  punching  without  subsequent  treatment  for  riveted 
work,  provided  that  the  punched  hole  can  be  increased 
25$  by  drif 'ing,  without  cracking  either  the  hole  or  the 
sheared  edge  of  the  plate.  But  this  practice  may  be  re- 
garded as  the  exception. 

The  Eussian  ministry  of  roads  in  1885  forbad  both 
punching  and  shearing." 

At  the  Forth  bridge  all  work  is  drilled,  and  all  sheared 
edges  are  planed.  * 

I  am  informed  that  the  best  German  engineers  rarely 
permit  steel  for  bridges  and  other  important  structures  to 
be  punched  without  reaming  or  annealing,  but  do  not 
require  reaming  or  annealing  in  case  of  punched  wrought- 
iron.K 

B.  Land-boiler  Plates  are  generally  punched  without 
reaming  or  annealing.  On  the  Pennsylvania  Railroad  loco- 
motive boiler-plates  less  than  f "  thick  are  thus  treated  : 


a  Discussion  on  "  The  Use  and  Testing  of  Open-hearth  Steel,"  etc.  Excerpt 
Proc.  Inst.  Civ.  Eng.,  XCII.,  p.  47,  1888. 

b Journ.  Iron  and  Steel  Inst.,  1878,  I  ,  p.  143. 

cR.  W.  Hunt,  School  of  Mines  Quarterly,  IV.,  p.  S28,  1883,  Private  Com- 
munication, Oct.  1st,  1888. 

d  Trans.  Am.  lost.  Mining  Engineers,  IX.,  pp.  204,  596. 

e  Eng.  and  Min.  Jl.,  XLTI.,  p.  93,  1886. 

*  B.  Baker,  Private  Communication,  Nov.  2d,  1888. 

«  A.  Martens,  Private  Communication,  Nov.  1888. 


234 


THE    METALLURGY    OF    STEEL. 


thicker  plates  are  drilled.  In  England  drilling  seems  to 
be  very  much  more  common  than  here,  in  fact  to  be 
the  rule  while  here  it  is  the  exception. 

C.  Marine-boiler  Plates,    being    much  thicker    than 
those  of  la::d  boilers,  are  usually  diilled,  and  in  the  best 
works  tire  drilled  and  countersunk  in  place.     The  drilling 
machinery  is  so  excellent  that  in  Britain  it  is  not  thought 
materially  more  expensive,  in  view  of  the  greater  accuracy 
of  fit,  to  drill  than  to  punch.     Indeed  Adamson  came  to 
this  conclusion  soon  after  1862. a    Most  American  boiler- 
makers,   however,  receive  this  statement  with  derision. 
The  difference  may  be  due  to  the  more  extensive  use  of 
gang-drills  in  Britain  than  here. 

No  punching  without  subsequent  reaming  or  annealing 
is  permitted  in  case  of  boilers  for  the  United  States  navy.b 

D.  Ship-work  is  usually  punched.  The  outer  shell-plates 
are  necessarily  countersunk,  which  removes  much  of  the 
injury  due  to  punching,  and  some  of  the  best  builders  ream 
or  anneal  the  more  important  members.     Yet  some  ship- 
builders of  the  highest  standing  in  Britain  and  most  of 
those  in  this  country  always  punch  without  further  treat- 
ment (except  the  countersinking  just  referred  to).     In 
France,    too,    the  mother  of  drilling,    only    exceptional 
pieces  are  drilled." 

For  the  United  States  navy  steel  shell-plates  are  punched 
and  countersunk :  important  steel  pieces  of  hull-work  are 
drilled  :  but  many  less  important  steel  pieces  are  punched 
without  subsequent  treatment.  No  wrought-iron  plates 
are  used  for  the  hulls,  except  for  monitor-turrets,  and 
these  are  punched  without  further  treatment.  Important 
wrought-iron  pieces  (not  plates)  for  the  hulls  are  usually 
punched  without  further  treatment.11 

E.  Steel  rails  are  always  drilled  in  this  country,  and,  so 
far  as  I  know,  in  others 

§  2S9.  OIHKR  FORMS  OF  COLD- WORK.—  Frigo- Tension, 
used  by  bell-hangers  to  give  wire  higher  elastic  limit,  con- 
sists in  subjecting  the  metal  to  intermittent  stress  some- 
what above  its  elastic  limit.  On  the  first  application  the 
weakest  parts  stretch  ;  during  rest  their  elastic  limit  rises  ; 
on  the  next  application  the  next  weakest  points  stretch, 
gain  in  elastic  limit  during  the  second  rest,  and  so  on.  The 
whole  piece  having  been  thus  affected,  on  further  treat- 
ment this  succession  of  effects  recurs,  raising  the  elastic 
limit  till  it  finally  coincides  with  the  ultimate  tensile 
strength.  Carry  the  treatment  farther  and  rupture  en- 
sues.4 

When  great  accuracy  of  pitch  is  needed,  soft  iron 
chains  are  treated  by  this  process,  being  stretched  exactly 
to  the  pitch  sought,  and  under  a  stress  greater  than  the 
expected  working  stress.  The  ultimate  strength  is  simul- 
taneously raised.* 

Cold-hammering  acts  much  like  cold-rolling.  Steel 
rods  are  reduced  to  wires  (e.  g.  Stubs'  wire)  by  rapidly 
repeated  blows  of  light  hammers  striking  over  the  whole 
circumference.  The  rod  is  reduced  a  little,  say  by  -fa"  at 
each  operation,  and  it  is  said  that  the  whole  reduction 


1  may  be  f.om  1J"  to  iV"-f  The  thin  shanks  of  sewing  ma- 
chine needles  are  in  like  manner  swaged  down  from  a  wire 
by  rapid  hammering. 

It  is  said  that  a  given  weight  of  wire  yields  by  this 
method  thrice  as  many  needles  as  by  the  old  method  of 
reducing  the  diameter  of  the  thinner  part  of  the  needle  by 
grinding.8  Cold-hammering  polishes  the  metal  highly, 
reduces  it  accurately  and  uniformly  to  the  section  sought, 
and  doubtless  raises  its  elastic  limit. 

Hammer -hardening. — According  to  Overman,  surgeons' 
and  engravers'  instruments  acquire,  by  hammering  with 
a  very  small  polished  hammer,  great  hardness,  a  finer  edge, 
and  greater  elasticity  than  can  be  given  otherwise."  Whe- 
ther this  operation  is  actually  practiced  for  these  purposes 
I  know  not :  but  makers  of  these  instruments  whom  I 
have  asked  have  never  heard  of  such  a  procedure,  believe 
that  it  would  not  be  effective,  and  actually  harden  their 
instruments  in  oil  after  heating  to  redness  in  a  gas-jet,  as 
I  know  by  observation. 

Dean's  Process1  of  hardening  and  strengthening  the 
bore  of  guns,  etc.,  by  forcing  through  them  one  or  a  suc- 
cession of  steel  cylinders  or  olives,  each  slightly  (say  0-05 
inches)  wider  than  the  preceding,  successfully  used  by 
him  and  by  Uchatius  for  bronze  guns,  is  said  to  be  applied 
now  in  Belgium  to  steel  gun-tubes,  and  by  the  Credenda 
Steel  Tube  Company  to  small  steel  tubes.  It  does  not, 
however,  appear  to  dimmish  erosion  in  case  of  steel  guns.1 


a "  Open-Hearth  Steel   f.ir  Boiler  Making:"   Excerpt  Proc.    Inst.   Civ.   Eng. 
XCII.,  p.  58,  1888. 

b  Asst.  Nav.  Constructor  R.  Gatewood,  PrivateCommunication,  Nov.  25,  1888. 

c  L'Emploi  de  1'Acier,  Pe'risse',  p.  35,  1884.  The  foregoing  statements  about 
punching-practice  are  based  on  extensive  inquiries  which  I  have  made  both  here 
and  in  Britain. 

dThurston,  Metallurg.  Rev.,  I.,  p.  126:  Matls.  of  Engineering,  III.,  p.  540. 

eH.  R.  Towne,  Yale  &  Towne  Mfg.  Co.,  Trans.  Am.  Soc.  Mech.  Eng.,VIIL, 
p.  180,  1887, 


BLUE-SHORTNESS. 

§  290.  BLUE-SHORTNESS. k — Not  only  are  wrought-iron 
and  steel  much  more  brittle  at  a  blue  heat  than  in  the  cold 
or  at  redness,  but,  while  they  are  probably  not  seriously 
affected  by  simple  exposure  to  blueness,  even  if  prolonged, 
yet  if  they  be  worked  in  this  range  of  temperature  they 
remain  extremely  brittle  after  cooling,  and  may  indeed  be 
more  brittle  then  than  while  at  blueness  (2  and  3,  Table 
130) :  this  last  point  however  is  not  certain.. 

The  loss  of  ductility  as  measured  by  endurance  of  bend- 
ing and  drifting  is  enormous  :  that  this  is  not  due  to  in- 
cipient cracks  is  shown  by  the  simultaneous  increase  of 
tensile  strength,  and  by  the  restoration  of  ductility  by 
annealing.  The  effect  of  blue-working  on  ductility  as 
measured  by  elongation  (on  rupture  by  static  tensile  stress) 
is  very  irregular,  and  apparently  anomalous :  in  five  out 
of  the  eight  cases  in  Table  1 29  the  elongation  is  greater 
after  than  before  blue- working.  Heating  to  redness  may 
completely  remove  the  effects  of  blue- working  (4,  6,  Table 
DO). 

There  is  thus  a  general  resemblance  between  the  effects 
of  cold-  and  those  of  blue-working,  and  we  may  suspect 
that  the  immediate  effect  of  these  two  operations  is  identi- 
cal in  nature.  It  is  true  that  the  gain  in  elastic  limit  does 


*  Sweet,  Trans.  Am.  Soc.  Mech.  Eng.,  VII.,  p.  266,  1836. 

g  W.  P.  Durfee,  Idem,  Priv.  Commun.,  Feb.  5tb,  8th,  1889. 

h  F.  Overman,  The  Manufacture  of  Steel,  p.  61,  1851. 

1  Ttmrston,  Mat'Is  of  Engineering,  III.,  p.  530;  Metallurg.  Rev.,  I.,  p.  123: 
Rept.  U.  S.  Commissioners  Vienna  Exhibition  of  1873,  III.,  p.  324:  U.  S.  Patent 
No.  90,244,  May  18,  1869,  S.  B.  Dean. 

i  Maitland,  "The  Treatment  of  Gun  Steel,"  Excerpt  Proc.  Inst.  Civ.  Eng., 
LXXXIX.,p.  127, 1887. 

k  "The  Woi  king  of  Steel,"  Stiomeyer,  Excerpt  Proc.  Inst.  Civ.  Eng.,  LXXXIV., 

1886,  with  a  very  important  discussion.    Also  U.  S.  Naval  Prof.  Papers,  No.  31, 

1887.  A  blua  heat  is  hero  used  generically  to  include  straw  and  blue  oxide-tint 
temperatures,  say  220°  to  320°  C. ,  430  to  600°  F.     Brass  is  said  to  have  a  critical 
temperature  of  brittleness  like  that  o£  iron,  and  some   varieties  of  aluminium 
tronze  appear  to  have  one. 


BLUE-SHORTNESS.      §  290. 


not  seem  to  excel  that  in  tensile  strength  as  markedly  in 
case  of  blue-  as  in  case  of  cold-working,  nor  is  it  clear  that 
the  tensile  strength  and  elastic  limit  increase  during  rest 
after  blue-  as  they  do  after  cold- working.  But  this  is  nat- 
ural :  for  we  saw  reason  to  believe  that  heating  cold- 
worked  iron  to  blueness  greatly  accelerated  the  changes 
which  cold-working  starts  :  so  that,  when  this  change  is 
started  by  distortion  at  blueness  instead  of  in  the  cold,  it 
may  occur  so  rapidly  and  so  nearly  reach  its  full  growth 
before  the  metal  grows  cold  that  no  considerable  further 
change  occurs  thereafter.  The  effects  of  bine- working  are 
more  intense  and  more  injurious  than  those  of  cold-work- 
ing. While  the  blue-worked  iron  in  tables  128  to  130  is 

TABLE  128. — EFFECT  OF  PKKVIOTS  COI.D  AND  BLUE-HEAT  TREATMENT  ON  FLEXIBILITY  (ENDUE 
AM  P.  UK  Ucl'KATKTJ  BKMHXI,).    STP.I.MEVEK. 


Thebendings  of  Inst  four  columns  for  line  2  wore  done  at  blueness,  all  others  were  done  in  the  cold. 


Preliminary  treatment. 


1  Fnprepnred 

2  Unprepared 

3  Annealed  at  blueness 

4  Quenched  at  bl  leness 

5  Annealed  at  redness 

I',  Annealed  at  redness,  then  lit  blueness. . . . 

7  Quenched  at  redness 

S  Quenched  at  redness,  then  at  blueness... 


Hammered  cold. 


In  Hammered  at  blueness 

lljQuenched  from  redness,  twisted  cold  b  .. 

12  Quenched  from  blueness.  twisted  cold  b. . 

13  Twisted  blue  b 


14  Bent  cold  once;  then  rest 

15  Bent  cold  twice;  then  rest 

16  Bent  once  at  blueness;  then  rest 

17  Bent  twice  at  blueness;  then  rest 


Number  of  40°  bondings  (after  preliminary   treat 
ment)  endured  before  rupture. 


I. 

,  o  w  in  o  o  r 
Iron  C  = 
0-02  %. 


21 

3  @  7  tine. 

14®  19 

17 

19 


r,  ,„•  7 

n 

15 

7 


II. 

Very  soft  Soft 
steel    C 
0-05  %. 


27 

2-5®  7  blue, 
1S@27 
10@  11 

25 


19a  @  83 


21 

0 

15 

18 

1 


III. 

steel   C 


6 

1T>  blue. 

7  @9 

0@10 

12-5 

7 

Ida 
9  @  12-25 


lla 
lla 


IV. 

Half-hard 
steel  C  = 
0-29  f. 


15 

2-5  blue. 
K@5 

1 

21 

22-5 

1@24 

17@26 


22a 

0'5a 

21 


Length  of  rest,  days,  between  preliminary  treatment 
and  bending. 


35    1 


85 


85 


7  35 


Number  of  40°  bondings  endured  before  rupture. 


Ill  @  16 


6  @  14 
0  @    2 


it 

4-5 

1-5 

0 


18'5 

5-5 

1 


a  Annealed  instead  of  being  quenched. 

1*  In  lines  11  to  13  the  preliminary  treatment  for  Lowmoor  iron  and  very  soft  steel  was  to 
twist  the  piece  90°  four  times  in  a  length  of  6  inches,  apparently  90°  and  back  twice.  In  case  of 
soft  and  half-hard  steel  it  was  to  twist  the  piece  45°  in  a  length  of  G  inches,  one  way  and  back. 
Kach  piece  of  the  half-hard  and  of  the  soft  steel  was  first  baked  for  two  nights  in  a  moulders'  core- 
oven.  The  bendings  of  the  last  four  columns  were  each  of  about  40°  to  a  radius  of  1'75  inches, 
the  piece  being  bent  40°,  straightened,  bent  40°  in  the  opposite  direction,  and  so  forth.  "  Blue- 
ings'" is  used  generically  to  include  straw  and  blue  oxide-tint  temperatures,  or  say  230°  to  316° 
C.  (440°  to  000°  F  ). 

In  every  case  except  lino  2  the  numbers  in  columns  I.  to  IV.  are  the  numbers  of  bendings  in 
the  cold  through  40°  which  the  piece,  after  receiving  the  treatment  specified  in  the  column  "  pre- 
liminary treatment,"  endured  before  rupture.  In  lino  2  the  numbers  indicate  the  number  ot  40° 
bendtofn  at  blueness  which  the  piece  without  previous  treatment  endured  at  a  blue  heat  before 
rupture. 


TABLE    ISO.— EFF10T  Or  Bum  AH0  COLD  Wqw   "N    IH.TIMIV   AS   INKHKKKI. 

SlKol    HI  I   \  . 


Drl  flint- 

Endurance  of 
drift!  n  IT. 

IHjuncter,  inches, 
at  rupture. 

1 

Unprepared  

Cold 

l-94@2-06 

9. 

Blue 

1-90 

:! 

Drifted  at     I  Cooled  slowly 

Cold 

1-52©!  '81 

4 

blueness      K  Heated  to  redness  and  ijiu-nched 

COM 

2-5 

5. 

to  1  5",  then  (          "              "         and  cooled  slowly  

Cold. 

2.09©2-5. 

Pieces  of  open-hearth  steel  frame-plate  1"  thic'~,  cut  in  a  planer  to  about  s"  square-,  had  a  hole 
1'' in  diameter  drilled  with  its  centre  ]-7.V'  from  each  edge.  These  holes  wnv  then  treated  us 
indicated,  and  then  drifted  with  drifts  having  a  taper  of5  per  100  of  length,  till  they  split.  In 
certain  cases  the  rupture  crack  was  from  005  to OT2  inches  open.  (IMscusMun  of  Slromeyer's 
l'a|>er,  p.  65.)  In  each  case  the  test-piece  first  underwent  the  treatment  given  in  the  sen, ml 
column:  was  then  drifted  at  the  temperature  indicated  in  the  iliird  column,  till  it  split,  when  the 
hole  had  been  drifted  out  to  the  diameter  indicated  in  the  third  column. 


usually  somewhat  stronger  and  in  one  case  (very  soft  steel, 
14,  Table  129)  8,000  pounds  stronger  than  the  correspond- 
ing cold-worked  iron,  the  loss  of  flexibility  and  drifting 
power  on  blue-working  is  on  the  whole  very  much  heavier 
than  on  similar  cold- working.  Chit  of  16  comparable  cases 
in  Table  1*28,  the  previously  blue-worked  pieces  endures  in 
1 5  less  than  50%  and  in  11  l^ss  than  25%  of  the  bending  en- 
dured by  the  corresponding  cold- worked  piece. 

Adamson,"  who,  after  Valton,b  early  called  attention  to 
blue-shortness,  thinks  that  it  is  the  more  severe  the 
greater  the  number  and  aggregate  percentage  of  non-fer- 
rous elements  present.0  No  such  relation  can  be  1  raced, 
however,  among  the  results  in  tables  128  to  180.  Thus  the 
half-hard  steel  of  tables  128  and  129,  with  1  -Yl%  of  non- 
ferrous  elements,  cannot  be  confidently  held  to  suffer  more 
either  in  flexibility  or  tensile  properties,  and  whether 
tested  at  blueness  or  after  cooling,  than  the  Lowmoor  iron 
with  only  0'36%  of  these  elements.  Nor  is  it  clear  that  the 
wrought-iron,  4  and  5  of  Table  129,  suffered  less  than  the 
corresponding  steel.  Indeed,  there  is  no  certainly  known 
connection  between  composition  and  blue-shortness. 

According  to  Stromeyer  the  fracture  at  blueness  is  silky, 
though  the  steel  is  fairly  rotten  :  but  blue-worked  pieces 
broken  cold  yield  a  crystalline  fracture. 


a  Journ.  Iron  and  St.  Inst.,  1878,  II.,  p.  396. 

bValton,  Metallurg.  Rev.,  I.,  p.  170,  October,  1877. 

cJour.  Iron  and  Steel  Inst.,  1887,  I.,  p.  9.  T.  Gillott,  Jeremiah  Head  aud 
Isherwood  state  that  steel  is  injured  more  than  wrought-iron  by  blue-working. 
Others  hold  the  opposite  view.  "  The  Working  of  Steel,"  Stromeyer,  pp.  89,  57, 
86,  67. 


TABLE  129.— EFFECT  op  COLD  AND  BLUE-HEAT  TREATMENT  ON  TKNSILE  PROPERTIES  (STROHZYER). 


Preliminary  treatment. 

Wronght-lron.    I. 

Very  soft  steel.    II. 

Tensile 
strength. 
1  bs.   per 
sq.  in. 

Elastic  lim.. 
Ibs.  per  sq. 
in. 

Elongation. 

Tensile 
strength. 
Ibs.    per 
sq.  in. 

Elastic  lim., 
Ibs.  per  sq 
In. 

Elongation. 

Tensile 
strength, 
Ibs.  per  sq. 
in. 

Elastic  lim., 
Ibs.    per 
sq.  in. 

Elongation. 

Tensile 

strength, 
Ibs.  per  sq. 
In. 

Elastic  lim.. 
Ibs.    per 
sq.  in. 

Elongation. 

66,52S 
71,680 
81,312 
64,512 
80.192 
68.320 

43  232 
45,920 
56,000 

20-1 
12'9 
9  5 
23 
15  2 
44  f 
9 
3 

\  2    Flattened  cold 

|S            "         blue     

50,624 

20'fi  @  24 
10    ®  1C'.-) 

~<    'iv^tvil  blue 

07,424 

6.  Unprepared  

7.   I'.i-ntcold  
8.       "    blue  

72.  123 

Lowmoor  wronght-iron.     Ill 
C  =  0  02  %. 

Very  (-oft  steel.    IV. 
C  =  0-05*. 

Soft  steel.     V. 
C  =  0-16*. 

Half-hard  steel.    VI. 
C  =  0-29*. 

/  9.   Unprepared  
!  lo.  Blue-annealed    . 

49.000 
49,900 

2S.OOO 
81,684 
31,584 

•J-..IIOII 

3t,04S 
36,512 

07 
U  2 
IS  8 
7  1 
S  5 
10  3 

r,i,ooo 
50,500 
6:i,000 
96,000 

63,100 
71,000 

40,992 
45,02* 
41,44t 

M,'17'2 
:;-.n^l 
55,104 

24-5 
10-4  @  20-6 
18-0 
29-4 
16-3 
27  9 

59,400 

65,000 
67,000 
66.100 
67,900 

36,064 

34,944 
40,992 

47,488 

34  7 

24-3 

20-2 
16-8 
22-4 

72,900 

71,000 
76,000 

43,904 

40,992 
4:!,'.I04 

11-5 

7  2 
10-7 

III.    IVnteold     

:>•!.  loo 

52,900 

:••>,  
55,000 

)  l'->        "    blue 

13.  Twisted  cold... 

Vl4.          "      blue  

In  every  coso,  except  lino  5,  the  numbers  in  columns  I.  to  VI.  are  the  results  of  tests  in  the  cold  made  on  test-pieces  which  had  endured  the  treatment  specified  in  the  column  "preliminary 
treatment," 

In  line  5  the  previously  untreated  piece  was  ruptured  tensilely  at  a  blue  heat 

The  treatment  is  supposed  to  be  identical  for  the  several  column*  of  each  line,  except  for  those  of  lino  9. 

The  lines  braced  together  are  supposed  to  represent  tests  of  the  same  material  or  materials. 

All  tests  were  made  cold  except  Number  5,  which  was  tested  while  blue-hot. 

2  and  3,  flattened  cold  on  a  smith's  anvil,  and  thus  thinned  apparently  by  1*5£, 

7  and  8*     W.  Strmidley,  discussion  of  Stromeyer's  paper,  p.  (H.     They  were  bent  once  45%  and  straightened  by  hammering. 

9  to  14.    The  unprepared  ('•*)  soft  and  half-hard  steel  had  been  annealed  from  redness. 

The  blue-annealed  <  1")  pieces  were  kept  at  blueness  during  four  niirhts. 

Thebcn,£  pieces  (11, 12)  were  bent  to  a  radius  of  IV  ami  Uittene.l:  I  think   this   m^ans  that  they  were  bent  do  ible,  an J  the  bend  flattened  close,  and  not  reopened  •  but  the  wording  is  obscure. 

Tli.'  twffttini  (!•'*,  1  I)  was  through  a-i  ariirl--  of'.*  i*  and  bick,  in  12". 

Btromeyer,  The  Working  of  Steel,  excerpt  Proc.  last,,  Civ.  Enj?.,  LXXXIV.,  1836. 


236 


THE    METALLURGY    OF     STEEL, 


The  strengthening  effect  of  blue- working  is  well  illus- 
trated by  bending  a  common  tensile  test-j  iece  in  the 
middle  while  blue-hot,  straightening,  cooling  and  pulling 
it,  when  it  breaks  as  in  Figure  7 17,  the  unstrengthened  ends 
contracting  and  yielding."  Extreme  blue-shortness  is 


~^v                                                                         yr^ 

r            ~~r~  ' 

B                             C                 ®             < 

!    -     1     -L- 

1 
? 
. 
1 

L  ^                  I                                 g         \            ^  • 

Local  Strengthening  by  Blue-working.    Unwin. 

reported  in  the  case  of  a  soft-steel  gun-coil, b  which,  cooled 
to  blueness  owing  to  delay  at  the  hammer,  shattered  when 
struck :  and  in  that  of  a  steel  plate"  which,  though  very 
malleable  at  whiteness  and  when  cold,  went  to  pieces  while 
rolling,  as  it  cooled  to  below  redness. 

Valton  found  that  his  workmen  had  long  recognized 
blue-shortness,  and  avoided  hammering  at  blueness :  it  is 
said  to  have  been  known  in  the  Yorkshire  iron  works  for 
more  than  fifty  years,  and  some  steel-makers'1  have  long 
urged  their  customers  to  avoid  blue-work:  yet  the  dis- 
cussion on  Stromeyer' s  paper  in  1880  showed  that  many 
experienced  iron-workers  then  disbelieved  in  or  were 
ignorant  of  blue-shortness,  and  I  have  found  this  true  of 
very  many  American  iron-workers. 

But  while  blue-working  even  in  moderation  certainly 
lessens  ductility,  at  least  in  the  great  majority  of  cases, 
yet  the  injury  is  not  necessarily  fatal.  Thus  Stromeyer 
found  that  two  twists  of  45°  in  a  length  of  six  inches  did 
not  diminish  the  bending-endurance  of  very  soft  steel  and 
Lowmoor  iron  materially,  though  four  twists  of  90°  in- 
jured them  greatly  (13,  Table  128).  Steel  plates  fa"  thick 
have  been  bent  to  a  nearly  closed  circle  19"  in  diameter, 
flattened  again,  and  again  bent  the  reverse  way  to  the 
same  circle,  all  at  blueness,  without  sign  of  rupture.6 

Two  plates,  one  heated  to  blueness,  the  other  forged 
while  its  temperature  fell  from  bright  redness  to  blueness, 
were  bent  double,  flattened  under  a  steam-hammer,  and 
again  broken  open  while  blue-hot :  no  crack  could  be  de- 
tected at  the  outside  of  the  bend.'  Their  fractures  ex- 
actly resembled  those  of  a  similar  p'iece  bent  double  and 
opened  similarly  but  cold.  Again,  though  many  recog- 
nize that  machine-riveting  has  a  great  advantage  over 
hand-riveting,  in  that  its  work  ceases  before  the  rivet  cools 
to  blueness,  while  the  hand-riveter  usually  continues  ham- 
mering while  the  rivet  is  passing  blueness8 :  yet  relatively 
few  hand -worked  rivets  f---il  in  use,  and  the  difficulty  in 
getting  riveted  work  apart  does  not  point  to  serious  in- 
jury. Millions  of  car  axles,  blue  from  "hot  boxes,"  are 
chilled  with  snow  and  jarred  under  heavy  load  at  loose 
rail-joints,  yet  are  apparently  unharmed.  Among  the 
many  thousand  steel  boilers,  tens  of  thousands  of  plates 
must  have  been  worked  more  or  less  at  blueness :  yet  fail- 

a  This  result  is  reported  by  three  observers  independently,  Unwin,  B.  Baker  and 
F.  W.  Webb,  (op.  cit.  pp.  44,  54,  96). 

b  Bramwell  and  c  Bessemer,  op.  cit.,  pp.  83,  87. 

<i  E.  g.,  the  Steel  Company  of  Scotland. 

«  W.Parker,  '  W.  Anderson,  Idem,  pp.  39,  61,  41.  I  use  Mr.  Anderson's 
words,  as  I  am  not  quite  certain  of  '.heir  meaning. 

e  In  riveting  ships'  plutos  the  rivet  is  usually  left  while  hot,  and  again  tightened 
up  when  cold,  while  in  boiler-riveting  the  rivet  is  worked  continuously,  and,  of 
course,  through  the  blue  heat.  This  is  bacause  the  flat  counter-sunk  head  of  the 
former  is  quiCKly  finished,  so  that,  if  it  is  to  b3  tightened  cold,  a  considerable  in. 
terruptiou  naturally  occurs  at  blueuess  :  while  so  mucli  more  work  is  need«d  in 
making  the  conical  head  of  the  boiler-rivet  that,  though  worked  continuously,  it 
grows  nearly  cold  before  it  is  finished. 


ures  are  rare.  Finally,  much  crucible  steel,  in  the  form 
of  bars,  plates,  etc.,  is  habitually  rolled  or  hammered  till 
its  temperature  has  fallen  below  visible  redness.  The 
lesson  thus  seexs  to  be,  avoid  blue-working  wholly  if  you 
can :  if  not,  then  use  it  cautiously  and  very  moderately, 
unless  you  anneal  later. 

By  heating  in  their  bearings  marine  and  other  shafts, 
railway  axles,  etc.,  are  liable  to  reach  blueness,  as  are  guns 
through  rapid  firing,  when  accidents  may  readily  occur. 
In  practice  many  of  the  best  American  bridge  engineers 
do,  others  do  not  positively  forbid  blue-working.  The 
Russian  Ministry  of  Roads  in  1885  ordered  that  all  bend- 
ing should  be  hot,  apparently  at  redness.11 

Blue- working  without  subsequent  annealing  is  rarely 
permitted  for  the  steel  of  the  Forth  Bridge,  though  the 
rivets  and  small  angles  and  tees  are  liable  to  be  worked  to 
blueness,  and  are  not  subsequently  annealed.1  I  am  in- 
formed that  good  German  bridge  engineers  permit  blue- 
working  occasionally  in  case  of  steel,  and  usually  in  case 
of  wrought-iron. 

It  is  said  that  some  boiler-makers  allow  no  blue-work- 
ing, stopping  work  when  the  metal  becomes  so  cool 
that  it  no  longer  glows  when  rubbed  with  wood:  others 
stop  while  the  metal  is  still  visibly  red.  Others  insist 
that  it  is  necessary  to  adjust  some  work,  e.  g.,  marine 
boiler-fronts,  at  blueness  :  that,  despite  the  most  careful 
hot- working,  adjustment  is  needed  after  the  distortion 
due  to  cooling,  especially  as,  owing  to  the  endless  variety 
of  patterns,  flanging  in  the  press  at  a  single  heat  is  not 
practicable  :  that  adjusting  cold  wou  d  lead  to  excessive 
waste  of  time,  as  iron  is  bent  more  quickly  at  blueness 
than  when  cold :  hence  these  pieces  are  warmed  locally 
to  blueness  by  applying  hot  irons.  To  anneal  afterwards 
would  be  useless,  as  fresh  adjustment  would  be  needed 
after  cooling.  Certain  it  is  that  most  American,  and  at 
least  many  foreign  boiler-makers,  habitually  adjust  at 
blueness.  Blue-working  without  subsequent  annealing  is 
forbidden  for  boilers  for  the  United  States  navy,  but  not 
for  the  hull-work.11 


THE  TREACHERY  OF  STEEL. 

§  291.  THE  TKEACHERY  OF  STEKL. — We  may  arbitrarily 
divide  the  failures  in  steel  and  wrought-iron  into  the  nor- 
mal ones  which  occur  because  the  known  proper  conditions 
of  manufacture  or  use  are  violated,  and  the  really  mys- 
terious ones.  Of  course,  many  failures  placed  in  the  first 
class  might  on  further  examination  be  found  to  belong  to 
the  second. 

The  evidence  seems  to  show  that  of  a  given  number  of 
pieces,  say  100, 000  of  wrought-  and  100,000  of  ingot-iron, 
more  of  the  former  than  of  the  latter  fail  in  manufacture, 
assembling  and  use :  ingot-iron  is  on  the  whole  more  trust 
worthy  than  puddled  iron.  But  though  the  failures  are 
fewer  among  the  100,000  ingot-iron  pieces,  yet  the  number 
of  mysterious,  i.  e.  as  yet  wholly  inexplicable  failures,  is 
greater  among  them  than  among  the  wrought-iron  pieces. 
To  this  evidence  I  will  return. 

In  the  early  use  of  Bessemer  and  open-hearth  steel 
many  then  unexplained  and  hence  then  mysterious  fail- 
ures occurred.  With  our  present  knowledge  an  easy  ex- 


h  Eng.  and  Mining  Jl.,  XLII.,  p.  93,  1886. 

1  Private  communication,  B.  Baker,  Nov.  2d,  1888. 

i  R.  Oatewood,  private  communication,  Nov.  S5th,  1888. 


THE    TREACHERY    OF     STEEL.      §292. 


237 


planation  of  most  of  them  would  probably  have  been 
seen.  But  even  to-day  certain  unexplained  and  appar- 
ently inexplicable  failures  occur  in  steel,  inexplicable  in 
spite  of  full  and  intelligent  investigation.  They  are  ex- 
tremely rare,  but  I  do  not  think  that  they  can  be  ignored 
or  ridiculed.  The  mystery  in  some  of  them  maybe  due 
to  overlooking  or  purposely  suppressing  conditions  which 
would  readily  explain  them  :  but  I  believe  that  the  true 
explanation  of  others  lies  beyond  our  present  knowledge. 

J  learn  of  a  few  truly  mysterious  accidents  to  wrought  - 
iron:  they  have  not  attained  the  publicity  that  has  be- 
fallen the  mysterious  failures  of  steel,  thanks  partly  to 
many  motives,  mostly  honorable,  and  partly  to  the  very 
nature  of  the  case :  the  newer  metal,  on  probation,  has 
deserved  the  closer  scrutiny. 

But  the  mysterious  accidents  reported  in  case  of  steel 
exceed  those  in  case  of  wrought  iron  to  a  greater  extent 
than  can  be  readily  accounted  for  in  this  way.  One  addi- 
tional explanation  is  that,  owing  to  the  very  nature  of  the 
processes  by  which  steel  and  wrought-iron  are  made, 
carelessness  and  ignorance,  whether  in  selecting  materialf > 
in  conducting  the  processes,  or  examining  the  product, 
is  more  likely  to  lead  to  the  making  and  selling  of  treach- 
erous steel,  treacherous  simply  because  unsuited  to  the 
purpose  for  which  it  is  sold,  /.  e.,  too  highly  carburetted ; 
or  positively  bad,  bad  owing  to  a  combination  of  high 
phosphorus  with  high  carbon,  to  serious  segregation,  to 
serious  pipes,  internal  cracks,  etc.  The  very  pliancy  of 
the  steel-making  processes,  the  ease  for  instance  with 
which  the  carbon-content  of  a  Bessemer  or  an  opeu-hearth 
charge  may  be  raised  at  the  shortest  notice  from  0'(5  to 
1%,  demands  increased  watchfulness  to  prevent  and  detect 
unsought  variation :  invaluable  to  the  watchful  and  the 
intelligent,  it  is  a  stumbling  block  to  the  ignorant  and  the 
hee  iless. 

Further,  it  is  conceivable  that  the  presence  of  slag  in 
wrought-iron,  while  a  source  of  weakness,  may  in  some 
obscure  way  lend  a  certain  security  against  the  mysterious 
failures  whose  very  nature  is  obscure. 

Let  the  mysterious  class  of  failures  be  illustrated  by  two 
famous  cases,  one  in  which  steel  plates,  which  had  passed 
an  examination,  seemed  to  become  extremely  brittle  after 
rolling  and  testing  but  before  the  boilers  made  fro  n  them 
were  tested,  a  case  which  caused  widespread  dismay  ; 
and  another  in  which  steel,  certainly  initially  good  enough 
to  endure  the  trying  conditions  of  boiler-construction, 
became  astonishingly  brittle  during  two  and  a  half  years' 
service. 

§  23.'.  Two  MrsTEitiors  CASES. — The  Limdia  Case." 
Some  i-inch  steel  boiler-plates,  containing  about  O'l  %  of 
carbon,  rolled  from  22-inch  ingots,  had  passed  tensile,  and 
quenching  and  bending  tests  well  (nearly  all  the  latter  being 
satisf  ictorily  passed  by  rough  sheared  unplaned  pieces), 
had  been  punched,  heated  slightly,  and  bent  to  the  proper 
curvature,  and  the  rivet  holes  had  been  reamed  out  about 
iV-inch  to  size  in  place,  when  an  accidental  concussion 
caused  the  steel  to  crack  between  some  rivet  holes  not  in  the 
immediate  neighborhood  of  the  spot  directly  injured.  The 
plates,  thought  to  be  injured  by  punching,  were  now  an- 
nealed, but  in  such  a  way  that  some  of  them  may  have  been 
much  overheated.  The  boilers  were  now  riveted  apparently 


»W.  Parker,  Chief  Kng. ,  Surveyor  to  Lloyd's  Register,  Trans.  last.  Nav.  Arch. 
XXII  ,  p.  13,  1881. 


safely :  but  one  tore  asunder  in  three  pieces  in  hydraulic 
testing,  before  reaching  1 40  pounds  pressure,  while  another 
was  found  cracked  behind  the  rivet  holes  before  the  test- 
ing water  was  introduced.  The  metal  was  now  carefully 
studied.  Large  pieces  could  be  broken  from  the  plates 
with  a  single  blow  of  a  hammer :  the  metal  still  showed 
normal  tensile  strength  and  elongation,  but  an  abnormal 
fracture,  in  part  with  brilliant  facets  from  <  n;i  eighth  to 
one  quarter-inch  wide.  Under  bending  tests,  strips  cut 
close  to  the  rivet-holes  and  others  purposely  punched  wcie 
extraordinarily  brittle,  while  others  cut  at  a  distance  from 
the  rivet-holes  behaved  normally.  Strips  containing  the 
original  rivet-holes  became  tough  on  annealing:  others 
purposely  punched  were  made  tough  by  either  reaming  or 
annealing.  Examination  of  one  plate  showed  marked  but 
not  extraordinary  segregation  (No.  62,  Table  96).  When 
the  plates  were  rolled  to  f,  or  half  the  original  thickness, 
the  fracture  and  properties  in  general  became  normal. 

T  offer  the  following  explanation  :  it  may  rot  be  the  true 
one,  but  it  seems  to  cover  the  ground.  The  plates  were 
bad  initially,  possibly  owing  to  excessively  high  casting 
temperature.  Witness  the  undue  brittleness  caused  by 
punching  and  the  segregation  :  but  not  so  bad  that  they 
could  not  pass  a  somewhat  perfunctory  examination.  If 
properly  annealed  they  would  ]  robably  never  have  been 
heard  from.  In  annealing  they  were  burnt:  witness  the 
brilliant  ultra-coarse  fracture.  The  burninT  was  natur- 
ally most  severe  along  the  edges  which  would  be  tte  hot- 
test part:  hence  the  much  greater  brittleness  near  the 
punched  holes  than  away  from  them.  The  burnt  steel  was 
naturally  made  extremely  brittle  by  punching. 

The  effects  of  burning  were  modified  to  a  certain  extent 
by  annealing,  but  not  completely  removed.  The  brittle- 
ness  directly  due  to  burning  was  greatly  lessened :  hence 
the  annealed  strips  bend  fairly.  But  the  tendency  to  be- 
come brittle  when  punched  is  not  removed,  or  not  re- 
moved so  completely :  hence  the  metal,  even  when  an- 
nealed, is  again  made  brittle  by  punching  But  while  the 
annealing  applied  before  punching  does  not. remove  this 
liability  to  be  made  brittle  by  punching,  applied  after 
punching  it  removes  the  effect  of  this  operation :  hence 
the  fair  bends  obtained  with  the  metal  annealed  after 
punching.  Remember,  all  this  is  hypothesis  :  we  do  not 
know  that  the  effects  of  burning  persist  in  this  specific 
way. 

The  Magmnis  Case* — Each  of  two  British  steamers,  1 
and  2,  in  the  transatlanlic  and  colonial  trades,  had  three 
boilers  built  by  Jack,  from  steel  made  by  the  Wear- 
dale  Coal  and  Iron  Company,  in  two-and-a  half  ton  acid 
Bessemer  converters,  cast  in  ingots  about  nine  inches 
thick,  and  reduced  to  plates  from  -41  to  '74  inch  thick, 
and  containing  (at  least  in  case  of  some  cracked  combus- 
tion chamber  plates) : 


Carbon, 
•12® 'IT 


Silicon, 
•005@'01S 


Manganese, 
•:i2@'5S 


Phosphorus, 
•OS© 'DCS 


Sulphur. 
•M8O061JC. 


The  tensile  properties  follow. 


Elonpation, 
In  10". 


Tensile  strength, 
[Kjunda  |>er  sq.  In. 

40  tests  before  leaving:  the  works 68.»«&68,090 

Tests  from  cracked  combustion  chamber  [dates,  steamer)   ^ 

],  4  tests,  fractures  fiiu'-crystallinc i  l()         90*720 

Do.          do.,          steamer  2,  7  tests,  fractures  "  fibrous,  \\ J^J"1 
nilky,  fine" {\o 

The  steel  actually  used  passed  an  inspection  by  Lloyds' 


15 

7-75 
13 
24T, 

8 
26 


1>A.  Maginnis,  "  The  Engineer,"  LX.,  p.  447,  1885.      Also  W.   Kent,  Trans. 
Am.  Inst.  Min.  Eng.,  XIV.,  p.  812,  1886. 


238 


THE     METALLURGY    OF    STEEL. 


and  the  Board  of  Trade,  but  forty  per  cent  of  that  supplied 
failed  to  pass,  and  was  replaced.  The  accepted  material 
endured  the  usual  boiler-shop  work,  welding  included, 
without  mishap.  The  furnaces  were  annealed  after 
welding. 

With  careful  scaling  and  the  usual  precautions,  the 
boilers  behaved  normally  in  service  for  two-and-a-half" 
years,  when  they  failed  in  the  following  remarkable 
way. 

Steamer  1  — Three  weeks  after  blowing  down,  and  while 
no  work  beyond  the  usual  scaling  was  going  on,  a  crack 
about  thirty  inches  long,  open  one-eighth  inch  at  bottom 
and  one-sixteenth  at  top, "formed spontaneously  in  a  com- 
bustion-chamber plate.  About  three  months  later,  and  a 
few  days  af  ler  shutting  off  steam,  a  circumferential  crack 
over  two  feet  long  formed  with  an  alarming  report,  in  a 
wing  furnace  rom  which  workmen  were  removing  the 
scale. 

Steamer  2. — At  the  same  period  of  work  as  in  case  of 
steamer  1,  and  thirteen  days  after  letting  down  steam,  a 
crack  twenty-seven  inches  long  formed  in  a  combustion- 
chain  ber  plate  with  a  report  which  nearly  deafened  even 
a  boiler-maker.  Three  months  later  a  further  crack 
formed. 

Parts  of  the  plates  now  being  extraordinarily  brittle, 
the  boilers  were  broken  up,  with  startling  results.  In 
unriveting  the  pipes  connecting  boiler  and  steam  chest, 
after  a  few  blows  they  were  found  cracking  in  all  direc- 
tions, so  much  so  that  none  of  the  nine  of  steamer  2  came 
off  whole.  Next  a  butt-strap  cracked  almost  across  be- 
tween rivet-holes.  Later  "a  general  smash  was  experi- 
enced, the  front-plates  cracking  and  starring,  and  the 
flanges  breaking  off.  The  furnaces  at  the  same  time  acted 
in  just  the  same  manner,  the  cracks  going  through  4he 
rivet-holes  to  such  an  extent  as  to  allow  the  ends  to  come 
off  whole,  and  so  form  hoops  for  the  lads  to  play  with  in 
the  meal-hour." 

I  see  no  easy  explanation.  Internal  strains  and  -de- 
terioration, homogeneousness,  crystallization,  excessive 
dimensions  of  plates,  and  untrtastworthiness  of  Bessemer 
steel  in  general,  are  justly  pointed  out  by  Kent  to  be 
improbable  causes :  innumerable  plates  appear  to  be  sub- 
jected to  conditions  favoring  failure  from  these  causes  as 
much  as  these  plates  were.  Yet  they  do  not  fail,  while 
not  one  or  two,  but  very  many  of  these  plates  fail  aston- 
ishingly. His  own  explanation,  heterogeneousness,  owing 
to  imperfectly  mixing  the  recarburizer  with  the  blown 
metal,  hoists  with  his  own  petard,  because  we  know  that 
plates,  rails,  etc.,  are  often  if  not  usually  markedly 
heterogeneous,  yet  they  fail  not.  Neither  is  it  probable 
that  a  degree  of  heterogeneousness  sufficiently  unusual  to 
indxice  such  unusual  results  would  have  happened  to  fall 
on  all  these  plates,  representing  many  different  Bessemer 
blows,  especially  as  good  boiler-plate  steel  had  been  made 
for  years  in  these  same  converters,  and,  according  to  the 
steel-maker,  under  exactly  the  same  conditions,  with  one 
exception — that  these  plates  were  thicker  than  those  pre- 
viously made.  Herein  lies  a  possible  explanation.  Clearly, 
if  the  temperature  to  which  the  ingot  is  raised  for  rolling, 
the  rapidity  of  rolling,  and  the  reduction  per  pass  be  the 
same,  the  metal's  temperature  will  be  much  higher  if 


a  These    numbers  are  as  given   by  Maginnis. 
correctly 


Others  have  quoted   him   in 


rolled  to  a  thick  than  if  farther  reduced  to  a  thin  plate  : 
so  that  these  thick  plate?,  made  from  thin  ingots,  may 
have  left  the  rolls  at  so  high  a  temperature  that  serious 
I  crystallization  occurred  during  the  subsequent  slow  un- 
disturbed cooling.  But  this  is  not  wholly  satisfying, 
first,  because  other  pieces  of  steel,  and  notably  rails,  are 
often  finished  unduly  hot  without  disaster:  and,  second, 
because,  so  far  as  I  know,  an  unduly  high  finishing  tem- 
perature does  not  produce  this  specific  effect  of  yielding  a 
metal  which,  only  moderately  bad  at  first,  undergoes 
extraordinary  deterioration  under  the  indefinitely  repeated 
expansion  and  contraction,  vibration,  etc.,  incident  to 
use.  This  objection,  indeed,  applies  with  equal  force  to 
all  other  theories  but  one,  to  wit,  that  the  boiler  under- 
went some  extraordinary  treatment  during  service,  such 
as  being  highly  heated  and  then  quenched  with  water. 
But  it  is  improbable  that  this  would  happen  to  all  six  of 
these  sister-boilers  in  two  different  vessels  at  the  same 
period  of  service. 

Careless  inspection,  permitting  some  plates  or  heats  to 
pass  untested,  might  account  for  the  difference  between 
the  original  tensile  properties  and  those  found  in  strips 
cut  from  the  broken  pieces,  but  not  for  the  extraordinary 
britf leness  after  service  of  plates  which  before  service  must 
all  have  been  at  least  moderately  tough,  for  they  endured 
the  trying  ordeal  of  boiler-making.  We  can  hardly  doubt 
that  the  metal  deteriorated  greatly  after  the  boilers  were 
made,  though  the  tendency  or  liability  to  deterioration 
was  probably  incurred  in  the  steel  works  or  the  boiler- 
shop,  or  in  both  :  but  how  incurred  we  know  not. 

One  striking  feature  must  not  be  overlooked  :  the  fail- 
ures occurred  when  the  boilers  were  not  under  steam. 
This  may  give  the  future  investigator  a  clue.  I  am  in- 
formed that,  on  the  Pennsylvania  Railroad,  there  have 
been  within  the  last  ten  years  perhaps  twenty  cases  in 
which  the  boiler-plates  of  locomotive  engines  have  snapped 
when  either  cold  or  under  half  steam.  My  informant  is 
not  sure  that  a  single  such  case  has  happened  under  full 
steam. b 

§293.  CASES  THOUGHT  TO  BK  NORMAL,  AND  OTHERS.— 
Of  the  other  class  of  failures  which  I  have  termed  normal, 
those  which  are  supposed  due  to  violation  of  known 
canons  of  manufacture  or  treatment,  we  find  a  large  part 
attributed  to  blue-working  :°  internal  stress  due  to  local 
heating,  and  heterogeneousness  of  strength  and  of  elastic 
limit  due  to  cold-working  come  in  for  their  share  also.  In 
1881  Parker  reported  that,  in  the  construction  of  1,10:) 
steel  boilers,  representing  17,000  tons  of  material,  none  of 
Lloyd's  surveyors  had  met  a  single  brittle  plate.  They 
had  investigated  many  of  the  supposed  mysterious  failures 
of  steel  plates  which  had  stood  all  the  required  tests,  had 
been  riveted  into  place,  and  then  had  been  reported  to 
crack  without  being  touched  ;  and  they  had  traced  them 
all  clearly  to  improper  manipulation,  the  metal  in  ihe 
neighborhoood  of  the  crack  being  found  ductile  as  soon 
as  rupture  had  relieved  the  internal  sLress.d  He  gives  the 
following  as  an  example:  A  10-foot  boiler  was  nearly  com- 
pletely riveted,  when,  on  returning  from  dinner,  the 


•>  Dr.  C.  B.  Dudley,  private  communication,  Nov.  20,  1888. 

e  J.  Riley  states  that  in  every  or  nearly  every  case  of  mysterious  failure  of 
ingot  iron  that  has  come  before  us  (the  steel  makers)  we  have  concluded  that  it 
was  due  to  working  at  blueness.  Trans.  Inst.  Nav.  Arch.,  XXVTl.,  p.  131< 
1886. 

d  Trans.  Inst.  Nav.  Arch.,  XXII.,  p.  12,  1881. 


THE    TREACHERY    OF    STEEL.       §293. 


239 


riveters  found  that  the  plate  which  they  had.  lately  been 
working  had  torn  for  a  distance  of  eighteen  inches.  By 
accident  the  bolts  that  had  been  holding  the  furnace  up 
to  the  front-plate  had  not  been  taken  out.  On  removing 
them,  the  rivet-holes,  though  originally  drilled  true  in 
place,  were  found  quite  £th  inch  blind,  showing  that  the 
furnace  had  been  smaller  than  the  circular  part  of  the 
plate  to  which  it  had  to  be  riveted,  had  been  stretched  in 
riveting,  stress  being  thrown  on  the  metal  which  eventu- 
ally sufficed  to  tear  it." 

It  is  surprising  that  the  workmen  could  put  enough 
stress  upon  the  plate  to  tear  it  at  all,  were  it  free  from 
initial  flaw  or  weakness:  further,  as  the  flue  was  nine  feet 
in  circumference,  and  as  the  metal  showa  26$  elongation 
in  tensile  testing,  uniform  stretch  should  enlarge  the 
flue  by  more  than  two  feet  before  causing  rupture,  while 
only  £  of  an  inch  displacement  orO'l'^is  actually  proved.1" 
Thus  this  explanation  is  not  exactly  convincing  on  its 
face  :  yet  it  may  be  the  true  one  :  for  we  have  seen  in  §  269 
and  especially  at  the  end  of  §  271 ,  B,  p.  217,  that  the  total 
elongation  may  be  greatly  lessened  by  cold-working,  and 
that  the  effects  of  cold-working  go  on  increasing  long 
after  the  cold-working  itself  has  ceased  :  and  so  may  the 
capacity  for  elongation  have  been  here  greatly  lessened  by 
the  peculiar,  oft-interrupted,  jerky  stretching  which  the 
material  underwent  as  it  was  drifted  and  stretched. 
Further,  it  is  possible  that  the  stretching,  far  from  being 
uniformly  distributed,  may  really  have  been  gradually  con- 
centrated by  successive  rivets,  so  that  a  continually  and 
at  last  rapidly  increasing  proportion  fell  on  successive 
parts  of  the  plate.  Thus  we  should  not  scout  Mr.  Parker's 
statement, — he  voices  the  opinions  of  many  intelligent 
engineers — yet  it  seems  to  me  probable  that  many  failures 
which  are  referred  to  brutal  treatment  from  the  boiler- 
maker  may  be  duo  to  other  causes,  such  as  a  line  of  brittle- 
ness  in  an  otherwise  tough  plate,  and  that  a  considerable 
proportion  of  the  failures  is  still  imperfectly  explained. 
We  instinctively  seek  explanation.",  and,  failing  a  satis 
factory  one,  gull  ourselves,  and  hatch  our  porcelain  nest- 
eggs. 

Many  of  these  surprising  cracks  in  ingot  iron  plates  occur 
without  reduction  of  the  metal' s  area  at  the  cracked  edge,c 
while  under  common  tensile  stress  the  area  would  usually 
be  reduced  by  more  than  40  and  sometimes  by  mere  than 
60  per  cent.  In  some  of  these  cases  the  metal  at  the  very 
edge  of  the  crack  seems  tough.  Again,  sometimes  the 
cracks  can  be  readily  extended,  or  even  extend  themselves, 
for  a  certain  distance,  while  beyond  they  obstinately 
refuse  to  go.  Here  are  a  few  examples. 

In  the  Maginnis  case,  some  cracks  which  were  started 
by  hammering  began  by  showing  a  peculiar  black  shade 
about  half  an  inch  w.'de,  and  after  another  blow  a  fain  t  hair- 
like  score  became  visible,  which  without  further  blows 
gradually  opened  and  extended  automatically,  till  fully  de 
veloped  :  other  cracks  formed  almost  simultaneously  with 
the  blow  of  the  hammer.  In  two  cases  Maginnis  had  the 
metal  on  one  side  of  the  crack  held  firmly,  while  that  on 
the  other  was  struck  in  order  to  extend  the  crack,  as  shown 
in  Figure  118.  In  one,  the  crack  extended  about  four 


»  W.  Parker,  discussiou  of  Stromeyer's  paper  on  the  Working  of  Steel,  Excerpt. 
froc.  lost.  Civ.  Eng.,  LXXXIV.,  p.  35,  1886. 
.   *>  Cf.  Unwin,  Idem,  p.  43 

«  A.  C.  Kirk,  Trans.  Inst.  Nav.  Arch.,  XXVI.,  p.  263,  1885, 


inches  at  the  first  blow,  leaving  only  2'5  inches  of  solid 
plate.  The  remaining  part  was  hammered  flat  and  re- 
straightened  without  extending  the  crack.  The  other  was 
hammered  flat  in  the  line  of  the  crack,  straightened,  and 
hammered  flat  in  the  opposite  way  without  lengthening 
the  crack. 

Fig.  118 


9 

SHADED  PART 
IOKEN  WITH  ONE  BLOW 


Fig.  9 


o 


QOOOQQQQQQOQQ 


Spontaneous  Cracks  which  cannot  be  Extended. 


In  another  case  a  crack  with  bright  crystallized  sides,  in 
an  open-hearth  steel  plate,  could  not  be  extended  by  wedg- 
ing, apparently  having  gone  its  full  length  automatically, 
and  then  refusing  to  go  further.  Tensile  and  bending  tests 
from  its  very  sides  were  normal.0 

In  removing  a  long-used  steel  locomotive  fire-box  to 
repair  its  cracked  crown  sheet,  two  opposite  side  sheets 
cracked,  one  of  which,  containing  0-17$  of  carbon,  was 
examined  at  the  Watertown  arsenal/  The  crack  extended 
into  five  stay-bolt  holes,  stopping  3-5  inches  short  of  the 
sheet's  edge,  and  was  formed  with  no  apparent  contrac- 
tion of  the  plate'  s  sectional  area  :  its  surfaces  were  granular 
with  a  marked  radiant  appearance.  Yet  the  metal  was 
fairly  ductile  around  and  even  at  the  very  edge  of  the 
crack:  for  a  strip,  cut  parallel  with  and  including  one 
edge  of  the  crack,  was  bent  180°  and  nearly  closed  down 
without  rupture,  and  tensile  test-pieces  cut  from  near  the 
crack  had  the  following  properties  : 


Tensile  strength 
Ibs.  per  sq.  in. 

From 64,000 

To 66,910 


Elastic  limit, 
Ibs  per  sq.  in. 
with  44,580 

"  44,240 


Elongation,  Contraction 

<lnlO".  of  area  f. 

15-2  and  43'4 

19-5  "  51 T 


C.  L.  Houston6  reports  that  a  f-inch  steel  plate  was 
flanged  into  a  locomotive  throat-sheet :  the  next  morning 
a  crack  appeared  at  the  'opposite,  unheated,  untreated, 
planed  end,  and  grew  for  about  a  week,  finally  reaching 
across  the  plate  to  the  part  which  had  been  heated. 
The  tensile  strength  of  a  test-piece  which  had  the  crystal- 
line face  of  the  crack  for  one  edge  was  68,580  pounds  per 
square  inch,  its  redjnction  of  area  42$,  and  its  fracture 
fibrous. 

The  stress  induced  by  sudden  cooling  is  doubtless  the 
cause  of  the  treachery  of  hardened  steel,  of  which  a  case 
has  been  noted  in  a  foot-note  on  page  181,  and  which  is  fur- 
ther illustrated  by  the  failure  of  some  steel  punches  and 
dies  which,  after  hardening  without  tempering,  were 
ground  O'OOl  inch  five  times  alternately  on  each  side, 
reducing  their  total  thickness  by  0*01  inch.  A  few  hours 
after  grinding  they  began  to  crack  and  nearly  all  were 
thus  ruined.'  Grinding  still  more  lightly,  so  that  only 
O'OOl  inch  was  removed  in  ten  grindings  (approximately 
of  O'OOOl  inch  each),  the  same  results  followed.* 

But  sudden  cooling  cannot  account  for  these  accidents 


<J  Kept.  Tests  of  Metals  at  Watertown  Arsenal,  year  1885,  p.  1,053,  1888.  This 
interesting  case  is  here  admirably  illustrated. 

e  Trans.  Am.  Soc.  Mech.  Eng.,  X.,  1889,  to  appear. 

'  L.  K.  Fuller,  Trans.  Am.  Soc.  Mech.  Eng.,  X.,  1889,  to  appear. 

8  Idem,  Private  Communication,  Dec.  12th,  1888.  I  have  one  of  these  inter- 
esting dies  in  my  collection. 


240 


THE    METALLURGY    OF     STEEL. 


to  boiler  plate  steel,  for  the  metal  itself  is  tough  as  soon 
as  the  stress  has  been  relieved  by  cracking. 

The  cause  of  such  cracks  as  these  is  certainly  obscure. 
They  may  be  due  to  defects  in  the  ingot,  such  as  a  pipe, 
or  heterogeneousness  due  to  segregation  or  to  imperfect 
mixing.  If  to  a  pipe,  it  is  not  easy  to  see  why  its  sides 
are  noi  welded  at  least  so  well  that  a  certain  amount  of 
reduction  of  area  occurs  on  rupture.  They  may  be  due  to 
the  splitting  apart  of  the  coarse  crystals  which  form  at 
a  high  temperature  :  but  if  so  it  is  surprising  that  these 
crystals  .-  re  not  broken  up  during  rolling.  They  may  be 
due  to  an  unduly  high  finishing  temperature :  but  if  so, 
why  does  the  crack  stop  so  abruptly  ?  They  may  be  due 
to  severe  highly  localized  stress,  due  in  turn  to  local  heat- 
ing. Such  stress  combined  with  unduly  high  finishing 
temperature  and  with  heterogeneousness,  seems  a  possible 
cause.  In  the  first  place  the  very  rarity  of  such  failures 
suggests  that  they  are  due,  not  to  a  single  condition,  but 
to  an  unusual  combination  of  conditions.  Next,  hetero- 
geneousness and  high  finishing  temperature  help  to 
account  for  the  brilliant  coarse  crystallization.  Hetero- 
geneousness helps  to  account  for  the  fact  that,  when  these 
failures  occur  at  all,  it  is  usually  in  bad  steel ;  because 
bad  steel,  whether  bad  because  cast  too  hot,  because  too 
phosphoric,  or  because  so  cold  that  the  recarburizer  does 
not  melt  and  diffuse  thoroughly,  is  especially  liable  to 
heterogeneousness,  high  casting  temperature  clearly 
favoring  segregation,  high  phosphorus  favoring  the  segre- 
gation of  phosphoric,  brittle,  coarsely  crystalline  bodies. 
Heterogeneousness  and  local  heating  help  to  account  for 
the  extreme  localization  of  tho  weakness.  Suppose  a  thin 
streak  of  some  segregated,  say  phosphoric  compound,  or 
of  an  unmelted  lump  of  recarburizer,  existing  in  \  he  plate: 
suppose  that  this  compound  tends  strongly  to  crystallize 
coarsely  :  suppose  that,  thanks  to  this  and  to  its  different 
rate  of  dilatation,  our  line  of  weakness  is  intensified  dur- 
ing heating  and  cooling :  that  a  high  finishing  tempera- 
ture further  favors  coarse  crystallization  :  that,  during 
the  cooling  which  follows  some  local  heating,  and  while 
the  temperature  is  sinking  past  some  point  of  critical 
weakness,  say  a  blue-heat,  irregular  contrac'ion  induces 
a  stress  perpendicular  to  our  streak,  sufficient  to  weaken 
the  adhesion  between  the  dissimilar  coarse  crystals  which 
constitute  it,  perhaps  sufficient  even  to  part  some  of  them, 
or  at  least  to  break  off  the  dowels  which  bind  them 
together.  The  weakness  of  our  streak  is  now  greatly 
exaggerated,  and  a  relatively  slight  stress  arising  in 
service  may  suffice  to  cause  rupture.  Now  if  we  lacked 
heterogeneousness,  or  if  the  stress  due  to  local  heating 
had  such  a  direction  and  intensity  that  it  just  failed  to 
part  our  crystals  at  blueness,  or  if  our  segregated  body 
had  not  been  made  coarsely  crystalline  by  high  finishing 
temperature,  our  weak  streak  might  still  be  but  little 
weaker  than  the  rest  of  the  metal :  for  while  a  stress 
which  just  fell  short  of  causing  incipient  rupture  at  a 
temperature  of  critical  weakness  might  do  little  harm,  a 
slightly  greater  stress  might  be  disastrous. 

The  above  is  not  offered  as  the  true  explanation :  in- 
deed, it  seems  to  me  forced  :  but  merely  as  an  example  of 
the  kind  of  rare  combination  of  circumstances  which  may 
lead  to  mysterious  failure. 

Here  are  a  few  other  cases. 

1.  In  testing  a  cylindrical  steel  boiler  13  feet  in  diam- 


eter, properly  designed  for  150  pounds  pressure,  when  the 
pressure  reached  240  pounds  a  plate  1J  inches  thick, 
weighing  nearly  three  tons,  tore  completely  across.  The 
tensile  strength  of  a  strip  from  this  plate  was  66,304 
pounds  per  square  inch,  and  its  elongation  20$  in  8  inches : 
other  strips  bent  nearly  double  cold,  yet  the  plate  now 
failed  under  less  than  a  quarter  of  this  stress,  and  without 
appreciable  elongation  or  reduction  of  area.  Its  failure  is 
attributed  to  its  high  proportion  of  carbon,  about  0'30$, 
unfitting  it  for  the  rough  treatment  of  the  boiler-shop : 
and  to  its  thickness,  which  probably  led  to  finishing  at  an 
unduly  high  temperature  and  to  unduly  slow  cooling, 
both  leading  to  coarse  crystallization.  Admitting  these, 
the  low  ductility  and  tensile  strength  of  material  which 
had  behaved  so  well  under  test  is  still  surprising." 

2.  A  ship's  steel  stringer  plate,  worked  into  place  satis- 
factorily, cracked  during  the  next  night  not  through  the 
rivet-holes  or  any  point  of  weakness,  but  through  its  solid 
body." 

§  294.  THE  TursTwoinniNESS  OF  STEEL,  both  abso- 
lute and  relative  to  that  of  vvrought-iron  is  here  evidenced. 

First,  we  have  the  simple  statements  of  eminent  engineers, 
such  as  B.  Baker,0  who  has  had  more  cases  of  mysterious 
fracture  with  the  few  tons  of  wrought-iron  than  with  the 
24,000  tons  of  steel  used  at  the  Forth  Bridge,  where  the 
work  is  pressed  forward  night  and  day  with  no  precau- 
tions which  would  not  be  needed  equally  in  case  the  best 
Lowmoor  wrought-iron  were  used :  Sir  E.  J.  Reed,d  who 
states  that  officers  ?nd  men  in  the  Admiralty  dockyards 
are  perfectly  enamored  of  steel,  finding  it  much  more 
trustworthy  in  every  way  than  wrought-iron  :  and  A.  C. 
Kirk,6  who,  far  from  having  to  treat  steel  more  carefully 
than  wrought-iron,  habitually  and  successfully  subjects 
it  to  treatment  which  would  be  fatal  to  wrought  iron. 

Then  we  have  such  remarkable  numerical  results  as  the 
following.  Adamson'  has  lost  but  one  plate  among 
3,  £00  received  from  a  certain  steel-maker  :  in  welding  600 
to  700  feet  of  steel  plates  weekly  he  loses  perhaps  one  plate 
or  so  in  three  months,  while  with  wrought-iron  the  failures 
amounted  to  12 '5$ :  and  not  an  accident  has  happened  to 
any  of  the  3,000  steel  boilers  which  he  has  built. 

Krupp, g  whose  guns  are  of  crucible  steel,  states  that 
not  a  single  gun  made  by  him  during  the  last  seventeen 
years  has  burst. 

J.  Wardh  of  the  famous  shipbuilding  firm  of  Wm.  Denny 


a W.  Parker,  "Experience  in  the  Use  of  Thick  Steel  Boiler-Plates."  Excerpt 
Proc.  Inst  Nav.  Arch.,  XXVI.,  1886. 

b  Sir  E.  J.  Reed,  discussion  of  Stromeyer's  paper  on  "  The  Working  of  Steel." 
Excerpt  Proc.  Inst.  Civ.  Eng.,  LXXXIV.,  p.  73,  1886:  Also  IT.  S.  Naval  Prof. 
Papers,  No.  21,  p.  64,  1887. 

c  Engineer  in  charge  of  the  construction  of  the  Forth  Bridge.  Trans.  Am .  Soc 
Mech.  Eng.,  VIII.,  p.  168,  1887.  It  is  but  fair  to  state,  however,  that  Mr.  Baker 
permits  no  punching,  requires  all  sheared  edges  to  be  planed,  and  rarely  permits 
blue-working.  (§  288,  A,  §  290.)  These  precautions  are  doubtless  desirable  even 
in  case  of  the  best  Lowraoor  iron,  but  opinions  may  differ  as  to  their  being  neces 
sary. 

d  Discussion  on  Stromeyer's  paper  on  Mild  Steel  the  Working  of  Steel.  Excerpt 
Proc.  Inst  Civ.  Eng.,  LXXXIV.,  p.  73,  1886. 

e  Of  the  great  ship-building  firm  of  R.  Napier  &  Sons,  Glasgow.  Trans.  Inst 
Nav.  Arch.,  XXVII.,  p.  134,  1886.  "  With  steel,  we  go  round  a  heavy  flang 
eleven  inches  deep,  as  I  have  done  often  enough,  knocking  it  down  with  a  steam 
hammer.  I  have  not  bad  a  case  of  failure.  If  it  bad  been  a  piece  of  (wrought- 
iron  plate  I  dare  not  have  done  such  a  thing  at  all,  tbe  first  blow  would  hava 
broken  it  right  through.  Again,  to  flange  a  steel  plate  for  a  furnace  mouth  we 
push  a  die  right  through  at  one  heat  which  we  dare  not  do  in  iron." 

(  Discussion  on  Goodall's  paper  on  "  Open-Hearth  Steel  for  Boiler-Making,"  es 
cerpt,  Proc.  Inst.  Civ.  Eng.,  XCII.,  p.  63,  1888. 

s  Stahl  und  Eiscn,  VIII.,  p.  52,  1888. 

h  Trans.  Inst,  Nav,  Arch.,  XXVII.,  p.  65,  1886, 


THE    TRUSTWORTHINESS    OF    STEEL.      §  294. 


241 


and  Brothers,  (which  goes  on  the  principle  that  if  steel 
cannot  stand  the  rough  usage  of  shipyard  in  punching, 
shearing  and  hammering,  the  sooner  it  tails  the  better),  in 
building  eighty  steel  vessels  used,  up  to  the  year 
1880,  7,000  tons  or  58,000  pieces  of  steel,  losing  six 
plates  and  one  angle-piece,  or  about  0-01$ ;  and  from  1880 
to  1886  48,000  tons  of  steel  or  350,000  pieces,  losing  12 
pieces,  or  0-003^.  They  have  often  lost  more  than  four 
times  this  amount  in  a  single  wrought-iron  vessel. 

B.  Martell,a  Chief  Surveyor  of  Lloyd's  Register,  reports 
that  up  to  and  including  the  year  1885,  444  steel  vessels 
were  built,  and  classed  by  his  company.  Among  these  he 
learns  of  seven  total  losses,  which  he  thinks  remarkably 
few  :  one  was  by  stranding,  two  vessels  foundered  in  gales, 
one  was  sunk  by  an  iceberg,  one  by  a  sailing  vessel,  two 
were  lost  by  means  not  stated.  In  an  investigation  by 
Lloyds'  surveyors  into  the  durability  of  steel  vessels,  sixty 
cases  were  specially  reported  on  :  in  five  out  of  the  eight 
typical  cases  which  Martell  reports,  the  steel  vessel  safely 
endured  grounding  or  collision  which  would  have  sunk 
a  wrought-iron  one. 

At  John  Brown  and  Company's  Worksb  more  than  four 
thousand  very  large  steel  boiler-front-plates  were  made  in 
the  five  years  ending  in  18b7,  being  "flanged  at  one  heat 
all  the  way  round,  and  without  a  single  failure." 

H.  Goodall"  states  that,  of  4,464  wrought-iron  plates 
which  he  has  used  for  boiler-making  since  the  introduction 
of  steel  for  boilers  in  1875,  2-68$  were  defective  and  0'2$ 
spoilt  in  working,  or  together  2'88$ :  while  of  4,23(5  steel 
plates  which  he  used  in  the  same  time  1  "04$  were  defective 
and  0-68$  spoilt  in  working,  or  together  1'72$ :  and  of  this 
a  considerable  proportion  seems  justly  chargeable  to  his 
workmen' s  lack  of  experience  with  the  new  material. 

W.  Parker d  states  that  not  an  accident  has  occurred 
under  steam  among  the  upwards  of  4,000  steel  marine 
boilers  built,  which  represent  over  160,000  tons  of  steel. 
The  Maginnis  case,  however,  suggests  that  boiler  ex- 
plosions may  account  for  some  of  the  cases  in  which 
steamers  have  been  lost  without  tidings. 

Next,  it  is  probable  that  wrought-iron  sometimes  fails 
in  the  same  mysterious  way  as  steel,  though  strikingly  few 
mysterious  failures  are  reported  in  case  of  the  former 
metal.  Stromeyer  reports  two  cases,  one  in  which  on 
examining  a  wrought-iron  boiler  which  had  been  out  of 
use  for  about  three  months,  he  found  a  crack  twenty- 
three  inches  long,  extending  from  one  plate  into  the  next, 
and  doubtless,  he  says,  formed  within  twelve  hours 
previous  to  his  survey :  the  iron  seemed  soft  in  chipping. 
In  the  second  a  plate  cracked  quite  across  with  a  loud 
report  during  the  dinner-hour,  and  about  two  weeks  after 
the  boiler  was  blown  down.6 

It  is  reported  that,  about  the  year  1848,  the  wrought- 
iron  boiler-furnaces  of  the  British-built  steamer  Leip- 
zig cracked  down  the  sides  after  several  trips  to  Hamburg 
and  back,  just  as  in  the  Maginnis  case.* 

a  Idem,  p.  50. 

bJ.  D.  Ellis,  discussion  of  Goodall's  paper  on  "Open-hearth  Steel  for  Boiler- 
making,"  excerpt  Proc.  Inst.  Civ.  Eng.,  XCIL,  p.  40,  1888. 

c  Idem,  p.  25. 

<l  Discussion  of  Stromeyer's  paper  on  "  the  Working  of  Steel,"  Excerpt  Proc. 
Inst.  Civ.  Eng.,  LXXXIV.,  p.  40,  1886. 

e  Idem,  p.  76. 

'J.Harrison,  letter  to  "  The  Engineer,"  LX. ,  p.  504,  1885.  I  have,  unfor- 
tunately, little  ground  for  judging  how  accurately  the  circumstances  of  this  failure 
have  survived  the  thirty-five  years  which  elapsed  before  Mr.  Harrison's  brief 
notice  of  it  appeared. 


Several  inquiries,  which  I  have  addressed  to  engineers 
whose  prolonged  experience  has  been  of  such  a  nature  as 
to  give  them  unusual  opportunities  for  observation,  have 
failed  to  bring  to  light  other  failures  of  wrought-iron 
boilers  which  could  reasonably  be  classed  as  mysterious. 

The  liability  to  injury  through  cold-  and  blue-working, 
through  local  heating,  overheating,  unduly  high  finishing 
temperature,  etc.,  probably  increases  rapidly  both  as  the 
percentage  of  carbon  and  as  that  of  phosphorus  increase. 
Moreover,  the  liability  to  injury  by  improper  heat  treat- 
ment is  probably  greater  in  ingot-  than  in  wrought-iron. 
Further,  heterogeneousness,  whether  from  segregation  or 
imperfect  mixing,  probably  in  creases  the  liability  to  in  jury . 
Finally,  injury  actually  received  from  certain  of  these 
causes  seems  to  increase  greatly  the  liability  to  injury 
through  certain  others :  overheating  and  too  high  finishing 
temperature  to  increase  the  liability  to  injury  through 
local  heating  and  cold-working,  though  on  this  point  one 
may  not  speak  too  positively. 

In  view  of  these  facts,  ignoring  our  natural  dread  of  the 
untried,  we  can  see  three  simple  reasons  why  the  treachery 
of  steel,  once  so  serious  a  thing,  is  now  almost  of  the  past. 

First,  the  steel-maker  has  learnt  by  experience.  He 
knows  to-day  far  better  the  effects  of  a  high  percentage 
of  carbon  or  of  phosphorus,  of  cracks,  pipes  and  blowholes, 
of  segregation  and  imperfect  mixing,  of  over  heating,  of 
finishing  too  hot  and  too  cold.  Knowing,  he  guards  against 
them  more  effectually,  and  keeps  at  home  much  steel  that 
he  would  formerly  have  sent  into  the  market.  Those  who 
woiild  not  or  could  not  learn  and  do,  have  been  driven  out 
of  the  business  :  the  conditions  necessary  for  producing 
good  sound  steel  by  the  acid  Bessemer  and  open-hearth 
processes  have  been  mastered.  By  and  by  the  basic  process 
came  along,  with  new  conditions,  new  liabilities  to  un- 
soundness,  a  great  hue  and  cry  about  mysterious  fractures 
followed,  and  Lloyd's  Register  provisionally  forbade  the 
use  of  basic  steel.8  Much  basic  steel  was  irregular,  much 
brittle  throughout :  too  much  car  hon,  too  much  phos- 
phorus, too  cold  teeming,  imperfect  m  bang.  Still  there  was 
little  doubt  that,  with  further  experience,  these  difficulties 
of  the  basic  process  would  be  mastered  as  those  of  the  acid 
process  had  been.  Later  still,  coming  to  the  present  time, 
these  difficulties  yield  more  and  more. 

A  second  reason  is  that  steel-users  have  learnt  better 
what  steel  will  and  whai  it  will  not  endure.  It  is  difficult 
to  estimate  the  importance  of  this.  On  the  one  hand 
eminent  steel-users"  insist  that  they  treat  steel  exactly  like 
wrought-iron,  or  even  more  severely,  yet  with  perfect  im- 
punity. Many  excellent  American  boiler-makers  are 
absolutely  ignorant  of  the  injury  caused  by  blue-working 


KThis  occurred  on  December  17th,  1885,  and  from  then  at  least  till  July  27th, 
1887,  no  basic  steel  was  used  in  vessels  classed  at  Lloyd's.  (Martell,  "  On  the 
Present  Position  Occupied  by  Basic  Steel."  Excerpt,  Proc.  Inst.  Nav.  Arch., 
XXVIII.,  1887.)  On  the  day  last  mentioned,  however,  W.  H.  White  reported 
that  a  small  trial  lot  of  basic  steel  ordered  by  the  Admiralty  for  the  less  important 
parts  of  vessels,  though  in  part  severely  tested  in  working,  behaved  so  well  as  to 
show  that  basic  steel  could  be  used  confidently  for  such  purposes.  ("On  Some 
Recent  Experiments  with  Basic  Steel,"  idem.) 

Lloyd's  Register  now  permits  the  use  of  basic  steel  for  ship  and  marine  boiler- 
work,  provided  that  it  be  made  at  works  inspected  and  approved,  and  that  it 
passes  the  specified  tests.  (Wm.  Parker,  Chief  Engineer-Surveyor  to  Lloyd's. 
Private  communication,  Feb.  5th,  1889.) 

&  J.  Ward,  Trans.  Inst.  Nav.  Arch.,  XXVIL,  p.  66,  1886,  speaking  of  the  re- 
markable success  of  his  firm  in  steel  ship-building,  states  not  only  that  in  his  yard 
steel  receives  the  same  treatment  as  wrought-iron  (save  the  annealing  of  certain 
straps)  but  that  "  no  amount  of  instruction  would  ever  gain  it  better  or  different 
treatment  at  the  hands  of  the  workmen  than  (wrought-)  iron  has  always  had." 
H.  H.  West  echoes  these  statements  (idem,  p.  127). 


242 


THE    METALLURGY    OF    STEEL. 


by  punching,  etc.  :  full  well  I  know  that  look,  sometimes 
puzzled,  of  tener  pitying,  which  a  question  as  to  the  advis- 
ability of  avoiding  a  blue  heat,  of  drilling  or  reaming,  of 
annealing  after  severe  abuse,  calls  forth. 

Now  it  seems  clear  that  steel  endures  certain  kinds  of 
abuse  much  better  than  wrought-iron,  and  here  it  is  prob- 
ably treated  as  badly  and  perhaps  worse  than  wrought-iron. 
But  it  is  probable  that  other  forms  of  abuse,  such  as  local 
heating  and  over-heating,  injure  it  more  than  wrought-iron. 
And  it  seems  to  me  very  probable  that  it  is  partly  because 
we  know  and  avoid  these  that  we  have  fewer  accidents  with 
ingot-iron  to-day  than  formerly.  Several  skilled  American 
ship-builders  assure  me  that  they  still  have  as  many  if  not 
more  accidents  with  ingot-  than  with  wrought-iron  :  and 
this  seems  readily  explained  by  supposing  that  their  fore- 
men and  workmen  do  not  yet  understand  the  metal's  weak- 
nesses fully,  for  I  know  that  they  use  admirable  metal. 

Again,  a  ship-builder's  statement,  that  in  his  yard  steel 
is  treated  exactly  like  wrought-iron,  must  be  received 
very  cautiously :  for  differences,  apparently  slight  but 


really  important,  arise  insensibly,  imperfectly  realized  by 
ship-builder,  foreman  or  even  workmen.  Owners  of  iron- 
working  establishments  have  assured  me,  and  I  believe 
honestly,  that  ingot-  and  wrought-iron  were  treated  ex- 
actly alike  by  their  men  :  within  five  minutes  their  black- 
smiths have  assured  me  that  they  dared  not  heat  ingot- 
iron  as  highly  as  wrought-iron,  though  they  were  not  sure 
that  if  they  did  the  ingot-iron-would  be  injured.  Ignore 
not  the  personal  equation  :  your  admirer  will  e'  er  mini- 
mize, your  distruster  exaggerate  your  faults. 


THE  EFFECT  OF  WORK. 

§  295.  The  almost  self-evident  proposition  that  wrought- 
iron, — consisting  originally  of  but  slightly  adherent  par- 
ticles, and,  after  fagotting,  of  wholly  inadherent  bars,— 
should  be  greatly  strengthened  and  toughened  by  work, 
abundantly  proved  by  experience,  led  naturally  to  the 
belief  that  ingot-metal  would  be  similarly  improved.  We 
will  first  consider  the  actual  improvement  due  to  work, 
and  then  its  rationale. 


TABLE  181. — RELATION  BETWEEN  THICKNESS  AND  PHYSICAL  PKOPEBTIES  OF  IKON  AND  STEEL  BARS,  PLATES,  ETC. 
The  composition  and  treatment  of  the  members  of  each  group  are  believed  to  be  nearly  alike,  the  thickness  alone  van-ing  considerably. 


Authority. 

DESCRIPTION. 

Thickness,  etc. 

Percentage  of  excess  of  tensile  strength, 
etc.,  over  that  of  thickest   member   of 
group. 

Tensile 
strength, 
pounds    pei 
square  inch. 

Elastic 
limit, 
pounds 
per 
square 
inch. 

Elongation. 

Contraction 
of  area,  f. 

Absol- 
ute, 
inches. 

In  percentage  of 
thickness,  etc., 
of  thickest 
member    of 
group. 

Tensile 
strength. 

Elastic 
limit. 

Elonga- 
tion. 

Reduction 
of  area. 

*. 

In. 

1 

••{ 

4.. 
6.- 

"{ 

j 

j 

10.1 

,,\ 

::i 
,{ 

A. 

B. 

C. 

D. 

E. 

F. 

Q. 

H. 

I. 

J. 

D. 

(I 

ti 

R. 

1 

B. 

1* 

H 

L. 
G. 

a 
w. 

0-87 
0-48 
0-20 
0-10 
0-87 
0-43 
0-20 

o-io 

0-87 
0-48 
0-29 
0-10 

i-oo 

0-50 
0-25 
1-00 
0-50 
0-25 

100 
49 
28 
12 
100 
49 
28 
12 
100 
49 
28 
12 
100 
DO 
25 
100 
50 
25 
100 
42-87 
28-58 
14-29 

100-00 

42-87 
28-58 
14-29 
100 
50 
25 
100 
50 
25 
100 
75 
67 
59 
49 
100 
62 
100 
100 
50 
100 
75 
50 
25 
100 
40 
100 
15 
14 
12 
11 

62,740 
65.100 

aviso 

79,490 
68,814 
57,690 
60,080 
69,800 
86,340 
83.470 
90,470 
91,026 
61,940 
64,330 
69,550 
59,180 
61,040 
62,880 
68,400 
72,520 
73,940 
79,060 
66,980 

89,600 
40,880 
89,824 
59,010 
80,890 
27,028 
24,740 
29,440 
41,020 
86,880 
86,260 
34,184 

20-62 
22-30 
19-70 
8-00 
28-60 
21-26 
21-70 
16-60 
15-80 
13-40 
8-87 
7-40 
22-82 
28-87 
21-50 
27-02 
26-83 
23-38 

7'97' 
«i 

29  62 
49-82 
42-60 
27-70 
48-40 
46-25 
89-80 
81-60 
S-2-35 
28-12 
21-00 
80-87 
88-47 
41-80 
89-88 
44-42 
47-45 
45-025 
42-5 
44-1 
42-0 
40-8 
47-0 
49-0 
40-6 
48-1 
42-7 
43-0 
42-0 
53-6 
52-1 
47-4 

53-95 
59-42 
64-78 
66-40 
68-11 

4-       8-76 
4-       5-17 
4-      26  70 

4-       8-28 
4-        0-54 
4-      49-01 

4-        8-14 
—       4-46 
—      61-20 

4-      68-28 
4-      48-85 
—       6-46 

—        1-05 
4-        8-05 
?.       1-71 

—     12-52 
—     18-97 

—       4-70 

—       9-92 
—       8-05 
—     29-66 

4-       6-57 
—        8-80 
—     27-19 

1  Terre  Noire  poft  Ing-ot-steel,  qiienched  In  water  of  28°  C.  I 

—       8-83 

4-        4-78 
+       6-40 

—      i6-28 
—      11-61 

—      16-81 

—      12-42 
—      42-08 
—      51-63 

—      18-07 
—      85-09 
—       6-12 

11  Unannealed.  -< 
482  testa  of  54  plates  rolled  from  12  Ingots) 
from  a  single  heat  of  open-hearth  Bteel.  ]                         ( 
!  Annealed.      -< 

+       8-87 
4-     12-30 

4-       4-60 
-       6-79 

4-      24-89 
4-      19-15 

4-        8  10 
4-        6-17 

—       0-70 

-     13-47 

4-        6-82 
4-        1-86 

21-75 
20-75 
19-5 

4-        6-03 
4-       8-11 
4-      15-59 

—       4-60  +       8-76 
—     1085—       1-18 

—      17-24—       4-00 

18-0 
22-8 

4-        8-18 
4-        8-28 
4-        8-92 

23-77 

4-       4-26 
—     18-62 

4-       2-34 

69,110 
72,520 
72,950 
71,950 
77,860 
80,490 
71,580 
71.100 
75,790 
63.000 
60,000 
59,000 
59,000 
58,000 
61,272 
63,631 
8S.S30 
51,888 
106,667 
69,880 
64,395 
65,630 
62,720 
(57,20(!©76,160 

17-0 
20-0 
22-0 
22-7 
19-2 
16-0 
23'7 
19-5 
14'0 
25 
25 
25 
24 
24 
26-05 
26-05 

o-io 

0  25 
2-00 

21'3@28-1 
21    @24 
23-1 
22-8 
19-8 
21-7 
21-6 

'l5" 

H 

n 
8 

10 
10 
10 

8 
8 

—      10  81 
-        1-84 

4-       7-51 
4-      11-86 



—      io-42 

—      29-52 

+       0-70 
-       1.64 



—       0-60 
4-        5-96 

—      17-72 
—      40-98 

—        2-80 
—      11-57 

!  Averages  of  many  (about  600)  testa  of  steel  boiler  plates 
made  for  an  American  engineer  ;  all  made  and  tested-< 
at  the  same  mill  

0-75 
0-56 
0  50 
0-44 
0-87 
0-617 
(1-830 
1-5 
1-5 
0-75 
1 
0-75 
0'50 
0-25 
1-25 
•50 
2"  sq. 
0-80 
0-284 
0-288 
0-220 

32,000 
87,000 
40,000 
40,000 
41,000 

-       4-76 
—        6-35 
—        6-85 
—        7-94 

+     15-6$ 

4-     25-00 
4-      25-00 
4-      28-12 

—       4-00 
—       4-00 

( 

BarsSj"  X  4"  

4-        8-85 

Swedish  Bessemer  billet,  1*2"  square,  carbon  1*5£  

—      41-82 
-f      20-48 

4-        1-50 
4-  1900-00 

I  Mean  of  48  sets  of  tests  by  Klrkaldy  on  open  hearth! 

42,670 
85,280 
85,165 
33,262 

7-85 
—       6-08 
—      10-24 

—      17-82 
—      17-59 
—      22-05 

J                                                I 

Parker.    1J"  boiler-plate  

i"  plate  of  similar  metal  

+      19-58 

—        8-91 

78,400©91,S40 
<H,S!I9 
67,939 
64,490 
67,782 
66,170 

"38,170' 
47.846 
45.629 
49,078 
46,883 

}H.  Allen.    Billet,  and  wire  rods  rolled  from  It.    Soft) 
steel  1 

4-        8-01 
12-53 
7-76 
5-20 

4-      25-85 
4-      19-54 

4-      28  •,« 
4-      22-83 

—      18  86 
—      29-54 
—      27-78 
—      23-13 

4-      10-14 
4-      20-07 
4-      2.3-08 
4-      26-25 

I 

1  to  3.    From  the  same  cast  of  soft  steel,  one  ingot  13-8  inches  X  8'7  inches  was  rolled  to  a  plate  0-87  inches  thick,  which  was  cut  in  two,  one  half  tested,  the  other  rolled  down  to  O'lO  inches.  A 
second  Ingot,  8-7  inches  square  was  rolled  to  0-43  Inches,  cut  in  two,  one  h»lf  yielding  the  test-piece,  the  other  being  rolled  to  0-1.    V.  Dcshayes,  Ann.  Mines,  7th  series,  XV.,  p.  345. 
4.    J.  Riley,  Journ.  Iron  and  Steel  Inst.,  1887,  I.,  p.  121. 
6  to  8.  Brauns,  Ledebur,  Handbuch,  p.  655,  from  fetahl  und  Eisen,  1883,  p.  4. 

9.  86  to  40  private  notes. 

10.  Gatewood,  Rep't.  U.  8.  Naval  Advisory  B'd  on  Mild  Steel,  1886,  pr.  67-8.    From  each  of  19  heats  of  Cambria  open-hearth  steel,  pieces  from  flats  2|"  X  4"  were  tested,  and  also  pieces 
from  angle-irons  rolled  from  these  flats,  in  all  95  tests.    In  every  case  the  tensile  strength  of  the  angle-Iron  exceeded  that  of  the  flat.     The  angle-irons,   however,  were  not  tested  on  the  same  ma- 
chine as  the  flats. 

12*     M.  White,  private  communication. 

14.     Kept.  U.  8.  Naval  Advisory  B'd  on  Mild  Steel,  1886-1885,  p.  133.  from  British  Parliamentary  paper,  C  2897,  London,  1881. 

16.    W.  Parker,  "Experience  in  the  Use  of  Thick  Steel  Boiler-plates,"  Inst.  Naval  Architects,  1885. 

16.  Pieces  from  a  2  inch  square  soft  steel  billet,  carbon  0-1 15,  silicon  0  009,  phosphorus  0-072,  are  rolled  hot  to  wire-rods  of  the  diameters  given.  The  wire-roils  were  annealed  before  tostins, 
the  billet  apparently  wu  not.  The  properties  of  the  unannealecl  wire-rods  are  also  given  in  the  original,  but  they  do  not  diflcr  greatly  from  those  here  given.  H.  Allen,  excerpt  Proc.  Inst.  Civ 
Eng.,  XCI V.,  18S8.  The  density  of  these  specimens  is  given  in  Table  431. 


RELATION    BETWEEN    THE    THICKNESS    AND    STRENGTH,     ETC.,     OF    STEEL       §  296.      243 


§  296.  RELATION  BETWEEN  THICKNESS  OF  PIECE  AND 
TESTING-MACHINE  PROPERTIES. 

A.  Ingot-iron. — Let  us  first  study  the  effect  of  varying 
thickness  with  one  inch  as  a  maximum,  and  then  for 
greater  thicknesses. 

1.  Pieces  1"  thick  and  less. — Numbers  4,  9  and  10  of 
Table  131,  collectively  representing  more  than  1,000  tests 
for  each  property,  indicate  that  thin  plates  do  not  excel 
thick  ones  in  ductility,  at  least  not  in  elongation :  while 
as  to  tensile  strength  their  teaching  is  contradictory,  the 
thin  plates  excelling  the  thick  in  4  and  10,  but  being  ex- 
celled by  them  in  9.  It  is  not  improbable  that  this  dis- 
crepancy is  due  to  differences  in  the  conditions  of  rolling  : 
possibly  the  plates  of  Number  4  were  finished  so  cold  as  to 
increase  their  tensile  strength :  for  we  find  that  in  the  case 
of  the  annealed  plates  of  Number  4  the  thin  are  but  little 
stronger  than  the  thick.  So  with  Numbers  1  and  2  of 
table  131,  and  so  with  the  half -inch  pieces  (Nos.  5  and  11) 
in  table  134,  which  when  annealed  are  not  markedly 
stronger  than  the  inch  pieces.  The  elastic  limit  in  Num- 
ber 9,  table  131,  increases  as  the  thickness  decreases, 
though  the  tensile  strength  at  the  same  time  diminishes. 


The  indications,  then,  seem  to  be  that  thinner  pieces  of 
soft  steel  may,  but  do  not  necessarily,  excel  similar  ones 
one  inch  thick  in  tensile  strength  and  elastic  limit :  that 
they  are  likely  to  be  less  ductile  than  the  one-inch  pieces : 
and  that,  if  heated  (e.  ,-?.  for  annealing)  they  are  likely  to 
lose  much  of  their  excess  (if  any  there  be)  of  tensile 
strength  and  elastic  limit,  while  recovering  their  deficit  of 
elongation. 

2.  But  when  we  come  to  pieces  as  thick  or  thicker 
than  one  inch,  the  case  is  different.  Of  these  Kirkaldy 

TABLE  182.    INFLUENCE  OF  THE  EARLY  vs.  THE  LATE  REDUCTIONS  ON  THE  PHYSICAL  PROPER- 
TIES OF  INGOT-IRON.    (KIRKALDY,  FAOERSTA  STEEL,  SERIES  C3,  0  15*  CARBON.) 


Percentage  ofincrease  of  properties 
in    reducing    from    3"  X  3"    to 
1"  X  1" 
EARLY  REDUCTIONS. 

Percentage  of  increase  of  properties 
in    reducing    from    1"  X  1"    to 
1"  X  1". 
LATE  REDUCTIONS. 

i 

-  1 

1' 

o 

=1 

W 

B 

J> 

O 

H 

|s 

|| 
i 

V 

**d 

H 

d 

I 

o 
W 

a 

3  £j 

(S 

TT~«  «    i  A  )  Hammered 
Unannealed  JRolled  

.__,ol,(1      j  Hammered 
Annealed..  .-j  Uo,]ed 

15-2 
3 
6-2 

5'9 

71-1 
86'2 
21-5 
28-2 

-88-9 
—10-6 
-42-8 
—  5'8 

53  5 
20-6 
88  8 

14  2 

10-6 
11-4 

8"8 
—1-1 

18-8 
8-8 
6-7 

—84-4 
—20-1 
—16  0 
—25 

—8-24 
8"8 
7'6 

TABLE  133.—  INFLUENCE  OF  WORK  OR  REDUCTION  ON  THE  PROPERTIES  OF  IRON. 


Percentage  ofincrease  of  tensile  strength,  etc.,  due  to  each  1*  of  diminution  of  sectional  area  by  hammering. 


Diminution  of  cross-section. 

Gain  in  tensile  strength,  *. 

Gain  in  elastic  limit,  *. 

Gain  in  elongation,*. 

Gain  in  contraction  of  area,  *. 

Size  of  piece,  inches.IDiminution 

Bl. 

B2. 

B3. 

B4. 

Aver- 
'ge. 

Bl. 

B2.  |    B3. 

B4. 

Aver- 
age. 

Bl. 

B2. 

B3. 

B4. 

Aver- 
age. 

Bl. 

B2. 

B8. 

B4. 

Aver- 
age. 

Initial.    |     Final,      j     original. 

Prop't'n  of  carbon 

0-8*. 

0-6*. 

04*. 

0-2. 

o-s* 

0-6*.  '  0-4*. 

0-2 

n  vr. 

0  6* 

0-4*. 

0-2 

0-8*. 

0-6*. 

0-4* 

0-2 

UNANNKALED  STEEL. 

6x6 
8x5 
4X4 
8X8 
Average 
6X6 

6X5 
4X4 
8X3 
2X2 
of  1  to  4 
2X2 

80-6 
86-0 
43-7 
55-6 

88:9 

•09 
•30 
•24 
•81 
•28 
•53 

—•21 
•63 
•83 
•17 
•23 
•49 

•39 
•47 
•04 
•08 
•23 
•40 

•18 
•12 
•05 
•02 
•09 
•15 

•11 

•3S 
•17 
•13 
•20 
•89 

•18 
•83 
•12 
•26 
•21 
•44 

•05 
•29 
•18 
•07 
•14 
•27 

•18 
•23 
•25 
•17 
•21 
•43 

•46 
•55 
•29 
•06 
•84 
•66 

•20 

•86 
•20 
•14 

•22 
•48 

0-S9 
0'60 
0-27 
0-28 
0'51 
1-12 

—0-98 
2'78 
1-96 
1-78 
1-87 
4-61 

1-87 
4-19 
0-48 
0'13 
1-67 
4-63 

2-28 
1-08 
—  O'lO 
—0-24 
0'74 
1.06 

1  00 
2  16 
•65 
•48 
1-07 
2'85 

0-65 
0-62 
O'lO 
0-70 
0-52 
1-28 

—0-92 
4-82 
2-09 
4-01 
2-88 
11-66 

1-25 
6-13 
3-15 
0  42 
2-74 
12-94 

0-88 
2-92 
0-34 
O'OS 
0-92 
4-67 

0-34 
8-50 
1-42 
1-29 
1-64 
7-64 

ANNEALED  STEEL. 

6X6 
5X5 
4X4 
3X3 
Average 
6X6 

6X5 
4X4 
8X8 

2X2 
of  7  to  10 
2X2 

80-6 
86-0 
43-7 
65-6 

•04 
•86 
•08 
•20 
•IT 
•40 

—•61 
•72 
•39 
•12 
15 
•27 

•48 
•40 
—•03 
•06 
•28 
•88 

•02 
•20 
—•07 
•04 
•05 
•08 

—•02 
•42 
•09 
•10 
•15 
•28 

•04 
•21 
•15 
•09 
•12 
•25 

•09 
•15 
•11 

•18 
•13 
•28 

•27 
•19 
•14 
•25 
•21 
•45 

•44 
•67, 
•22 
•12 
•86 
•72 

•21 
•81 
•16 
•16 
•21 
•42 

0-19 
1-85 
0  61 
0-81 
0-86 
2-61 

-2-27 
2-01 
4'18 
OM4 
1-01 
0-86 

1-71 
6-21 
—0-19 
O'Ol 
1-94 
3'99 

00 

0-88 
1-02 
—0-46 

2-98 
1-27 
I'll 
1-00 
1-59 
8-02 

—2-60 
2-83 
9-10 
1-12 
2'49 
2-82 

1-91 
9-17 
1-27 
0-06 
8  10 
11-84 

0-69 
1-50 
0  52 
0-05 
0  69 
I'M 

0-74 
8-57 
8-00 
0-56 
1-97 
4-55 

2-61 
1-40 
0-12 

88-9 

0-25 

1-90 

This  table  is  calculated  from  Klrkaldy's  data,  "Experimental  Enquiry  into  the  Mechanical  Properties  of  Fagersta  Steel,  1878."    It  gives  the  increase  of  tensile  strength,  etc.,  due  to  a  unit  of 
diminution  of  sectional  area  by  forging.     This  increase  for  each  particular  redaction  (e.  g.  from  4  X  4  to  8  X  3)  is  measured  In  percentages  ot  the  tensile  strength,  etc. ,  which  the  metal  has  when  of 

4X4 

the  initital  area,  in   this  case  4  X  4.    The  unit  of  diminution  of  area  is  one  per  cent,  of  said  Initial  area,  in  this  case =  0-16  square  inches.    Example.    To  find  the  gain  In  tensile  strength 

100 

or  unanncaled  steel   B3,  due  to  a  unit  of  diminution  of  area,  while  being  hammered  from  4  X  4  to  3  X  3.   Tensile  strength  of  the4  X  4  piece,  72,260  pounds  per  square  Inch:   ofthe3x3  piece, 
1,320  X  100  (4  X  4)—  (8  X  8)  1-827 

73,580  .  Gain  =  1,320  Ibs.  = %  =1'S27*.    Diminution  of  area  = X  100*  =  43'75£    Gain  per  1*  diminution  of  area  = =  0'04*.    The  results  for  the  other  properties 

72,260  4X4  43-75 

are  obtained  mutatis  mutandis. 


TABLE  184. — INFLUENCE  OF  WORK  OR  REDUCTION  ON  THE  PROPERTIES  OF  IRON.    (ROLLING.    KIRKALDY'B  DATA). 


I.  Percentage  of  excess  (4-)  or  deficit  ( — )  of  the  tensile  strength  of  smaller  steel  bars  over  the  tensile  strength,  etc.,  of  similar  3"  square  bars. 


Number. 

Size  of  piece. 

Tensile  strength. 

Elastic  limit. 

Elongation. 

Contraction  of  area. 

Absolute,  inches. 

In  percentage  of  sectional 
area  of  3  X  3  bar. 

Cl 

C2 

C8 

C  1      I     C2      1       C  3 

C  1 

C  2 

C8 

Cl 

C  2     |      C8 

3* 

0-6* 

0-15* 

1*       1    0  5*     I    0-15* 

1* 

0-5* 

0-15* 

g 

05*     1     0-15* 

Unannealed  Ingot-Steel  and  Ingot-Iron. 


21  X  2f 
2X2 
H  X  H 
1    X  1 
1X1 


69-44 
44-44 
25-00 
11-11 

2-78 


11 
24 


+    85 


16 
35 
27 
41 

45 


11 

'.'0 

81 


+  20 

+  26 

+  33 

+  42 

+  54 


+  228 
4-  586 
+  308 
+  548 
+  540 


-    85 


—  12 

—  11 


-f  80 
+3900 
'  820 
-f-2300 
-f-8900 


184 
873 
259 
566 
877 


—  46 

—  10 

—  8 

+  21 

+  25 


Annealed  Ingot-Steel  and  Ingot-Iron. 


7  

•21  X  21 

69-44 

--    11 

19 

4-      6 

5 

4-    18 

114 

_t-    90 

4-  263 

i:. 

4-  104 

--  557 

6 

8  

2X2 

44*44 

--    25 

-    83 

1    li 

4-     5 

_L     81 

23 

4-  180 

_j_  842 

28 

4-    96 

--  620 

8 

B... 

H  x  H 

25  -(K) 

--    49 

-    87 

T      8 

4-    21 

4-    37 

25 

4-  185 

4-  800 

—    31 

4-  182 

4-  617 

6 

in 

1X1 

ll'll 

4-    63 

-    89 

4-      6 

4-    38 

-     45 

i-    2S 

4-  200 

4-197 

5 

4-  543 

635 

4-    14 

11  

IX    I 

2-78 

--    76 

-    83 

+      5 

4-    46 

4-    49 

4-    88 

4-  825 

4-  158 

—    29 

4-  971 

-  844 

+    21 

II.  Percentage  ofincrease  of  tensile  strength,  etc.,  due  to  each  \%  of  diminution  of  sectional  area  by  rolling,  from  3  X  3  to  \  X  i. 


Unannealed  Ingot-Steel  and  Ingot-Iron. 

13  |                 txi                  |                     2-78                       140-67  140-46  |  +  0-15  11+11-48  145-55  l—fl-SO  II  4 

j]-48  J45-55    |—  0-80   H                  |                 | 

Annealed  Ingot-Steel  and  Ingot-  Iron. 

III.  Percentage  ofincrease  of  tensile  strength  due  to  1*  of  diminution  of  sectional  area  by  rolling  from  1 

X  1  to  1  X  i. 

15  ..                                     1                                             I 

Unnanealed. 

Annealed. 

16  |  |  

14-  '10    |  |  114-   -08  |4-  -04  |4-  -05  ||... 

1  1  II+-S9     I  +  -38     I  +  -09 

244 


THE    METALLURGY    OF    STEEL. 


TABLE  185.— INFLUENCE  OF  THE  PROPORTION  OF  CARBON  ON  TUB  INCEEASE  OF  TENSILE  STRENGTH,  ETC.,  DUE  TO  FORCING,  ETC.    (Kirkaldy.) 


Unannealed  steel. 

Annealed  Bteel. 

Bl 

0-80$  C. 

B2 
0'60*C. 

B8 

0'40*  C. 

B4 

0-20*  C. 

Mean. 

Bl 

0-80$  C. 

B2 

0-60*  C. 

B3 

0-40*  C. 

B4 

0-20*  C. 

Mean 

Reduction  from  6X6  inch  ingots  to 

46-8 
89"! 
113- 

48'5 
23-7 
1036- 

85-8 
88-5 
1150- 

13-3 
58-5 
415' 

36-1 
88-0 
626- 

86'5 
22-3 
2S6- 

24-0 
24-6 
209- 

83-6 
39-6 

loos- 

6-7 
64-3 
186 

25-3 
83-6 
258' 

2  X  2  Inch  bars  by/  E,astjc  ,,mit  fncren8e<1  hy_  ff/  »  

Reduction  from  3x3  bars  to  i 

^Contraction  of  area  increased  by,  %  

Cl 

1*0. 

C  2 
0-5*  C. 

C3 
0-lSjtC. 

Cl 

1*  C. 

C2 
0-5*  C. 

es 

0-15*  C. 

93-2 
85-1 
53-2 
80-6 

1116- 

4900- 
3900- 

86-9 
45-4 
101-8 
63-9 

540- 
968- 
877' 

27-4 
14-8 
102-5 
47-6 

29' 
41- 
24-6 

64'2 
52-6 
78-7 
40-8 

73-1 
75-5 
49-6 
46-3 

825- 
1462- 
971- 

17-9 
83*3 
60-4 
49-3 

158- 
555- 
844- 

10-2 
4-8 
29-7 
33*5 

—  29- 
43- 
21- 

86-2 
42'3 
47-8 
44-3 

14S-6 
120- 

Tensile  strength  increased  by,  #....-j  Kjjf^3'ered  

Elastic  limit                               •••••)  Rolled      

Elongation                                 ••••\Rolled         

169- 
115' 

Contraction  of  area    "           "   i  Boiled 

Calculated  from  Kir! 
ured  in  percentage  of  tl: 


rkaldy.  "Experimental  Enquiry  into  the  Mechanical  Properties  of  Fagersta  Steel."    The  numbers  in  this  table  give  the  increase  of  tensile  strength,  etc.,  due  to  forging,  meas- 
:io  tensile  strength,  etc.,  of  the  6"  ingots  in  the  first  three  lines,  and  measured  in  percentage  of  the  tensile  strength,  etc.,  of  the  8"  bars  in  the  last  eight  lines. 


gives  twenty-four  comparable  pairs  of  cases  of  soft  steel, 
in  which  the  thinner  differs  from  the  thicker  in  size  only : 
here  the  thin  excels  the  thick  in  elastic  limit  in  22  cases, 
or  91  '1%  of  the  whole,  in  contraction  of  area  in  21  cases, 
and  in  tensile  strength  in  18  cases,  or  15%  of  the  whole 
(columns  B4  in  table  133  and  C3  in  table  134).a 

Table  132  indicates  that  the  reduction  from  3"  to 
1"  square  increases  the  elastic  limit  and  contraction  of 
area  for  soft  steel  much  more  than  that  from  1"  to  J", 
without  corresponding  difference  in  case  of  tensile 
strength. 

B.  Ingot-Steel. — In  the  cases  before  us  the  tensile 
strength  and  ductility  of  ingot-steel  are  increased  very 
much  more  than  those  of  ingot-iron  by  reduction  of 
thickness  :  but  as  regards  the  gain  in  elastic  limit,  ingot- 
iron  and  steel  stand  more  nearly  on  a  par,  that  of  ingot- 
iron  being  greater  than  that  of  ingot-steel  in  Table  133, 
while  in  Table  134  neither  class  has  a  decided  advantage. 

Out  of  64  pairs  of  comparable  cases  of  ingot-steel  in 
Kirkaldy' s  work,  the  tensile  strength,  elastic  limit,  and 
contraction  of  area  of  the  thinner  excel  those  of  the 
thicker  pieces  in  56,  61  and  58  cases  respectively,  or  in 
87'5,  95*3,  and  90'6$  of  the  total  number  of  cases. 

Taking  all  of  Kirkaldy' s  Fagersta  cases  together,  I  can 
trace  no  simple  relation  between  the  proportion  of  carbon 
and  the  effect  of  reduction  on  the  elastic  limit,  whether 
for  annealed  or  unannealed  metal,  nor  on  the  ductility  for 
annealed  metal :  but,  within  the  limits  carbon  0  '60$  and 
0*15%,  for  given  diminution  of  area  by  hot  work,  the 
higher  the  carbon  the  greater  the  gain  in  tensile  strength 
for  both  annealed  and  unannealed  metal,  and  in  ductility 
for  unannealed  metal  (Table  135).b 

2.  Annealed  vs.  Unannealed. — If  E  =  the  percentage 
of  excess  (due  to  hot  working)  of  any  given  property  in 
an  unannealed  bar  over  that  of  the  unannealed  bar  or 
ingot  from  which  it  is  made,  and  if  E'  =  the  correspond- 
ing excess  for  annealed  steel :  then  we  learn  from  Tables 
133  to  135  that,  in  case  of  2"  bars  from  6"  ingots  and  of 
i"  bars  from  3"  bars,  E  for  tensile  strength  is  almost 
always  and  E  for  elongation  usually  greater  than  E1,  but 
not  for  elastic  limit  or  contraction  of  area.  Nor  does  E 
appear  on  the  whole  to  be  greater  than  E1  for  any  of  these 

a  The  elongation  of  the  different  sizes  in  Kirkaldy's  experiments  is  not  compar- 
able, because  the  different  test-pieces  had  unlike  diameters. 

b  For  the  effect  of  annealing  as  influenced  by  the  proportion  of  carbon,  see  §  46, 
p.  4.  Mr.  C.  A.  Marshall  announces  it  as  a  law  that  the  effect  ot  work  is  greater 
and  that  of  heat -treatment  less  on  the  physical  properties  of  low-  than  of  high- 
carbon  steel.  Doubtless  true  as  regards  certain  forms  of  heat-treatment,  e.  g. 
quenching,  this  harmonizes  poorly  with  our  inferences  from  Kirkaldy's  data  as 
regards  work  :  and  in  this  respect  it  is  also  opposed  to  Metcalf  s  judgment  and 
experience.  Trana.  Am.  Soc.  Civ.  Eng.,  XV.,  pp.  349,  351,  1887. 


properties  in  case  cf  bars  of  intermediate  size  made  from 
6"  ingots  and  from  3"  bars.  In  other  words,  in  Kirkaldy's 
experiments,  hot-working  appears  to  increase  the  elastic 
limit  and  contraction  of  area  belonging  to  the  an- 
nealed state  probably  about  as  much  on  the  whole  as 
those  belonging  to  the  unannealed  state  ;  and  the  tensile 
strength  and  elongation  belonging  to  the  annealed  state 
in  very  many  cases  as  much  as  those  belonging  to  the  un- 
annealed state. 

But  in  numbers  1,  2  and  4  of  Table  131  E  is  greater  than 
E1  for  elastic  limit  and  tensile  strength. 

This  indicates  that  the  improvement  differs  from  that 
induced  by  cold-working,  which  is  lessened  by  annealing. 
(Cf.  §271,  p.  217). 

3.  Early  vs.  Late  Reduction. — If  i  =  the  percentage  of 
increase  of  any  property  following  an  amount  of  hot  work- 
ing which  diminishes  the  sectional  area  of  the  piece  by 
lfc,  then  we  find  in  Table  133  that,  for  each  of  the  four 
properties,  i  is  greater  when  the  size  is  reduced  from  5  in. 
X  5  in.  to  4  in.  X  4  in.  than  for  either  earlier  or  later  re- 
ductions. This  is  true  in  83  out  of  the  96  cases  in  which  i 
for  other  reductions  is  compared  with  i  for  reductions  from 
5  X  5  to  4  X  4.  In  other  words,  under  these  conditions  a 
given  percentage  of  diminution  of  area  between  5  in.  X  5 
in.  and  4  in.  X  4  in.  does  more  good  than  either  earlier  or 
later  diminutions.  Further,  i  is  greater  here  for  reluction 
from  5  in.  to  4  in.  than  from  4  in.  to  3  in.  in  28  out  of  32 
cases  ;  and  for  4  in.  to  3  in.  than  for  3  in.  to  2  in.  in  21 
out  of  32  cases.  Whether  this  is  due  to  the  special  con- 
ditions of  these  cases  or  not,  further  investigation  must 

TABLE  136.— IMPEOVEMENT  OF  WKOUGHT-IRON  F  WITH  DIMINISHING  SIZE. 
TJ.  8.  Board  on  Testing  Iron,  etc.,  I.,  p.  88,  1881. 


Sectional 

Tensile  strength,  pounds  per 

Elastic  limit,  pounds  per 

Size  of 

Sectional 

area  of  bar 

square  inch. 

square  inch. 

bar. 

area  of  pile. 

in  per  cent 

pile. 

Entire  bar. 

Core. 

Entire  bar. 

Core. 

4 

SO 

15-70 

46,322 

23,480 

81 

80 

18-80 

46,667 

23,686 

80 

12  03 

47,000 

24,951 

8 

80 

10-87 

47,014 

24,591 

8 

80 

8-83 

47,761 

26,887 

2* 

SO 

7  42 

46,466 

26,333 

>I 

so 

0-13 

iV'.sii 

47,428 

29,TS8 

29,941 

2* 

72 

5-52 

48,505 

49,290 

81,287 

82,163 

2 
H 
H 

72 
86 
86 
86 

4-36 
7-67 
6-68 
5-76 

47,872 
49,744 
50547 
50,529 

48,280 
49,870 
48,792 
49,144 

85,864 
85,615 
85,954 
85,394 

81,892 
87,042 
88,992 
34,208 

1} 

86 

4  90 

50820 

51,888 

35,087 

86,467 

86 

4-12 

52,839 

48,819 

89,  103 

86 

8  41 

52,729 

49,801 

39,608 

40,584 

i  A 

25 

8-96 

50,149 

50,530 

85,493 

87,771 

Js 

25 

8  14 

51,921 

51,128 

89,066 

88,596 

1 
I 

I2i 

4  91 

50716 

50,874 

38,931 

83,204 

I 

m 

3-60 

50,673 

50,276 

83,933 

85,988 

m 

2  50 

52,297 

51,431 

34,450 

34,545 

9 

2-17 

52,275 

52,775 

38,445 

39,126 

9 

8  68 

54,098 

M,10S 

88,475 

40,218 

i 

8 

1-60 

67,000 

59,585 

Lost. 

Lost. 

NOTE.— The  number  3-68  in  the  third  column  for  the  f  "  bar  is  given  thus  in  the  original 
Apparently  it  should  be  1'22. 


THE    EFFECT    OF    WORK    ON"    THE    PROPERTIES    OF    STEEL. 


297. 


245 


5    .  20 

*e 

1 

3 

5 

7 

y 

ij 

<  j 
ii-  _i 

0  0 

s  E 

MUCH  WORKED  PREVIOUSLY. 

F 

LITTLE  WORKED 
PREVIOUSLY. 

N 

A 

p 

Fx.1 

RATIO  OF  SECTIONAL 

Fx,3 

RATIO  OF  SECTIONAL 

i* 

ss; 

NEARLY  CONSTANT. 

AREA  OF  BAR  TO  PILE 
NEARLY  CONSTANT* 

g   I 

!       1« 

B  9  to 

m  x 

3 

'?« 

s 

o!  s 

2«                                     ]X 

*"    'X 

W)4 

„ 

s| 

!><    *X  IK  .„ 

1M 

**        1H 

1xi« 

x~v 

C  K 

<  IJ- 

ffl    UJ 

'     *  "1  xvt 

IM      1 

15,'«H 

gjQ 

(35i> 

•^JH*&S 

u.  -1 

«            M 

1 

v2/ 

oz    0 

3  £  2O.OOO                     3O.OOO                4O.OOO           30.OOO                  4O.OOO           20.OOO                   3O.OOO                  4O.OOO            30,OOO                  40,000           80,000                   40,000           80  OOO                 4O.6OO 

ELASTIC  LIMIT,  POUNDS  PER  SQUARE  INCH. 


Q  20 

3 

_j 

MUCH  WORKED  PREVIOUSLY. 

4 

j 
0 

F 

LITTLE  WORKED 
PREVIOUSLY. 

a 

« 

N 

•  ~ 

?x 

2     IX 

2  10 

" 

IJjijJi 

!!  S 

2»''« 

li? 

X 
0 

2^2% 

'« 

(C 

1U^ 

V,H      N 

C 

u.     0 

"•^           S 

O40.00O                  6O.OOO                    60.OOO          60,000                   6OjOO( 

6 

A 


40,000 


BO,OOO 


8 
P 


W"« 


10 

Fx.1 


RATIO  OF  SECTIONAL 
AREA  OF  BAR  TO  PILE 
NEARLY  CONSTANT. 


12 

Fx.3 

RATIO  OF  SECTIONAL 
AREA  OF  BAR  TO  PILE 
NEARLY  CONSTANT. 


60.00O     50,000        60,000     BO,OOO        6O,OOO     CO.OOO 


60.OOO 


TENSILE  STRENQTH,  POUNDS  PER  SQUARE  fNCH. 


Fig.  USA.— Influence  of  Kednction  on  the  Properties  of  Wronght-iron. 


The  diagrams  are  to  be  taken  in  pairs,  1  with  2,  3  with  4,  etc.  The  tensile  strength  (even-numbered  diagrams)  and  elastic  limit  (odd-numbered  diagrams)  of  wronght-iron  bars  were  determined,  and 
the  results  here  plotted.  Each  pair  of  diagrams  represents  results  obtained  with  many  bars  of  the  same  kind  of  wrought-iron.  but  of  different  thicknesses  and  produced  with  different  amounts  of  reduc- 
tion from  the  pile  from  which  they  were  made.  The  numerals  in  diagrams  1  to  8  inclusive  represent  the  thickness  of  the  bars  tested,  in  inches.  In  diagrams  9  to  12  inclusive  the  results  fell  so  cloaely  to- 
gether that  numerals  would  have  obscured  each  other  :  the  thickness  of  the  bar  is  therefore  represented  in  these  diagrams  by  the  size  of  the  circles.  The  results  are  those  of  the  United  States  Test  Board, 
Sept.  1881. 


decide :  but,  taken  collectively,  the  evidence  here  present- 
ed seems  to  indicate  pretty  strongly  that  the  improvement 
is  on  the  whole  more  marked  and  constant  for  reductions 
between  large  sizes  than  for  those  between  small  sizes,  es- 
pecially when  the  small  sizes  are  materially  below  one 
inch. 

Quantitative  Effect  of  Work. — Table  133  indicates 
that,  under  the  conditions  here  existing,  if  the  sectional 
area  of  the  piece  be  reduced  by  from  30  to  45$  by  hot- 
working,  then  on  an  average  each  \%  of  diminution  of  area 
increases  the  tensile  strength  and  elastic  limit  by  about 
0-2$  and  the  elongation  and  contraction  of  area  by 
about  1  •&% 

To  sum  up,  diminution  in  the  thickness  of  ingot-metal 
is  usually  but  not  necessarily  accompanied  by  an  increase 
in  tensile  strength,  elastic  limit  and  ductility :  the  ex- 
ceptions are  more  numerous  in  case  of  ductility  than  of  the 
two  other  properties,  and  in  case  of  thin  ingot-iron  than 
in  other  cases.  The  increase  of  tensile  strength  and  con- 
traction of  area,  but  apparently  not  that  of  elastic  limit, 
usually  increases  with  the  proportion  of  carbon,  at  least 
till  this  reaches  0'6$.  The  increase  is  on  the  whole  greater 
for  the  early  than  for  the  late  reductions,  and,  while  often 
as  great  in  case  of  annealed  as  in  that  of  unannealed  metal, 
the  latter  class  in  many  and  perhaps  most  cases  gains 
most.  To  verify  these  inferences,  which  are  only  pro- 
visional, the  study  of  a  much  larger  number  of  cases  is 
necessary. 

C.  Weld-Iron.—  The  results  of  the  United  States  Test 
Board,  represented  graphically  in  Figure  118A,  diagrams 
1  to  8,  indicate  that  the  tensile  strength  and  elastic  limit 
of  weld-  like  those  of  ingot-metal  increase  as  the  thickness 
diminishes.*  In  Table  136,  the  improvement,  though  halt- 


ing, continues  down  to  the  smallest  size  reached,  \" .  From 
li"  to  f"  there  is  little  change  :  from  f "  to  i"  the  im- 
provement is  marked. 

§  297.  INFLUENCE  OF  THE  THICKNESS  OF  THE  INGOT  OR 
PILE  ON  THE  PROPERTIES  OF  THE  RESULTING  BARS,  ETC. 
—The  examples  in  Tables  137-8  seem  to  indicate  that  the 
properties  of  ingot-iron  plates  are  independent  of  the  size 
of  the  ingot  from  which  they  are  made.  Table  137  gives  a 
case  in  which  pieces  of  various  thicknesses  were  cut  from 
an  ingot  and  rolled  down  to  plates  i"  and  \"  thick.  Pieces 
i"  and  J"  thick  were  also  cut  directly  from  the  ingot. 

TABLE  137. — INFLFBNCE  OF  THE  INITIAL  THICKNESS  OF  THE  INGOT  FROM  WHICH  THEY 
BOLLED  ON  THE  PKOPEETIE8  OF  STEEL  PLATES.    (PiRKEE). 


Tensile  strength, 
pounds  per 
square  inch. 

Elongation  in 
8  inches. 

"  2 

fPieee  15   inches"thick  drawn  down  to  |  inch... 

58,016 

27-0 

•I 

"     12i            ''                   "                    "         

59,186 

27'0 

• 

"     10              "                    "                    "         .       . 

59860 

26-0 

«  « 

«S 

"5               •                    "                    " 

68,«88 

tw  912 

24-0 
22  '0 

i 

"            .... 

58464 

24'0 

h 

58  896 

25  5 

.u  • 

"2              '                  "                  "        

58,240 

26'0 

§  <D 

58,240 
49280 

27-0 
9'0 

0,° 

68,168 

24  5 

"9s, 

"    121            "                    "                   " 

65,184 

22'5 

o  t.  a 

..    jo* 

63.168 

22-0 

^  "    ^^       "            "            "     

66,528 

16-0 

52,864 

10' 

. 

The  same  piece  after  testing,  hammered  to  i  in.  sq.  . 

71,904 
60,928 

II1 

(25- 

Piece  1J  cut  from  ingot  and  rolled  to  |  inch  round  .  . 

68,544 

(27- 
28' 

Journ.  Iron  and  Steel  Inst.,  1887,  I.,  pp.  188-4;  also  1888,  I.,  p.  100. 


TABLE  138. — INFLUENCE  OF  THICKNESS  OF  INGOT  ON  PROPERTIES   OF  STEEL  PLATES 


Size  of  ingot. 


12"  X    6" 
24''  X  15" 
Thickness    7' 
12' 
"          18' 


Thickness  of     Number  of  Tensile  strength  El- 
plate,  tests.         pounds  persq. in. 


0-25" 

025" 

0"25± 

0-24 

0-258 


16 
82 

11  to  15 
2 
2 


65,500 
68,000 
55,820 
52,250 
60,115 


[ongation    in 
8  inches. 


Contraction  of 
area. 


29-6 
82-5 


88-2 

44-2 

60-2 

57-25 

57-75 


a  The  formulae  T  =  e^'000  and  T  =   52,000  —  7-°^QA|    in  whicll  d   =    the 

diameter,  A  =  the  area  and  B  =  the  periphery  of  the  section,  all  in  inches,  and  T 
=  the  tensile  strength  in  pounds  per  square  inch,  are  proposed  by  Thurston  and 
the  Edgemoor  Iron  Co.  respectively.  Thurston,  Mails,  of  Engineering,  II., 
p.  407,  1885. 


1  and  2.  From  two  ingots  24"  X  15"  four  slabs  S  inches  thick  were  forged,  and  from  two 
ingots  12"  X  6"  from  the  same  cast  two  slabs  4  inches  thick.  These  six  slabs  were  rolled  to 
plates  i  inch  thick,  and  from  each  plate  eight  tensile  tests  were  made.  The  results  are  calculated 
fromJ  Riley'sdata,  Journ.  Iron  and  Steel  Inst.,  1887,  I.,  p.  122,  Table  I.,  and  Abstract  IV. 
Cf.  J.  Eiley.  Idem,  1883,  I.,  p.  77. 

3.  4  anA  5.  A.  K  Hunt,  Trans.  Am.  Inst.  Mining  Engrs.,  XII.,  p.  815.  From  ingots  7",  12" 
-Jd  18"  thick,  all  from  the  same  heat  of  open -hearth  steel,  of  carbon  0-15^  plates  about  0-25"  thick 
were  rolled.  Those  from  the  7"  ingots  were  rolled  direct  from  the  ingot  apparently:  those  from 
the  12"  and  18"  ingots  were  rolled  from  slabs  5"  thick,  hammered  from  the  ingots. 


246 


THE    METALLURGY    OF    STEEL. 


While  these  latter  pieces  were  weak  and  brittle,  the 
strength  and  ductility  of  the  rolled  plate  pieces  seem  quite 
independent  of  the  thickness  of  the  piece  from  which  they 
were  rolled." 

The  examples  in  Table  139  similarly  indicate  that  the 
tensile  strength  and  elastic  limit  of  wrought-iron  bars  of 
given  size  is,  within  the  limits  here  given,  independent  of 
the  sectional  area  of  the  pile  from  which  they  are  rolled. 
At  least  the  influence  of  the  size  of  the  pile  is  here  so 
slight  as  to  be  wholly  masked  by  that  of  other  variables. 

TABLE  139.— INFLUENCE  OF  THE  INITIAL  THICKNESS  or  THE   PILE  FROM  WHICH  THEY  WERB 

BOLLED  ON   THE  PROPERTIES  OF  WROTTGHT-lRON  BARS. 

From  Data  of  IT.  S.  Board  on  Testing  Iron,  Steel,  etc..  1881,  pp.  I.,  88  to  44. 


2-inch  square  bars 

1?4"  square  bars. 

Number. 

i 

fc 

Pile. 

Bar. 

Number. 

i 

Pile. 

Bar. 

Size,  inches. 

1 

•s  . 

Tensile  strength, 
Ibs.  per  sq.  iu. 

Elastic  limit, 
Ibs.  per  sq.  in. 

Size,  inches. 

£ 

3 

s 

=   . 

Tensilestrength, 
Ibs.  per  sq.  in. 

Klastic  limit, 
Ibs.  per  sq.  in. 

J" 

N. 
A. 

6  X  4%  X  26 

27 
86 
45 

72 
80 
80 

11-68 
8-72 
6-98 
6-85 
4-86 
8-93 
8-92 

51,848 
50,171 
50,884 
52,599 

52^011 
50,763 

82.461 
27,600 
81878 
81,198 
31,892 
84702 
38,258 

1 
2 
8 
4 
5 

7 

N. 
A. 
Px. 

F. 
Fx.8 
P. 
Fx.  1 

4  X  8%  X  17 

15 

31-5 
86 
36 
45 
48 

8-18 
4-90 
3-89 
3-41 
3-41 
2  72 
2-55 

56,478 
53,87!) 
56,884 
49,801 
58,248 
56,871 
55,307 

33,251 
27,600 
38,921 
40,834 
88,520 
36.S6* 
34,784 

g 

p. 

4.. 

Px. 

F.  • 



6X6 

f,.. 
7   . 

Fx.  1 
Fx.8 

8X  10 
8  X  10 

6X8 

Mechani- 
cally 


§  298.  RATIONALE  OF  THE  EFFECT  OF  WORK. — We  can 
conceive  six  ways  in  which  hot-working  may  influence  the 
properties  of  iron  and  steel : 

"1,  by  expelling  slag  and  by  changing  its  dis- 
tribution. 

2,  by  welding  together  separate  particles  or 

pieces  which  were  initially  more  or  less 
detached.  These  two  apply  chiefly  to 
weld-iron. 

3,  by  closing  blow-holes  and  pipes. 
Structurally,  4,  by  preventing  or  obliterating  crystalliza- 
tion. 

j  5,  by  pressure  as  such. 
Specially   j  ^  by  kueading  as  snch 

Care  is  needed,  especially  in  case  of  thin  and  hence 
cool-finished  pieces,  to  distinguish  the  results  of  hot- 
f  rom  those  of  cold-working :  the  latter  are  probably  more 
thoroughly  removed  by  annealing  than  the  former.  A  gain, 
the  increase  of  elastic  limit  probably  bears  a  higher  ratio 
to  that  of  tensile  strength  in  case  of  cold-  than  of  hot- 
working.  Further,  while  hot-working  toughens,  cold- 
working  makes  brittle  :  whence  we  infer  that  the  cold- 
working  range  of  temperature  has  been  reached  in  the 
following  case. 

TABLE  139A.— NOEMAL  AND  COOL  WORK.    BETAN. 


Boiled  at 

Tensile  strength,  Ibs.  per  sq.  in  . 

Elongation  . 

Bright  redness  
Dull           " 

70,845 
70,673 

69,942 
71,954 

68.135 
64,060 

59,190 
61,590 

25  9 
22-4 

24-8 
22-6 

24  9 

22  8 

28-8 
24  5 

Eept.  Naval  Advisory  Bd.  on  Mild  Steel,  Gatewood,  p.  92,  1886.  Part  of  each  of  four  heats  of 
Cambria  "cruiser"  steel  was  rolled  at  bright  redness,  part  at  dull  redness.  The  finishing-tempera- 
ture is  not  riven. 


Of  the  above  six  ways,  the  first  three  are  mechanical. 
That  work  may  benefit  thus  is  self-evident.  The  ex- 
pulsion of  slag  must  occur  chiefly  during  the  early  part  of 
each  rolling  or  hammering,  while  the  slag  is  liquid  and  the 
metal  soft  and  open.  Table  140  tends  to  show  that  little 
is  removed  in  reducing  wrought-iron  from  2  in.  to  f  in. 


»  The  %"  plates  rolled  from  the  7)4"  piece  has  low  ductility,  but  this  can  hardly 
be  attributed  to  its  being  rolled  from  a  thin  piece,  as  %"  pieces  rolled  from  5'',  8", 
8"  and  1"  pieces  bad  shown  high  ductility. 


TABLE  140.— INFLUENCE  OF  WOKK  ON  THE  PROPORTION  OF  SLAG  IN  WELD  IKON. 


Slag  in  chain-cable  iron  of  various  cross  sections 


Diameter  of  piece, 
inches. 

f. 

i. 

1. 

H. 

H. 

If  and 
1  7-16. 

H. 

if  and 
1  11-16. 

U. 

1  18-16 

2. 

Percent- 
age of 
slap. 
Number  o 

Maximum 
Minimum 
Average  . 
'pieces.... 

1-168 

1-096 

O-IRII 
•873 
2 

1-738 
0-U« 
1-058 
6 

1-724 
0-326 
0-959 
5 

1-026 
0-808 
•658 
5 

1  -281) 
0  354 
•943 
4 

2-202 
0  546 
1-228 
4 

0-570 

•668 
1 

•383 
1 

•862 
:) 

1-258 
1 

0-376 
1 

This  table  is  calculated  fiom  data  furnished  by  the  U.  8.  Board  on  testing  iron,  steel,  etc., 
Rep.,  1881,  Tol.  I.,  p.  223,  Trans.  Am.  Inst.  Mining  Engineers,  VI.,  p.  102,  1879. 


The  fourth  is  structural.  Here  the  influence  of  work  is 
of  the  same  nature  as  that  of  heat-treatment. 

The  fifth  and  sixth  may  be  called  the  special  effects  of 
work,  which  cannot  be  produced  otherwise.  By  chemical 
additions  and  by  compression  in  casting  we  can  prevent 
mechanical  defects  :  by  heat-treatment  we  can  in  great 
measure  govern  the  structure.  But  it  is  generally  be- 
lieved that  work  has  a  further  influence  :  that  its  pressure 
and  kneading  as  such,  work  some  lasting  benefit  which  is 
not  simply  mechanical,  which  is  not  the  same  as  that  of 
heat-treatment,  but  which  is  comparable  to  the  effect  of 
kneading  on  clay,  on  dough,  on  putty.  Let  us  term  this 
the  "  special  effect "  of  work. 

Now  it  is  a  question,  and  a  very  important  one,  whether 
this  special  effect  exists  at  all,  whether  ' '  we  want  a  forg- 
ing machine  at  all,"  whether  "the  steel  can  be  made  to 
forge  itself  by  static  pressure  and  by  heat"b  with  as  good 
results  as  when  forging  is  added  to  static  pressure  and 
heat :  whether  "it  is  possible"  (and  profitable)  "to  make 
a  steel  in  its  cast  state  just  as  strong  as  if  it  had  been 
hammered"0:  whether  the  superiority  of  thin  over  thick 
pieces  even  of  mechanically  sound  ingot-metal  (here  ex- 
cluding that  improvement  due  to  cold  -working  and  re- 
movable by  annealing)  is  due  to  increased  reduction  as 
such,  or  to  the  lower  temperature  at  which  the  thinner 
piece  is  habitually  finished,  and  thence  to  the  smaller 
opportunity  for  crystallization. 

The  question  may  be  resolved  into  two :  (1),  is  there  a 
special  effect  of  work  differing  in  nature  from  that  of 
heat-treatment  ?  (2),  If  not,  and  if  their  effects  are  of  the 
same  nature,  may  not  these  effects  often  be  produced  in  a 
higher  degree  by  work  than  by  heat-treatment  ? 

If  this  special  effect  exists  and  is  important,  then  qual- 
ity will  be  benefited  by  casting  very  thick  ingots  and 
giving  abundant  reduction  :  if  not,  we  should  cast  the 
metal  (1)  in  ingots  as  thin,  i.  e.  as  near  the  shape  of  the 
finished  piece  as  we  can  without  causing  excessive  casting- 
defects,  (external  cracks,  pipes,  blowholes,)  weighing  the 
increased  cost  of  reducing  thicker  ingots  to  the  finished 
shape  and  their  greater  proportion  of  crop  ends  against 
their  greater  soundness  and  cheapness  ;  (2)  in  ingots  of  a 
weight  convenient  for  casting  and  working,  remembering 
that  heavy  ingots,  demanding  powerful  cranes  and  roll- 
trains,  etc.,  mean  costly  installation,  danger  of  segrega- 
tion, difficulty  with  heating-furnace  bottoms  (Aiken's 
crane  promises  to  obviate  this);  light  ingots  mean  excessive 
cost  per  ton  for  handling  in  casting-pit,  furnace  and  mill. 
If  the  use  of  high  working-temperature, — adopted  to  save 
power  and  to  close  blowholes  effectively, — and  of  thin 
ingots,  lead  to  finishing  the  metal  so  hot  that  hurtful  crys- 
tallization during  cooling  is  feared,  cool  quickly  to  V:  or,  if 
the  best  quality  is  needed,  reheat  to  W  (Cf.  §  250;p.  179X 

DMetcalf,  Trans.  Am.  Soc.  Civ.  Ene.,  XV  ,  p.  396,  1887. 
c  Holley,  Metallurg.  Rev.,  II.,  p.  381,  1878. 


RATIONALE    OF    THE    EFFECT     OF    WORK. 


298. 


247 


Again,  if  this  special  effect  of  work  does  not  exist,  or  is 
unimportant,  the  prospective  value  and  use  of  steel  cast- 
ing is  enormous,  enormous  the  prospective  cheapening  of 
steel  pieces  of  castable  shape :  the  gun-  the  armor-plate- 
the  marine-shaft-question  assume  a  different  phase. 

While  it  is  conceivable  that  work  should  have  a  special 
lasting  influence,  it  is  not  easy  to  understand  what  its 
nature  is,  that  it  can  survive  the  complete  metamorphoses, 
not  only  of  crystalline  form  but  actually  of  mineral 
species,  which  heat-treatment  causes.  It  is  hard  to  be- 
lieve that,  when  the  whole  structure  of  steel  has  been 
completely  revolutionized  by  heating  t>  W.,  it  should 
make  any  difference  whether  the  supposed  special  effect 
had  previously  been  induced  or  not. 

The  effect  of  work  surely  ceases  when  the  metal  melts : 
I  for  one  find  it  hard  to  conceive  or  believe  that  the 
special  direct  effect  of  kneading  and  pressure  survives 
heating  to  temperatures  approaching  the  melting  point. 
In  this  view,  if  this  supposed  effect  exists  at  all,  so  that 
larger  ingots  yield  better  finished  pieces  than  smaller 
sound  ingots  do,  the  benefit  of  each  working  is  still  likely 
to  be  effaced  when  the  metal  is  heated  again. 

Our  first  question,  is  the  superiority  of  thin  pieces  due 
to  lower  finishing-temperature  or  to  greater  reduction  or 
both,  and  if  to  both  in  what  pi-oportion  to  each,  is  not 
easily  answered,  since  the  finishing  temperature  usually 
sinks  as  reduction  increases.  That  is  to  say,  if  we  start 
with  ingot  or  pile  of  given  size,  then  the  greater  the  total 
reduction  the  lower  also  will  be  the  finishing  temperature. 
Hence  we  should  expect  common  practice  to  answer 
equivocally,  and  should  look  to  special  cases,  in  which 
these  two  variables  do  not  vary  alike,  for  light.  Nor  do 
we  look  vainly. 

To  mako  this  question  of  the  finishing-temperature  clear, 
let  ordinates  in  Figure  118  B  represent  temperature  and 
abscissae  coarseness  of  grain..  Now,  the  line  AW  may 
be  taken  as  representing  roughly  the  size  of  grain  which 
steel  of  given  composition  tends  to  assume  with  varying 
temperature,  or  the  line  of  maximum  coarseness  of  grain 
(Of.  Figure  63,  p.  178).  If  the  grain  be  smaller  than  the 
maximum  for  existing  temperature  it  always  tends  to 
grow  and  to  approach  that  maximum.  If  it  be  coarser 
than  that  maximum  it  does  not  tend  to  shrink  back  to- 
wards the  maximum,  except  when  the  temperature  is 
risingpasiVf .  Let  us  suppose  that  we  cease  rolling  a 
piece  of  steel  while  its  temperature  is  at  L,  the  mechan- 
ical work  of  the  rolls  having  broken  the  grain  down,  and 
reduced  its  size  to  B.  During  subsequent  cooling  the 
grain  will  grow,  somewhat  as  sketched  in  the  line  BCE. 
If,  however,  we  resume  rolling  when  the  grain  had 
reached  C,  we  will  again  break  down  the  grain,  and 
drive  it  back  to  D.  And  so,  keeping  on,  between  passes 
the  grain  grows  and  the  temperature  simultaneously  falls, 
while  at  each  pass  the  squeeze  which  we  give  the  metal 
breaks  up  the  grain,  and  the  curve  of  grain  and  tempera- 
ture follows  the  zigzag  line  BCDG. 

If  we  cease  rolling  when  the  temperature  has  fallen  to 
G,  then  the  grain  will  grow,  as  the  metal  cools  till  the  line 
of  the  actual  size  of  grain  intersects  that  of  the  maximum 
size,  the  line  AW :  with  further  cooling  no  further 
growth  ensues,  and  the  final  size  of  grain  is  OP.  If  we 
had  quenched  the  metal  while  at  G,  the  final  size  of  grain 
would  have  been  OH.  If  we  had  ceased  rolling  when  the 


temperature  was  at  L,  the  final  size  of  grain  in  the  cooled 
steel  would  have  been  OE.  Needless  to  say,  far  from 
pretending  that  these  curves  are  drawn  to  scale,  I  cannot 

Fig.  118  B. 


V/ 


vE 


OHP 

The  Influence  of  the  Finishing-Temperature  on  the  Size  of  Grain. 

ven  insist  that  their  general  teaching  is  true :  but  it 
certainly  seems  to  harmonize  with  our  phenomena. 

If  these  ideas  be  true,  then  the  temperature  at  which 
rolling  or  hammering  ceases  has  a  most  important  effect 
on  the  size  of  the  grain,  and  through  this  on  the  proper- 
ties of  the  metal. 

Let  us  now  consider  certain  cases  which  throw  light  on  the 
question  as  to  whether  it  is  the  total  quantity  of  reduc- 
tion which  the  metal  undergoes,  or  the  temperature  at 
which  that  reduction  ceases,  i.  e.  the  finishing  tempera- 
ture, which  chiefly  causes  the  superiority  of  thin  over 
thick  pieces  of  steel  and  wrought-iron. 

1.  If  the  superiority  in  question  were  due  to  lowered 
finishing- temperature,  and  not  to  increased  work,  then, 
since  the  tendency  to  crystallize  diminishes  rapidly  with 
the  falling  temperature  and  becomes  very  faint  when  "V  is 
reached  (Figure  61,  p.  171),  the  improvement  for  given 
fall  of  finishing-temperature  should  diminish  as  the  region 
covered  by  this  fall  is  lowered  ;  i.  e.,  the  lower  the  finish- 
ing temperature  the  less  should  the  metal  be  benefited  by 
lowering  it  further.  If  the  finishing  temperature  be  already 
at  V,  it  profits  not  as  regards  crystallization  to  lower  it 
further.  Lowering  it  beyond  a  certain  now-unknown  point 
in  turn  produces  a  new  different  effect,  that  of  cold-work- 
ing. Now  we  have  seen  (§  296)  that  the  lower  the 
finishing-thickness  (and  hence  the  finishing-temperature) 
the  less  do  thin  excel  thick  pieces,  the  reduction  from  1" 
or  at  least  from  £"  downward  often  causing  no  improve- 
ment. We  reasonably  infer  that  this  is  because  the  £ " 
plate  was  finished  at  a  safe  temperature  in  these  cases ; 
the  still  thinner  pieces  are  no  better  though  they  have  re- 
ceived more  work,  simply  because  their  still  lower  finish- 
ing-temperature is  of  no  material  advantage.  It  may 
indeed  be  found  that  the  supposed  "special  effect" 
diminishes  thus  with  falling  temperature :  but  one  would 
hardly  anticipate  it,  rather  expecting  exaggerated  effects 
due  to  cold- working.  Nor  can  the  matter  be  referred  to 
greater  closing  of  blowholes  in  the  early  welding-hot 
passes,  for  Table  133  indicates  that  the  very  earliest  re- 
duction, from  6"  to  5",  profits  the  annealed  metal  but 
little :  so  with  the  unannealed :  whence  we  suppose 
that  the  5"  piece  is  finished  so  hot  that  it  crystallizes 


248 


THE    METALLURGY     OF    STEEL. 


nearly  as  much  as  the  6",  while  the  4"  piece  is  finished 
materially  cooler. 

2.  In  case  of  wrought-iron  the  improvement  continues 
down  to  1".    In  Table  136  the  only  series  which  runs 
below  1",   we    saw  little  change  between  1J"  and  f", 
then  a  marked  increase  between  f"  and  J".     A  single 
series  gives  no  safe  guidance.     The  lack  of  improvement 
between    1J"    and    f"    may  be    accidental   or    normal. 
If  normal,  it  may  be  that  the  1J"  is  finished  at  a  safe 
temperature,  so  that  the  lower  finishing  temperatures  of 
the    li",    1",    |"  and    £"  bars    does    not  profit    them. 
At    |"    cold- working    may   set   in,   raising    the    tensile 
strength    and    elastic  limit    of  the   |",   i",  f"  and    J" 
bars.    If  accidental  (perhaps  through  individual  peculiar- 
ities, though  fortuitious  variations  in  finishing  tempera- 
ture, etc.),  it  may  be  that  the  improvement  in  wrought- 
iron  continues  down  to  a  smaller  thickness  than  in  case 
of  ingot-metal,  because  the  working-  and  hence  the  finish- 
ing-temperature for  the  former  is  higher  than  for  the  lat- 
ter, so  that  a  safe  finishing-temperature  is  reached  only 
with  thinner  bars  of  the  former  than  of  the  latter. 

3.  Further,   while  in  Table  336  the  bar-diameter  di- 
minishes regularly,   the  pile-area  diminishes    only    oc- 
casionally and  by  great  jumps.     Each  jump,  counteract- 
ing the  decrease  of  bar-diameter,  should  tend  to  raise  the 
finishing  temperature  ;  and,  in  case  of  small  bars,  these 
jumps    actually  diminish  the    improvement  which  the 
smaller  bar-diameter  should  give,  nay  usually  turn  it  into 
a  loss,  and  this  even  when  the  percentage  of  reduction  in 
the  rolls  increases. 

4.  If  the  superiority  of  thin  pieces  were  due  to  the  sup- 
posed "special  effect,"  one  would  anticipate  that  iron  pre- 
viously little  worked  would  receive  this  special  effect  more, 
and  be  improved  more,  by  reduction  than  iron  previously 
much  worked  and  in  so  far  saturated  with  it.     If  due  to 
finishing  temperature,  it  should  be  independent  of  previous 
work;  and  in  diagrams  1  to  4  of  Figure  118A  it  seems  to  be  : 
the  improvement  seems  on  the  whole  as  great — indeed  in 
elastic  limit  it  is  greater— in  iron  previously  much  worked 
as  in  that  previously  little  worked. 

5.  In  Diagrams  9  to  12,  in  Figure  118A,  the  metal  on  the 
whole  improves  slightly  as  the  diameter  decreases :  the 
size  of  pile  diminishing  almost  proportionally  to  that  of 
bar,  the  special  effect    should   increase    very  slightly, 
and  the  finishing-temperature  decline   but   little  more. 
These  cases  give  no  clear  indication  as  to  whether  the 
slight  improvement  is  due  to  reduction  or  to  finishing- 
temperature. 

6.  The  United  States  Test  Board  believed  that  the  ten- 
sile strength  and  elastic  limit  of  wrought-iron  bars  tested 
whole  exceeded  that  of  cylinders  turned  from  their  mid- 
dle in  a  proportion  that  diminished  with  the  diameter  of 
the  bar.     This,  too,  points  neither  way  :  for  in  a  thin  bar 
the  difference  between  core  and  shell,  both  as  to  finishing- 
temperature  and  amount  of  work,  should  be  less  than  in 
a  thick  one. 

7.  What  we  may  provisionally  regard  as  approximately 
the  greatest  attainable  excellence,  since  it  is,  I  believe,  as 
yet  unsurpassed,  has  been  reached  by  heat-treatment  with- 
out forging.     Such  had  Chernoff's  famous  steel,  plotted 
thus  -f-  in  Figure  49,  page  159. 

He  cut  a  coarse-grained,  sound,   steel  ingot  into  four 
pieces.     One  was  tested  without  treatment  of  any  kind  :  a 


second  was  heated  to  a  bright  red  and  hammered  till  its 
temperature  fell  to  about  W,  and  then  allowed  to  cool 
undisturbed :  a  third  was  heated  to  about*  the  tempera- 
ture Jit  which  the  hammering  of  the  second  stopped,  and 
cooled  slowly.  Their  properties  are  given  in  Table  141. 
He  says  that  he  has  verified  his  belief  that  the  effects  of 
forging  can  be  produced  by  heat-treatment,  by  a  whole 
series  of  experiments. 

TABLE  141. — ANNEALED  Ti.  FOKGED  STEEL. 


Increase  of  tensile  strength, 

etc.,   per  100  of  that  of 

the  ingot,  due  to  treat- 

ment. 

B  j 

-"'  o  JS 

i£ 

P.-S 

c 

Vi 

—  ^i 

§ 

aw. 

£*<"" 

.§   0 

|s 

C        ® 

iff  i 

~%   0   0- 

1 

a 

1  g 

1  s 

if! 

i§ 

I! 

111 

§  to  p.  10 

S 

V 

§    M  •— 

ea  .H 

c  .;; 

v    «S 

H 

H 

H 

M 

H 

M 

M 

»H 

.    .  (  Untreated,  direct  from  ingot.. 

139,400 

2-3 

«o"}  Forged  

166,400 

5'3 

19-4 

180 

^  fl  (  Reheated,  without  forging  .  .  . 
.    .  \  Untreated,  direct  from  casting. 

155,000 
82,400 
107,240 
100,560 
47,070 

16-6 

ll'l 

622 

167 

147 

248 

127 

29,000 
58,000 
46,000 

4-9 
13-1 
12-1 
0-269 

6  6 
28-1 
15-0 
O'l 

80-1 

22 

100 
59 

S~=  |  Reheated  without  forging  
•    .  I  Untreated,  direct  from  ingot.  . 

110,800 

52,750 

8'46 

68 

135 

1186 

6200 

H  H  (  Keheated  without  forging  

78,800 

50,550 

0-88 

3'2 

57 

227 

3100 

Chernoff.  Revue  Universelle,  2d  Ser.,  I.,  p.  406.  1877. 

Marshall,  Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  p.  345,  1887. 

Tunner,  Jeans,  "Steel,"  p.  662,  1SSO,  from  Oest.  Zeitschrift.    Steel  containing  O'Sg  of  carbon, 

and  free  from  blowholes,  was  cut  into  four  pieces  of  like  section, 
noent.  Two  others  were  heated  in  an  annealing  furnace  for  fifteen  minutes.  Of  these  one  was 
cooled  slowly,  the  other  after  reaching  dull  redness  was  forged  till  its  section  was  reduced  to  one 
twenty-fifth  of  its  original  size. 


Holley  gives  an  almost  equally  remarkable  instance,  an 
unforged  heat-treated  cast  gun-tube,  whose  properties  are 
given  in  Table  142. 

TABLE  142.— PROPERTIES  OP  AN  UNFOBOED,  HEAT-TREATED  STEEL  GUN  TCBE 
(Maillard,  Holley,  Metallurg.  Eev.,  II.,  p.  382). 

1.                    2.                   8.  4. 

Tensile  strength \  rh.          ,„  ,„    (    101,920           83,704           85,344  86,240 

Elastic  limit                            . . . .  /  •Lt)8-  per  8q' ln"  1     49,280           49,728           50,400  50.840 

Elongation ll'l                8'7              15'1  15'8 

It  will  be  found  that  these  compare  favorably  with  the 
very  best  examples  in  Figures  49  and  50. 

We  cannot  assert  confidently  that  these  castings  would 
have  been  bettered  by  work,  for  their  properties  equal 
those  of  the  best  heat-treated  f  orgings.  But  we  can  claim 
that  Marshall's  and  Tunner' s  heat-treated  castings  (Table 
141)  could  have  been  made  much  more  nearly  equal  to 
their  forgings  by  better  heat-treatment,  in  view  of  their 
inferiority  to  Chernoff's  and  Maillard' s. 

8.  Finally,  if  bars  and  plates  of  given  section  and  thick- 
ness made  from  large  ingots  or  piles  were  better  than 
those  from  smaller  ones,  we  could  refer  their  superiority 
to  more  effective  mechanical  action  (the  first  three  of  our 
six  modes),  and  little  light  would  be  thrown  on  our  present 
question.  But  we  find  these  properties  independent  of 
ingot-  or  pile-area.  (Tables  137-8.)  This  argues  directly 
against  the  existence  of  the  supposed  "special  effect," 
and  (admitting  that  the  finishing-temperature  is  approxi- 
mately constant  for  given  finishing-thickness)  in  favor  of 
finishing-temperature  as  the  cause  of  the  superiority  of 
thin  pieces.  Indeed,  one  would  expect  the  thicker  ingot 
or  pile  to  lead  to  somewhat  lower  finishing-temperature, 
unless  this  were  purposely  regulated,  and  hence  to  better 
quality  :  but  this  effect  we  can  hardly  trace. 

To  sum  up,  most  of  the  facts  here  presented  agree  well 
with  either  view.  All  agree  with  the  view  that  the  su- 
periority of  thin  pieces  is  due  to  lower-finishing  temper- 
ature and  not  to  greater  reduction  :  those  under  1,  3  and 
4  I  think  agree  rather  better,  and  those  under  7  decidedly 


a  Chernoff  is  incorrectly  quoted  as  saying  that  the  third  piece  was  heated  to  the 
temperature  at  which  the  forging  of  the  second  stopped.  He  merely  says  that  it 
was  heated  to  "about-'  that  temperature. 


HAMMERING    VS.     EOLLING. 


299. 


249 


better,  with  this  tlnn  with  the  opposite  view,  to  which 
those  under  8  are  directly  opposed.  Cumulatively,  then 
the  evidence  raises  a  presumption  in  favor  of  the  view  that 
the  supposed  "  special  effect "  of  kneading  and  pressure 
as  such  does  not  exist,  or  is  relatively  unimportant,  and 
that  hot-working  acts  chiefly  like  heat-treatment  in  pre- 
venting or  reinoving  crystallization.  But  the  evidence 
under  8  is  too  scanty  to  be  conclusive :  and,  without  an 
investigation  directly  aimed  to  test  this  theory,  we  can- 
not hold  it  confidently. 

Those  of  us  who  have  held  for  years  as  almost  an  axiom 
that  work  directly  benefited  steel,  will  not  give  up  their 
belief  readily  :  I  think  they  will  find  in  the  foregoing 
food  for  reflection,  and  reason  to  doubt  but  hardly  to 
deny  their  old  faith. 

Admitting  provisionally  that  the  supposed  special  effect 
of  work  is  a  myth,  and  turning  to  our  second  question, 
it  seems  probable  that,  to  pieces  of  moderate  thickness 
once  freed  from  cracks  and  cavities  and  shaped,  we  shall 
learn  some  day,  and  indeed  soon,  to  confer  a  given  de- 
gree of  structural  excellence  more  cheaply  by  heat-treat- 
ment alone  than  by  hot-working  alone  or  jointly  by  heat- 
treatment. 

But,  to  give  the  best  results  by  heat-treatment  it  now 
seems  necessary  to  cool  quickly  to  V :  this  is  impossible 
for  the  middle  of  thick  solid  pieces,  so  that  here  heat- 
treatment  alone  cannot  prevent  hurtful  crystallization : 
but  for  that  matter  it  is  hard  to  see  how  forging,  even 
hydraulic  forging,  can  either  ;  for  the  colder  outside  must 
to  a  great  extent  cut  the  interior  off  from  foreign  pressure 
before  it  cools  to  V.  For  thick  pieces,  then,  we  cannot 
answer  this  question  as  yet. 

§  299.  HAMMKUING  vs.  ROLLING. — Clearly  these  two 
operations  do  not  act  in  exactly  the  same  way :  the  for- 
mer rather  pushes,  the  latter  rather  pulls  the  metal's 
particles  into  the  desired  position. 

TABLE  143.— INCREASE  or  TENSILE  STRING™,  ETC.,  ON  FOHOING  AND  ROLLINO  FAOERSTA  STEEL 

FROM   3  X  3  TO   4;  X   i   INCH,  MEASURED  IN   PERCENTAGES    OF    THE    TENSILE    STRENGTH,  ETC.,  OF 

THE  3  X  8  BAR.    (FROM  KIRKALUY'  DATA.) 


Tensile  strength.. 
Elastic  limit  
Contraction  of  area 

By  hammering. 

By  rolling. 

Ratio  of  increase  by  ham- 
mering to  increase  by 
rolling. 

Unannealed 
steel. 

Annealed 
steel. 

ITnannealec! 

Anncaled. 

Unannoaled. 

Annealed. 

78-7 
169- 

86-2* 
47-8 
1486 

52-6* 
40-3 
115- 

42-3* 
44-3 
120- 

1-03  :  1 
1-95  :  1 
1-46  :  1 

0-85  :1 
108:1 
1-23  :  1 

TABLE  144.  —  ABSOLUTE 
MERED  BESSE 

EXCESS  (OR  DEFICIT,  —  )  OF  TUB  TBNSILK  STRENGTH-,  ETC.,  OF 
MER  STEEL  BARS  OVER  THAT  OF  SIMILAR  BUT  ROLLED  BARS. 
(Kirkalily's  Fagersta  data). 

HAH- 

n 

Tensile  strength,  pounds 
per  square  inch. 

Elastic  limit,  pounds 
per  square  inch. 

Elongation,  %  In  10 
Inches. 

Reduction  of  area, 

MO. 

0-50*    |0-15j«  C 
0.      I 

Wft 

0-50^  C. 

C. 

1*C. 

0-50;*  1  0-15^ 
C.    |    C. 

1*C. 

0'50*|  0-15* 
C.     |    C. 

Unanncalcd  Bars. 

i* 

I 

—  4,260 
—   6,220 
—  7,610 
—10,460 
-  5,470 
—  5,348 

5.230 
—  4,040 
—  1,560 
—  3,153 
6,255 
7,687 

11,360 
10,660 
150 
-   1,861 
—      52S 
3,661 

15,60(1 
8,300 
3.501) 
3,100 
1.100 
1,300 

31.51KI 
u,70ll 
6.200 
(1,51  III 
—   1,900 
8,400 

23.7IXH- 
17,400  - 
10.200  - 
8,700- 
8,400- 
5,500- 

-  1-6 
-  0-8 
-  0-5 
-  0-8 
-  01 
-  0'2 

—  9-1  - 
—    -2 
2-4- 
8  3 
13-2 
—  0-2- 

-12-1 
-12  4 
-14-3 

i-s 

6-2 
-5-9 

0 

—  1-8 
—  0-8 
—  O'l 

—  o-i 
-  o-i 

4-0 
15  4 
23  0 
14-7 
15'9 

o-o 

-i:>-o 
—  5-4 
S-6 
6-7 
17-4 
—15-9 

Annouled  Bars. 


4 

—  5,220 

1,910 

4,230 

4.900 

6,600 

4,00(1 

—  0-2 

—  2-1 

—10  5 

—  5-0 

4-0—  80 

1 

—      930 

—  5,070 

1,581) 

5,300 

70I> 

3,100 

14 

8-9 

—15-8 

—  6-0 

14-3 

—  8-6 

H 

—  6,580 

—  4970 

—  1,510 

4,900 

4,500 

2,200 

0-1 

—  1-5 

—  36 

—  03 

9-0 

1-1 

2 

—  9,039 

—   1,437 

—   1,806 

4,300 

5,200 

•_',i'il»l 

—  02 

0-9 

8-5 

—  08 

2-3 

5-1 

n 

-  2,970 

—  5,490 

—      870 

1,90(1 

—   1.400 

4,700 

—  0-5 

09 

—  2-9 

—  1-1 

9-9 

T-8 

8 

—  1,987 

9,447 

1,1SCO 

2,400 

2,200 

3,700 

—  08 

3-9—  6-7 

-  12 

8-0 

—11-9 

Kirkaldy's  Fagersta  data  as  condensed  in  Table  143,  at 
first  seem  to  show  that  hammering  from  3"  X  3"  to  f "  X 


\"  raises  the  elastic  limit  much  more  and  the  contraction 
of  area  somewhat  more  than  rolling.  But,  looking  more 
closely,  we  note  in  Table  141  that  the  advantage  which 
hammering  offers  is  confined  chiefly  to  the  reduction  from 
1"  to  J",  the  rolled  bars  which  are  from  1"  to  3"  square 
being  as  a  whole  about  as  good  as  the  hammered  if  we 
take  into  account  tensile  strength  as  well  as  elastic  limit: 
further,  that  the  difference  between  the  rolled  and  ham- 
mered £"  bars  is  greatly  lessened  by  annealing.  This  sug- 
gests strongly  that  the  superiority  of  the  hammered  bars 
is  due,  not  to  any  occult  superiority  in  the  action  of  the 
hammer,  but  simply  to  the  fact  that  the  hammer  finishes 
the  thin  bar  at  a  much  lower  temperature  than  the  rolls. 

In  240  tests  on  thirty  soft  steel  plates  (carbon  0'18%)  1", 
i"  and  i"  thick,  fifteen  from  slabs  hammered  and  fifteen 
from  similar  slabs  rolled  from  the  same  ingots,  .1.  Riley 
found  that  the  plates  from  the  hammered  slabs  were  practi- 
cally identical  in  quality  with  those  from  the  rolled  ones, 
excelling  them  in  tensile  strength  on  average  by  only  2  '4$, 
while  in  many  cases  the  results  were  in  favor  of  rolling. 
They  follow: 

TABLE  14B. — PROPERTIES  or  STEEL  PLATES  FROM  ROLLED  AND  FROM  HAMMERED  SLABS. 

J.  Riley.    (240  tests.) 

Tensile  strength,           Elongation  in  8  Reduction  of 

pounds  per  square  inch.          inches.  %.  area  jt. 

Hammered 63,280                             24-85  42-2 

Rolled 61,824                            24-5  42-6 

Jonrn.  Iron  and  Steel  Inst.,  1887,  I.,  p.  124  and  Sheet  III. 

In  point  of  fact,  it  is  very  doubtful  whether,  on 
the  whole,  hammering  in  general  practice  yields  a 
materially  different  quality  from  rolling,  which  is  readily 
understood  if  the  effect  of  both  is  chiefly  to  prevent  or 
obliterate  crystallization  :  their  efficiency  in  this  respect 
depending  in  large  part  on  finishing-temperature,  here  the 
hammer,  there  the  rolls  may  finish  the  piece  at  the  better 
temperature. 

Be  this  as  it  may,  the  considerations  which  in  general 
practice  determine  the  choice  between  hammer  and  rolls 
for  ingot-metal  are  for  the  most  part  those  of  cheapness 
and  ease  of  working,  and  not  of  quality  of  product, 
hammering  being  employed  chiefly  for  pieces  which  can- 
not readily  be  rolled,  e.  g.,  those  of  varying  cross-section, 
such  as  axles,  or  of  irregular  shape,  such  as  crank-shafts: 
those  which  are  so  large  or  of  which  so  few  of  given 
dimensions  are  demanded  that  the  preparation  of 
special  rolls  would  not  be  justified :  and  bars  of  tool-steel, 
these  perhaps  because  the  finishing-temperature  is  more 
readily  controlled  in  hammering  than  in  rolling.  For 
working  red-short  or  mechanically  unsound  metal  the 
hammer  offers  a  certain  advantage,  in  that  it  permits 
coaxing  the  material  with  well-weighted  blows,  while  the 
reduction  in  the  rolls  is  usually  invariable  ;  and  in  that 
unsound  spots  arc  easily  chipped  out  by  the  blows  of  the 
hammer  itself,  while  in  rolling  any  needed  chipping  must 
be  done  by  hand.  In  case  of  weld-metal  the  sharp  blow 
of  the  hammer  may  expel  slag  more  effectually  than  the 
more  gradual  squeeze  of  the  rolls,  especially  if  the  piece 
be  rolled  alternately  in  opposite  directions  (as  in  reversing 
I  and  in  3-high  mills)  since  here  the  slag,  instead  of  being 
moved  ever  in  the  same  direction,  is  squeezed  first  back, 
then  forth.  But  these  considerations  usually  couiit  for 
nothing  against  the  much  greater  cheapness  and  rapidity 
of  rolling,  and  the  more  accurate  section  of  rolled  than  of 
hammered  pieces.  This  is  important  even  in  case  of  inter- 
mediate products  (blooms):  if  pf  accurate  section,  they 


250 


THE     METALLURGY     OF     STEEL 


can  be  cut  more  accurately  to  weight,   and  less  loss  in 
cropping  follows." 

§  300.  WELDING. — Its  essential  conditions  are  adhes- 
iveness and  contact,  and  for  both  plasticity  is  usually 
essential,  though  under  the  peculiar  conditions  of  Coffin's 
weld,  §  254,  p.  184,  it  is  not.  Hence  the  need  of  a  very  high 
temperature,  and  in  fact  one  near  the  melting  point  is  used. 
As  under  usual  conditions  the  surfaces  inevitably  become 
coated  with  oxide,  to  ensure  contact  this  oxide  must  be 
made  so  fluid  that  it  readily  squeezes  out :  hence  another 
need  of  a  high  temperature  to  melt  the  scale ;  or  if  a 
scale-melting  heat  cannot  be  used,  of  some  flux  to  make 
with  the  scale  a  relatively  fusible  compound. 

But  an  excessive  temperature  must  be  avoided.  Why  ? 
According  to  current  belief  because  it  entails  excessive 
oxidation.  In  favor  of  this  view  it  is  pointed  out  that 
steel  scrap,  heated  "in  a  box  composed  of  wrought-iron 
side  and  end  pieces  laid  together,"  is  r  lied  on  a  commer- 
cial scale  into  well-welded  bars.b  As  far  as  contact  is  con- 
cerned an  excessive  temperature  should  be  harmless,  for 
a  thick  layer  of  scale  should  be  as  easily  expelled  as  a 
thin  one  :  and  the  higher  the  temperature  the  more  fluid 
the  scale. 

I  think  that  the  reason  why  we  must  avoid  an  excessive 
temperature  is  that  it  causes  the  structural  deterioration 
known  as  burning :  but  here  we  are  thrown  back  on  the 
question  "is  burning  essentially  oxidation  or  structural 
change,"  already  discussed  (§  263).  In  this  view  the 
wrought-iron  box  facilitates  welding  steel  scrap  not  by 
excluding  oxygen  (enough  will  surely  enter  to  coat  the 
steel  scrap):  but  by  holding  together  the  scrap  (crystal- 
line and  friable,  or  even  mushy  if  very  hot),  so  that  it  may 
undergo  the  squeeze  of  the  rolls,  which  breaks  up  the 
coarse  crystallization  induced  by  the  excessive  temper- 
ature. But  for  this  the  coarsely  crystallized  steel  would 
crumble  at  the  first  pass.0 

§  301.  WELDING  POWER  OF  DIFFERENT  CLASSES  OF 
IKON. 

A.  Ingot-  vs.  Weld- Iron. — Apparently  competent  judges 
insist  that  ingot  iron  welds  as  well,  as  easily,  and  even  under 
precisely  the  same  conditions  as  wrought-iron:  all  of  which 
is  as  positively  denied  by  others  apparently  equally  com- 
petent A  comparison  of  their  printed  and  of  many  oral 
statements  indicate  : — 1,  That  the  conditions  most  favorable 
to  welding  are  not  the  same  for  •.  hese  two  classes  of  iron. 
2,  That  the  range  of  conditions  which  permit  excellent 
welding  is  narrower  in  case  of  ingot-  than  in  that  of 
wrought-iron,  so  that,  3,  in  careless  hands  the  latter  yields 
on  an  average  better  welds  than  the  former.  4,  that  this 
difference  diminishes  as  care  and  skill  increase,  so  that, 


«  Mr.  J.  B.  Pearse  advocated  the  use  of  hammers  for  blooming  rail-ingots  on  the 
ground  that  rolled  steel  was  more  graphitic  than  hammered,  quoting  a  hammered 
steel  with  1  '03$  of  carbon  of  which  0'65$  was  graphitic,  against  a  hammered 
steel  with  0'334$  carbou  all  combined.  Even  if  the  former  very  improbable  com- 
p  isition  be  correct,  the  two  steels  are  not  comparable,  nor  could  we  attribute  the 
graphite  of  the  former  to  hammering  much  more  safely  than  to  its  being  made 
cu,  say,  Wednesday,  or  in  proximity  to,  say.  potatoes.  To-day  we  know  that 
rolled  rail-steel  is  not  graphitic.  (Trans.  Am.  Inst.  Mining  Engineers,  I.,  pp. 
162,  203) . 

*>  Holley,  Trans.  Am.  Inst.  Mining  Engineers,  VI.,  p.  113,  1879. 

c  We  need  not  discuss  Weddings'  explanation  (indeed,  it  is  a  definition,  not  an  ex- 
1  lanation)  that  welding  represents  the  change  from  adhesion  to  cohesion.  It  is  prob- 
»i)ly  a  mixture  of  both,  such  as  we  find  in  granite.  I  see  no  practical  importance 
In  t  ho  question,  for  adhesion  is  now  weaker,  now  stronger  than  cohesion.  Wit- 
ness t  he  splitting  of  a  bank-bill  well  glued  to  two  flat  surfaces  which  are  then 
forced  apart,  the  cohesion  between  the  bill's  particles  being  weaker  than  the  ad 
hesion  of  bill  to  glue.  (Journ,  Jron  and  St.  Inst.,  1885,  I.,  p.  196.) 


under  the  most  favorable  conditions  and  with  the  greatest 
skill,  each  welds  practical y  perfectly,  the  strength  and 
ductility  at  the  weld  practically  equalling  that  of  the  rest 
of  i  he  piece.  5,  That  it  is  practicable  to  weld  ingot-iron 
on  a  commercial  scale  more  perfectly  than  wrought-iron  is 
usually  welded.  6,  Finally,  as  the  ease  and  thoroughness 
of  welding  of  course  differ  among  different  varieties  of  each 
class,  so  some  varieties  of  ingot-  excel  some  of  wrought- 
iron  in  welding  power.  Some  of  the  evidence  follows.6 

On  the  one  hand  several  boiler-  and  ship-builders  have 
assured  me  that  ingot-iron  does  not  weld  as  well  or  as 
easily  as  wrought-iron  :  experienced  foreign  boiler  makers 
and  others  in  some  cases  hold  this  view.d  Results  obtained 
at  Berlin  appear  to  be  unfavorable  to  ingot-metal.  W. 
R.  Hodge,  a  boiler-maker  for  nearly  forty  years,  states 
that  there  is  still  difficulty  in  welding  open-hearth  steel. 
Petersen,  of  Eschweiler,  holds  that  ingot-  cannot  com  pare 
with  wrought-iron  in  welding-power.  (Van  Nost.  Eng. 
Mag.  XXIII.,  p.  346,  1880.)" 

On  the  other  hand,  we  have  many  assertions  not  only 
that  ingot-iron  welds  well  and  easily,  but  even  that  it 
welds  as  well  or  even  better  than  wrought-iron. 

Among  the  former  we  have  Holley' s  statement  that  the 
Terre  Noire  steel  castings  weld  readily:'  Tunner's  that 
ingot-iron  welds  as  well  and  almost  as  easily  as  puddled 
iron:8  Kartell's  that  it  welds  as  easily  and  satisfactorily 
as  wrought-iron  :h  and  the  description  by  G.  Ratliffe1  and 
by  A.  H.  Hill,3  of  excellent  welds  in  steel,  which  endured 
trying  tests  successfully.  Among  the  latter  we  find  that, 
welding  some  8,000  feet  of  ingot-iron  plates  every  quarter- 
year,  Adamsonk  loses  only  one  plate  or  so:  that  Zyromski,1 
Cramps  and  W.  E.  Koch™  state  that  ingot-iron  welds  as 
well,  andT.  J.  Braynthatit  welds  better  than  wrought- 
iron  :  with  the  last,  Tetmajer's  results  seem  to  agree.0 
A.  Thielen"  says  that  about  half  of  his  basic  open-hearth 
steel  is  sold  as  wrought-iron. 

Finally,  the  results  in  3,  4  and  5  of  Table  140  prove 
that  ingot-iron  may  be  welded  with  a  surprising  perfec- 
tion, much  greater  than  is  usual  in  case  of  wrought-iron. 

In  comparing  the  strength  of  welded  and  un  welded 
pieces  we  must  remember  that  imperfect  welding  is  not 
the  sole  cause  of  the  inferiority  of  the  welded  pieces. 
The  high  temperature  employed  in  welding  tends  to  cause 
coarse  crystallization. 


d  Discussion  of  Stromeyer's  paper  on  "  The  Working  of  Steel,"  Excerpt  Proc. 
Inst.  Uiv.  Eng.,  LXXXIV.,  p.  67,  1886. 

Metcalf  would  discriminate  between  the  "  interlacing"  welding  of  wrought- 
iron  and  the  "  sticking"  welding  cf  ingot-iron,  holding  that,  though  ingot-iron  may 
be  "  stuck"  with  "  wonderful  success,"  w'jen  a  weld  in  ingot-iron  is  parted  its  sur- 
faces are  smoother  and  with  less  sign  of  interlacing  than  in  case  of  wrought-iron, 
(Trans.  Eng.  Soc  ,  W.  Penn.,  1888,  p.  30).  Apparently  in  this  view  he  believes 
(Trans.  Am.  Soc.  Civ.  Eng.,  XV.,  p.  301,  1887,)  that  "  steel  cannot  be  welded," 
while  in  the  wider  sense  he  admits  that  even  tool-steel  welds  well.  (The  Treat- 
ment of  Steel,  p.  14,  1884.)  The  distinction  may  be  fair,  but  for  cur  present 
purpose  we  ask  how  strong  the  weld  is,  rather  than  how  its  parted  surfaces  look. 

f  Priv.  Kept.  3d  ser.,  VII.,  p.  45,  1877. 

x  Journ.  Iron  and  St.  Inst.,  18SO,  I.,  pp.  395-7. 

&  Engineering  1878,  p.  414,  fr.  Trans.  Inst.  Nav.  Arch. 

l  Idem,  1879,  II.,  p.  460. 

J  Trans.  Am  Inst.  Mining  Eng.,  XL,  p.  353,  1883. 

*  Discussion  of  H.  Goodal.'s  paper  on  "Open-hearth  Steel  for  Boiler-making,1'1 
excerpt  Proc.  Inst.  Civ.  Eng.,  XCIL,  p.  64,  1888. 

1  Stahl  und  Eisen,  IV.,  p.  535,  1884, 

""Trans.  Eng.  Soc.  W.  Penn.,  1888,  pp.  81,  49. 

n  Idem,  p.  9. 

"Iron  Age,  XXXVI.,  Nov.  5,  p.  5,  1885.  This  is  the  inference  1  draw  from 
his  statement  that  16-6$  of  the  steel  was  poorlj  welded  against  33' 3$  of  the 
wrought-iron. 

P  Jour.  Iron,  and  Steel  Inst.,  1887,  II.,  p.  132. 


WELDING.      §  300. 


Of  the  results  in  Table  140,  those  under  numbers  1  anil  .r>  deserve  especial  confidence.     Number 

•1   is  ^ivell  :l.  illililMtill!,'   results  olll:l!llell   ill  eotll  !llerei;n    work. 

TAUI.E  146.  —  STKKM;TII  UK  \\"KMI>  i>  -i:  N   IN  PKI-.I-FNTAGK  (IF  THAT  OF  TMF.  I'NWF.I.I)KI) 

Ml  TAL. 

Wrought-iron,  #.            Introt-iron,  %. 
1.   Clinin  cables;!:  amon;:  2111  lots 
1  hail                                                                   85+ 

much  as  the  carbon,  and  the  silicon,  phosphorus,  and  sul- 
phur collectively  not  over  O'l()$.f    While  adherence  to  this 
formula  may  favor,  I  doubt  very  much  if  it  is  essential  to 
thorough  welding  :  note  how  widely  the  compositions  of 
many  steels  in  Table  147,  reported  to  weld  well,  differ  from  it. 

TAHLK  147.  —  COMPOSITION  OF  WKLIIINII  ANN  or-  NON-\VKU>IN<;  STKKLS. 

•21     "     75-t-@S5-j- 

14    '•              .                                                      70+  @  7'i+ 

107    "                                                                55      @  70 

67    "  less  than  55 

J.    A  I  iernmn  commission  found 

Welding  power. 

Composition. 

'•  suit  ingot-iron  (0'1U#  C.)  71 

"  harder    "         (tl-20^  (_'  )                                                                                             58 

:'..  Tests  reported  by  Hupfeld  ;  (A  not  over  -02;J) 

C. 

Li 

Mil 

P. 

8. 

Miiiiniuni                                .                                                                        ..  '.I'.;' 

1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 
16 
17 
18 
19 
20 
21 

11. 
K. 

I.. 
I!. 

F.Xeellellt  

Pipes  

•05 
•15 
•14 
•14 
•IS 
•15 
•17 
•14 
•16 
•12 

•08 
tr. 

•08 
•08 
•02 
•08 

•01 

•38 
•22 

'•a 

•u 

•58 

•I'll 

•72 
•S3 

•:;i 
--II 

•60 

••jc  >(,>,•:;(! 
•20 
•12 

•105 

•in 

•07 
•04 
•04 

•o:! 

•M 

•06 

•06 
•07 
•05 

•01; 

•12 
•106 
•129 
•077 
•112 
•093 
•l*i 

•06 

•0-2 

•OB 

•05 
•0-2 
•ll.-> 
•112 
•04 
H« 
•12 
•» 
•07 

•ur, 
•048 
•049 
•Ml 

T)    Ii;iu=chin<Ter                                                                                 '.H  'J                                  "' 

1.  a  Kept.  V.  S.  lid.  on  Testing   Iron,  ^tecl,  etc.,    I.,  p.    2u:i.     These  results  are   not  very 
closely  comparable  with  the  others.     In  the  records  of  21  It  lots  of  stations  of  weliled  wrought  iron 
chain  cables,  the  strength  of  the  cable  is  coinpiiivd  with    th:it  oCthc  kirs  from  which  it  was  made. 
\Vet-e  the  wrld  ptTt'rrt,  the  c.';ble  should  be  about  twiee  as  strong  as  the  bar.     If  we  assume  that 
the  unwelded  portion  of  the  weakest  link  exerts  the  full  resistance  of  Ihc  bar,  then  when  as  in  the 
first  line  of  table  the  strength  of  the  cable  isl'S5  times  that  of  the  bar,  the  strength  of  the  weld 
may  be  taken  as  about  s.vj  of  that  of  the  bar.    This  assumption  dues  not  seem  strictly  accurate  : 
out  perhaps  accurate  enough  to  afford  a  rough  basis  for  comparison. 
2*  Lcdclmr,  Iliindbueh  der  Kisenhiittenkunde,  p.  I»H,  Isst.     Kesults  obtained  by  a  commis- 
sion of  the  Vei-ein  /ur  lieforderung  des  Gewerbtleisses.     These  are  numbers  1U  and  14,  Table  117. 
3.  Hupfeld,  of  1'rcvali,  Mittheil  ous  dtiu   Mcch-Tech.  Lab.  in  Miinchcn,  XIV.,  p.  :I2,  Iss.-,  : 
Van.  Nost.  Eng.  Wajr.,  XXXI.,  p.  88,  1884.     22  uuwelded   and   27   welded  bars  of  common  Bes- 
semer ingot-iron  w«-re  tested  tensilely. 
4*  Discussion  of  II.  (loodall's  paper  on  Open-hearth  Steel  for  Boiler-making,  excerpt,  Proc. 
Inst.  Civ.  Kng.,  XI  'II.,  p.  5ti,  1888. 
5.  From  (apparently)  12  bars  of  12  different  sizes  or  shapes,  of  best-welding  I'eine  (probably) 
basic  ingot-iron,  12  unwelded  and  22  welded  pieces   were   tested   ten-ilelv.     From    (apparently)  7 
bars  of  best  Nassau  wroiiL'ht-iron,  7  unwelded  and  S  welded  pieces  of  o  different  sixes  or  bhapea 
trd  tensilely.    The  welded  pieces  were  in  general  cut  from  the  same  bars  as  the  un- 
welili-d  ones.    The  results  here  given  are  the  avrratrrs  for  each  class.    Six  of  the  welded  ingot-iron 
tars  were  stronger  than  the  eorivsponding  unwelded  pieces.    Bauschinger,  Mittheil  aus  Mech.- 
Tech.  Lab.  in  Miincheu,  XIV.,  p.  31,  1885. 

•15 

•14 

•o:; 

Kair 

•20 

(Joocl  

•10 

Wholly  unwel.hililr.  .  .  . 
Excellent       .     .  . 

•12 

•086 
•101 

•o 

•005 
•012 

I'oor  

Very  bad     . 

•057 

•016 

Bad 

•21 
•11 

•12 

•017 
•028 
•019 

•88 
•20 
•24 

Fair 

1,  Admirably  welding  Bessemer  steel  for  pipes.    A.  E.  Hunt,  discussion  of  T.  .J.  Bray's 
paper  on  •'  Welding  Steel  Tubes,"  Trans.  Kng.  Si"'.,  W.  I'enn    p.  82,  1888. 
2  to  12,  Steel  welded  in  largo  quantities,  by  W.  A.  Koch,  Idem.,  p.  52. 
13-15,  Ledebur.  Handhuch  der  Kisenhuttenkunde,  p.   6H9-11.    13,  Strength  after  welding 

Thus  iu  an  experiment  of  Armstrong's  a  welded  coil, 
though  it  did  not  break  through  the  weld,  showed  lower 
tensile  strength  and  elastic  limit,  and  much  lower  elonga- 
tion than  the  untreated  metal"  :  and  Bauschinger  appears 
to  have  reached  similar  results  for  both  ingot  and  wrought- 
irou.b 

Before  1864  E.  Biley  reported  that  Bessemer  ingot-iron 
welded,  though  not  very  well :°  before  18b6  Galloway 
welded  Bessemer  steel  shavings.11  Steel  boiler-tubes  have 
been  successfully  welded  for  many  years,  though  until 
lately  from  carefully  selected,  costly  material :  now  the 
welding  of  pipes  of  common  ingot-iron  is  carried  out  on  a 
large  scale  and  successfully.  H.  J.  Bray  reports  that  of 
this  pipe,  when  butt-welded,  the  proportion  which  fails  on 
testing  with  three  hundred  pounds  hydrostatic  pressure  is 
less  than  0'5$.e  Two-foot  lengths  of  two-inch  pipe,  some 
of  ingot-  some  of  wrought-iron,  filled  with  water  and 
firmly  closed  at  their  ends,  were  exposed  to  the  cold.  The 
iron  j  ipes  all  burst,  the  steel  ones  had  their  diameter  in- 
creased one-eighth  of  an  inch,  but  were  otherwise  unin- 
jured. Hundreds  of  furnaces  and  combustion-chambers 
for  marine  boilers  have  been  welded  successfully. 

The  readier  welding  of  wrought-iron  is  usually  and 
reasonably  attributed  to  the  slag  which  it  contains.  If 
but  a  little  of  this  is  squeezed  out  into  the  weld  during 
welding,  that  little,  uniting  with  the  oxide  of  iron  formed 
during  heating  on  the  faces  to  be  welded,  makes  it  more 
fluid,  more  easily  expelled. 

B.  Effect  of  Composition  on  Welding  Power. — Carbon 
and  sulphur  certainly  lessen  the  welding  power  :  the 
effect  of  silicon  is  uncertain  :  the  other  elements  probably 
lessen  it,  but  I  do  not  know  that  we  have  definite  proofs 
that  such  quantities  of  them  as  are  commonly  met  in  a 
carbon  steel  are  seriously  hurtful.  Arsenic,  antimony  and 
copper  are  said  to  oppose  welding. 

Adamson  believes  it  established  that,  to  ensure  good  weld- 
ing, the  carbon  must  be  low,  the  manganese  four  times  as 


a  Repts.  British  Assn.,  1882,  p.  398. 

blroa  Age,  Jan.   7,   1886,  p.    13,    from    Mitthei'.ungen   Mech.    Tech.    Lab., 
iu  Munchen,  1885,  la,  p.  31. 
c  Percy,  "Iron  and  Steel,"  p.  7. 
<I  Jeans,  "  Steel,"  p.  663. 
<•  Trnm.  Eng.  Soc.  W.  Penn.,  1888,  p.  27-8. 


.'JTU7J6  or  the  unwelded  metal.  14,  -Do.  do.  TO  92*  or  that  or  the  unweldeu  metal.  15,  Wholly 
unweldable  Be  semer  ingot-iron.  Cause  of  lack  of  welding  power  unknown. 

16-18,  Bauschinger,  Mittheil.  aus  Meeh -Tech.  Lab.  in  Munchen.,  XIV.,  p.  31,  1885.  They 
are  included  in  number  6  of  Table  146. 

19-21,  Hard  and  soft  opon-hearth  ingot-irons,  tested  by  the  Berlin  Commission.  They  ore 
included  in  number  2,  Table  146.  Bauschinger,  loc.  cit.,  from  Verhand.  Vereins  licforderuiig 
des  Gewerbfleisses,  ls>S3  p.  146. 


Sulphur. — Though  Adamson  cannot  weld  ingot-iron 
uniformly  when  it  contains  more  than  0'02$  of  sulphur, 
the  data  in  Table  147  indicate  that  even  as  much  as  '06  or 
'07$  permits  the  successful  welding  of  pipes.  Steel  with 
'12 %  of  sulphur  is  reported  as  not  very  weldable,  and 
with  0'1.0$  as  quite  unweldable. 

Carbon. — It  was  formerly  thought  that  the  presence  of 
a  little  carbon  was  indispensable  or  at  least  very  favorable 
to  welding :  but  this,  I  think  is  no  longer  believed.  Cer- 
tain it  is  that  in  general  the  difficulty  of  welding  increases 
with  the  proportion  of  carbon,  and  the  welding  power 
probably  practically  disappears  when  the  carbon  rises 
above  ]  '3$.  The  larger  the  proportion  of  other  elements 
present,  probably  the  lower,  in  general,  is  the  welding 
power  for  given  percentage  of  carbon.  Thus  the  welding 
of  apparently  common  Bessemer  steel  is  said  to  be  hardly 
possible  with  0'20  to  '0'35$  of  carbon,  and  impracticable 
with  0-35  to  0'50$  :g  while  to  the  practiced  worker  the  weld- 
ing of  the  relatively  pure  crucible  steel  is  said  to  be  easy 
with  0-87$,  and  possible,  using  the  greatest  care,  with 
1  '25%  of  carbon. h  Though  the  difference  is  probably  much 
less  than  this  rather  loose  wording  implies,  and  though 
there  are  welds  and  welds,  it  appears  to  be  very  marked. 

A  reason  why  rising  carbon  lowers  the  welding  power, 
is  that  it  lowers  the  point  to  which  we  can  heat  the  metal 
without  danger  of  burning,  but  does  not  lower  corre- 
spondingly the  temperature  at  which  plasticity  sets  in  :  in- 
deed, it  seems  to  diminish  the  plasticity  and  adhesiveness 
for  given  temperature. 

Silicon  is  said  by  some  to  injure,1  by  others  to  improve1 


'  Presidential  Address,  Jour.  Iron  and  St.  Inst.,  1887, 1.,  p.  19. 

K  J.  Cockerill,  Soo.,  Jour.  Iron  and  St.  Inst.,  1880,  I.,  p.  318. 

h  H.  Leebohm,  Sheffield,  idem,  1884,  II.,  p.  388.  Ledebur,  too,  puts  the  weld- 
inp;  limit  at  slightly  above  1  "2%  C. 

'  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  638.  "  Silicon  doubtless  lessens 
the  welding  power."  Also  Peterson,  of  Eschweiler,  Van  Nost.  Eng.  Mag.,  XXIII., 
p.  346,  1880. 

J  Kochler,  of  Bonn,  idem:  Holley,  Priv.  Kept,  3d  Ser.,  VII.,  p.  45:  Bohme 
Jour.  Iron  and  St.  Inst.,  1884,  II.,  p.  656,  from  Chem  Centralblatt,  XV.,  p.  462, 
Cf.  this  work,  p.  41. 


THE    METALLURGY    OF    STEEL. 


the  welding  power  :  but  I  doubt  if  we  have  any  trustwor- 
thy evidence.  The  good  welding  power  of  crucible  steel, 
usually  rich  in  silicon,  goes  to  show  that  silicon  is  not 
especially  injurious  in  this  respect. 

Those  who  think  it  beneficial  believe  that,  oxidizing  to 
silica  during  welding,  it  yields  a  flux  for  the  iron-oxide 
which  forms  on  the  surfaces  to  be  welded.  It  seems  to 
me,  however,  improbable  that  the  small  differences  in 
the  silicon  content  of  different  steels  should  have  an  im- 
portant direct  effect  of  this  kind. 

If  steel  A  has  0'50$  more  silicon  than  steel  13,  and  if  the 
oxidation  of  silicon  is  confined  to  that  layer  of  metal 
which  is  itself  oxidized,  and  if,  to  fix  our  ideas,  we  sup- 
pose the  iron  of  that  layer  to  be  oxidized  to  scale-oxide, 
Fe8  O0,  then  the  scale  which  forms  on  steel  A  would  have 
only  about  0'8$  more  silica  than  that  formed  on  steel  B, 
a  difference  from  which  one  would  expect  no  very  im- 
portant result,  either  directly  or  through  its  causing  a  cor- 
responding minute  quantity  of  scale-oxide  to  change  to 
magnetic  or  even  ferrous-oxide.  Nor  would  one  expect 
that  the  silicon  contained  in  layers  of  steel  beneath  those 

B' 


injury  attributed  to  manganese  may  be  due  to  the  carbon, 
which  usually  increases  with  manganese. 

Welding  unlike  irons. — There  is  a  belief  that  like 
irons  and  like  steels  weld  more  easily  than  unlike.0 
Without  denying  this,  my  own  observations  lead  me 
to  think  it  a  misleading  half-truth.  Doubtless  wrought- 
iron  welds  far  more  easily  to  itself  than  to  steel :  but  it 
has  seemed  to  me,  and  many  smiths  have  assured  me,  that 
less  care  and  skill  are  needed  to  weld  steel  to  wrought- 
iron  than  to  steel.  In  welding  two  classes  of  iron,  A  the 
more,  B  the  less  highly  carburetted,  if  they  can  con- 
veniently be  heated  separately,  either  in  different  furnaces 
or  fires,  or  in  different  parts  of  the  same  one,  each  may  be 
(and  in  practice  is)  brought  to  its  own  welding  point,  and 
B  being  now  more  plastic  and  adhesive  than  A,  the  con- 
ditions seem  to  favor  welding  much  more  than  if  the  hot 
plastic  B  were  replaced  by  another  piece  of  relatively  cool 
rigid  A.  It  should  be  easier  to  unite  a  more  sticky  to  a  less 
sticky  substance  than  to  unite  two  less  sticky  ones. 

When,  as  in  case  of  rail  and  beam  piles,  made  in  part 
of  wrought-iron  in  part  of  steel,  both  classes  must  be 


which  are  themselves  oxidized,  would  be  oxidized  rapidly, 
nor,  if  oxidized,  that  the  infusible  microscopic  particles 
of  silica  would  be  able  to  ooze  out  of  the  welding  surface, 
and  so  flux  the  scale-oxide. 

The  slag  of  wrought-iron  stands  in  quite  a  different  posi- 
tion, being,  first,  fusible  and  fluid,  and  second,  in  relative- 
ly large  and  more  or  less  continuous  threads,  so  that  com- 
paratively large  quantities  of  it  might  be  squeezed  to  the 
welding  surfaces,  even  from  points  say  half  an  inch  or  even 
an  inch  back.  If  the  silicon  in  ingot-metal  does  favor 
welding,  it  may  possibly  act  through  difference  of  poten- 
tial, or  through  increasing  the  metal's  plasticity,  or  chang- 
ing the  composition  and  hence  fusibility  of  the  scale. 
Manganese  is  now  said  to  injure,8  now  not  to  affect  the 
welding  power,  at  least  when  it  does  not  exceed  l$.b  The 


a  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  638.  "  Silicon  doubtless  lessens 
the  welding  power."  Also  Peterson,  of  Escbweiler,  Van  Nost.  Eng.  Mag.,  XXIII., 
p.  346,  1880. 

b  W.  E.  Koch,  Trans.  Eng.  Soc.  W.  Penn.,  p.  53,  1888.  He  states.  Idem,  p. 
33,  that  he  has  welded  steel  with  from  O'OS  to  l'S5  of  manganese. 


brought  to  nearly  the  same  temperature,  B  must  be  kept 
down  nearly  or  quite  to  the  low  welding  heat  of  A :  but 
even  here,  since  for  given  temperature  B  is  probably  more 
plastic  and  adhesive  than  A,  union  should  be  easier  than 
if  B  were  replaced  by  another  piece  of  A. 

In  harmony  with  this  view  is  the  not  uncommon  prac- 
tice, in  welding  two  pieces  of  steel,  or  even  in  welding 
steel  to  the  softest  basic  ingot-iron,  of  welding  a  thin 
piece  of  wrought-iron  between  them.  The  wrought-iron, 
even  at  the  low  welding  heat  of  the  steel,  is  or  is  thought 
so  much  the  more  adhesive  that  this  double  weld  seems 
easier  and  more  thorough  than  the  single  weld  of  steel  to 
steel.  In  Drolling  steel-headed,  wrought-iron  bodied  rails, 
the  steel  probably  welded  better  to  the  wrought-iron 
than  it  could  have  to  a  steel  body.  But,  as  it  could  not 
weld  as  well  as  wrought-iron  to  wrought-iron,  and  as  the 
welding  was  the  weak  point  of  wrought-iron  rails,  there 
was  little  reason  to  expect  good  results  from  the  steel 
head. 

c  Holley  seemed  to  hold  this  View.     (Trans.  Am.  Inst.  Min.  Eng.)  VI.,  p.  112. 


WELDING. 


302. 


253 


§  302.  MANNER  OF  WELDING. — The  more  common  welds 
are  illustrated  in  Figure  119. 

The  Scarf-  Weld,  J,  is  perhaps  the  most  common  of  all 
for  steel,  especially  for  small  pieces.  In  some  cases  the 
scarfed  faces  are  riveted  together  with  a  single  rivet, 
before  welding,  to  aid  alignment  during  welding.  The 
points  A  A'  are  made  narrower  than  the  body  of  the  piece, 
apparently  to  lessen  the  danger  of  burning  and  the  degree 
to  which  the  point  cools  :  and  also  that  the  point  may  be 
the  more  deeply  imbedded  into  the  opposite  face  B  B'  at 
the  first  blow,  and  that  the  pieces  may  thus  be  quickly 
attached.  To  compensate  for  the  narrowness  of  A  A', 
and  also  to  allow  for  reduction  of  section  in  hammering 
together,  the  obtuse  parts  B  B'  must  be  made  consider- 
ably wider  than  the  body  of  the  piece. 

In  making  this  weld  the  piece  is  so  held  that  the  thin 
point  A  does  not  at  first  come  in  contact  with  the  anvil, 
which  would  cool  it  below  the  welding  heat.  The  other 
point  A'  is  welded  to  B'  with  a  few  light  blows  :  the  piece 
is  then  rotated  180°,  A  is  in  like  manner  welded  to  B,  and 
the  whole  weld  is  then  hammered  together. 

The  scarf-weld  as  applied  to  chain-cables  is  shown  at 

li 

The  V-weld  2,  6,  is  applied  oftener  to  heavy  pieces. 
They  are  more  readily  aligned  and  held  in  place  with  this 
than  with  the  scarf -weld  during  the  welding  operation. 
This  weld  is  sometimes  started  while  the  pieces  to  be 
welded  are  in  the  fire,  the  male  piece  being  pressed  into 
the  female,  be  it  by  hand,  be  it  (in  case  of  very  heavy 
pieces)  by  heavy  blows  from  a  sledge  or  even  a  battering- 
ram  against  one  end  of  one  piece :  be  it  by  drawing  the 
pieces  together  with  bolts  as  at  6,  Figure  119.  But  we 
should  regard  the  adhesion  thus  given  chiefly  as  an  aid 
to  alignment,  relying  on  the  subsequent  hammering 
for  the  strength  of  the  weld. 

The  scarfing  angle,  both  in  the  scarf-  and  V- welds, 
should  be  rather  acute,  as  shown  at  6,  so  that  the  com- 
ponent AB  of  the  welding  pressure  CB  which  is  at  right 
angles  to  the  welding  faces  may  be  great,  the  pressure 
thus  acting  chiefly  to  force  these  against  and  less  to  slide 
them  past  each  other. 

In  welding  hard  steel  to  wrought-iron  by  the  V-weld, 
the  steel  is  always  used  for  the  male,  the  wrought-iron  for 
the  female  piece,  as  the  latter  is  exposed  to  the  higher 
temperature.  One  face  of  the  male  piece  is  generally 
notched  ;  the  female  piece  is  then  heated,  the  male  piece 
placed  within  it,  and  the  two  hammered  lightly  together. 
The  sharp  edges  of  the  notching  on  the  male  piece  dig 
into  the  hot,  soft,  female  piece,  and  the  two  are  thus  readily 
held  in  line  :  thus  lightly  adhering,  they  are  now  heated 
to  a  welding  heat  and  hammered  firmly  together. 

The  extreme  end  of  the  male  piece  has  a  fish-tail  shape 
as  shown,  so  that,  when  it  is  driven  well  home,  it  may  fill 
the  extreme  crotch  of  the  female  piece  at  its  outer  sur- 
faces. 

The  weld  shown  at  8  is  also  known  as  a  V-weld.  In  this 
particular  case  a  steel  forging  eight  inches  square  was 
welded.  It  was  first  shaped  according  to  the  solid  lines, 
A,  B,  O,  B,  C,  and  bound  together  with  tie-rods,  some- 
what as  shown  at  u.  It  was  then  heated  to  a  welding  heat, 
and  the  V-piece  D,  E,  B,  was  welded  in,  being  reduced  to 
the  shape  F,  G,  B,  in  welding.  Then  the  "binder"  H,  F, 
G,  I,  was  welded  in  and  the  points  A  and  C  hammered 


down,  the  upper  surface  thus  being  levelled.  The  other 
side  was  then  cut  past  the  point  of  the  first  weld  and 
shaped  as  at  K,  J,  L,  and  a  V-piece  and  a  binder  were 
welded  in  as  on  the  first  side. 

The  jump-  or  butt-weld,  3,  4,  is  used  oftener  for  wrought- 
iron  than  for  steel. 

The  split-weld,  5,  is  a  good  weld  for  flat  thin  pieces 
of  steel,  such  as  carriage  springs  and  carriage  tyres,  to 
which,  clearly,  the  V-weld  is  inapplicable,  while  the  pieces 
are  more  readily  held  in  place  and  aligned  with  the  split 
than  with  the  scarf -weld. 

In  general  the  welding  faces,  as  at  4,  should  not  fit  ac- 
curately, both  that  there  may  be  a  ready  path  for  the 
escape  of  the  molten  scale,  and  that  only  a  little  surface 
may  be  brought  together  at  a  time,  the  force  of  each  blow 
being  thus  concentrated  on  a  relatively  small  extent  of 
welding  surface.  Thus  in  the  V  weld  the  male  piece  may 
f  be  more  acute  than  the  female,  as  indicated  at  7,  though 
this  makes  alignment  less  easy.  For  like  reason  machined 
faces  usually  weld  less  thoroughly  than  rough-forged  ones. 

So  too  the  hammering  should  aim  to  squeeze  the  slag 
out  as  fully  as  possible :  thus  in  the  V-weld  the  first  blows 
may  be  struck  opposite  the  crotch  of  the  female  piece,  say 
at  B,  7,  moving  thence  to  the  left,  so  as  to  squeeze  out  the 
slag  in  the  direction  of  the  arrows. 

The  pieces  to  be  welded  should  be  so  shaped  that  their 
thickness  across  the  weld  is  much  greater  than  that  of  the 
finished  piece  is  to  be,  to  allow  for  reduction  in  hammer- 
ing the  weld  together.  The  hammering  and  consequent 
reduction  would  have  to  be  considerable,  even  if  the  weld- 
ing itself  did  not  require  it,  and  should  be  kept  up  till  the 
temperature  has  sunk  much,  so  as  to  prevent  the  coarse 
crystallization  which  sets  in  during  undisturbed  exposure 
to  a  high  temperature.  For  like  reason  quick  fire  and 
work  are  recommended,  to  shorten  the  exposure  to  the 
high  temperature :  and,  because  of  the  metal's  tenderness, 
rather  gentle  blows  should  be  used,  the  first  ones  being 
mere  taps,  increasing  rapidly  in  force  as  the  coarse,  feebly 
adhering  crystals  formed  during  heating  are  broken  up 
and  their  successors  hammered  into  firmer  union. 

The  temperature  most  suitable  for  welding  is  a  white 
heat  for  wrought-iron  ;  a  lower  white  or  a  bright  yellow 
for  soft  ingot-iron  ;  a  bright  yellow  for  half-hard  and  for 
common  tool  steels  ;  a  moderate  yellow  for  the  hardest 
weldable  steels.  Unfortunately  these  terms  convey  no 
very  accurate  idea :  and  what  one  calls  white,  another 
terms  light  yellow,  etc. 

Fluxes. — In  all  usual  cases  the  welding  surfaces  inevit- 
ably become  oxidized  during  heating  :  to  produce  actual 
contact  of  metal  with  metal  the  oxide  thus  formed  must 
be  removed.  To  remove  it  mechanically  would  be  useless, 
for  new  oxide  would  form  instantly.  It  therefore  must  be 
made  so  fluid  that  it  will  squeeze  out  as  the  plastic  surfaces 
are  forced  together  during  welding,  contact  of  metal  and 
metal  following  that  of  metal  and  slag  immediately,  air 
being  wholly  excluded. 

Wrought-  and  soft  ingot-iron  may  be  safely  heated  to  a 
temperature  at  which  the  iron  oxide  itself  is  fluid  :  this  is 
true  even  with  rail  steel  of  say  0'3.j  to  OMft^of  carbon. 
Here  flux  is  not  usually  necessary,  though  it  may  facili- 
tate welding  Thus  ingot-iron  pipes,  though  demanding  a 
very  thorough  weld,  are  welded  without  flux.  If  anything, 
sand  is  used. 


254 


THE    METALLURGY    OF    STEEL 


Steel  with  a  higher  percentage  of  carbon  cannot  be 
heated  to  a  point  at  which  the  oxide  itself  becomes  fluid, 
without  danger  of  burning :  hence  a  flux  must  be  added 
to  form  with  the  oxide  a  more  fusible  compound.  The 
higher  the  carbon,  and  the  lower  consequently  the  tem- 
perature to  which  the  steel  can  be  safely  heated,  the  more 
fusible  must  this  compound  be.  Hence,  while  sand,  form 
ing  the  moderately  fusible  iron  silicates,  does  well  with 
moderately  hard  steels ;  for  harder  ones,  such  as  tool-steel, 
borax,  which  yields  the  very  fusible  iron-sodium  borate,  is 
used,  preferably  first  melted  to  expel  its  water  and  thus  to 
prevent  frothing,  and  then  pulverized.  For  soft  steels,  too, 
borax  is  sometimes  mixed  with  sand.  Ferrocyanide  of 
potassium  (yellow  prussiate)  is  liked  by  some,  and  is 
thought  to  counteract  the  tendency  of  the  steel  to  lose 
carbon  during  heating. 

Beyond  these,  pulverized  clay  is  used  for  soft,  and 
numberless  nostrums  for  harder  steels.  They  are  mostly 
alkaline  salts,  sodium  chloride  or  carbonate,  sal  ammoniac, 
etc.,  and  a  legion  of  mixtures,  for  which  the  usual 
ridiculous  claims  are  made.  Remembering  that  the  flux 
cannot  benefit  the  steel  itself,  and  that  fluidity  and  cheap- 
ness are  probably  its  sole  important  qualities,  borax  and 
sand  leave  so  little  to  be  desired  that  they  are  not  likely 
to  be  supplanted.  Unfortunately,  such  warnings  as  these 
can  rarely  reach  those  who  need  them. 

Condensed  Instructions. — For  tool  steel  Metcalf*  recom- 
mends a  bright  yellow  heat ;  and  melted  and  pulverized 
borax  as  flux.  For  ingot-iron  Bauschinger  ad  vises  fluxing 
with  sand ;  a  temperature  between  redness  and  whiteness  ; 
a  quick  fire,  and  quick  work  :b  the  steam  hammer  gave 
much  better  welds  than  the  hand-hammer.  The  Steel 
Company  of  Scotland  recommend  a  bright  yellow  heat ;  if 
any  flux,  three  parts  of  sand  to  one  of  common  salt,  mois- 
ened ;  a  V-weld,  which,  with  the  neighboring  parts,  is  to 
be  lightly  hammered  during  and  after  welding ;  and  sul- 
phurless  coal.0 

§303.  ELECTRIC  WELDING.* — A.  IN  THOMSON'S  PROCESS 
the  pieces  to  be  joined  firmly  held  end  to  end,  aligned, 
and  strongly  pressed  together  by  copper  clasps,  are  raised 
to  the  welding  point  by  an  enormous  current  of  very  low 
potential,  which  is  transmitted  to  the  pieces  to  be  welded 
by  the  clamps  which  hold  them,  and  thus  passes  through 
and  heats  but  little  of  the  metal  on  either  side  of  the  joint. 

The  metal  is  heated  by  the  resistance  which  it  offers  to 
the  passage  of  the  current,  quite  as  a  common  incandes- 
cent burner  is,  and  as  the  current-strength  is  under  close 
control  and  quickly  varied,  so  is  the  temperature  of  the 
metal. 

The  ends  to  be  united  are  usually  made  convex,  and, 
as  they  soften  under  the  intense  heat,  the  pieces  are 
forced  together,  and  indeed  slightly  upset.  A  little  borax 
is  added  at  the  joint  to  liquefy  the  iron-oxide  formed. 
Sand  would  be  used  in  welding  wrought-  or  ingot-iron  on 
a  large  scale. 


»  The  Treatment  of  Steel,  p.  14,  1884. 

bMittheil.  aus  Mech.-Tech.  Lab.  in  Munchen,  XIV.,  pp.  34-5,  1885:  also 
Iron  Age,  Jan.  7,  p.  13,  1886. 

c  Journ.  Iron  and  St.  Inst.,  1881,  I.,  p.  2S9. 

a  H.  D.  Hibbard,  Trans.  Eng.  Soc.  W.  Penn.,  p.  25,  1889  :  C.  J.  H.  Woodbury, 
Trans.  Am.  Soc.  Mecb.  Bug.,  X.,  1889,  to  appear  :  Eng.  Min.  Jl.,  XLVII  ,  p. 
136,  1889:  Engineering,  XLVII.,  p.  571,  1889.  Proc.  Soc.  Arts,  Mass.  Inst. 
Technology,  p.  35,  1886-7:  Journ.  Franklin  Inst.,  XCI1I-,  p.  357,  1887.  This 
section  is  baspd  chiefly  on  information  given  me  by  the  Thomson  Electric  Welding 
Company,  April  3d,  1889. 


As  the  heat  developed  is  proportional  to  the  square  of 
the  current  strength,  /.  e.,  to  the  amperes — and  not  pro- 
portional to  the  tension  of  the  current,  i.  e.,  to  the  volt- 
age, very  low  potential  is  used,  from  0*125  to  6  volts.  In 


121. — EUhu  Thomson' 


welding  Machine. 


general  the  smaller  the  sectional  area  of  the  piece  the 
higher  the  volts  used.  Electricity  of  this  low  potential  is, 
of  course,  perfectly  harmless  to  the  human  body  :  indeed 
but  a  trifling  current  at  such  potential  would  pass  through 
so  poor  a  conductor. 

The  current  (amperes)  needed  increases  with  the  sec- 
tional area  of  the  piece  to  be  welded.  As  we  proceed  from 
very  small  wires  the  current  needed  at  first  increases  a 
little  more  rapidly  than  the  sectional  area,  say  with  the 
2>8th  power  of  the  diameter.  But  as  the  sestional  area  in- 
creases the  rate  of  increase  of  needed  current  diminishes, 
so  that  in  passing  from  1"  to  2"  bars  the  current  needed 
apparently  increases  less  rapidly  than  the  sectional  area. 

The  horse  power  needed  is  roughly  proportional  to  the 
current,  and  of  course  increases  not  only  with  the  sec- 
tional area  but  with  the  rapidity  of  heating  desired.  Thus 
it  is  estimated  that  a  1"  round  bar  can  be  welded  with  12 
horse  power,  but  slowly :  to  weld  it  in  from  25  to  30  sec- 
onds 18  to  20  H.  P.  should  be  provided.  To  weld  a  2" 
round  bar  in  one  minute  about  40  H.  P.  are  needed,  and 
say  20  000  amperes. 

The  preceding  data  must  be  taken  as  very  rough  ap- 
proximations to  the  truth,  in  view  of  the  paucity  of 
experimental  data  available  and  of  the  many  variables. 

For  given  sectional  area  iron  needs  much  less  current 
to  reach  given  temperature  than  copper,  owing  to  its 
lower  conductivity  both  for  electricity  and  heat,  its  low 
thermal  conductivity  preventing  the  rapid  conduction  of 
heat  from  the  intentionally  heated  parts. 

"As  the  resistance  increases  with  the  temperature,  so 
while  the  joint  is  forming  its  several  parts  tend  ever  to 
uniform  temperature  ;  for,  if  the  temperature  be  uneven, 
an  undue  share  of  the  current  passes  through  the  cooler 
and  less  resisting  parts,  and  thus  their  heating  is  hastened 
while  that  of  the  hotter  parts  is  retarded. 

Though  it  is  only  within  a  few  months  that  the  process 
has  nctually  reached  a  commercial  stage,  some  fifteen  or 


ELECTRIC    WELDING.      §  303. 


265 


twenty  electric  welding  machines  have  already  been  sent 
to  licensees,  for  regular  use  in  manufacturing  and  similar 
establishments. 

The  largest  sectional  area  yet  welded  is  that  of  2'5" 
iron  bars,  but  a  larger  machine  is  now  building  for  weld- 
ing the  four-inch-square  irons  of  locomotive  frames. 

.Among  the  more  important  uses  so  far  developed  are 
the  welding  of  telegraph  wires  end  to  end,  especially  in 
installing  lines,  a  portable  storage  battery  being  used : 
welding  lead  pipes  end  to  end :  welding  iron-pipes  end 
to  end,  and  so  making  very  tight  joints  (welding  the 
seams  of  pipes  is  not  yet  done) ;  welding  brass  to  iron  in 
pump  piston-rods  :  welding  and  assembling  the  drop- 
forgings,  etc.,  of  carnage  work.  I  understand  that  all 
these  operations  are  now  carried  out  on  a  commercial 
scale. 

The  links  of  chains  are  also  welded  with  success,  but 
not  yet  commercially,  as  the  chain  making  machine  is  not 
perfected.  The  links  are  welded  by  preference  with 
double  welds,  one  in  each  of  the  long  sides  of  the  link : 
links  thus  welded  do  not  break  through  the  weld,  but 
through  the  shoulder.  The  faces  to  be  welded  are  in  this 
case  plane,  instead  of  convex,  as  in  most  other  cases. 

Links  can  also  be  welded  with  a  single  weld,  just  as  in 
common  chain-welding  practice.  It  might  at  first  be 
thought  that  the  electricity  would  pass  chiefly  through 
the  solid  body  of  the  link,  as  offering  the  largest  sectional 
area,  rather  than  through  the  smaller  section  of  the  con- 
tact between  the  faces  to  be  welded.  But  these  faces  are 
made  flat,  and  so  give  broad  contact,  and  moreover  the 
electricity  is  purposely  introduced  very  close  to  the  faces 
to  be  welded,  so  that  the  path  through  them  is  very  much 
shorter  than  that  around  through  the  solid  part  of  the 
link :  and  it  actually  happens  that  most  of  the  heat  is 
localized  closely  at  the  weld.  So  in  welding  locomotive- 
frames. 

Of  the  many  other  uses  of  this  interesting  process,  I 
need  only  mention  the  welding  of  wire-ropes  ;  an  applica- 
tion for  a  patent  for  this  is  now  pending. 

The  strength  of  the  welds,  as  indicated  by  the  data  in 
Table  148,  compares  well  with  that  of  hand-welds  as  given 
in  Table  146.  In  the  latter  Bauschinger,  whose  results 
command  implicit  confidence,  found  that  wrought-iron 
lost  less  than  10$  in  hand  welding,  and  that  ingot-iron 
lost  12$.  With  wrought-iron  and  soft-steel,  numbers  I. , 
II.,  IV.,  V.  and  VI.  of  Table  148,  the  strength  of  the 
welded  bars  is  in  general  very  high  :  in  number  II., 
however,  there  is  a  very  heavy  loss  of  strength  in  weld- 
ing. Moreover,  in  other  tests  applied  to  the  material  used 
in  I.,  the  sectional  area  at  the  weld  was  much  greater  than 
in  the  rest  of  the  bar  :  nevertheless  the  bar  broke  at  the 
weld. 

The  hard  steel,  III.,  lost  strength  very  heavily  in 
welding. 

The  inference  seems  to  be  that  admirable  welds,  equal- 
ling if  not  excelling  hand-welds,  can  be  obtained  by  this 
process  :  but  that  with  the  degree  of  skill  as  represented 
by  the  results  in  Table  148  (especially  if  we  assume  that 
these  were  obtained  from  picked  welds),  the  welding  is 
much  less  certain  than  hand-welding.  As  the  conditions 
seem  under  closer  control,  one  expects  that,  with  experi- 
ence, as  good  and  more  certain  welding  will  be  made  with 
this  process  than  by  hand, 


TABLE  H«.— STKKNHTII  OK  KI.K<TKII:AI.I.V-\VKI.IIKII  JOINTS. 


No. 

Material. 

Sectional 
area. 

Position  of 
fraeture  of    . 
welded  bar. 

Ten  silo  strength. 

A\Vr:lLM-of 

unwoldud 

bar,     His. 

IHT  M|.  ill. 

Of    welded    bar    in 
pcrcent-atfc  of  that 
ol  unweldtd  bar. 

At 

weld 
sc).  in. 

Of  bar 

.s.j.  in. 

Maxi- 
mum. 

Mini 

[mini  . 

A  ver- 

Ufie. 

I.     / 
II.    { 
III.  I 
IV. 

V. 
VI. 

•41)8 

54,363 

•408 

•408 
•1M 

At  weld 

94-77 

1)060 

92  69 

re.iaa 

•198± 

LH 

•360 

At  weld. 

87-55 

6745 

77-50 

Octaponal  steel,  not  welded 
The  same,  welded  
qtral]                  fnotweld.-d 

127,040 

:iii(i± 

•SCO 
•JW 

•197± 
•802 

At  weld. 

I,M  18 

5007 

.Vi.10 

75,450 

""  1  welded.... 

•19S± 

At  or  near  weld  . 

04,930 

ioi:88 

99-17 

100-50 

M'-'-1  {welded.... 
Wn.^ht-ironl^,-^' 

809 

•802 
•812 

At  weld. 

97  00 

52,440 

•312 

•312 

At  or  near  weld. 

1)9  50 

US-7C 

'J'J-13 

These  results  were  obtained  with  tho  United  States  testing-machine  at  Watertown,  Mass.,  In 
charge  of  Mr.  J.  E.  Howard.  I  here  itfve  only  the  results  obtained  with  pieces  in  whieh  the 
sectional  area  at  tho  weld  was  tho  sumo  as  in  the  rest  of  the  bar  :  other  cases  are  less  readily  com- 
parable. 


Electric  welding  is  at  a  disadvantage  in  that  the  metal 
is  exposed  to  a  very  high  temperature  without  receiving 
the  work  as  it  cools  which  it  undergoes  in  hand- welding, 
and  which  removes  much  of  the  coarse  crystallization 
which  arises  at  the  high  temperature.  In  Thomson's  pro- 
cess the  welded  piece  is  not  forged  :  but  it  seems  to  me 
that  it  would  be  very  desirable,  at  least  in  case  of  impor- 
tant pieces,  to  hammer  the  weld.  This  would  increase  the 
expense  considerably,  but  without  it  the  coarse  crystal- 
lization set  up  around  the  weld  will  remain  a  source  of 
weakness,  or  at  least  of  brittleness. 

The  advantages  claimed  for  the  process  are  that  the 
alignment  is  easy  and  accurate :  the  welding  is  extremely 
rapid :  the  parts  to  be  welded  are  visible  during  heating  and 
their  temperature  is  thus  under  better  control,  so  that  less 
skillful  and  hence  less  costly  labor  may  be  used  than  in 
hand- welding :  and  the  heat  is  closely  localized,  so  that  less 
energy  is  needed  and  that  there  is  less  oxidation  and  loss 
of  iron  than  in  hand-welding.  One  might  add  that  the 
power  for  generating  the  electricity  may  be  obtained  by 
burning  sulphurous  and  hence  often  much  cheaper  fuel 
than  can  be  used  in  hand-welding. 

Clearly,  as  different  classes  of  machines,  different  cur- 
rent and  potential,  are  needed  for  different  conditions, 
the  process  is  not  applicable  to  the  work  of  the  common 
jobbing  smith,  nor  to  the  forges  of  most  establishments, 
where  all  kinds  of  welds  are  to  be  made  on  pieces  of  all 
sizes  and  shapes.  But  I  am  confident  that  the  process 
will  find  very  valuable  and  somewhat  varied  fields  in  es- 
tablishments in  which  there  is  an  abundance  of  work  of 
certain  tolerably  uniform  kinds,  so  that  the  welding  plant 
and  skilled  workmen  may  be  kept  occupied.  Central 
jobbing  establishments  in  large  manufacturing  centres, 
too,  should  eventually  be  profitable. 

Important  uses  in  welding  cast-iron,  and  in  heating, 
welding  and  brazing  the  other  metals,  lie  beyond  the  field 
of  this  treatise. 

B.  In  Bernardos1  process*  an  electric  arc  melts,  between 


the  pieces  to  be  united,   chips,  etc.,   of  the  material  of 
which  these  pieces  are  composed.  It  is  therefore  a  soldering: 


Engineering,  XLV.,  p.  173,  1888.    Zeit.  Vereius.  Deut.  lug.,  XXXI.,  p.  863, 
1887.    Scientific  Am,  Supp.,  No.  635,  p.  10,144,  Men.  3,  1888, 


256 


THE    METALLURGY    OF     STEEL. 


but  this  is  not,  as  some  would  persuade  us,  a  fault.  The 
pieces  to  be  welded  are  made  the  negative  pole,  the 
positive  pole  being  a  carbon  pencil.  Were  this  arrange- 
ment reversed  the  metal  would  be  oxidized  rapidly.  As  it 
is,  the  carbon  wastes  rapidly,  but  is  of  course  readily  re- 
placed. It  is  held  in  a  scissor-like  tool  as  shown  in  Figure 
121  A,  with  a  wooden  handle  through  which  the  flexible 
electric  cable  passes,  and  a  screen  to  further  protect  the 
workman's  already  stoutly  gloved  hand,  his  eyes  and  face 
being  guarded  by  a  dark  glass. 

In  joining  plates  the  edges  may  be  feathered  as  shown 


works  of  Messrs.  Struve  in  Russia  :  it  has  not,  I  believe, 
been  introduced  into  this  country. 

§  304. — THE  DENSITY  OF  STEEL,*  so  far  as  my  observa- 
tion goes,  lies  with  rare  exceptions  between  the  limits  sp. 
gr.  7-6  and  8,  that  of  annealed  steel  usually  lying  between 
7'82  and  7'87  sp.  gr.  The  sp.  gr.  of  wrought-iron  is  re- 
ported in  certain  cases  as  only  7 '52.  The  density  is 
lowered  by  quenching  and  by  cold-working,  but  returns 
almost  or  quite  completely  to'its  initial  value  when  the 
cold-worked  or  quenched  steel  is  heated  to  redness  and 
cooled  slowly.  Hot-working  when  above  W  probably 


and  the  furrow  filled  with  iron  turnings,  which  are  melted  does  not  affect  it,  when  slightly  below  W  probably  raises 
by  the  arc,   fresh  turnings  being  then  supplied  till 
the  furrow  is  filled.    In  joining  bars  end  to  end  one  is  (M 
centred  in  a  lathe  which  is  connected  with  the  nega- 
tive pole :  the  other  is  pressed  against  the  first  and 
stack  lightly  to  it  with  a  few  touches  of  the  carbon : 
the  lathe  then  revolves  slowly,  and  iron  is  added  to  7 
the  joint  little  by  little.   Wires  are  joined  by  slipping  786, 
a  ring  over  their  hooked  ends,  and  melting  the  whole 
to  a  button. 

As  compared  with  Thomson' s  this  process  is  at  a 
very  serious  disadvantage  in  lacking  ready  control 
over  the  temperature,  and  in  the  much  higher  tem- 
perature developed,  with  consequent  greater  tendency 
to  crystallization  in  cooling,  liability  to  burn  and  e-n 
blister  adjacent  parts,  etc.  It  is  stated  that  the  results 
of  tests  furnished  by  Bernardos  indicate  a  serious  loss 
of  tensile  strength :  the  loss  of  ductility,  especially 
under  shock,  should  be  still  greater.  Subsequent 
forging  may  remedy  this  in  certain  cases. 

It  seems  less  fitted  than  Thomson's  for  joining  bars  ?7(X> 
and  pipes  end  to  end :  and,  at  least  at  first  sight,  less 
fitted  for  joining  wires  than  Thomson's:  in  short  less 
desirable  than  Thomson's  where  the  sectional  area  to  be 
joined  is  small.     But  for  joining  the  edges  of  large  thick 
plates,  for  patching  thick  plates,  etc.,  in  short  where  the 
sectional  area  is  so  very  large  that  it  would  be  extremely 
difficult  to  heat  it  all  simultaneously,  Bernardos'  system 
seems  at  first  sight  to  have  an  ad  vantage.    But  unless,  as 
here  seems  improbable,  the  crystallizing  at  the  weld  can  be 


QCruciblo  steeL 

•     Bessemer  steel  and  unknown. 

V  Open-hearth  steel. 

LL 


M3 


Trealui 

inered  i - —    —     - 

perature  decreasing  gradually  towards  the  other  end.    They  were  then  quenched  in  water.     . 
gives  the  density  of  the  part  which  was  slightly  below  visible  roilness  when  quenched,  M.i  that  of 
the  part  which  was  at  white-hot  when  quenched,  and  Ml  that  of  this  last  after  subsequent  Blow 
cooling  from  a  hiyh  yellow  heat.     Idem. 

K,  Koppmeyer,  forced  Bessemer  steel,  TMngler's  Journal,  ('0X1.,  p.  22. 

81,  S2  Sandviken  liessemer  steel.  "Metallurgy,"  Crookes  and  BShriflr.  II.,  P. 

k,   W.  Kent,  Trans.  Am.  Inst.  Mining  Engineers,  XIV.,  p.  585,  1886. 

M   O.  8.  Miller,  Idem,  p.  583,  Bsssemer  steel. 

G,  F.  L.  Garrison,  Idem,  XV.,  p.  90, 1887,  Bessemer  steel. 


.13. 


7.88 

* 

• 

G        7.86 

•  /  *   r 

4            .          •       • 

•  . 

- 

o 

M 

•  ••*. 

•     * 

•  ..*,•••           . 

'•*••  •  •  ••      ... 

*       •                 • 

• 

•  *     *                        * 

• 

• 

7.84 

* 
* 

70 

000 

•      90 

TENSO.E  STRENGTH,  PO 

000 
JNDS  PER  SQUARE  INCH 

110, 

000 

Fig.  124 

overcome,  it  will  be  better  to  rivet  the  edges  of  plates  than 
to  weld  them  by  this  system.  Its  future  seems  less  prom- 
ising than  that  of  Thomson's  process,  though  it  is  still 
too  early  to  pronounce  judgment  with  complete  con- 
fidence. 
Bernardos'  process  is  said  to  have  been  adopted  at  the 


it.     With  increasing  carbon-content  the  density  probably 
decreases  slightly. 


aPure  iron,  7'85-7'88  :  steel,  7'60  to  7'80,  Landolt  und  Bornstein,  Phys.- 
Chem.  TabelUn,  1883,  p.  78. 

Clark's  "  Constants  of  Nature,"  I.,  p.  13,  1873,  gives  the  sp.  gr.  of  iron  as  from 
6  03  (iron  by  hydrogen,  Stahlcchmidt)  and  7'130  (reduced  by  carben,  Playfair 
and  Joule),  to  8'007,  and  8'1393  (the  last  electrolytic). 


DILATATION.      §  305. 


257 


TABLE  149.    Srncirio  GRAVITY  OF  STEEL. 


No. 


Authority. 


Uinman. 

Caron. 

Eisner. 

Wrlghtson 


Kent. 

Miller. 
Garrison. 

Holley. 
Kohlmun 


Henry. 
Pearson. 


Description. 


rsnu]  limits,  unhardened  sU'el. . . . 

Kxtrcme  "     

Unhardeneil  blister  steel,  '2  pieces. 

same  pii res  Imnk-Med 

Unhardened  steel 

the  same  hardened  80  times 

Cast  steel 

the  same  h  irdened 

Wrought  iron 

the  same  quenched  50  times. . . 
"      "  "        100    " 

"       "  "         125     "      

Soft  ingot-iron,  carbon  0'14 

•'        "         "       0-10  to  0-12. 
"         "       0-08  to  0-10. 

A  nm-jtlnl  ousting 

Bessemer  steel  ingot 

bloom  from  '22 

rail  from  28 

Wootz. . . 


hardened . 


Sp.  Gr. 


7-85      to  7-87 
7-6        to  8- 
7-751  and  7-991 
7 -553  and  7  7ns 
7-817 
7-743 
8-0923 
7-7647 
J-6400 
7-5520 
7-5200 
7-5260 

7-9275  to  7-9S56 
7-800     to  7-86« 
to  7-886 
7-9IKI 
7-500 
7-760 
7  710 
7  727 
/7-lsi<E 
\7-647 
7-166 


7-758 


3  to  4,  Percy,  Iron  and  Steel   p.  849  fr.  Geschichte  des  Elsens,  1785,  p.  134. 

6  to  6,  Comptes  Kendus,  LVI  ,  p.  211,  1S68. 

7  to  8,  Cf.  Note  to  Figure  128. 

10,  11.  idem,  fr.    Jou'n  fur  Prakt.  Chem..  1340,  XX..  p.  110. 

14  to  17,  T.  Wrightson,  Journ.  Iron  and  St.  Inst.,  1879,  II.,  p.  425. 

1 8  to  20,  Cf.  Note  ti  Figure  128. 

21,  Holley.  Priv   Kept.,  2d.  Ser.,  VII.,  p.  41, 1877.    Annealed  Terro  Noire  steel  castings 

22  to  24,  Kohlman.  Engineering,  1881,  p.  125. 

25  to  27,  Percy,  Iron  uml  Steel,  pp.  775-6,  1864. 


The  effect  of  cold-working  is  shown  by  line  LL  in  Fig- 
ure 123,  where  repeatel  cold-hammering  lowers  the 
specific  gravity  by  0'047 :  we  have  seen  in  §  270  a  loss  of 
0'040  on  punching  and  0-047  on  wire-drawing. 

The  lightening  effect  of  quenching  increases  with  the 
suddenness  of  the  cooling,  the  quenching-temperature, 
and  the  proportion  of  carbon  in  the  steel :  thus  Langley 
found  that,  under  like  conditions,  quenching  from  white- 
ness lowered  the  specific  gravity  of  steel  with  0'529$  of 
carbon  by  0 '026,  that  of  steel  with  1*079$  of  carbon  by 
0135. 

Quenching  from  even  as  low  a  temperature  as  212°  F. 
appears  to  lower  the  density  slightly :  in  four  cases 
Langley  found  that  the  specific  gravity  fell  by  from  O'Oll 
to  0-027. 

Repeated  quenchings  lower  the  density  cumulatively, 
but  at  a  gradually  diminishing  rate.  Thus  Wrightson 
found  that  on  fifty  heatings  and  quenchings  the  specific 
gravity  of  wrought-iron  fell  from  7'61  to  7 '552  :  after 
fifty  more  heating*  and  quenchings  it  had  fallen  still 
farther  to  7'52,  the  total  loss  being  0-120.  But  after 
twenty-five  additional  quenchings  it  had  risen  slightly, 
by  0-006  (to  7-526). 

Caron  found  that  thirty  quenchings  reduced  the  density 
of  steel  by  -074.  Much  greater  losses  are  reported,  so  great 
indeed  that  one  hesitates  to  accept  them.  Such  are  3  and 
4  of  Table  149. 

The  rapid  divergence  of  lines  Ml  M1  and  M2  M2  from 
line  M3  M '  in  Figure  12,  the  first  representing  steel  ingots, 
the  second  bars  forged  from  them  and  q'uenched  from  be- 
low redness,  the  last  like  bars  quenched  from  scintillat- 
ing whiteness,  indicates  that  the  effect  of  quenching  is 
much  greater  in  high-  than  in  low- carbon  steel :  but  this 
relation  is  not  well  marked  in  lines  S1  S1  and  S2  S2  of  which 
the  first  represents  unhardened,  the  second  hardened 
Bessemer  steel.  But  though  the  difference  between  the 
density  of  high-  and  that  of  low-carbon  steel  depends 
greatly  upon  the  conditions  of  cooling,  it  is  probable,  to 
judge  from  the  general  direction  of  lines  M4  M4  and  S1  S1 
and  K  K  in  Figure  123,  that  even  in  well  annealed  metal 
the  density  decreases  slightly  with  rising  carbon-content, 
probably  at  about  the  rate  of  0  06  per  \%  increase  of  car- 


bon-content.   This  indicates  that  cementite  is  lighter  than 
ferrite. 

That  hot-forging  above  W  does  not  materially  increase 
the  density  we  infer  from  the  fact  that  slowly  cooled  bars 
do  not  appear  to  be  mate  ially  denser  than  the  ingots  from 
which  they  are  forged.  Indeed,  the  density  of  unforged 
castings  is  surprisingly  hi->h.  Thus,  Holley  reported  the 
specific  gravities  of  annealed  Terre  Noire  castings  as  7-9, 
a  point  rarely  reached  by  forged  steel :  Mr.  T.  T.  Morrell 
found  the  specific  gravity  of  a  rail  ingot  7-8464.a  Figure 
124,  representing  many  commercial  steels  examined  by  the 
United  States  Board  on  testing  iron,  steel,  etc.,  shows  that 
the  sp.  gr.  usually  lies  between  7'85  and  7  87.  In  Figure 
123  a  comparison  of  lines  M1  M1  and  M*  M4  shows  that  the 
steel  ingots  here  represented  are  nearly  as  dense  as  the 
bars  forged  from  them  and  slowly  cooled  from  a  light 
yellow  heat,  after  previous  quenching  from  whiteness. 
Broling  found  that  the  specific  gravity  of  a  button  made 
by  melting  bar-iron  was  7 '8439 :  Percy  found  that  of  a 
button  from  iron  wire  to  be  7-8707  :  hammering  and  cold- 
rolling  reduced  it  to  7'865.b 

Chernoff  reported  that  hot-working  at  a  temperature 
below  W  increased  the  density,  sometimes  to  8.  The  roll- 
ing of  rails  made  from  reheated  bloom  <  ceases  while  they 
are  at  about  W,  a  low  yellow  heat :  that  of  rails  rolled 
direct  from  the  ingot  without  reheating,  at  a  little  above 
V,  say  a  dull  red.  The  density  of  the  latter  is  said  to  be 
about  1  lo  1-5$  higher  than  that  of  the  former,  which 
would  make  their  specific  gravity  from  about  -0785  to  '117 
higher,  or  about  7  93.  This  is  inferred  from  the  appa- 
rently excessive  weight  of  direct-rolled  rails  of  given 
section :  but  I  know  of  no  direct  determinations. 

§  305.  DILATATIOK.  THE  FLOATING  OF  COLD  IRON. — 
It  were  beyond  the  scope  of  this  treatise  to  consider  the 
dilatation  of  iron  exhaustively.  (See  Table  109,  §  273,  p. 
218.)  I  will  confine  myself  to  two  points.  First,  late  in  ves- 
tigationa  at  the  Watertown  Arsenal  show  that  the  co- 
efficient of  dilatation  in  like  steels  diminishes  as  the  pro- 
portion of  carbon  increases."  This  raises  a  new  difficulty 
in  the  way  of  the  tension  or  stress  theory  of  the  harden- 
ing of  steel,  since  the  high-carbon  steel  which  hardens 
intensely  contracts  less  on  quenching  than  non-hardening 
low-carbon  material.  Quenching  from  bright  redness 
increased  the  coefficient  of  expansion  greatly,  especially 
in  case  of  highly  carburetted  steels. 

The  floating  of  solid  on  molten  iron  is  clearly  due  to  the 
simplest  of  possible  reasons,  to  wit,  that  the  solid  iron  is 
lighter  than  the  molten  iron.  Wrightsond  has  shown  this 
in  two  ways.  First  by  means  of  his  autographic  ' '  oncosi- 
meter,"-  he  measured  the  force  with  which  balls  of  cast- 
iron  immersed  in  molten  cast  iron  sought  to  rise  or  fall, 
obtaining  diagrams  like  that  in  Figure  125.  He  found  that, 
when  first  immersed,  the  tendency  of  the  ball  was  down- 
ward :  this  downward  tendency  quickly  gave  way  to  an 
upward  tendency,  which,  as  the  ball  grew  hotter,  gradu- 
ally reached  a  maximum,  then  declined  slightly  till,  at 
the  point  of  fusion,  it  suddenly  fell  to  zero. 

Reversing,  he  measured  the  diameter  o'f  a  15-28"  cast- 
iron  ball  during  cooling,  beginning  two  minutes  after  cast- 
ing it  in  a  sand  mould.  During  the  first  24  minutes 

a  Private  communication,  Feb.  S20,  1889. 

b  Percy,  Iron  and  Steel,  p.  1. 

<•  Jas.  E.  Howard,  private  communications,  Feb.  8th,  20tb,  1889. 

d  Journ.  Iron  and  Steel  Inst.,  1879,  IL,  p.  418  :  1880, 1.,  p.  11, 


258 


THE    METALLURGY    OF     STEEu 


WEIGHT  OF  BALL  AND  PORTION  OF  STALK  IMMERSED.__252K  02. 

SPECIFIC  QRAVITY  OF  DITTO. 6.86 

MAXIMUM  SINKING.  EFFECT iM  OZ. 

"         FLOATING '1 8OZ. 


X.      X       »      [ 


Fig.  125. — Oncosimeter  Diagram  of  the  Effort  of  a  Gradually  Heating  Cast-iron  Ball  to  Sink  and  Else  in  Molten  Cast-iron.     Wrightaon. 


the  ball  expanded  0  078"  in  diameter,    then  remained 
stationary  for  3  h.  13  m.,  then  contracted  for  more  than 
4    h.    30   m.,   the  total  contraction  from  the  maximum 
diameter  being  0'18". 
Thus  in  both  cases  the  maximum  volume  (or  minimum 


density)  occurs  decidedly  below  the  melting  point,  so  that 
both  solid  iron  in  melting,  and  molten  iron  in  solidifying 
and  further  cooling,  first  expand  to  a  maximum  volume, 
then  again  contract. 
Moreover,  while  the  cold  iron  is  denser  than  the  molten, 


TABLE  150. — COMPOSITION  OF  STEEL. 

SEE  FURTHER  pp.  18  to  20  :  88,  guns  and  rails :  40,  silicon  steel :  48,  manganese  steel :  53-4,  rail  steel :  09,  phosphoric  steel  :  71,  phosphoric  steel  :  74,   78,  chrome  steel :  81  Tungsten  steel : 
83,  cupriferous  steels  :   92,  oxygen  :  162,  castings. 


C. 

Si. 

Mn. 

P. 

8. 

0. 

Si. 

Mn. 

P. 

8. 

Anchors,  cast  

•58 
•75 
•28 
•66 
•95 
1'08 
•10  to  -85 
1-05 
•16 
•15 
•16 
•46--S2 
•15 

•18  to  -21 

•14 
•09 
•16 
•16 

•16 

•186 

•w 

•02 

•65 
1-45 
•48 
•78 
•88 
•88 

•75--80 
•75--80 
•78--80 
Ml  to  -83 
•60 

•60  to  -80 

47 
•8 
•25 
•75 
•52 
•30  to  '40 
/         -80 
\         -08 

•39 
•1  to  I'l 
•36 
•21 
•29 

1-35  to  '65 

•5  to  -6 

•06 
•06 

•07 

•023 
•046 

•10 
•105 
•102 

":07° 
(  as  high 
-[       as 
\        -07 
•047 
•07 
•069 
•066 
•047 

•07 
•05 

•05 

•04 

•04 
•03  to  '06 
•034 

•05 
•038 
•032 
•082 
•11 

04  to  -09 

•005  to  -007 
•022 
•06  or  less 
•02 
•04 

•10 
•051 
•08  to  -09 

•027 

•io± 

•10  to  -12 
•08 
•05 

•06 
•05 
•05 

•018 
•082 

•04  or  -10 
•046 
as  high 
as 
•06 
•061 

•05 
•03 

•06 

•04 

•06 
•045 

•025 
•009 
•013 
•014 
•09 

tr. 
tr. 

0 
•03 

•034 
•06  to  '076 

below  -10 
•045  to-055 
•12 

•05 

•55 

•55 
1-04 

•285 
•053 

•321 
/         '510 
\          -054 

1-20 
/  -30  to  -40 

027 
•054 

•10 
}not  over 
•10 

•oc 

•075  to  -090 

Cu 
•51  to  '66 
P 

07 
•105  to  -147 
•20  to  '26 

•165 

•04  to  -05 

•04 
•05 
•10 
•026 
•024  to  080 
•033 
•11  to  -120 
•069 

•088 
•05 

•09 
•06 

•04  to  '05 
•09 

•oc 

•075 
•037 
<         '08 

<         -05 

•04 
•025 
•027 
•02 
•02 

•11 

•05 
<         '055 

•05 

•096 
•034 

•008 
•035 

•07 

•08  to  -10 

05  to  -08 
•021to  -097 
•075 

•05 

0 
•005 
•06 

•09  to  -12 

•042 
•05 

•07 
•06 

•04  to  '06 

•10 
•06 

•t)5 
•014 

•04 

•015 
•005 

•05 
•05 

•068 

•04  to  -05 
•006 
•15 

•009 
•10 

•04 

•181 

Armor-plate,  face  

"         "     protective  deck  
Augur  bit  

Axe  "overcoat"  

•081 
•096 

<     -015 
'"•'6i2 

•11 
\not  over 
/         -04 

**           <• 

"      Dudley's  formula  -j 

25  to  '85 

"     crank  

"      Bethlehem    have    sometimes  been 
held  below  

"     light... 

"     some   late  best   American,  special 
order  

•50  to  '55 
•60 

•33  to  -48 

•40 
34  to  "49 
•20 

•125 

•03  to  "08 

•111 
•02  to  -07 
'»<!) 

•100  to  -115 

1-05  to  1-25 

•SO  to  -90 
1-1  Ho  1-63 
•547 

j 
railway  

"    now  have  up  to  

Beams,  tees,  angles  

Boiler-plate... 

•085 
•02  to  -08 

"    bad  U  S  e 

"         \ 

"    average  of  one  month  at  an  Ameri- 

•ou 

02  to  05 
|  -02  to  -03 

Kazors  

1-5 

•22 
•20  to  -24 
•60 
•852 
1-020 
•40 
•93 
90  to  1  16 
1-20 
•10  to  -12 
I'll 
•86 
•87 
•30 
•16 
20  to  -30 
•17  to  -20 
•17 
•08  to.  50 
•48 
1-04 
•45  to  I'OO 
•53 
40 
•55 
•87 
•8 
•60 
1-05 
•25 

•35  to  -45<J 
•6  to  -7 

•448 
•425 
•60 
•31 
•14  to  '45 
•18 
•40 
•17 
•72 

•57 
•882 

•5  to  -8 

•70  to  '80 

•41 
rto!25± 
•72 
•90 
•8 
•34 
•60 
•40 
•26 
•50 

-     { 

•09 
•15 
3 

1-00 
•78 
•75 
•5  to  -6 

"      and  shot-gun  barrels  

•01  to  -02 
•20± 
•18 
•195 
•02 
•29 
•194  to  -30 
•26 

Boulat  

'     chipping.  

Cutlery,  Bessemer 

*'     JcBsop's  best  

Die  for  iron  pipes.  .  . 

•       1  09 
•98 
1  06 

j-  -09  to  -14 

•14  to  -18 
•13  to  -16 

1-88 

"     U.  S.  ,  very  good  

Drill,  rock.   .„.      .. 

•293 

Drop-forgings,  complex  ,  J  S'^JljSP168"  ' 

(          -OOS 
<  -015  rare 
I         '02 

•02i 

Sett  

•18 
•03 

•02± 
•04 

"       **         less  complex,  e.  g.  plstol- 
barrcls  

'*            "      cast        

Eye-bars  

Shafting  (small)  

««       it 

0-82 
1  87 
MB 

1-42 
1-48 
1-48 
•14 
not  over 
•80 
•2  to  -8 
•25  to  -5 
more  C. 
•28  to  -38 
•25 
•35  to  -45 
T18 
•50 
•888 
•40 
•800 
•417 
•240 
•272 
•148 
•194 
•85 
•95  to  -108 
•88 

0-02 

•60 

•20 
•52 
•17 
•52 
•54 

Ship-plate,6  British 

File,  saw  .  . 

Shovel   .. 

"  mill  

•25 
•251 
•186 
•270 
•014 

H 

**      "  14"  round  

4*     "  10"  square  

6-i2 

"      "  12"  half  round... 

Fish-plates  

•12 
•05 

Forgings  *  J 

"        British  

**      heavy..  .. 

open-hearth  

•08 

(  English  

•8  to  '08 

•32  to  -88 
•036 
•40  to  -60 
tr. 
•16 
•075 
•126 
•812 
•240 
•216 
•225 
•841 
•248 

•20 
•82 
•60 
•18 
•4 

•14 

•40 
•35  to  -40 
•66 

•8 

•50  to  -60 
•43 

OllTIK-f    F.fiTloh                t                  . 

•05  to  -06 
•234 
•25  to  -40 
•88 
•11 

•148 
•06 

(Spanish  

"    barrels  

"        "     Swedish  

swfigis 

**    tubes,  Woolwich... 

Taps  for  nuts  i  

1-08 
1-12 
•10  to  -15 
•7 
1-00 
TOO 
•92 
•60 
•85 
1-09 
0-55 
•22  to  -60 
•62  to  '78 
85  to  -55 
•82 
•07 
•04  to  '12 

•216  to  'SO 
•26 
•27 
•08 
•12 

•52 

•72 
•80  to  I'OO 

0-8 
•15  to  -80 
•50 
0-899 

I 

•03 
•10 
•06 
•09 

•20 

"       "    Midvale  

••    ••       «  | 

**        *'     French  

Tool,  German  

Harrow-disc,  rail-stock  

"    mason's  

Knife-section  

Lawn-mower  knife  

•28 
•98  to  1-24 
08  to  "12 
•10 
•15 
•10  to  -12 
08  to  -10 
•07 
•15 
12  to  '15 
•8  to  -85 
45to  -60 

•so 

•02 
•826 
•01 

{         -02 

•01  or  less 
•009  to  -01 
•016 

"      R  R 

Nails  

"          "      British     

•04 
'01  or  less 
•04 
•081 

\ 

Nail-plate  

Wire  —  Bessemer  

»4 

•12 
•828 
12  to  -16 

12  to  -15 
1-64 

under  '015 
•148 
•02± 

•65  to  -70 
•587 
•50  to  '80 
}not  over 
•40 

•10 
0 
•09 

{        - 

steam-hammer  
Plough-beam  

•25  to  "80 
•06 

"      fencing  

Projectiles,  Terre  Noire  

Wootz  (Henry)  

•045 

a  A  famous  shell  of  Whitworth'.s  :  the  metal  had  '213,000  pounds  tensile  strength  per  square  inch,  and  an  elongation  of  11#,  probably  in  two  inches. 
b  Ship-plate  is  usually  much  like  boiler-plate  in  coin  position,  but  with  rather  more  phosphorus 

C  American  tyres  are  harder  than  British,  probably  ehieily  because  tho  brake-service  is  more  trying,  the  weight  of  cars  per  wheel  heavier,  and  the  track  rougher  here  than  iu  Britain. 
d  Ft  v"»s  necessary  to  keep  the  manganese   below  0'45#.    With  higher  manganese  the  turnings  were  so  tough  as  to  deflect  the  turning  tool :  with  0*35  to  0'4#  of  manganese  the  turnings  broke 
off  short 

e  Rails  habitually  made  at  an  American  mill  using  cast-iron  direct  from  the  blast-furnace  without  remelting  in  cupolas. 

/  Open-hearth  steel  rails  formerly  made  in  South  Wales  from  old  iron  rails.     Bell,  Principles  of  Manuf.  of  Iron  and  Steel,  p.  427,  18S4, 

g  The  phosphorus  is  intentionally  high,  in  order  that  the  turnings  may  break  off  short,  and  not  clog  the  cutting  tools. 

h  Punched  27,000  fish-plates, 

i  Tapped  99,000  nuts.  * 


DIRECT    PROCESSES.      §  310. 


250 


the  difference  is  slight,  less  than  one  fifth  as  great  as  the 
difference  between  the  density  of  the  molten  metal  and  the 
minimum  density  which  occurs  slightly  below  the  melting 
point. 
He  deduced  the  following  values. 

Specific  gravity  of  solid  Cleveland  (.'ray  east-iron 6-95 


inolton 


6-60 

6-v> 


This  explanation  of  the  invariable  floating  of  cool  on 
molten  iron  is  so  simple  and  natural  to  one  who  has  seen 
ice  float  on  water,  that  we  wonder  as  much  as  we  regret 
that  energy  should  have  been  diverted  from  our  pressing 
needs  to  unpromising,  far-fetched,  if  ingenious  attempts 
to  attribute  it  to  remote  causes,  which  could  hardly  oper- 
ate constantly. 


CHAPTER     XV 

DIRECT  PROCESSES.* 


Wrought-iron  and  steel  are  usually  made  by  the  indirect 
method  of  first  making  cast-iron  in  the  blast-furnace  and 
then  decarburizing  it.  I  )irect  processes  are  those  in  which 
wrought-iron  or  spongy  iron  is  made  directly  from  the  ore, 
and  either  used  as  such,  or  converted  into  steel,  usually 
by  melting  it  with  cast-iron,  more  rarely  by  cementing  it 
with  carbonaceous  matter :  or  in  which  weld-  or  even 
ingot-steel  is  made  directly  from  the  ore. 

§310.  POSSIBILITIES  OF  u  HE  DIRECT  PROCESS. — Before 
confusing  ourselves  with  the  details  of  the  numberless  direct 
processes,  let  us  in  a  general  survey  see  what  are  the  possi- 
bilities, not  of  this  or  that  particular  process,  but  of  the 
direct  process  in  general,  what  the  advantages  which  we  can 
conceive  and  may  hence  seek,  what  the  necessary  obstacles. 

The  fields  for  the  direct  process  are  the  production  of 
weld-metal  (wrought-iron  weld-steel)  to  be  used  as  such,  and 
of  raw  material  for  the  open-hearth  and  crucible  processes. 

The  former  field  I  think  holds  out  little  promise,  for  weld- 
metal  made  by  direct  process  is  not  only  liable  to  red-short- 
ness and  slag-shortness,  but  also  usually  varies  capriciously 
in  its  carbon-content  and  is  markedly  heterogeneous. 

In  the  latter  field  direct-process  metal  must  compete  with 
scrap  iron,b  with  cast-iron,  and  with  puddled  and  charcoal- 
hearth  iron.  But  if  it  can  compete  with  the  product  of 
the  blast-furnace  alone  (cast-iron),  it  can  surely  compete 
with  puddled  and  charcoal-hearth  iron,  which  have  each 
undergone  an  additional  very  costly  operation  after  pass- 
ing through  the  blast-furnace  ;  hence  we  may  narrow  the 
discussion  and  ask,  "Can  direct-process  metal  compete 
with  scrap  iron  ? "  and  "  Can  it  compete  with  cast-iron  ? " 

Competition  with  scrap  iron.  As  a  material  for  the 
crucible  and  acid  open-hearth  processes,  I  do  not  think 
that  we  can  forecast  the  future  of  direct -process  metal 
with  complete  confidence. 

As  a  material  for  the  crucible  process,  direct-process 
metal  made  from  ores  relatively  free  from  phosphorus  has 
a  great  advantage  over  most  of  the  scrap  iron  in  the 
market,  in  that  its  phosphorus-content  may  be  known  and 
guaranteed.  For  this  purpose  old  steel  rails  are  of  course 
quite  out  of  the  race.  But  boiler-plate  shearings  of  known 
composition  are  made  in  great  quantities  :  and  with  more 
perfect  organization  the  composition  of  the  plates  of  worn- 
out  boilers  may  be  known  and  guaranteed.  It  is  true  that 
most  if  not  all  of  even  the  best  boiler-plate  steel  h*s  more 
phosphorus  than  is  desirable  for  the  crucible  process,  which, 
I  believe,  will  be  ever  more  and  more  restricted  to  the  pro- 
duction of  the  very  best,  i.  e.  the  least  phosphoric,  classes 
of  steel.  But  on  the  other  hand,  wjth  the  basic  open-hearth 


a  See  an  article  by  Ledebur,  Stahl  und  Eiseu,  VI.,  p.  576,  1886. 
b  In  this  discussion  I  use  "  scrap  iron  "  generically,  to  include  scrap  wrought-iron 
and  scrap  ingot-metal. 


process  looming  up,  those  interested  in  the  future  of  direct 
processes  should  bear  in  mind  that  ere  long  boiler-plate 
containing  even  less  than  0-02%  of  phosphorus  may  be 
made  of  enormous  quantities.  Much  the  same  may  be 
said  of  direct-process  metal  considered  as  competing  witli 
scrap  iron  as  a  material  for  the  acid  open-hearth  process. 

This  process,  however,  should  it  continue  to  flourish, 
would  demand  much  more  scrap  iron  of  guaranteed  compo- 
sition than  is  likely  to  be  offered.  Here,  too,  old  rails  are  so 
heavily  handicapped  by  their  high  phosphorus-content  as 
to  be  out  of  the  race,  at  least  for  the  production  of  those 
classes  of  steel  for  which  the  open-hearth  seems  suited. 

But  it  is  as  a  material  for  the  basic  open-hearth  that  the 
future  of  direct-process  metal  seems  brightest.  We  have 
in  this  country  very  extensive  deposits  of  readily  mined 
ore,  too  phosphoric  for  either  the  acid  Bessemer  or  the  acid 
open-hearth  processes,  but  not  sufficiently  phosphoric  to 
yield  cast-iron  desirable  for  the  basic  Bessemer  process. 
Some  of  them  are  situated  where  fuel  suitable  for  the  direct 
and  for  the  open-hearth  processes  is  very  cheap  relatively 
to  that  suitable  for  the  blast-furnace  ;  the  conditions  here 
seem  especially  favorable  to  the  combination  of  direct  pro- 
cess with  basic  open-hearth,  for  the  latter  readily  takes 
metal  of  any  phosphorus-content  whatsoever,  high,  low  or 
moderate. 

Now  the  extensive  development  of  the  basic  open-hearth 
process  which  may  be  looked  for  in  these  fields,  should  i.i 
itself  create  a  demand  for  scrap  iron.  How  this  demand 
is  to  be  met  one  hardly  sees. 

It  hardly  seems  probable  that  a  great  quantity  of  old  rails 
will  be  offered.  According  to  Poor' s  Manual  there  were 
about  82,000  miles  of  iron  rails  in  this  country  in  1880,  of 
which  more  than  one-quarter  had  been  taken  up  before  18S8, 
so  that  on  an  average  somewhere  about  300,000  tons  of  old 
iron  rails  have  been  taken  up  per  annum  and  sold.  This  is 
about  the  present  production  of  open-hearth  steel  in  this 
country,  and  about  one-tenth  of  that  of  Bessemer  steel. 

Now  no  very  large  proportion  of  these  old  rails,  so  far  as 
I  can  learn,  goes  into  the  open-hearth  furnace.  They  are 
re-rolled,  slit  into  bars  of  many  kinds,  etc.  Nor  does  it  seem 
probable,  judging  from  the  statements  of  railway  engineers 
whom  I  have  consulted,  that  the  supply  of  old  steel  rails  will 
increase  rapidly.  As  the  old  iron  rails  are  taken  up,  in  many 
cases,  e.  g.  where  they  have  stood  on  sidings,  on  branches 
but  little  used,  etc.,  they  are  replaced  with  nearly  worn-out 
steel  rails.  It  seems  probable  that  as  the  supply  of  old  iron 
rails  ceases,  it  will  be  about  made  good  by  that  of  worn-out 
steel  rails,  of  which  a  considerable  quantity  is  now  sold  every 
year.  In  the  basic  open-hearth  process,  then,  we  have  a 
great  prospective  demand  for  direct-process  metal  and  scrap 


THE    METALLURGY    OF    STEEL. 


iron,  a  demand  which  is  likely  to  outstrip  any  probable 
increase  in  the  supply  of  scrap  iron  for  sale,  so  that  as 
a  remainder  we  are  likely  to  have  a  large  demand  which 
direct-process  metal  can  fill. 

§313.  COMPETITION  WITH  HIE  BLAST-PORN  ACE. — In 
studying  this  question  I  consider  the  relative  cost  of  making 
metallic  iron,  whether  sponge,  blooms  or  balls,  by  the 
direct  process,  and  of  making  cast-iron  in  the  blast-fur- 
nace. I  assume  that  the  two  competing  materials  are,  1st, 
direct-process  iron  to  be  used  in  the  open-hearth  furnace 
with  a  little  cast-iron  (in  a  process  parallel  with  the  pig- 
and-scrap  process);  and,  2d,  cast-iron  to  be  used  in  the 
.  open-hearth  furnace  with  ore,  in  the  pig-and-ore  process: 
and  this  without  discussing  the  relative  merits  of  the  pig- 
and-scrap  and  the  pig-and-ore  processes. 

If  direct  process  iron  can  be  made  as  cheaply  or  nearly 
as  cheaply  as  cast-iron,  it  will  of  course  be  a  much  better 
material  for  the  open-hearth  process. 

The  cost  of  the  combination,  blast-furnace  plus  puddling, 
as  preparatory  to  the  open-hearth  process,  must  ever  re- 
main so  high  that  it  will  be  chiefly  confined  to  the  produc- 
tion of  steel  of  exceptional  purity.  Indeed,  the  basic  open- 
hearth  process  threatens  to  extinguish  the  combination 
altogether  as  preparatory  to  the  open-hearth  process. 

For  making  steel  by  the  open-hearth  and  crucible 
processes  we  seek  metallic  iron  without  much  carbon  or 
silicon.  In  the  blast-furnace  we  not  only  bring  our  iron 
to  the  metallic  state,  which  can  be  done  at  a  low  tem- 
perature, but  raise  our  deoxidized  iron  to  a  very  much 
higher  temperature,  at  vast  outlay  of  fuel ;  this  excess  of 
fuel  causes  such  energetic  deoxidation  that  all  the  phos- 
phorus of  the  ore  is  deoxidized  and  unites  with  the  iron, 
as  does  much  carbon  and  silicon,  which  must  later  be 
removed.  This  does  not  at  first  seem  the  straightest  way, 
but  it  has  enormous  incidental  advantages,  in  that  the 
carbon  and  silicon  absorbed  prevent  the  metallic  iron  from 
reoxidizing  ;  in  that  we  obtain  all  the  products  in  a  molten 
condition,  in  which  they  can  be  very  cheaply  handled ; 
in  that  we  can  convert  the  gangue  into  a  sulphur-devouring 
basic  lime-silicate  and  can  melt  this  silicate,  thus  at  once 
removing  from  the  iron  the  gangue  with  which  it  is 
associated  in  nature,  and  the  sulphur  of  the  mineral  fuel 
used  for  smelting. 

This  procedure,  making  steel  by  carburizing  iron  in  the 
blast-furnace  and  again  decarburizing  it,  has  been  long 
ridiculed  as  indirect  and  illogical.  But  the  objection  is 
rather  of  sentimental  than  practical  importance,  unless  the 
indirect  and  illogical  process  necessarily  cos  s  more  than  the 
direct  and  logical  one :  metallurgy  lives  by  prof  it,  not  logic. 
Indeed,  the  cheapest  possible  process  for  given  results, 
quality  and  certainty  included,  no  matter  how  indirect  is 
logical  when  all  factors  are  considered  :  it  seems  illogical 
only  to  the  shallow  logician  who  ignores  certain  premises. 

A.  Advantages  and  Disadvantages  of  the  Direct  Pro- 
cess.— For  all  ores  the  direct  process  has  an  advantage 
over  the  blast-furnace, 

1,  In  yielding  iron  relatively  free  from  carbon  and  thus 
fitter  for  the  open-hearth  and  crucible  processes. 

2,  In  that  its  gentle  deoxidizing  conditions  may  permit 
dephosphorization — at  the  cost  of  heavy  loss  of  iron.    The 
loss  of  iron  may,  however,   be  avoided  if  dephosphoriza- 
tion be  not  sought    by  strengthening  the  deoxidizing 
tendencies  (Cf.  §  315,  B  I.). 


3,  In  that  it  can  use  fuels  (producer-gas,  water-gas, 
natural  gas)  which  are  often    much  cheaper  than  the 
anthracite,  coke  and  charcoal  to  which  the  blast-furnace 
is  apparently  hopelessly  restricted. 

It  is  at  a  disadvantage. 

4,  In  leading   to    greater    absorption   of    sulphur   if 
sulphurous  (solid  mineral)  fuel  is  used,  since  at  the  usual 
low  temperature  of  the  direct  processes  we   cannot  melt 
and  hence  cannot  use  the  desulphurizing  lime  slags. 

5,  In  its  greater  outlay  for  labor,  greater  because  opera- 
tions are  more  scattered,  and  because  the  product  is  usual 
ly  solid  and  less  easily  handled  than  the  molten  product 
of  the  blast-furnace. 

6,  In  its  probably  necessarily  greater  loss  of  iron. 
For  rich  ores  it  has  a  further  advantage. 

7,  In  requiring  less  fuel,  thanks  chiefly  to  its  lower  tem- 
perature. 

8,  In  case  of  lean  ores  the  fuel-consumption  of  the  direct 
process  may  be  brought  below  that  of  the  blast-furnace, 
but  only  at  the  cost  of  heavy  loss  of  iron,  which  however 
at  the  same  time  causes  dephosphorization.     The  leaner 
the  ore,  the  heavier  the  loss  of  iron  to  which  we  must 
submit  in  order  to  obtain  the  fuel-economy   which  the 
direct  process  permits. 

B,  Applicability.  Hence  the  direct  process  is  especially 
applicable, 

1,  To  rich  ores  ; 

2,  To  cheap  ores,   especially  if  dephosphorization  be 
needed ; 

3,  Where  fuel  is  dear  ; 

4,  Where  fuels  which,  though  nearly  or  quite  sulphur- 
less,    cannot  be  used    in    the    blast-furnace,   are    much 
cheaper  per  unit  of  calorific  and  reducing  power  than 
those  fuels  which  are  suited  for  the  blast-furnace. 

I  believe  that  these  are  not  simple  accidents  of  the  direct 
processes  now  proposed,  but  essential  conditions  of  the 
problem. 

§  314.  DISCUSSION.— Let  us  now  consider  in  some  detail 
the  conditions  which  give  rise  to  these  advantages  and 
disadvantages,  first  noting  that,  as  a  material  for  the  open- 
hearth  process,  it  is  not  imperative  that  the  product  of  the 
direct  process  should  be  completely  deoxidized.  Any 
small  quantity  of  iron-oxide  in  the  balls  of  spongy  iron, 
if  these  were  sufficiently  dense  to  sink  quickly  beneath  the 
slag  of  the  open-hearth  furnace,  would  probably  be  almost 
wholly  deoxidized  by  the  carbon  (and  silicon)  of  the  bath 
during  the  early  part  of  the  process,  especially  if  this 
were  carried  out  on  a  basic  lining.  But  towards  the  end 
of  the  operation,  when  the  bath  contains  but  little  car- 
bon, any  oxidized  iron  in  the  sponge-balls  would  prob- 
ably escape  reduction  and  would  be  lost  in  the  slag. 

Fuel.  To  bring  100  parts  of  iron  from  the  condition  of 
iron  ore  to  that  of  metallic  iron  the  essential  requisites  are, 
enough  chemical  energy  to  deoxidize  the  iron,  and  enough 
heat  energy  to  raise  the  ore  to  a  temperature  at  which  de- 
oxidation  can  occur. 

To  deoxidize  100  of  iron  from  magnetic  oxide  takes 
100  X  1582  =  158,200  calories. 

To  develop  this  quantity  of  heat  needs  19 -5  parts  of  car- 
bon burning  to  carbonic  acid,  while  to  satisfy  the  equation 
Fe3O4  +  20  =  3Fe  +  2CO2  needs  only  14 '3  parts  of  carbon. 
It  is  conceivable  that  during  the  subsequent  cooling  of 
the  metallic  iron  and  carbonic  acid  we  can  almost  com- 


HEAT-REQUIREMENT    OP    THE    DIRECT    PROCESS. 


201 


pletely  recover  the  heat  expended  in  raising  the  iron  oxide 
and  carbon  to  the  temperature  of  deoxidation  :  so  that  in 
one  sense  a  consumption  of  19-.0  parts  of  carbon  per  100  of 
iron  may  be  taken  as  the  limit  towards  which  we  work, 
and  which  in  the  nature  of  things  we  can  never  quite 
reach.  But  even  if  we  admit  that  half  of  the  heat  used 
in  heating  the  iron  oxide  and  carbon  must  practically  be 
thrown  away,  the  carbon-requirement  rises  but  little. 
yome  forms  of  iron  oxide  begin  to  deoxidize  at  tempera- 
tares  even  below  150°  C.  :  but  here  deoxidation  is  very 
slow  and  probably  necessarily  very  incomplete.  Probably 
it  will  always  be  expedient  to  heat  the  oxide  at  least  to 
800°  C.  (1472°  F.).  To  do  this  requires 

/    Fe3  O4.       8.  H.        C.        S.  H.\ 

(lOO  x  ^  x  0-17  +  19-5  x  0-30  )  (800°—  20°)  =  22,877  calorie-,. 
\  72-4  ' 

Now,  supposing  that  half  of  this  heat  is  utilized  when 
the  products  cool,  to  supply  the  other  half  requires  1  -42 
parts  of  carbon,  which  raises  our  total  carbon-requirement 
to  21  parts  per  100  of  iron.  In  case  of  ferric  oxide  the 
requirement  would  rise  to  about  24  parts  of  carbon  per 
1()(t  of  iron. 

As  the  necessary  carbon-requirement  is  an  extremely 
important  factor  in  any  forecast  of  the  probable  future  of 
the  direct  process,  let  us  seek  it  again  in  a  wholly  inde- 
pendent way. 

For  the  deoxidation  alone  of  ferric,  oxide  by  carbon, 
supposing  that  all  the  carbon  were  burnt  to  carbonic  acid 
by  means  of  oxygen  yielded  to  it  by  the  ore,  by  the  re- 
action :  — 

2Fe2Os  +  3C  =  4Fe  -f  bCO2, 

4  X  56  =  224  of  iron  needs  3  X  12  =  36  of  carbon,  or 
100  kg.  of  iron  needs  16  kg.  of  carbon,  which  would 
develop  16  x.  8,080  =  129,280  calories. 

But  to  deoxidize  100  of  iron  by  the  above  reaction  de- 
mands 100  X  1887  =  188,  7>  0  calories,  or  59,420  calories 
more  than  is  developed  by  our  carbon  :  and  to  develop 
this  excess  we  must  burn  59,420  -r-  8,080  =  7,354  kg.  of 
carbon  :  so  that  altogether  we  need 

Reducing  carbon  ....................................................  16    kg. 

lleating  carbon  ......................................................    "  *    ' 

Total  carbon  ...................................................  23-4  kg., 

or  26  parts  of  a  fuel  containing  90$  of  carbon. 

But  here  we  assume  that  all  the  heat  developed  in  the 
apparatus  and  by  the  reactions  is  utilized  with  100$ 
efficiency,  a  condition  manifestly  unattainable  :  no  less  un- 
warrantable is  our  assumption  that  all  the  carbon  is 
oxidized  to  carbonic  acid  by  the  oxygen  of  the  ore.  But 
I  think  it  within  the  bounds  of  possibility  that  a  direct 
process  should  be  devised  in  which  the  carbon  would  be 

CO 
oxidized  by  the  ore  so  fully  that  the  ratio  -^  in  the  escap- 


could  be  practically  completely  utilized  in  heating  and  re- 
ducing the  ore  :  and  in  wMch  75$  of  the  heat  evolved 
by  the  further  combustion  of  the  escaping  gases  could  be 
utilized.  But  the  heat  developed  by  reducing  fuel  and 
the  escaping  gases  would  not  suffice  for  reducing  and 
heating  the  ore  :  additional  fuel  must  be  supplied:  and 
we  may  asssume  that  it  is  within  the  bounds  of  possibility 
that  75$  of  the  heat  evolved  in  burning  this  fuel  would  be 
utilized.  Under  these  assumptions  and  neglecting  the 
moisture  in  the  blast,  we  may  calculate  the  fuel  require- 
ment as  follows  for  an  ore  with  10$  of  gangue,  90$  of  ferric 
oxide,  or  63$  of  iron: 

CO 
Composition  of  the  Gases. — The  ratio  -~TJ-  being  1  -34, 

we  would  have  of  carbon  burning  to  carbonic  acid 

1"34  X  12  1  X  12 

— —  =  -366,  and  to  carbonic  oxide  -r-^--.     -  =  -4285  : 

oJ  -p   Lit  ID  -f-  Lit 


or 


\/    1  f\C\ 


4-  -4285  =  46*04$  of  the  carbon  burns  to  carbonic 

acid,  and  53  '96$  to  carbonic  oxide  :  so  that  each  equivalent 
of  carbon  takes  up  1  -46  of  oxygen.  Hence  to  deoxidize  10\) 
kg.  iron  we  need 

o 
16  X  YT-O  =       21  '92  instead  of  16  kg.  of  carbon  :  of  which 

21-92  X  '4604  =  10*09  kg.  burn  to  carbonic  acid,  and 
21-92  x  *5396  =  11  '83  burn  to  carbonic  oxide. 

21-92 

The  waste  gases  from  the  reducing  apparatus  then  will 
contain,  per  100  kg.  of  iron, 

32 
10-09  X  -^  =  26-84  of  oxygen,  or  36-93  kg.  of  carbonic 


acid : 


12 


16 


11-83  X  ^  =  15-73  of  oxygen,  or  27-56  kg.  of  carbonic 

.,  12       42-57 

oxide. 

As  the  carbon  is  supposed  to  be  oxidized  by  the  oxygen 
of  the  ore,  the  waste  gases  escaping  from  the  ore-reducing 
chamber  may  be  supposed  to  be  free  from  nitrogen. 

Heat  Requirements.  — Heating  the  following  substances 
from  20  to  800°  C.,  a  range  of  780°. 

Kg.  SH.  Calorics. 

lOOofiron"  100         X  -169  =  16-9 

10 
100  X —  =  15-87  of  gangne 15-87  X      '22  =    8'5 

68 

86  93  carbonic  acid 86-93  X '2164  =    7'992 

2T-56        "       oxide 27-56X2479=6-832 

TotalW.  X  SH...  85-224 

780  X  35-224 27,475 

Reduction  of  100  of  iron,  100  X1.8S7  = 188,700 


Heat  Denelopment.- 


216,175 


ing  gases  would  be  1-34  by  weight  :a  in  which,  the  reduc- 
tion could  be  practically  completed  without  raising  the 
temperature  above  800°  C.  :  in  which  90$  of  the  heat  given 
out  by  the  spongy  iron  in  cooling  from  this  temperature  to 
250°  C.  could  be  utilized,"  admitting  that  all  the  heat  given 
out  as  the  products  cool  from  250°  down  is  lost:  in  which  the 

CO 
heat  evolved  by  the  combustion  of  the  carbon  to  -^~  =  1  '34 

a  The  gases  from  the  Bjornbyttan  charcoal  blast-furnace  are  reported  to  have 
this  composition  :  Bell,  Princ.  Mauuf.  Iron  and  Steel,  pp.  276-9,  from  Aker- 
man. 

b  The  temperature  of  the  gases  escaping  from  the  Consett  No.  4  and  the  North 
Chicago  No.  7  furnaces  is  reported  as  248°  and  249°  C.  respectively.  Gordon, 
Journ.  Iron  and  Steel  lust.,  1886,  II.,  p.  784. 


10-09  kg.  of  carbon  burn  to  carbonic  acid  10-09  X  8,080 81,530 

11 -.S3  kg.  burn  to  carbonic  oxide  11"83  X  2,473 29,250 

yo<6  of  the  heat  given  out  by  gas,  sponge  and  gangue,  in  cooling  from  800°  to  250*,  W.  X 

SH.  X  550  X  -90  =  85.224  X  550  X  -90  = 17,435 

75£  of  the  heat  evolved  in  the  further  combustion  of  27-56  kg.  of  carbonic  oxide  to  carbonic 

acid,  27-56  X  2,408  X  '75 49,670 

In  order  to  bring  the  sum  up  to  the  heat  requirement  wo  must  burn  6*82  kg.  of  carbon, 

which  by  assumption  would  contribute  of  available  heat  8,080  X  '75  X  0-32  = 38  290 

216,175 

Reducing  carbon  needed 21  '92  kg.  per  100  kg.  of  iron. 

Heating  carbon  needed 6-32 

Total 28'24  or,  say  30  kg. 

To  sum  this  up,  under  the  several  sets  of  assumptions 
the  carbon  requirement  for  100  of  iron  is  as  follows  : — 

For  deoxid.ition.  For  beating.  Total. 

Pure  magnetite- 19'5                     1-42  21 

Pure  ferric  oxide,  1st  calculation .... 

>•      2d          "           HrOO                     7-40  «S-4 

90£     ferric  oxide,  10£  gangue 21'92                       6'32  28'24 

I  repeat,  these  are  limits  towards  which  we  may  work. 


<•  This  is  not  strictly  accurate,  because  during  the  first  part  of  the  operation  we 
are  heating  oxide  of  iron  and  carbon  instead  of  iron  and  oiide  of  c  irbon.  But  the 
error  thus  introduced  is  not  sufficient  to  affect  our  results  materially. 


262 


THE     METALLURGY    OF    STEEL 


Now  we  find  that  the  modern  blast-furnace,  wonderfully 
efficient8  thermo-chemical  engine  that  it  is,  almost  always 
uses  more  than  twice  and  usually  more  than  thrice  the 
largest  quantity  of  fuel  above  calculated.  The  following 
are  among  the  best  results  thus  far  published. 

Pounds  of  carbon  per  100 
pounds  of  pig-iron. 

Consctt  furnace 78-9   b 

North  Chicago  Coke  Furnace,  probably  1886 6T95  c 

Martel  Charcoal  Furnace 54'90  d 

While  part  of  the  difference  is  due  to  our  assuming  a 
higher  efficiency  for  the  direct  process,  smaller  losses  of 
heat  by  radiation,  etc.,  than  are  actually  attained  in  the 
blast  furnace,  yet  the  greater  part  is  clearly  due  to  the 
fact  that  the  blast  furnace  does  much  work  which  the 
direct  process  may  avoid. 

To  compare  the  requirements  of  the  direct  process  with 
those  of  the  blast-furnace,  I  give  in  the  following  table 
the  heat  requirements  of  the  latter  when  smelting  Cleve- 
land ore,  according  to  Bell,  and  those  of  a  direct  process 
in  which  I  assume  that  the  charge  is  heated  to  800°  C  , 
that  no  limestone  is  used,  that  neither  phosphoric  nor 
silicic  acid  is  deoxidized,  and  that  the  loss  by  radiation, 
tuyere-water,  expansion  of  blast,  etc.,  is  but  little  more 
than  half  as  great  as  in  the  blast-furnace. 

TABLE  152. — HEAT  REQUIRED  FOK  MAKING  20  Ko.  OP  PIO-IEON,   AND  SPONGE  CONTAINING 
THE  SAME  QUANTITY  (18'6  KG.)  OF  IEON,  FBOM  CLEVELAND  OKI. 


Pig-iron.a 

Sponge. 

Kg. 

Cal. 

Cal. 

Kg. 

Cal. 

Cal. 

Evaporation  of  the  water  In  the  coke. 
Reduction  01  18'60  kg.  of  iron  from  I 
ferric  oxide      ( 

•58  X 
18-60  X 
•60  X 
11-OOC»CO3 

1-82  C 
•OBH 

540  = 
1,780  = 
2,400  = 
870  = 

3,200  = 
84,000  = 

818 
88,108 
1,440 
4,070 

4,224 
1,700 
8,500 

6,600 
15,856 

•30  X 
18-60  X 

540  = 
1,780  = 

163 
88,108 

900 

2,518 

8,907 
4,500 
4,000 

Expulsion   of  carbonic    acid    from  1 

Decomposition  of  carbonic  acid  from  I 
limestone  i 

"Decomposition  of  water  in  blast  
Reduction  of  phosphoric,  sulphuric  ( 

20-00  X 
27-92  X 

880  = 
550  = 

Heating  iron: 
Kg.     8.  H. 
To  800°  C    18'6  X  '169  X  800 

Heating  gangue  : 
Kg.      8.  H. 
to  S00°  C     22-2  X  '22  X  800. 

Radiation,  tuyere-water,  expansion  1 

8,789 
7,900 

Carried  off  in  escaping  gas.  

87,000 

49,095 

a  Bell,  Princ.  Manuf.  Iron  and  Steel,  p.  95,  1884. 

These  numbers  indicate  that,  with  approximately  like 
efficiency,  the  direct  process  may  be  carried  on  with  a 
little  over  half  the  fuel-consumption  of  the  blast-furnace : 
and  I  fancy  that  this  is  not  very  far  from  the  point  which 
it  may  some  day  reach. 

Aa  already  hinted,  the  chief  reason  for  the  greater  fuel- 
consumption  in  the  blast-furnace  is  that  the  material  is 
heated,  not  merely  to  the  temperature  of  rapid  deoxidation, 
say  800°  C.,  but  to  a  vastly  higher  temperature,  so  as  to 
completely  liquefy  the  product.  When  mineral  fuel  is 
used  the  sulphur  which  it  contains  would,  unless  special 
precautions  wer3  taken,  contaminate  the  iron.  To  prevent 
this  it  is  necessary  that  the  slag  should  contain  much 


a  Gruner  estimated  that  in  large  blast-furnaces  from  70  to  88$  of  the  heat  gen- 
erated was  utilized.  In  an  example  given  by  Bell  81$  of  the  beat  developed  is 
usefully  applied.  In  another  case  74$  of  the  total  calorific  power  of  the  fuel  is 
utilized.  (Princ.  Manuf.  Iron  and  Steel,  p.  144,  1884.) 

bGruner,  Studies  of  Blast>Furnace  Phenomena,  L.  D.  B.  Gordon,  p.  78,  1674. 

c  F.  W.  Gordon,  Journ.  Iron  and  Steel  Inst.,  1886,  II.,  p.  784. 

<!  Bell,  Princ.  Maouf.  Iron  and  Steel,  pp.  301-1,  1884,  from  Journ.  TJ.  S.  Ass. 
Charcoal  Iron  Woikers,  III.  From  this  number,  54 '9,  we  should  apparently  de- 
duct something  like  three  pounds,  to  allow  for  the  carbon  taken  up  by  the  iron,  in 
order  to  make  this  case  comparable  with  the  others  :  so  that  here  the  carbon 
burned  is  about  5~  pounds  Per  1°°  o£  cast-iron  produced. 


lime,  so  that  the  sulphur  may  enter  the  slag  as  sulphide 
of  calcium,  instead  of  combining  with  the  iron. 

But  these  highly  calcareous  slags  are  exceedingly  in- 
fusible. In  order  to  liquefy  them  completely  the  temper- 
ature is  raised  not  simply  to  the  melting  point  of  cast- 
iron,  say  1,050°  C.  for  white  iron  and  1,200°  C.  for  gray,  but 
probably  at  least  to  1,600°  C.,  and  much  higher  when  the 
open  gray  iron  needed  for  the  Bessemer  process  is  made.6 
This  high  temperature  plays  another  important  part  in 
making  iron  for  the  Bessemer  process :  it  affords  the 
strongly  carburizing  and  deoxidizing  conditions  which 
give  the  iron  a  high  proportion  of  carbon  and  silicon,  but 
which  have  a  compensating  disadvantage  in  deoxidizing 
the  phosphorus  of  the  burden,  and  thus  causing  it  to  enter 
the  iron. 

Beyond  this,  in  using  lime  we  increase  the  fuel  re- 
quirement not  only  by  increasing  the  quantity  of  material 
to  be  heated  and  melted,  but  because  the  decomposition 
of  the  limestone  absorbs  heat,  and  because  the  carbonic 
acid  driven  off  from  it  attacks  the  carbon  of  the  fuel,  by 
the  reaction 

C02  +  C  =  SCO, 
both  consuming  fuel  and  absorbing  heat. 

Again,  the  deoxidation  of  phosphoric,  sulphuric  and 
silicic  acids,  and  the  absorption  of  carbon  by  the  iron, 
demand  heat  and  fuel. 

In  an  example  given  by  Bell  the  items  calculated  in  the 
last  two  paragraphs  consume  0'48  times  as  much,  the 
sensible  heat  carried  out  by  the  molten  products  is  0'70 
times  as  great,  and  that  carried  out  by  radiation,  by  the 
tuyere-water  and  by  the  escaping  gases  0*40  times  as  great, 
as  the  heat  needed  for  deoxidation  proper,'  which  is  thus 
but  about  one-third  of  the  total  heat-requirement. 

Finally,  the  high  temperature  of  the  blast-furnace 
greatly  increases  the  loss  of  heat  by  radiation  and  by  the 
tuyere-water :  but  this  is  partly  offset  by  its  great  com- 
pactness and  concentration.  In  short,  it  is  clear  that,  as 
far  as  fuel-requirement  is  concerned,  the  uncarburetted 
and  hence  more  valuable  product  of  the  direct  process 
should  be  more  cheaply  produced  than  cast-iron. 

But,  as  we  shall  see,  this  advantage  may,  except  in  case 
of  rich  ores,  be  more  apparent  than  real,  since  the  further 
treatment  of  the  direct-process  metal  in  the  open-hearth 
or  crucible  process  may  necessitate  reheating  the  gangue 
of  the  ore  to  a  temperature  which  is  very  much  higher, 
and  with  a  heating-efficiency  which  is  very  much  lower, 
than  those  of  the  blast-furnace  :  a  reheating  wholly  dis- 
pensed with  in  case  the  ore  is  treated  by  the  blast-fur- 
nace instead  of  by  direct  process. 

Cost  of  Installation.  It  is  generally  believed  that  the 
output  of  the  direct  process  from  plant  of  given  cost  is 
and  must  be  nrach  less  than  that  of  the  blast-furnace :  but 
I  doubt  if  this  is  true.  To  give  a  rough  idea  of  the  rela- 
tive cost  of  installation  for  the  direct  and  for  the  blast- 
furnace process,  I  here  estimate  the  annual  output  of  iron 
from  $40,000  worth  of  plant,  i.  e.,  the  annual  output  for 
each  $40,000  of  cost  of  installation. 

American  Bloomary.  Assuming  that  each  fire  turns 
out  300  tons  a  year:  furnace  assumed  at  $600,  I  of  a  ham- 
mer assumed  at  $234,  other  items,  excluding  buildings,  at 


e  Bell  found  that  wrought-iron,  whose  melting-point  is  not  far  from  1,600°  C., 
was  partly  melted  when  held  in  a  stream  of  slag  from  a  blast-furnace  making  No. 
8  pig-iron  (Journ.  Iron  and  Steel  Inst.,  1871,  I.,  p.  299). 

'  Journ.  Iron  and  St.  Inst.,  1871, 1.,  p.  879. 


THE    DIFFICULTIES     OF    THE    DIRECT    PROCESS.      §  315. 


263 


$166,  total  $1,000  :   output  from  $40,000  worth  of  plant 

-  12,000  tons. 


Siemens''  Rotator:  Holley's  estimate  that  four  rotators, 
with  crusher  and  hammer,  but  without  buildings,  cost 
$40,000,  with  an  output  of  125  tons  per  week.  Output 
125  X  52  =  6, 250  tons. 

Blair  Sponge-making  Plant,  to  turn  out  60  tons  of 
sponge,  or  say  50  tons  of  iron  in  sponge,  per  24  hours, 
$75,000,  8,180  tons. 

Blast-furnace  10'  x  70',  turning  out  say  48,000  tons 
per  annum,  and  costing,  excluding  buildings,  $180,000 ; 

$40,000  worth  of  plant  would  turn  out  48,OoO  x 


180,000 
-  10, 667  tons. 

I  infer  from  these  numbers  that  any  difference  between 
the  cost  of  installation  for  the  direct  and  for  the  blast- 
furnace process  is  a  relatively  unimportant  factor  in  fore- 
casting the  future  of  the  direct  process. 

§  315.  Tim  DIFFICULTIES  OF  THE  DIRECT  PROCESS,  some 
of  them  already  touched  on,  are 

1,  Loss  of  iron  through  re-oxidation  or  imperfect  deoxi- 
dation, 

2,  Heterogeneousness  and  carburization  of  product, 

3,  Absorption  of  sulphur,  and 

4,  Heavy  outlay  for  labor,  can  I  think  be  best  studied  by 
examining  certain  general  divisions  of  the  direct  process, 
to  wit,  those  carried  out  at  a  sponge-making,   a  welding 
and  a  steel-melting  heat  respectively  :   at  the  same  time 
we  learn  the  characteristics  of  these  classes. 

A.  Sponge-making  Processes. — If  the  temperature  be 
low,  so  that  unmelted,  unwelded  spongy  iron  results,  de- 
oxidation  is  slow,  the  output  of  given  plant  small,  and 
hence  the  outlay  for  labor  is  large.  The  spongy  product 
absorbs  sulphur  greedily,  hence  it  is  better  to  use  sulphur- 
less  or  desulphurized  fuel,  for  we  lack  the  sulphur-absorb- 
ing lime  of  the  blast-furnace  :  it  reoxidizes  readily,  hence 
the  loss  of  iron  is  likely  to  be  excessive  without  special  pre- 
ventives, which  must  cost  something.  The  gangue  of 
the  ore  is  not  eliminated,  but  remains  to  swell  the  cost 
of  subsequent  operations.  The  phosphorus  of  the  ore  is 
not  indeed  deoxidized,  but  it  remains  in  the  spongy  metal, 
and,  if  this  is  later  melted  in  presence  of  an  acid  slag,  as 
in  the  acid  open-hearth  and  crucible  processes,  the  phos- 
phorus enters  the  iron.  Here  is  a  tremendous  obstacle 
which  many  promoters  of  direct  processes  have  completely 
lost  sight  of :  but  to-day  the  basic  open-hearth  process 
promises  to  overcome  it.  However,  it  mus1;  be  clearly 
understood  that  sponge-making  processes  do  not  in  them- 
selves guard  against  the  deoxidation  and  absorption  of 
phosphorus :  they  are  not  dephosphorizing  processes  in 
any  sense,  nor  do  they  help  towards  dephosphorization. 

Wken  the  ore  is  heated  in  reverberatory  furnaces,  in 
externally  heated  retorts,  etc.,  and  so  does  not  come  into 
contact  with  the  heating  fuel,  the  excess  of  the  deoxi- 
dizing fuel  need  not  be  so  great  as  to  cause  more  than 
moderate,  or  at  most  locally  serious  carburization,  which 
does  little  harm  when  the  product  is  to  be  used  for  the 
open-hearth  or  crucible  process.  When  the  ore  is  heated 
by  the  passage  of  the  hot  reducing  gas  .through  it,  one 
would  expect  that  this  would  deposit  carbon  abundantly, 
and  might  thus  lead  to  carburization. 

To  purposely  carburize  the  product,  the  use  of  hydro- 


carbon reducing  gases  (Gurlt,  Blair,  §§  325,  8ci3  A)  has 
been  proposed.  Another  plan  is  to  compress  the  spongy 
iron  together  with  carbonaceous  matter  (Chenot  §  332),  in 
the  hope  that  the  iron  will  combine  with  the  carbon  in  the 
open-hearth  or  crucible  process  before  fusion  actually 
occurs. 

I.  For  Slow  Deoxidation,  two  remedies  suggest  them- 
selves, the  use  of  lime,  as  practiced  by  Blair  (Cf  .  §  333,  A) 
and  that  of  natural  gas  or  of  artificial  hydrogenous  gas. 
The  former,   rich  in  methane,  should   deoxidize    much 
more  rapidly  than  the  carbon  or  carbonic  oxide  generally 
used.     Bell*  lound  that,  while  pure  carbonic  oxide  re- 
moved only  9-4$  of  the  total  oxygen  from  calcined  Cleve- 
land ore  in  seven  hours  at  about  427°  C.  (800°  i-\),  a  mixture 
of  100  parts  of  carbonic  oxide  with  12  of  hydrogen  re- 
moved 68$  in  ninety  minutes  at  approximately  the  same 
temperature,"  thus  acting  34  times  as  fast,  roughly  speak- 
ing.    At  bright  redness  the  same  mixture  removed  about 
70%  of  the  total  oxygen  in  one  hour. 

II.  The  Absorption  of  Sulphur.*—  By  placing  the  ore 
within  retorts,  etc.,  it  may  be  protected  from  the  heating 
fuel,  but  this  of  course  increases  the  consumption  of  fuel  : 
this  procedure  should  be  desirable  chiefly  in  places  where 
sulphurous  is  much  cheaper  than  sulphurless  fuel.     But 
the  ore  must  necessarily  come  in  contact  with  the  deoxi- 
dizing fuel,  and  of  this  at  least  16  parts  must  be  used  per 
100  of  iron,  supposing  that  by  some  regenerative  contriv- 
ance or  other  the  ore  oxidizes  the  whole  of  the  carbon  to 
carbonic  acid,  and  at  least  21  '92  parts  per  100  of  iron  if 
we  assume  that  the  ore  cannot  oxidize  the  carbon  farther 

CO 
than  to  make  the  ratio  -      =  1-34. 


We  have  two  common  sulphurless  deoxidizing  agents, 
charcoal,  which  is  usually  very  expensive,  and  natural 
gas,d  which  is  often  cheap.  Even  if  solid  mineral  fuel  be 
used,  the  absorption  of  sulphur  may  perhaps  be  prevented 
by  gasifying  the  fuel  and  desulphurizing  the  gas  by  pass- 
ing it  through  lime  or  over  spongy  iron,  as  in  Tourangin's 
process  (§  327).  The  practicability  of  this  plan  on  a  large 
scale  is  not  yet  shown. 

III.  Reoxidation  may  be  prevented  by  cooling  the 
ipongy  iron  before  exposing  it  to  the  air,  as  in  Chenot'  s 
process,  and  probably  as  contemplated  by  Lucas  in  1792. 
The  sponge  should  then  be  compressed  powerfully,  to 
lessen  the  surface  exposed  to  oxidation.  Or  reoxidation 
may  be  cured  as  in  Gurlt'  s  process  by  balling  the  sponge 
under  strongly  deoxidizing  conditions,  e.  g.,  in  a  charcoal- 
liearth.  But  we  cannot  re-deoxidize  in  the  necessarily 
strongly  oxidizing  atmosphere  of  the  puddling  or  other 
open  reverberatory  furnace  —  without  adding  much  solid 
deoxidizing  matter,  and  even  then  a  considerable  quantity 
of  iron  will  remain  oxidized.  As  already  pointed  out,  a 


The  temperature  when  the  mixed  gases  were  used  was  below  redness:  incipient 
redness  may  be  taken  at  about  525°  C. 

b  Princ.  Manuf.  Iron  and  Steel,  p.  310,   1884. 

c  There  is  a  belief  that  only  part  of  the  sulphur  of  the  fuel  is  liable  to  be  evolved 
during  combustion,  at  least  when  this  occurs  in  gas-producers.  It  is  true  that 
only  part  of  the  sulphur  of  the  pyrites  of  the  fuel  is  volatilized  as  such  :  but  the 
rest  will  be  expelled  almost  completely  as  sulphurous  anhydride  or  otherwise  by 
the  time  that  the  fuel  itself  is  completely  burnt,  quite  as  in  the  roasting  of 
pyritiferous  ores,  and  relatively  little  will  remain  in  the  ash  if  the  combustion  of 
the  fuel  is  thorough. 

d  I  have  met  no  authoritive  statements  about  the  presence  or  absence  of  sulphur 
in  natural  gas.  A  chemist  who  has  paid  close  attention  to  the  natural  gas  supply, 
and  whose  writings  on  the  subject  are  well-known,  informs  me  that  he  thinks  the 
gas  brought  to  Pittsburgh  practically  free  from  sulphur,  but  that  he  believes  thaf 
the  gas  in  certain  fields  has  a  sulpurous  smell. 


264 


THE    METALLURGY    OF    STEEL. 


little  reoxidation  may  do  no  harm  in  case  of  spongy  iron 
which  is  to  be  melted  in  a  bath  of  cast-iron  in  the  early 
part  of  the  open-hearth  process,  for  the  carbon  and  silicon 
of  the  cast-iron  should  take  up  any  slight  quantity  of 
oxygen  in  the  sponge. 

The  term  "reducing  flame"  is  responsible  for  enor- 
mous waste  of  energy  and  money  in  carrying  out  ill 
advised  direct  processes.  In  a  certain  sense  it  is  possible 
to  produce  in  a  reverberatory  furnace  a  high  temperature 
with  a  reducing  flame  :  we  can  reach  a  white  heat  with  a 
flame  which  is  reducing  towards  oxide  of  silver,  of  gold, 
or  of  copper ;  which  is  reducing  in  the  sense  of  being 
relatively  reducing,  or  less  strongly  oxidizing  than  some 
other  flames.  If  in  a  direct-firing  reverberatory  we  burn 
carbon  to  carbonic  oxide  with  exactly  the  proportion  of 
air  chemically  required,  their  products  would  reach  a 
temperature  of  about  1,500°  C.  if  no  heat  were  lost  by 
radiation.  But  of  course  such  a  combustion  could  not 
heat  the  furnace  highly,  for  its  heat  is  distributed  over 
much  matter  other  than  its  own  products.  If  we  go  a  step 
farther  and  burn  ever  so  little  of  this  carbonic  oxide  to 
carbonic  acid,  the  atmosphere  becomes  oxidizing  towards 
iron,  though  still  reducing  towards  copper,  for  carbonic 
acid  oxidizes  iron,  even  in  the  presence  of  a  great  excess 
of  carbonic  oxide.  In  a  regenerative  or  other  gas  furnace 
using  carbonic  oxide  no  combustion  whatever  would  be 
possible  without  yielding  an  atmosphere  which  would  oxi- 
dize iron  slightly. 

The  presence  of  hydrogen  and  of  hydrocarbons  in  the 
gas  of  regenerative  gas  furnaces  may  modify  this  some- 
what :  but  I  fail  to  see  how  it  is  possible  in  common  gas- 
furnaces,  Siemens  or  others,  to  obtain  a  high,  say  a  weld- 
ing, heat  without  thereby  generating  an  atmosphere 
oxidizing  towards  iron  By  saying  that  it  is  possible  to 
produce  at  will  a  reducing,  neutral  or  oxidizing  flame  in 
the  Siemens  furnace,  the  admirers  of  this  invaluable 
apparatus  have,  doubtless  unintentionally,  spread  con- 
fusion on  the  subject.  But  in  Morrell's  and  certain  other 
gas-furnaces  the  ore  may  be  heated  by  white-hot  producer 
gas  wholly  unmixed  wiih  air,  or  with  a  slight  quantity  of 
aii1  if  desired.  By  a  similar  arrangement  producer  gas  for 
reducing  ore  by  direct  contact  in  shafts  and  vertical 
retorts,  and  hence  with  better  heating  efficiency,  might 
be  intensely  preheated  without  admixture  of  air. 
Furnaces  of  this  class  may  be  of  great  value  in  develop- 
ing the  direct  process. 

In  MorreW  s  gas-furnace*  Figure  126,  both  gas  and  air 


Figure  126.—  Morrell'8  Gas-furnace. 


are  preheated,  each  in  its  own  regenerator,  quite  as  in  the 
common  Siemen'  s  type,  but  the  hot  gas  alone  enters  the 
laboratory  or  working  chamber  of  the  furnace,  the  hot 


>U.  S.  Patent,  313,754,  March  10th,  1885,  T.  T,  Morrell. 


air  meeting  it  as  at  d'.  Hot  gas  and  hot  air  then  burn  in 
descending  through  the  regenerators  :  in  the  case  shown 
this  occurs  in  the  left-hand  regenerators.  On  reversing  the 
furnace  the  dampers  F  and  G  now  shown  in  solid  lines 
are  moved  to  the  position  shown  in  dotted  lines. 

B.  Balling  Heat  Processes. — If  we  use  a  temperature  so 
high  that  the  product  may  be  welded  or  balled,  deoxida- 
tionismore  rapid,  and,  as  the  danger  of  reoxidation  is  less, 
it  is  not  necessary  to  cool  the  relatively  compact  prod- 
uct before  exposing  it  to  the  air :  hence  it  would  seem 
possible  to  lessen  the  cost  of  installation  per  unit  of  daily 
output,  and  the  outlay  for  interest  and  labor.  Further, 
we  are  saved  the  expense  of  compressing  the  product. 
Again,  it  is  now  possible  to  dephosphorize,  but,  alas,  only 
at  the  cost  of  heavy  loss  of  iron  On  the  other  hand, 
there  is  danger  of  carburizing  the  product,  and  the  con- 
sumption of  fuel  must  be  greater,  at  least  in  cases  of  rich 
ores.  Indeed,  we  directly  sacrifice  one  chief  advantage 
sought  by  the  direct  process,  the  saving  of  fuel  due  to 
lower  working-temperature.  Finally,  the  liability  to 
absorb  sulphur  is  aggravated,  both  because  the  larger 
proportion  of  fuel  brings  in  more  sulphur,  and  because  we 
can  hardly  avoid  bringing  the  ore  into  contact  with  the 
heating-fuel,  or  at  least  with  the  sulphurous  products  of 
its  combustion. 

We  will  now  consider  some  of  these  points  separately. 

I.  DephospJtor ization. — If  we  would  dephosphorize, 
the  slag  must  be  basic  so  as  to  hold  the  phosphorus  as 
phosphate,  and  so  fluid  that  it  either  separates  from  the 
metal  before  or  during  balling,  or  can  be  removed  by 
hammering  or  squeezing ;  for  if  it  remains  mechanically 
held  in  the  balls,  its  phosphorus  will  be  deoxidized  and 
will  unite  with  the  iron  as  soon  as  the  balls  are  melted  in 
contact  with  acid  slag,  whether  in  the  acid  open-hearth  or 
in  the  crucible  process.  But  it  can  only  be  made  fluid  by 
the  presence  of  a  large  proportion  of  iron-oxide,  and  this 
of  course  means  large  loss  of  iron.  The  silicates  of  the 
alkaline  earths  are  not  fluid  enough  at  this  temperature 
to  be  squeezed  out :  the  alkalies  and  manganese-oxide  are 
too  costly  to  be  usel  as  fluxes  :  iron-oxide  is  the  only  flux 
available  under  usual  conditions.  Strengthening  the  deoxi- 
dizing conditions  in  order  to  lessen  the  loss  of  iron,  not 
only  directly  opposes  dephosphorization  by  strengthening 
the  tendency  to  deoxidize  phosphorus  as  well,  and  thus 
cause  it  to  combine  with  the  iron,  but  further  and  indi- 
rectly by  depriving  the  slag  of  base,  (iron-oxide),  and  so 
removing  its  dephosphorizing  power,  and  of  liquidity  and 
so  preventing  it  from  running  off  with  whatever  phos- 
phorus it  contains. 

II.  Carbur  ization  is  more  likely  to  occur  if  we  use  a  balling 
heat,  both  owing  to  the  higher  temperature  and  to  the 
larger  proportion  of  fuel  employed  for  generating  that 
temperature.  If  the  operation  is  carried  out  in  shafts,  the 
same  fuel  both  heating  and  deoxidizing,  the  product  is 
very  likely  to  be  heterogeneous,  here  and  there  absorbing 
a  considerable  quantity  of  carbon,  unless  we  permit  a  very 
heavy  loss  of  iron :  this  unfits  it  for  direct  use  as  wrought- 
iron,  but  it  is  not  a  serious  disadvantage  when  material  for 
the  open-hearth  or  crucible  process  is  sought. 

If  the  ore  is  inclosed  in  retorts,  we  may  add  enough  car- 
bon to  deoxidixe,  with  no  excess  so  considerable  as  to  cause 
serious  carburization  :  unfortunately  it  is  not  practicable 
to  bring  material  within  a  retort  to  a  welding  heat  by  heat 


THE    DIFFICULTIES    OF    THE    DIRECT    PROCESS. 


315. 


265 


applied  outside  it,  for  we  have  no  material  of  which  we 
could  make  a  retort  that  could  enduiv  the  temperature  to 
which  the  outside  would  have  to  be  exposed  Balling  pro- 
cesses cannot  be  carried  out  in  retorts. 

If  deoxidation  occur  in  o(en  reverberatory  furnaces,  a 
certain  but  not  excessive  amount  of  carburization  may  be 
looked  for.  As  the  atmosphere  is  usually  strongly  oxi- 
dizing towards  iron,  a  considerable  excess  of  carbon  must 
be  added,  so  that,  after  deoxidizing  the  ore,  there  may  be 
enough  to  re-deoxidize  any  iron  which  reoxidizes.  If  the 
balls  are  for  the  open-hearth  or  crucible  process,  it  is 
desirable  that  they  should  retain  a  little  carbon  to  deoxi- 
dize during  fusion  any  iron  reoxidized  after  leaving  the 
deoxidizing  furnace.  Now,  as  different  proportions  of 
this  excess  will  be  consumed,  not  only  in  different  charges 
but  in  different  parts  of  the  same  charge,  local  excesses  of 
carbon  will  remain  here  and  there,  and  will  carburize  the 
metal  locally. 

Clearly,  the  more  difficultly  oxidizable  the  reducing 
agent,  the  less  of  it  will  be  attacked  by  the  atmosphere  of 
the  reducing  furnace,  the  more  will  persist  till  the  metal 
is  formed  into  a  solid  bloom  or  is  melted,  i.  e.,  till  danger 
of  reoxidization  is  passed,  and  hence  the  smaller  excess 
will  it  be  necessary  to  add.  To  this  m  y  be  attributed 
the  encouraging  yield  obtained  in  the  Eames  process  (§ 
340),  in  which  the  difficultly  oxidizable  graphitic  anthra- 
cite or  "retarded  coke"  is  used. 

III.  Heterogeneousness.—  Wrought-iron  made  directly 
from  direct-process  balls  should  be  heterogeneous  not  only 
from  local  carburization  already  dwelt  on,  but  from  the 
presence  of  slag,  unless  excessive  loss  of  iron  is  permitted, 
for  reason  already  given  in   cons  dering  dephosphoriza- 
tion.     The  gangue  of  the  ore  can  only  be  converted  into  a 
slag  fluid  enough  to  be  thoroughly  expelled  by  converting 
it  into  a  highly  ferruginous  silicate,  and  this  except  with 
the  very  richest  ores  means  heavy  loss  of  iron.     More- 
over, local  excesses  of  carbon  are  likely  to  reduce  the  iron 
here  and  there  from  this  slag,  and  thus  remove  its  fluidity 
and    make  the  metal    unforgeable  from  slag-shortness. 
Further,  if  the  deoxidizing  conditions  are  so  gentle  that 
enough  iron-oxide  remains  to  make  all  the  slag  fluid, 
there  may  be  enough  unscorified  iron-oxide  to  cause  red- 
shortness.     So  gentle  deoxidation  leads  to  red-shortness, 
and  heavy  loss  of  iron,  strong  deoxidation  to  slag-short- 
ness, local  carburization,  and  retention  of  phosphorus. 

IV.  Deoxidation  and  Reoxidation. — As  the  affinity  of 
oxygen  for  the  carbon  with  which  the  ore  is  in  contact  in- 
creases with  rising  temperature  relatively  to  its  affinity 
for  iron,  so  it  should  be  easier  to  deoxidize  at  a  balling 
heat  in  shaft-furnaces,  charcoal  hearths,  etc.,  in  which  an 
excess  of  carbon  is  present,  than  at  a  sponge-making  heat 
in  retorts  :  moreover,  in  balling  we  weld  the  spongy  metal 
together,  close  its  pores,  and  so  remove  or  greatly  lessen 
its  tendency  to  reoxidize 

In  open  reverberatories  the  higher  temperature  needed 
for  balling  implies  a  more  strongly  oxidizing  atmosphere 
(unless  some  device  such  as  Morrell' s  succeeds),  and  hence 
more  difficulty  in  deoxidizing  and  greater  proneness  to 
reoxidize,  than  in  sponge-making  processes. 

In  short,  the  loss  of  iron  should  be  less  in  balling  than 
in  sponge-making  direct  processes  when  shafts  and  re- 
torts are  used,  but  greater  when  open  reverberatories  are 
used, 


V.  The  Fuel-Requirement. — To  raise  the  charge  to  a 
welding  temperature  we  clearly  need  more  heat  than  in 
the  relatively  cool  sponge-making  process  :  but  this  dis- 
advantage of  the  balling  processes,  while  real  in  case  of 
preparation  for  the  crucible  process,  disappears  if  the  hot 
balls  are  plunged  as  soon  as  formed  into  the  bath  of  the 
open-hearth  furnace,  the  whole  of  their  sensible  heat 
being  thus  utilized,  while  in  the  most  promising  sponge- 
making  processes  (Chenot's,  Blair's,  Tourangin' s)  the  heat 
used  in  heating  the  ore  is  thrown  away  when  the  spongy 
iron  cools.  Be  it  remembered  that  the  sensible  heat  thus 
utilized  in  case  of  balling  processes  has  in  many  of  them 
(e.  g.  those  which  heat  by  direct  contact  with  solid 
fuel),  been  imparted  in  furnaces  which  are  much  more 
efficient  transferors  of  heat  than  the  open-hearth  furnace, 
and  hence  represents  a  much  smaller  outlay  for  fuel  than 
would  be  needed  to  raise  the  metal  to  the  same  tempera- 
ture in  the  open-hearth  furnace. 

This  consideration,  in  case  of  rich  ore,  still  farther  in- 
creases the  fuel-economy  which  we  may  hope  that  the 
direct  process  will  effect  over  the  blast-furnace  ;  and  the 
same  is  true  in  case  of  lean  ores,  if  the  balling  heat  be 
high  enough  and  the  loss  of  iron  great  enough  to  convert 
the  gangue  into  a  slag  so  liquid  as  to  separate  itself  from 
the  metal,  so  that  the  balls  carried  to  the  open-hearth 
furnace  are  nearly  pure  iron.  But  if,  in  treating  lean 
ores,  this  be  not  done,  then  the  advantage  of  the  balling 
direct  process  over  the  blast-furnace, — that  the  sensible 
heat  given  the  iron  is  preserved  by  plunging  the  hot  balls 
into  the  open-hearth  bath, — may  be  greatly  outweighed 
by  the  fact  that  we  now  have  to  heat  the  gangue,  in  the 
open-hearth  furnace,  to  a  temperature  much  higher  than 
than  that  of  the  blast-furnace,  and  that  the  efficiency  of 
the  open-hearth  furnace  as  a  heating  apparatus  is  probably 
hardly  one-third  as  great  as  that  of  the  blast-furnace. 
The  same  objection  applies  to  sponge-making  processes  as 
applied  to  lean  ores.  Hence,  if  this  class  of  ore  is  to  b  3 
treated  by  any  direct  process,  it  should  be  by  one  using  a 
balling  heat  so  high  that  the  slag  liquefies  and  separates. 

C.  Steel-Metting-Heat  Processes. — If  the  process  is  car- 
ried out  in  a  shaft  furnace  at  a  steel-melting  heat  we  have 
at  once  a  cast-iron-making  and  not  a  direct  process.  Hence 
a  direct  process  at  a  steel-melting  heat  can  hardly  take 
place  except  in  an  open  reverberatory,  as  in  F.  Siemens' 
process,  or  in  crucibles,  as  in  Mushet's. 

I.  In  Open  Reverberatories.— As  a  basic  lining  would  be 
essential,  we  are  brought  pretty  near  to  the  pig-and-ore 
process  in  the  basic  opon  hearth  furnace.  Clearly  phos- 
phorus would  be  removed.  The  sulphur  of  the  reducing 
fuel  would  be  taken  up  by  the  iron,  but  later  removed 
at  least  in  part  by  the  lime  slag.  But  though,  as  far  as 
fluidity  is  concerned,  the  slag  does  not  need  iron  oxide,  for 
basic  lime-silicates  are  fluid  at  this  temperature,  yet  it  is 
hard  to  see  how  we  could  avoid  heavy  scorification  and 
loss  of  iron  without  employing  a  very  great  excess  of  re- 
ducing fuel,  of  which  at  any  rate  a  great  excess  should  be 
needed  to  compensate  for  its  rapid  oxidation  by  the  atmos- 
phere of  the  furnace.  This  must  be  violently  oxidizing  to 
yield  the  extreme  temperature  needed  to  m  jlt  and  keep 
molten  the  metal,  which  would  be  almost  absolutely  car- 
bonless  and  hence  extremely  infusible,  thanks  to  the  con- 
tinual influx  of  ore. 

Further,  this  class  stands  at  a  disadvantage,  compare  I 


266 


THE    METALLURGY    OF    STEEL. 


with  the  balling  processes,  in  having  to  heat  not  only  the 
iron  but  < he  oxygen  of  the  ore  and  the  products  of  the 
combustion  of  the  reducing  fuel  to  a  steel-melting  heat, 
in  a  relatively  inefficient  heating  apparatus.  The  thermal 
capacity  of  chemically  pure  ferric  oxide  per  degree  of 
temperature  is  probably  about  twice  that  of  the  iron  which 
it  contains.  If,  in  addition,  the  ore  contains  much  gangue, 
the  necessity  of  heating  this,  with  its  very  high  specific 
heat,  (on  an  average  probably  about  double  that  of  iron) 
to  a  steel-melting  heat  puts  the  process  out  of  the  race. 

II.  In  Crucibles  (Mushet's  process). — Here  the  same 
objections  apply  with  greater  force.  Moreover,  the 
quantity  of  iron  in  the  charge  of  ore  and  charcoal  which 
could  be  placed  in  a  crucible  of  given  size,  would  probably 
be  only  about  one-tenth  as  great  as  when  we  pack  the 
crucible  with  metallic  iron  bars,  taking  into  account  the 
lightness  and  irregular  shape  of  the  iron  ore  and  charcoal. 
The  cost  of  melting  by  the  crucible  process  is  about  $12.00 
per  ton  of  ingots,  with  the  cheap  fuel  of  Pittsburgh.  It 
would  cost  nearly  as  much  for  fuel,  crucibles  and  labor  to 
melt  a  crucible-full  of  ore  and  charcoal  as  one  of  iron : 
so  that  the  cost  of  such  an  operation  might  be  roughly 
estimated  as  about  $100.00  per  ton  of  matal  produced,  in 
addition  to  the  ore  and  charcoal,  or  $0.05  per  pound. a 
This  should  frighten  the  wildest  dreamer,  as  crucible  steel 
is  quoted  at  4£  cents  per  pound. 

§  316.  CLASSIFICATION  BY  MODE  OF  HEATING. — The 
direct  processes  may  be  further  classified,  as  in  Tables 
153-4,  into  those  in  which  the  heating  fuel  serves  also  for 
deoxidation,  and  those  in  which  separate  fuel  is  used  for 
deoxidation. 

The  former  class  may  be  divided  into  those  (A)  which 
use  solid  and  those  (B)  which  use  gaseous  fuel ;  the  latter 
into  those  (C)  in  which  the  ore  is  inclosed  in  externally 
heated  retorts,  those  (D)  in  which  it  is  heated  by  a  current 
of  hot  gas  passing  through  it,  and  those  (E)  in  which  it  is 
treated  in  open  reverberatories. 

At  the  risk  of  repetition  I  will  discuss  these  classes 
briefly,  first  pointing  out  that  C  is  almost  necessarily  a 
sponge-making  process,  while  the  other  classes  may  be 
either  balling  or  sponge-making,  if  not  steel-melting. 

TABLE  153.— DIEECT  PROCESSES  CLASSIFIED  BY  MODE  or  HEATING. 


Order  of  merit  (I  best,  V  worst). 

Fuel-econ- 
omy. 

0*3 

II 

o 

<B  ej 

cc  o 

oi 

tt 

Dephosphor- 
ization. 

Heating  and  deoxidation  by  /A.  By  solid  fuel. 

I. 
III. 

V. 
II. 
IV. 

III. 
V. 

I. 

IV. 

II. 

V. 
IV. 

I. 
III.? 

IU 

I. 

V. 

V. 
I. 

the  same  fuel.                     \  B.  By  gaseous  fuel 

/C.  Ketorts    etc.,    heated  cxter- 
Heating  fuel  distinct  from)           nally 

reducing  fuel.                   "S  D.  Internally  heated  vessels  
\E.  Open  revWberatories  

A.  Fuel  Economy.— In  treating  relatively  poor  ores,  in 
which  the  proportion  of  gangue  is  so  considerable  that  we 
must  slag  it  away  before  further  treatment,  and  in  which 
consequently  we  must  reach  a  slag  melting  temperature, 
the  direct  contact  of  the  solid  heating-fuel  with  the  ore 
should  give  class  A  the  best  fuel-economy.  D  is  a  little 
worse  off  than  A  in  case  artificial  gas  is  used,  because  of 

a  To  produce  100  of  iron  would  take  say  170  of  ore  and  30  of  charcoal  by 
weight.  Considfiring  the  greater  irregularity  of  the  lumps  of  charcoal  and  of  ore 
than  of  the  rectangular  closely  fitting  pieces  of  iron,  we  may  estimate  that  the 
pound  of  ore  will  occupy  twice  as  much,  and  one  of  charcoal  twenty-five  times  as 
much  space  as  one  of  iron,  so  that  we  need  170  x  2  +  30  x  25  =  1,090  volumes 
pf  ore  and  oharcoal  where  we  would  have  but  100  of  closely  packed  iron, 


the  necessarily  great  waste  of  heat  in  gasification  ;  and 
for  the  same  reason  B,  in  which  all  the  fuel  is  gaseous,  is 
still  worse  off.  But  as  in  B  and  D  the  heating  is  by  direct 
contact  of  gas  passing  through  the  charge,  the  fuel-economy 
should  be  better  than  in  E,  in  which  the  heating  is  chiefly 
by  radiation  from  flame  passing  over  the  charge.  Last  of 
all  comes  C,  in  which  the  heating  is  by  conduction,  usually 
through  fire-clay,  itself  heated  not  by  direct  contact  with 
solid  fuel,  but  less  efficiently  by  passing  flame.  The  order 
of  merit  then  is  A,  D,  B,  E,  C. 

If  in  treating  extremely  rich  and  almost  gangue-less  ores 
B,  C,  D,  and  E  were  used  as  sponge-making  processes,  the 
order  of  fuel-economy  would  probably  be  the  same.  I 
will  again  point  out  that  the  necessarily  balling  division 
A  is  only  under  an  apparent  disadvantage  in  having  to  heat 
the  charge  to  a  higher  temperature  than  the  sponge-making 
processes,  because  the  higher  temperature  is  a  great  ad- 
vantage when  the  hot  product  is  immersed  in  the  bath  of 
the  open-hearth  furnace. 

B.  Absorption  of  Sulphur  and  Carbon. — In  both  re- 
spects class  C  stands  best.     Indeed,  by  adding  only  a  very 
slight  excess  of  carbon  over  that  needed  to  deoxidize  the 
iron  by  the  reaction  Fe2O3  +30  =  2Fe  +  SCO,  or  32%, 
the  absorption  of  carbon  may  be  practically  completely 
prevented.     In  B  and  D  a  considerable  absorption  of  car- 
bon would  be  looked  for,  since  the  carbonic  oxide  of  the 
gas  should  deposit  carbon  if  an  excess  of  carbon  over  that 
needed  for  reduction  is  present.     But  it  is  reported  that, 
for  reasons   unknown,    when   producer  gas   made    from 
charcoal  is  used,   the  sponge  is  nearly    or    quite    free 
from     deposited     carbon.       When,     however,     natural 
gas    is    used,    it    deposits    carbon    copiously.      As    in 
many    parts    of    this    country    natural    gas    is    very 
cheap,    some     device    by    which     the     deposition     of 
carbon     from     it     can      be     prevented     is      urgently 
needed. 

The  absorption  of  sulphur  should  be  high  and  about 
alike  in  A,  B,  and  D,  since  in  all  three  the  charge  comes 
in  contact  with  the  whole  of  the  fuel,  though  with  less 
fuel  in  A  than  in  D,  and  less  in  D  than  in  B.  In  E  it 
should  be  greater  than  in  C  but  less  than  in  the  others, 
since  part  of  the  sulphur  of  the  flame  may  be  taken  up  by 
the  charge. 

The  order  of  merit  then  as  regards  sulphur  absorption, 
should  be,  C,  E,  A,  D,  B. 

In  A,  D  and  B  the  opportunity  for  absorbing  sulphur  is 
so  great  that  it  is  extremely  desirable,  if  not  almost  abso- 
lutely necessary,  to  use  sulphurless  fuel,  such  as  charcoal, 
natural  gas,  or  desulphurized  artificial  gas. 

C.  Dephosphor  Lzation  and  loss  of  iron  usually  accom- 
pany each  other,  though  it  is  quite  possible  in  the  sponge- 
making  varieties  of  B,  C,  D,  and  E  to  lose  much  iron 
without  dephosphorizing.     Dephosphorization  and  loss  of 
iron  should  reach  a  maximum  under  the  oxidizing  condi 
tions  of  E,  if  a  slag-melting  heat  be  reached,  and  a  mini- 
mum in  C. 

317.  THK  FUTURE  OF  THE  DIRECT  PKOGESS. — To 
sum  up  what  has  gone  before  :  the  direct  process  is  chiefly 
adapted  to  preparing  material  for  the  open-hearth  and 
crucible  processes. 

There  seems  little  reason  to  expect  that  it  can  be  ap- 
plied to  lean  ores,  unless  they  be  very  cheap,  since  it 
cannot  remove  their  gangue  except  with  fearful  loss  of  iron. 


FUTURE    OF     DIRECT     PROCESSES.       §317. 


267 


Incase  of  rich  ores,  it  holds  out  good  hope  of  produci  i.u 
a  ton  of  malleable  iron  with  less  fuel,  but  with  greater 
outlay  for  labor,  than  is  needed  to  make  a  ton  of  cast-iron 
in  the  blast-furnace. 

It  can  remove  phosphorus,  but  this  implies  heavy  los: 
of  iron.  In  any  event  the  loss  should  be  greater  than  in 
the  blast-furnace. 

The  sponge-making  processes  are  very  heavily  handi- 
capped by  their  small  output  if  the  sponge  be  cooled  before 
drawing,  by  the  heavy  loss  of  iron  if  it  be  not.  The  use  of 
natural  gas  or  of  lime  may  indeed  enormously  increase  the 
output :  but  the  trouble  of  cooling  the  sponge  before  draw- 
ing still  remains. 

In  the  steel-melting-heat  processes  the  f  uel-consiimption 
will  probably  be  greater  not  only  than  in  other  direct 
processes,  but  even  than  in  the  blast-furnace.  Moreover, 
the  loss  of  iron  is  likely  to  be  excessive. 

The  balling  processes  seem  to  hold  out  the  most  promise. 
Of  the  many  processes  which  have  been  proposed  and 
tried,  only  those  of  this  class  show  any  vitality,  the 
American  bloomary,  the  highbloomary  (e.  g.  Ilusgaf vel' s), 
the  Eames  process.  Whether  the  last  will  stand  the  test 
of  prolonged  use  remains  to  be  seen.  This  class  has  the 
advantage  of  getting  rid  of  the  gangue  at  once  :  of  deli- 
vering hot  balls  ready  for  the  open-hearth  process :  of 
dephosphorizing.  On  the  other  hand  the  loss  of  iron  is 
considerable,  the  product  somewhat  carburetted  and 
heterogeneous  ;  but  these  last  two  objections  are  of  little 
weight  in  preparing  materials  for  the  open-hearth  process. 
If  carried  out  in  shafts,  the  sulphur  of  the  fuel  is  absorbed 
by  the  iron,  but  the  consumption  of  fuel  should  be  small. 
If  in  open  reverberatories,  more  fuel  is  consumed,  but  the 
iron  does  not  take  up  the  sulphur  of  the  heating  fuel. 

These  balling  processes  then  should  be  best  suited  to 
places  where  ore  is  cheap,  sulphurless  fuel  available  at  a 
price  which  does  not  put  it  out  of  competition  with  sul- 
phurous blast-furnace  fuel,  and  the  open-hearth  process 
at  hand  to  consume  the  balls. 

If  direct  processes  offer  real  advantages,  why,  we  are 
asked,  have  they  failed  so  often,  so  almost  universally  ? 
Knowing  that  the  blast-furnace  has  defeated  them  in  the 
past,  how  can  we  expect  them  to  compete  with  it  in  the 
future  ? 

First,  their  failure  has  not  been  so  complete  as  many 
believe.  Remember  the  steam-engine  before  Watt.  Num- 
berless foolish  processes  have  failed,  but  even  so  crude  and 
wasteful  a  process  as  the  American  bloomary  has  yielded 
a  profit,  directly  or  indirectly,  within  a  few  miles  of  elabor- 
ately equipped  and  apparently  well-situated  blast-furnaces 
which  in  the  same  period  have  failed.  And,  passing  by 
the  rather  feeble  existence  of  Guiit's  and  of  the  Catalan 
process,  we  have  the  present  increased  activity  of  the  high 
bloomary  as  modified  by  Husgafvel,  even  in  face  of  a  very 
great  shrinkage  in  prices. 

Next,  we  can  see  reasons  why  the  direct  process  has 
failed  in  the  past  which  apply  with  much  less  force  to  the 
future.  The  blast-furnace  process  was  stumbled  into, 
along  the  path  of  least  resistance.  It  was  developed  with 
little  comprehension  of  the  principles  on  which  it  rests. 
At  one  end  \ve  have  the  modern  blast-furnace  :  to  manage 
this  with  highest  efficiency  demands  skill,  knowledge, 
talent.  At  the  other  we  have  the  crudest  forms  of  charcoal- 
hearths,  and  in  these  it  is  probably  easier  to  make  wrought- 


than  cast-iron.  But  as  we  begin  to  elaborate  the  process 
and  seek  greater  fuel-economy,  greater  output,  and  less 
loss  of  iron,  it  becomes  easier  to  make  cast-  than  wrought- 
iron :  hence  the  line  along  which,  thanks  to  existing  ignor- 
ance, development  began :  and  the  tendency  of  develop- 
ment to  follow  its  original  lines  need  not  be  dwelt  on. 

As  the  desire  to  economize  fuel  and  increase  output  led 
to  lengthening  the  charcoal-hearth  into  the  shaft- furnace, 
the  difficulty  of  removing  from  beneath  the  overlying 
charge  shapeless,  unwieldy,  pasty  masses  of  wrought- 
iron  and  of  forging  them,  and  the  ease  of  running  molten 
cast-iron  into  easily  handled  pigs,  led  irresistibly  to  the 
development  of  the  cast-iron-making  rather  than  of  the 
direct  process.  To-day  the  former  has  reached  an  ex- 
traordinary degree  of  efficiency :  probably  few  human 
devices  have  so  closely  approached  the  highest  perfection 
of  which  in  their  very  nature  they  are  capable.  Fifty 
years  ago  nearly  thrice  as  much  fuel  was  often  used  as  is 
to-day  needed  in  our  best  blast-furnaces. 

The  direct  process,  on  the  other  hand,  while  easy  if 
wastefully  conducted,  becomes  extremely  difficult  the 
moment  we  attempt  high  fuel-economy.  We  must  guard 
against  the  absorption  of  sulphur  and  keep  that  of  carbon 
within  limits.  If  we  make  sponge  we  must  guard  against 
reoxidation :  if  we  make  balls  in  a  furnace  economical  of 
fuel,  to  wit  a  shaft-furnace,  we  have  the  serious  difficulty 
of  forming,  withdrawing  and  further  handling  them. 

To  do  all  this  demands  a  high  degree  of  metallurgical 
and  engineering  talent  and  knowledge,  and  just  for  lack  of 
these,  as  I  take  it,  direct  processes  have  failed  in  the  past. 
But  to-day  our  knowledge  is  greater  the  amount  of  trained 
talent  available  for  solving  difficult  metallurgical  prob- 
lems incomparably  greater  than  formerly,  and  both  knowl- 
edge and  the  quantity  of  available  talent  are  increasing 
rapidly. 

Just  as  the  open-hearth  process  failed  in  the  hands  of 
the  greater  man,  Josiah  Marshall  Heath,  who  realized  its 
intrinsic  merits,  but  succeeded  later  under  Martin,  thanks 
to  the  better  technical  appliances  and  skill  of  his  day  : 
just  as  advancing  civilization  constantly  sees  the  more  dif- 
ficult, when  capable  of  being  made  more  economical,  win 
a  place  beside  the  easier,  the  triple  expansion  compete 
successfully  with  the  single-cylinder  engine,  the  automatic 
cut-off  with,  the  plain  slide-valve,  the  railway  with  the 
coach  ;  so  may  we  hope  that,  the  obstacles  in  the  way  of 
the  direct  process  understood  and  overthrown,  its  disad- 
vantages minimized,  it  will  win  a  place  of  real  importance, 
under  the  special  conditions  which  favor  it,  rich  ores  and 
cheap  sulphurless  or  desulphurized  fuel. 

It  is  clearly  fallacious  to  reason  that  the  process  will 
never  succeed  because  the  past  usually  ill-advised  attempts 
have  failed,  have  wasted  much  iron  and  more  gold,  have 
used  more  fuel  than  the  blast-furnace  and  puddling  com- 
bined ;  because  the  direct  process  in  the  infancy  of  its 
intelligent  life  was  weaker  than  the  blast-furnace  in  its 
perfection.  They  failed  because  they  did  not  overcome 
obstacles,  often  unseen,  not  understood,  serious,  but  not 
in  their  nature  insuperable.  They  failed  not  because 
the  direct  process  lacked  capability  but  because  it  was 
difficult. 

But  a  new  and  most  promising  feature  is  our  natural  g  as 
If  with  the  most  reckless  waste  it  competes  easily  with 
slack  co^l  costing  $0.90  per  ton,  it  should  compete  easily 


2G8 


THE    METALLURGY    OP     STEEL. 


with  coke,  which  costs  about  $2.00  per  ton  even  at  Pitts- 
burgh. It  has  enormous  advantages  in  its  freedom  from 
sulphur  (if,  as  reported,  it  be  usually  free  from  sulphur), 
and  in  its  cheapness.  A  greater  stimulus  to  the  direct  pro- 
cess could  hardly  be  imagined.  As  we  do  not  see  how 
natural  gas  cai  be  used  to  a  great  extent  in  the  blast-fur- 
nace, we  may  expect  its  successful  application  to  the  direct 
process.  It  has,  indeed,  already  given  encouraging  results 
in  the  Eames  process  :  in  shaft-furnaces  the  consumption 


of  gas  should  be  less  and  the  loss  of  iron  less,  while  the 
graphite  or  retarded  coke  of  the  Eames  process  could  be 
replaced  by  natural  gas,  which  would  thus  both  heat  and 
deoxidize. 

If  the  wasteful  American  bloomary  can  exist  where 
charcoal,  labor  and  rich  fine  ores  are  cheap,  some  such 
improvement  of  it  as  Ilusgaf vel' s,  which  reduces  the  cost 
of  fuel-consumption  enormously,  should  flourish.  With 
some  quick  way  of  cooling  the  sponge,  some  modification 


TABLE  154. — GENERAL  SCUKMK  OF  TUB  PIKKCT  PnoCBasXB. 


Description. 

Bate,  approx  mately.  a 

Fuel  consumption.  1* 

Labor. 

T.OK8  Of  ifoll. 

Described 
o  r    pat 
ented  ii 
A.  D. 

Used   In 
A.  D. 

A  b  an  d  o  n  cd   or 
not.  e 

Per  100  o 

For 
rot}  uolng. 

For 
heating. 

Total. 

IVi-    2,000 
Ibs.  of 

Dajs 

From    .in 
to 

IV-i-  100  of 

iion     tn 
ore. 

Oro  reduced  by  solid  tad  and  heated  by  other  than  the  reducing  fuel.  Ore  ^^  ^  ^^  w  ^  _  Ore  reduced  and  heated 

Reduction  in  open  reverberatories.  Eeduction  in  retorts,  shaft-furnaces,  etc?  «™  in  a  shaft-furnace  or  retort.  fuel  ^^00^1  balled! 

'  Cha 
hear 

lifc'pi 

Shaf 
nace 
proce 

t 

o. 
£• 

5* 

! 
i 

be 

a 
o 

& 

to 

+  &  • 

Jin 

r 

to 

5 
Hi 
"•1  . 

E£ 

K 

I 

C, 

I 

i 

?| 

"•  ?  - 

It 
,11 

'  4  i*« 
IP 

00  «  & 

ri 

CJ 

ti> 

c 

1 

£<•>• 

It- 

11 

to  J3 

r-coaZ- 
«As,  ball-  ^ 
ocesses  . 

t-fur- 

S,  balling  ^ 

SS6S. 

'  Gurlt's 

passed 
sponp; 

Cooper 

throng- 
duced 
throng 

Touran 

ducer 
to  heal 

,  Laurea 
f  Bull.    ( 
melted 
shaft-fi 

!  Lucas 
Kont.il 
Chenot' 
charcoi 
,     torts  h 
cooled 

Blair's 

charcoi 
„     In  tern  a 

f  Clay's 

retorts 
sponge 
and  ba 

Schmid 

charcoB 
of  hot  i 
DuPuy 

^      charco.i 

f  Mushct 
in  cruc 

Siemens 
retort 
type. 

'  Thoma; 

in  an 
copper 

Harve 

Gerhan 

Eame 

C.   W. 

,      rotary 

Leckie 

F.  Sieiru 
Eustif 

'  Catalan  and  Corsican  h 
fuel  in  separate  colun 
American  Moomary, 

•arths,  ore  am 

l,:u-s. 

2W)  (ft  S(J 
190  @  321 

Lars, 
blooms. 

19-7 
1'25@1-S 

tan. 

blooms. 

27  <£  Alt 
17®  25 
83@50 

'iv    and    fue 

"  Osmund  furnace,  a  ver 
German  hij*h  bloouiary 

(atiickofen),  a 

280  @  4ft 
105  @  14.' 
121 
S4h 
90  h 

blooms, 
blooms. 

12 
4 

llus^ufvi-l's     liloomar} 

,    still    taller. 

now  In  use 

blooms, 
blooms, 
blooms. 

21@28 
8'1!S  f 
10       ? 

Ny  ham  mar  bloouiary, 
raked  inlo  charcoal  h 

type  ;    carbonic    oxide 
through     ore,    product- 
ir«m  . 

5,  carbonic  oxide  passed 
i  ore,  resulting  CC>2  re-_ 
to     CO     by    passing" 
h  fuel,  etc. 

jin.     Hot  CO  from  hot 
mssed  through  ore:  resid 
the  blast 

spoiiiry    iron 
>arth 

1882 
1856 

1882  ± 

1884 

/flurlt 

« 

J  Chenot   d'i- 

1  rect-heating. 
[  l^uiidohr.  .  . 

probably  in  use. 
abandoned. 

1871 

1S73  ± 

1888 

blast  gas  pro 
ml  CO  burned 

1882 
1889  ± 

1883 
1702 

u.     (Application  for  patent  pending).. 
>re  reduced  and   heated  and  pr<  duct 
by  combustion  of  hot   water-gas  in 

projected. 

abandoned. 

east   iron. 

700 

Oro    reduced    in  hori-_ 
•etorts  with  charcoal. 
s  type.   Oro  reduced  try 
I  or  coke  in  vertical  re- 
nted externally:  sponge 
»cfore  removal, 

later:  Ore  reduced   by 
1  in  vert,  retorts  heated 
lly  by  hot  carbonic  oxide 

ype.      Ore   reduced  in 
over  puddling  furnace: 
dropped  into  puddler"* 
led. 

hammer.     Oro  reduce* 
1,  and  heated   directly  b 
vater-gas:  balled  in  foreli 
Ore  reduced  in  sheet 
1:  resulting  sponge  rolled 

Reduction  and  fusion 
ble 

/'Chenot.  .  .  , 
Blair..  .   . 

1831 
1872 

abandoned. 

abandoned. 

H 

iron  in  ore- 
ingots. 

i>5  @  48 
4S  c 

96  @  157 
68  0 

1!)1  (ft  205 
101  c 

iron  in  ore 
ingots. 

3-3 

l-8c 

bloom*. 

ingots 

86  ± 
24 

>•  Blair... 

/Clay 

1837 

ISM 
1884 
1862 

1886 
1878 

1800 
1H6S 

1SG8 
1MB 

Renton  .    .. 
Wilson.  .  .  . 

•1 

blooms. 

180 

urn  ± 

250  ± 

in  shaft  by 
y  combustion 

iron  cases  by 
out  into  bars 

with  charcoal 

abandoned. 

blooms. 

2!'5 

(Ore  reduced  in  vert, 
retorts  within  opon- 
hearth        furnaces; 
sponge  melted    by 
bath  of  cast-iron  in 
the  same  furnace. 

ore  uniformly  mixed  vit 
open  reverberatory;  spo 

'Siemens.  .. 

yPonsard.  .  . 

i  coal,  heated 
nge  used  for 

...( 

aband'n'd  within  ( 
a  few  years,      J 

ron  in  ore 

45 

114 

1K9 

sponge,  -j 

appar'ntlj 
1« 

f  Ore    reduced  with    charcoal    on 
y.  •<      shelves    above     reverb.,    then 

ISM  ± 

187-t 
1886-9 

1S73 

ISfiD  ± 
1887  ± 

-nsso 

I 

fOre  bricked   with  tar,  flux,   and 
It.  \      carbonaceous  matter  in  a  pud- 

/  Reduction    with     graphite,    and 
'•    \     balling,  in  open  reverberatory.. 
Siemens*   reduction    and    balling  In 

now  in  use. 

abandoned. 

abandoned, 
projected, 
abandoned. 

balls, 
blooms. 

balls, 
blooms. 

1-17 
5-5 

ingots, 
blooms. 

21-< 
12@25 

18R1 

2S  f  @  138 

126  g»  237 

149  @  875 

TOre  bricked  with  co 
fore  hearth  of  op 
\     nace,  then  melte'i 
/Melted  ore  reduce 
1     open  -hearth  furnji 
/Ore  coked   with  c< 

al,  reduced  in 
en-hearth  fur 
on  its  hearth. 
1  by  coal  in 

al,  melted  in 

a  Dates.    No  attempt  has  been  made  to  tnic.e  the  earliest  and  latest  dates.     I  give  simply  those  met  in  a  superficial  examination,  without  aim  at  historical  methods. 

b  Fuel.     In  certain  cases  the  consumption  of  charcoal  is  j-iven  in   bushels  :  I  have  in  these  cases  assumed  a  probable  weight  for  the  bushel :  but  this  is  only  a  guess. 

c  The  quantity  of  fuel,  etc.,  is  used  in  sponge-making,  per  100  parts  of  ing'-ts  obtained  from  the  resulting  sponge. 

e  "Abandoned"  is  not  meant  to  imply  that  the  projector  has  abandoned  all  hope,  but   that  operations  are  suspended  or  practically  so,  according  to  such  informatio 

t  This  process  or  its  equivalent  was  in  use  till  within  a  few  years. 

gThe  kind  of  rotort  used  is  not  given. 

h  Fuel  used  in  sponge-making,  per  100  of  blooms  made  in  charcoal-hearth  from  the  sponge. 


.M-iln.-.l. 


CATALAN    PROCESS. 


318. 


269 


of  Gurlt's  process  should  under  the  same  conditions  be 
applicable.  Where  rich  ores  are  cheap  and  not  charcoal 
but  some  non  -blast-furnace  mineral  fuel  is  also  cheap  this 
same  process  should  be  applicable,  provided  the  producer- 
gas  which  it  uses  can  be  cheaply  desulphurized. 

The  pressing  problems  for  the  direct  process  then  seem 
10  be 

1,  The  application  of  natural  gas  in  some  shaft  furnace 
like  Husgafvel's. 

2,  Better  means  of  the  removing  the  balls  than  in  Hus- 
gaf  vel'  s  process. 

3,  Some  quick  cheap  way  of  cooling  sponge  for  sponge- 
making  processes. 

4,  An  automatic  compressing  apparatus  for  sponge,  so 
simple  that  a  single   mechanic   can  compress   enormous 
quantities  rapidly. 

5,  Some  cheap  way  of  desulphurizing  producer-gas. 
Let  not  us  who  have  seen  Thomas  solve  the  basic  prob- 

lem which  had  long  baffled  the  wisest,  say  that  this  goal 
unreached  is  unattainable. 

SOME  DIRECT  PROCESSES  DESCRIBED. 

Under  most  conditions,  whether  in  making  weld-metal 
to  be  used  as  such  or  in  making  material  for  the  open- 
hearth  or  crucible  process,  iron  relatively  free  from  carbon 
is  sought  :  and  I  assume  that  it  is  in  the  following  descrip- 
tions.  I  have  pointed  out  in  considering  the  sponge- 
making  and  balling  processes  (§§  31,5,  A,  B)  how  a  carbur- 
etted  product  may  be  obtained. 

§  318.  IN  THE  CATALAN  PROCESS  ore  and  charcoal  are 
charged  in  separate  columns  in  a  low  one-tuyered  hearth, 
the  column  of  charcoal  lying  between  tuyere  and  ore,  and  the 
deoxidizing  carbonic  oxide  generated  in  it  passing  through 
the  ore  column.  The  temperature  is  low  at  first,  to  avoid 
fusion  before  reduction,  later  reaching  a  welding  heat, 
when  the  pasty  iron  is  balled  beneath  the  charcoal. 

The  hearth  is  built  chiefly  of  heavy  iron  plates,  with  a 
tuyere  inclining  downwards  from  30°  to  40°.  The  follow- 
ing dimensions  are  given  : 

Area. 
Pyrenees  ........................  20"  X  20 

Navarre  .........................  80"  X  24"  .. 

Biscay  ...........................  40"  X  82"          24"  @  2 

After  cleaning  and  while  still  hot  from  the  last  charge, 
the  hearth  is  filled  to  the  tuyere  level  with  charcoal.  On 
this  the  ore  in  lumps,  not  more  than  two  inchjbs  cube, 
is  piled,  together  with  charcoal,  the  charcoal  against 
the  tuyere-side,  the  ore  against  the  other,  as  at  5,  Figure 
131,  a  sheet  of  iron  (later  removed)  separating  them.  The 


Total  depth.     IT  eight  to  tuyeres. 


16" 
14"-@  15" 


Charge. 
8@4cwt. 
5@  6     " 
7@9     " 


Figure  131.— Catalan  Hearth. 


talus-face  b  being  plastered  over  with  fine  moist  charcoal, 
the  blast  is  turned  on  gently  and  reduction  sets  in,  the 
gases  (chiefly  carbonic  oxide  and  nitrogen  thanks  to  the 


thickness  of  the  charcoal  body)  passing  by  preference 
through  the  open  pile  of  lump  ore,  and  escaping  at  its 
apex.  As  the  charcoal  burns  away  more  is  charged,  and 
with  it  is  added  fine  ore,  moistened  to  prevent  blowing 
away  and  sifting  down.  The  fine  ore  sinks  with  the  char- 
coal, apparently  reaching  the  zone  of  fusion  less  com- 
pletely deoxidized  than  the  lump  ore. 

After  two  hours  the  lump  ore  column  is  gradually 
pushed  downwards,  and  the  temperature  raised  ;  as  suc- 
cessive portions  of  the  ore  become  sufficiently  deoxidized 
they  are  pushed  into  the  hotter  region  nearer  the  tuyere. 
By  the  time  that  a  given  portion  is  pushed  into  the  hotter 
region  much  of  its  iron  has  reached  the  metallic  state, 
though  much  still  remains  more  or  less  oxidized.  The 
temperature  in  this  region  is  so  high  that  the  unreduced 
part  of  the  ore  melts  and  forms  a  slag  with  the  gangue, 
and  that  the  completely  reduced  part,  growing  pasty, 
welds  readily  into  a  bloom. 

The  whole  of  the  lump-ore  reduced  and  balled,  the  blast 
is  stopped  and  the  bloom  pried  out  of  the  hearth  and  ham- 
mered. It  is  reheated  in  the  upp«r  part  of  the  same  hearth 
while  a  second  charge  is  reducing. 

The  slags  are  essentially  basic  ferrous  silicates.  To  avoid 
carburizing  and  phosphorizing  the  iron  we  should  (1)  have 
plenty  of  highly  ferruginous  slag,  which  devours  phos- 
phorus and  carbon,  and  should  hence  add  much  fine  ore 
with  the  charcoal  and  tap  the  slag  but  rarely:  (2)  hasten  the 
operation  and  so  shorten  the  carburizing  and  phosphoi  izing 
exposure  :  (3)  use  much  blast,  to  weaken  the  reducing  and 
carburizing  tendencies  :  (4)  incline  the  tuyere  downwards 
towards  the  iron,  that  the  blast' s  oxygen  may  be  less  fully 
converted  into  carbonic  oxide  before  reaching  iron  and  ore, 
and  the  reducing  conditions  thus  weakened.  These  steps 
increase  the  necessarily  great  waste  of  iron,  and,  in  spite  of 
them  the  metal  is  liable  to  be  carburized  and  steely :  it  is 
necessarily  heterogeneous,  but  nearly  free  from  phosphorus. 

In  the  Genoese  modification  of  the  Catalan  process, 
which  aimed  at  fuel-economy,  a  flat-bedded  reverberatory 
received  the  hearth's  flame  at  one  end,  delivering  it  at  the 
other  through  a  horizontal  grating,  on  which  the  raw  ore 
was  piled,  into  a  vertical  chamber  leading  to  the  chimney. 
Roasted  and  somewhat  desulphurized  here,  the  ore  was 
next  made  friable  by  quenching  in  water  ;  was  crushed, 
spread  on  a  charcoal  layer  on  the  reverberatory' s  hearth, 
heated  by  the  flame  again  and  partly  reduced  by  the 
charcoal  on  which  it  lay  ;  was  here  mixed  with  cast-  or 
wrought-iron  scrap,  pushed  into  the  charcoal  hearth,  and 
further  reduced  and  balled. 

Some  economic  data  follow. 

Table  155. — CATALAN  HEARTH  PRACTICE. 


I. 

II. 

III. 

Percy,  1841. 

1840±,  Richard, 
Percy. 

1868,  Mussy, 
Phillips. 

368  ± 

884 

6  hours. 
6b 
19-T 
S'59 
30-9  a 

374 

2-00 
28-3 

»S1  99 
7.76 
813 
1-22 

149.10 

2  76 
27"2  a 

|42.  S2 

Loss  from  ore  to  bars,  per  100  of  iron  in  ore.  . 
Cost  per  2.000  Ibs.  of  bars 

Ore 

10.09 
10.25 
1.88 

$65.14 

I.  Francois,  Percy,  Iron  and  Steel,  p.  310,  1864. 
II.  Klchard,  idem,  p.  298. 
111.  Mussy.  Pliillips  and  Bauerman,  Elements  of  Metallurgy,  p.  175,  A.  B.  1SS7. 
a  The  ore  is  asssumed  to  contain  45£  of  iron. 
6  It  i.s  assumed  that  there  were  two  lirats  per  shift.     There  were  altogether  ten  persons  nt  the 
forge,  but  of  these  only  six  seem  directly  chargeable  to  bloom-making. 

270 


THE    METALLURGY    OF    STEEL. 


§319.  THE  AMERICAN  BLOOMARY  PROCESS," resembling 
the  Catalan  process  in  its  general  features,  differs  from  it 
in  that  the  ore  is  charged  wholly  in  a  fine  state  and  mixed 
with  charcoal,  instead  of  chiefly  in  lumps  and  in  a  sepa- 
rate column. 

The  furnace,  Figure  132,  costing  (Eglestou)  $550  to 
$600,  consists  of  a  nearly  rectangular  box,  of  thick  cast- 
ings. It  is  from  20"  to  30"  wide,  and  from  27"  to 
32"  long,  its  depth  being  from  15"  to  25"  above  the 
tuyere  and  from  fc"  to  15£"  below  it.  It  has  a  single  Q- 
shaped  tuyere,  about  1"  X  1'75",  supplied  with  blast 
heated  in  overhead  cast-iron  pipes  to  from  550°  to  800°  F., 
and  at  1-5  to  2 '5  pounds  pressure  per  square  inch. 

Operation. — The  hearth  being  filled  heapingly  with 
burning  charcoal,  charcoal  and  coarsely  pulverized, 
washed,  and  nearly  pure  ore  are  thrown  on  at  short  inter- 
vals, usually  one  to  live,  occasionally  12  to  25  minutes,  to- 
gether with  slag  from  previous  operations  if  the  gangue 
be  very  scanty.  The  ore  reduces  in  sinking,  the  usually 
silicious  gangue  forms  with  unreduced  ore  a  basic  fer- 
ruginous slag,  which  is  tapped  intermittently.  The  re- 


Scole 
Figure  132. — American  Bloomary  Furnace. 

duced  iron  gradually  agglomerates  to  a  pasty  ball  (loup), 
which,  after  nearly  three  hours,  is  pried  through  the  char- 
coal towards  the  tuyere  for  greater  heat,  is  then  drawn, b 
hammered  to  a  bloom,  reheated  usually  in  the  bloomary 
itself,  rarely  in  a  chamber  heated  by  its  waste  gases,  and 
rehammered. 

The  operation  lasts  about  three  hours,  so  that  eight 
loups,  usually  of  300  to  400  pounds  each,  are  produced 
per  twenty-four  hours,  at  an  outlay  of  from  250  to  350 
bushels  of  charcoal  and  1'25  to  1'5  days'  labor  per  2,000 

a  For  an  admirable  description,  see  T.  Sterry  Hunt,  Geol.  Survey  of  Canada, 
Kept.  Progress  1866-9,  p.  274.  Also  T.  Egleston,  Trans.  Am.  Inst.  Mining  Eng., 
VIII.,  p.  515,  1880. 

b  A  noted  writer  tells  us  that  the  bloom  is  dug  up  by  the  clock,  but  leaves  us  in 
the  dark  aa  to  how  the  time  keeping  properties  of  this  instrument  are  thereby  af- 
fected. 


pounds  of  blooms,  and  with  a  yield  of  say  80%  of  the  iron 
in  the  ore.     Table  156  gives  some  numerical  details. 


TABLE  156. — AMERICAN  BLOOMARY  PRACTICE. 


Lake 
Cham- 
plain. 
1SS9. 

Lake  Cham- 
plain, 
1879. 

Palmer. 

New  Russia. 

Moisie. 
1S6S. 

I'..  Middlebury 

Dimensions  of 
hearth: 
Width  

0. 
29" 

I. 

24"  @  80" 

II. 

III. 

20" 

IV. 

80" 

V. 
24J" 

Length  

81" 

27"  ®  32" 

32" 

32" 

29" 

Height  to  tuyere  

151" 

14" 

12" 

"      above  tuyere.  . 

25  J" 

"      total  

41" 

28"  @  86" 

24" 

Blast  : 
Pressure,  Ibs  persq.in. 

2  ©2} 

1} 

Ij  @  1} 

1  ®  li 

1J  @2 

Temperature,  C.  .  , 

815  @  427 

'  -       'F 

COO  @  SIIO 

"  

550  @  000  cst 

Size    of  tuyere-no/zle 
(one  only)  

2"  y  J" 

1J"  @  i 

1"    X  IS" 

1"  X  11" 

Inclination  of  tuyere.. 

12° 

very  slight. 

Ore,  kind  J 

Chateau- 

/magnetic 

"    %  iron  

c'ntr'ted 
65 

65 

60 

70  ± 

55  ± 

Length  of  one  heat.  .  .  . 

*}  hours 

1  hrs.  iivrr. 

3  hours. 

Labor  : 

Men    per   hearth    per 

Bhitt  

1 

1 

1J 

Length  of  one  shift.  .  .  . 
Output  per  hearth  : 
Weight  of  blooms  per 
heat,  pounds.. 

i2  hours 
400 

12  hours. 
800  @  4(10 

12  hours. 
210 

Weight  of  blooms  per 
24  hours,  pounds.... 
Slag: 
Composition,  silica  % 

8,200 

2,  COO 
24'6  @2(V4 

2,400 

1,680 
S'7  @  11 

16'70 

Iron-oxide  f 

48'  6  ©411-7 

52     ®  07 

62-06 

alumina.  .. 

irs  (^  )  •<> 

17'38 

"       phos.  acid,  . 

0'iftff,  n-n:j 

Outlay      per     2,00(1 
pounds  blooms  : 
Charcoal,  bushels..   .. 

810 

•_'.v,  dr.  '••"(> 

212  @  255 

896 

230 

"       poundsa  

5,425 

4,640  @5,400 

3,SOO@4,55ll 

6,240 

4,100 

Ore,  tons  

2 

1*5  washed 

Labor,  days 

1-25 

1'5 

1-8 

Loss    from     ore     to 
blooms,  per   100  of 
iron  in  ore... 

28  '07 

28 

16-7 

6 

<  7'9 

4S 

I.  T.  Egleston,  Trans.  Am.  Inst.  Mining  Kngineers,  VIII.,  p.  515,  1880. 

II.  to  V.  T.  Sterry  Hunt,  Kept.  Geol.  Survev  Canada,  1SC6-9,  pp.  274,  et  se<i. 
a  It  is  assumed  that  a  bushel  of  charcoal  weighs  18  pounds. 

&  Itis  stated  that  1'5  tons  of  nearly  pure  magnetite  yield  one  ton  of  blooms.  If  the  magnetite 
were  absolutely  pure  this  would  imply  a  loss  of  only  7  89$  ;  but  as  it  never  is,  the  loss  implied  is 
probably  nearer Bjfc  This  is  Intrinsically  Improbable:  and  the  statement  that  1'5  tons  of  ore 
yields  one  ton  of  blooms  is  probably  intended  to  be  only  approximately  true.  No  doubt  in  an 
occasional  heat,  in  which  a  considerable  quantity  of  rich  slag  from  previous  operations  is  added, 
such  results  may  be  reached. 


Indications. — The  condition  of  the  operation  is  judged 
from  the  color  and  brightness  of  the  flame,  which  should 
be  blueish  or  reddish,  and  not  brilliantly  white  ;  the  ap- 
pearance and  consistency  of  the  slag ;  and  the  hardness 
and  shape  of  the  loup,  which  should  be  moderately  soft. 
If  the  loup  is  very  soft  so  that  a  bar  sinks  deeply  into 
it  the  hearth  is  too  hot,  and  the  proportion  of  ore  must 
be  increased  :  if  the  loup  is  hard  the  temperature  is  too 
low.  and  the  proportion  of  charcoal  must  be  increased. 

The  ore  is  so  charged  that  a  rim  of  iron  shall  form 
around  the  outer  edge  of  the  upper  face  of  the  loup,  and 
thus  form  a  basin  which  remains  filled  with  slag,  and  pro- 
tects the  loup's  face  at  once  from  the  blast  and  from  car- 
burization. 

TABLE  157. — COMPOSITION  OF  AMERICAN  BI.OOMABT  IRON. 


i 

.    2 

8 

4 

5 

6 

7 

8 

•008 

trace. 

trace. 

•001 

trace. 

trace. 

trace. 

trace. 

015 

•042 

•084 

•028 

•028 

.042 

•on 

•015 

Silicium  

•095 

•280 

•021 

•512* 

•025 

•100 

•018 

•018 

•079 

0 

•228 

•170 

•220 

•180 

•1711 

•165 

•2iO 

•10  @  -30 

Slag                               

•180 

•014 

•155 

•075 

•150 

•25  C*  '50 

1  to  7.    Billets,  Egleston,  Op.  Cit.    1   and  6,  Saranac,  Ilasegawa.    2,  8,  4.  Au  Sable  Forks, 
Brltton.     6,  Peru  Iron  Company,  Wiith.    7,  Chateaugay. 

8.    Bloom,  A.  E.  Hunt,  Trans.  Am.  Inst.  Mining  Kngineers,  XII.,  p.  313,  1884.  Chateaugay. 


The  cost  of  making  blooms  in  the  Lake  Champlain  re- 
gion is,  I  am  credibly  informed,  about  $45.00  per  ton 
at  a  mill  which,  I  understand,  is  closely  connected  with 
an  iron-mining  concern.  The  estimated  cost,  under  such 
conditions,  is  in  large  part  a  matter  of  book-keeping,  de- 
pending chiefly  on  the  price  at  which  the  fine  ore,  which 
is  to  a  certain  extent  a  bye-product,  is  charged  against 


HUSGAFVEL'S    BLOOMARY.      §  322. 


271 


the  smelting  works.    Charcoal  blooms  are  quoted  at  $52.00 
to  $54.00  per  ton  in  Philadelphia. 

The  output  of  the  American  bloomaries  is  decreasing 
rapidly,  as  the  following  table"1  indicates  :  but,  as  it  more 
than  doubled  between  1 876  and  1882,  it  would  be  rash  to 
predict  the  early  decease  of  the  process  confidently.  Yet 
it  certainly  seems  moribund.  output  of  blooms 

and  billets, 
Year.  net  tons. 

1674...  80.450 

1876  20,784 

1882  48,854 

1887!..  15,088 

1888 14,088a 

a.I.  M.  Swank,  private  communication. 

From  the  following  table,  compiled  from  the  "Direc- 
tories to  the  Iron  and  Steel  Works  of  the  United  States" 
for  1884  and  1888,  we  see  that  some  of  the  bloomaries  now 
standing  are  extremely  old,  and  that  the  building  of  bloom- 
aries continued  till  1883.  Between  1870  and  1880  no  less 
than  sixteen  establishments  were  built. 

TABLE  157A.— UISTOBY  OK  TIIK  AMERICAN  BLOOMAKY  ESTABLISHMENTS  EEPOETED  IN  1884 

AND  1887. 


Years  in   which  the  bloom- 
aries reported  in  1888  and 
1887  were  built  or  rebuilt. 

Of  those  built  in  the  several  periods  of  Column  1.  the  following  num 
bers  were 

Years. 

No. 
built. 

No. 
rebuilt. 

Idle  or  abandoned 
before  1884. 

Abandoned    be- 
tween 1883  and 
1887. 

Idle  but  apparently  not 
abandoned  in  1887. 

Run- 
ning in 
1887. 

1797 
1819 
1820 
1829 
1880 
1889 
1840 
1859 
1860 
1869 
1870 
1879 
1880 
1881 
1882 
1883 
1884-7 

2 
3 
6 

7 
6 

16 

3 
2 
0 
1 
0 

1 

1 
1 

2 
5 

4 

6 

2 

3 

2 

1 

1 
1 
1 

6 

1 

4 
3 
1 

11 
1 
1 

2 

5 

1 
1 

2 
0 

Clearly  the  process  is  applicable  only  where  rich  fine 
ore,  charcoal,  and  labor  are  cheap.  Even  under  these  con- 
ditions it  could  not  compete  with  fuel-saving  processes 
such  as  Husgafvel's. 

§320.  THE  OSMUND  FCRNACE  (blaseofen,  bauernofen), 
is  intermediate  between  the  low  and  the  high  bloom- 
aries. It  appears  to  be  about  eight  feet  in  height. 
Smelting  calcined  phosphoric  bog-ores  with  charcoal,  it 
yielded  1£  tons  or  less  of  good  malleable  wrought-iron 
weekly,  with  a  loss  of  from  33  to  50$  ''  in  working  up  the 
bloom  :b  the  enormous  loss  tallies  with  the  production 
of  good  iron  from  phosphoric  ores. 

The  osmund  furnace  is  said  to  be  used  still  to  a  very 
considerable  extent  in  Finland,  apparently  solely  by  the 
peasants.0 

§  321.  THE  OLD  HIGH  BLOOMARY  (STUCKOFETT.)— Here 
the  height,  and  with  it  the  carburizing  tendencies  and 
the  economy  of  fuel,  were  carried  so  far  that  there  was  a 
strong  tendency  to  make  cast  instead  of  malleable-iron: 
indeed,  cast-iron  was  often  made  unintentionally  in  these 
furnaces.  They  differed  but  slightly  from  the  blauofen 
ID  which  cast-iron  was  habitually  and  intentionally  made, 
and  in  which  indeed  by  varying  the  strength  of  the  car- 
burizing conditions  wrought-  or  cast-iron  could  be  made 
at  will. 

furnace.—  The  old  Stiickofen  was  a  shaft-furnace  from 
10'  to  16'  high:  round  or  rectangular  in  section:  say  2'  6" 

a  Ann.  Statistical  Kept.  Am.  Iron  and  Steel  Ass.,  p.  37,  1888. 
•>  Percy,  Iron  and  Steel,  p.  320.    The  wording  is  obscure:  I  infer  that  this  loss 
is  fioru  ore  to  hammered  bloom. 
oF.  L.  Garrison,  .Private  Communication,  April  10th,  1889, 


wide  at  top  and  1'  6"  (at  Eisenerz  4'  X  2'  6")  at  bottom, 
usually  bellying  out  midway  to  say  4'  2":  and  had  one 
tuyere  say  14"  to  20"  above  the  bottom,  and  at  the  bottom 
a  drawing-  hole  say  2'  wide,  opened  for  removing  the  bloom, 
but  closed  at  other  times. 

Operation.  —  The  furnace  was  filled  With  charcoal,  which 
was  lighted  from  below  :  as  soon  as  the  fire  reached  the 
top  the  blast  was  turned  on,  and  charcoal  and  burden  (rich 
slags  and  ore)  charged.  The  burden  was  at  first  light, 
gradually  increasing  to  the  normal  —  one  volume  to  four  of 
charcoal.  Descending,  its  iron  was  deoxidized,  and, 
reaching  the  bottom,  agglomerated  to  a  bloom.  The  slags 
ran  out  constantly  through  a  notch  in  the  stopping  of  the 
drawing-  hole.  As  soon  as  the  bloom  was  found  by  probing 
to  be  large  enough,  charging  ceased,  the  furnace  was 
blown  down  and  the  bloom  loosened  and  drawn  through 
the  drawing-hole.  The  furnace  was  then  cleaned  out,  re- 
paired. its  bottom  brasqued,  and  charging  began  again. 

To  guard  against  carburization  and  the  production  of 
cast-  instead  of  malleable  iron,  the  carburizing  tendencies 
were  purposely  restrained,  e.  g.  by  charging  a  large  pro- 
portion of  ore  to  charcoal.4 

Some  economic  data  follow. 

TABLE  158  —  STCCKOFEN  PRACTICE. 


Usual. 
Weight  of  blooms  per  charge,  Ibs 

Length  of  charge 8  hrs. 

Men  per  furnace  per  shift 8 

Labor,  days  per  2,000  Ibs.  blooms I2± 

Charcoal,  tons  per  2,000  Ibs.  blooms 4'5a 

Ore,  "       


Eisenerc. 


j  1,800  ±,  wli 


Old  I'orsas- 
koski. 


±  of  cast-iron. 
1  shift.      18  hrs. 


4-8 
8-86 


a  At  10  Ibs.  per  cubic  foot,  or  say  15  Ibs  per  bushel. 

§  322.  HUSGAFVEL'S"  HIGH  BLOOMARY  or  continuous 
stiickofen  is  a  tall  shaft-furnace,  with  double,  air-cooled, 
wrought-iron  walls,  and  a  movable  hearth. 

These  arrangements  tend  to  diminish  the  quantity  of 
fuel,  ore  and  labor  needed  per  ton  of  blooms,  and  increase 
the  output  per  furnace  :  but  this  last  is  still  very  small, 
while  the  consumption  of  fuel  is  certainly  moderate. 

The  Furnace,  Figure  133. — The  air-space  between  the 
double-walls  serves  for  heating  the  blast,  which  by  the 
spiral  partitions  B  B  is  forced  to  travel  circuitously.  The 
lower  five  feet  of  the  shaft  are  lined  with  fire-brick,  the 
rest  is  naked  within.  The  outer  walls  are  lagged  with 
four  inches  of  fire-clay,  to  lessen  heat-radiation. 

A  movable,  air-cooled,  cast-iron  section  is  provided 
between  shaft  and  hearth,  as  this  part  is  relatively  perish- 
able, because  its  temperature  is  high,  and  because  it  is  cut 
by  the  reduced  iron  which  often  adheres  to  it,  and  by  the 
workmen' s  tools  used  in  removing  these  accretions. 

The  movable  hearth  has  four  water-cooled  tuyere-holes  * 
on  each  of  two  opposite  sides  :  four  slag  notches  t  at 
different  levels :  trunnions  b  for  dumping :  and  a  false 
bottom  u  that  accretions  may  not  form  on  the  hearth 


a  Percy  (Iron  and  Steel,  p.  330),  from  whose  description  the  above  as  well  as  part 
of  Table  158  is  condensed,  further  says  that  one  essential  condition  of  obtaining 
malleable  iron  from  the  blauofen,  (which  was  really  a  stiickofen,  the  difference 
originally  referring  to  the  mode  of  working  the  furnace  and  the  consequent  pro- 
duct, not  to  construction),  was  to  allow  the  slag  free  escape,  so  that  it  might  not 
protect  the  bloom  from  the  blast.  As  the  slag  was  highly  fining,  containing  say 

'7$  of  ferrous  oxide,  one  might  have  anticipated  that  if  present  it  would  not 
only  oppose  carburization,  by  preventing  charcoal  from  resting  against  the 
bloom,  but  would  tend  to  decarburize  the  gradually  arriving  particles  of  iron. 

e  Cf.  P.  L.  Garrison,  Trans.  Am.  Inst.  Min.  Eng.,  XVI.,  p.  334, 1888:  and  Journ. 
TJ.  8.  Ass.  Charcoal  Iron  Workers,  III. ,  p.  380,  1887.  He  refers  to  Husgafvel,  Jerc- 
kont.  Annal.,  1887:  Russian  Mining  Jl.,  1887,  II.,  pp.  398,  435.  See  also  Bug. 
Mining  Jl.,  XIV.,  p.  90,  1888:  also  Stahl  un<l  Eisen,  IX.,  pp.  35, 131,  1889.  The 
last  has  appeared  since  this  article  was  written,  and  I  have  only  been  able  to  avail 
myself  of  part  of  its  data. 


212 


THE    METALLUEGY    OF     STEEL. 


proper.  It  rests  on  a  lifting  platform,  which  facilitates 
removal  and  adjustment. 

From  the  fact  that,  in  experimenting  with  slow  charg- 
ing and  lightened  burden  in  the  Dobriunsky  furnace, 
whose  internal  capacity  is  400  cubic  feet,  no  cast-iron  was 
made,  it  is  inferred  that  the  limits  of  size  have  not  been 
reached,  and  furnaces  of  a  capacity  of  1,000  cubic  feet  are 
projected. 

The  Blast  at  a  pressure  of  |  to  l£  inches  of  mercury 
(3'9toll'8  oz.  per  sq.  in.),  is  heated  in  passing  down- 
wards through  the  doable  walls  of  the  shaft  and  of  the 


charged  apparently  in  uniform  horizontal  layers :  the  fine 
charcoal  is  charged  after  the  coarse,  so  as  to  close  the 
interstices  and  hinder  the  fine  ore  from  sifting  down. 
The  burden,  descending  gradually,  reaches  the  hearth 
quite  reduced,  and  probably  considerably  carburetted. 
The  conditions  in  the  hearth,  contact  with  the  ferruginous 
slag  and  exposure  to  the  blast,  appear  to  be  decidedly 
decarburizing. 

A  fresh  hearth  being  in  place,  the  tuyeres  are  inserted 
in  the  lower  tuyere-holes,  and  the  blast  turned  on.  The 
slag  is  apparently  tapped  at  intervals,  its  level  being  kept 


Figure  183.— Husgafvel's  High  Bloornary,  at  Dobriausky,  1SSG— Vertical  Section. 

movable  section,  to  from  150  to  250°  C.  (302  to  482°  F.),  its 
temperature  and  to  a  slight  extent  that  of  the  furnace 
being  regulated  by  varying  the  proportion  of  blast  ad- 
mitted at  the  points/1,/2,/3,/1  and  g.  The  tuyeres  and 
their  trunks  /,  counterweighted  at  I,  m,  n,  o,  are  moved 
vertically  to  the  appropriate  tuyere-holes  s,  and  have  ball- 
joints  p,  permitting  change  of  direction  in  all  ways. 

The  Materials.— The  ore  and  rich  (e.  g.  puddling)  slags 
are  crushed  to  "quite  a  fine"  size,  apparently  about  J"  to 
i"  cube. 

The  fuel  is  charcoal,  divided  into  coarse  and  fine.  Coke 
was  used  with  apparent  success,  but  for  so  short  a  while 
that  the  results  are  inconclusive. 

Operation  is  continuous,  charcoal  and  ore  being 


Elevation. 

somewhat  above  that  of  the  top  of  the  gradually  forming 
bloom,  so  that  the  reduced  iron,  arriving  little  by  little, 
sinks  through  a  layer  of  molten  decarburizing  slag  before 
reaching  and  coalescing  with  the  iron  already  present. 
When  the  bloom  has  grown  nearly  to  the  level  of  the 
lower  tuyere-holes,  the  tuyeres  are  raised  to  the  upper 
holes,  and  the  lower  ones  stopped.  When  it  has  reached 
the  upper  tuyere-holes  the  blast  is  stopped,  the  hearth 
lowered,  and  immediately  replaced  by  a  fresh  one,  the 
blast  being  interrupted  for  only  about  five  minutes.  The 
old  hearth  is  now  dumped,  the  false  bottom  being,  if 
necessary,  driven  out  by  blows  on  the  shaft  x. 

As  false  bars  are  not  used,  the  charge  sinks  somewhat 
during  changing  hearths :    to  equalize  this,  the  hearths 


HUSGAFVEL'S     HIGH    BLOOMARY. 


273 


are  changed  alternately  to  right  and  left,  two  dumping- 
rests,  c,  being  provided.  Before  running  a  fresh  hearth 
into  place  it  is  filled  with  charcoal. 

Indications. — In  normal  work  the  tuyere  is  clear  and 
bright ;  the  throat-flame  lively  ;  the  slag  bright  and  fluid  ; 
the  bloom  hard  and  slippery.  A  rod  thrust  against  it  hea's 
quickly,  and  particles  of  iron  adhere  to  it. 

\Vith  too  fast  driving  or  too  heavy  burden,  /.  e.  with  in- 
sufficient reduction,  the  bloom  is  uneven  and  porous,  the 
slag  is  very  ferruginous,  ultra  fluid,  yellowish  red  (/.  e. 
cool)  v.  Idle  molten,  solidifying  abruptly,  and  sub-metallic 
and  black  when  cold,  a  ''scouring  cinder;"  the  throat- 
flame  is  thin  and  feeble  ;  the  tuyeres  dull. 

With  too  slow  driving  or  too  light  burden,  i.  e.  too  strong 
reduction  and  carburization,  the  slag  becomes  less  ferru- 
ginous and  hence  less  fluid,  and  the  metallic  product  steely, 
or  even  cast-iron. 

When  the  slag  is  too  refractory,  either  from  faulty 
fluxing  or  because  excessive  reduction  robs  it  of  its  fer- 
rous oxide,  scaffolds  form,  and  the  throat-flame  grows  blue 
and  hot. 

Remedies. — The  reducing  conditions  are  strengthened 
by  running  more  slowly  (lowering  the  blast  pressure)  ;  by 
lightening  the  burden  ;  by  raising  the  blast- temperature 
through  admitting  a  larger  part  of  the  blast  through  the 
upper  part  of  the  inter-nmral  space,  thus  increasing  the 
heating  surface,  and  the  average  of  travel  and  length  of 
exposure  of  the  blast. 

They  are  weakened  by  the  opposite  steps. 

Difficulties.  The  product  is  heterogeneous,  thanks 
partly  to  the  irregular  descent  and  hence  varying  length 
of  exposure  to  the  reducing  and  carburizing  conditions. 
It  tends  strongly  to  adhere  to  the  walls,  especially  where 
these  are  of  brick. 

Products.  The  bloom,  according  to  the  following  analy- 
ses, is  liable  to  be  extremely  heterogeneous  :  e.  g.  lines  3, 
5,  8,  11,  12.  The  proportion  of  silicon  is  in  some  cases 
astonishingly  high,  and  indeed  hardly  credible.  There  is 


a  variation  of  0-57^  between  the  different  parts  of  Num- 
ber 5. 

TAHLK  159. — COMPOSITION  «v  T.I.OOMS   KI:OM   H rsi; AFVKI.  Hn;ii  HLOOMAUIKS. 


M:iik-  from. 

C. 

81. 

Mn. 

P. 

8. 

1. 

2. 
3. 
4. 

5. 

<; 

7. 
8. 

9. 

in. 
11. 

12. 
13. 

Shingled  bloom  >  Magnetite...                              .       "'',"rc' 

•07 
•06 
•1:; 
•07 
•07 
•82 
•  !•-'<&. 
2-00 
•05 
•09 
1-5 
1-22 
•06 
•19 
•01 
•01 
•01 
•OU 
•so 

•14 
•01 
01 
Ml 
•08 

tr. 
tr. 
•22 
•32 
•023 
•061 

o-wir, 
•08 
•08 

•iiK 
•UK 
•015 

•02 

•it; 
•02 

•03 
•02 
04 
•02 
•03 
•03 
•01 
•02 
•08 
•02 
•04 
•06 

"              "        VOre  .. 

"        J  Moll  seal,-  ':™tr'- 

W'irtsilS     "      . 

•29® 
•85 

Shingled    "      fracture  urn-veil...                     ..    "v"tn' 

•114 
•61 
•08 

•03 

•(« 

Molted  product  fi  0111  hot-WOrktllg  

Hammered  bloom,  granular                              .  .  .  J  SH" 

"        coarse  gram.lar                           '  •"*" 

.<               K            ,«           u                                \  centre 

•06 
•02 

05 

•411 
.._,., 

•09 
•45 

•52 

Unhauimcrcd  loun,  hot-working.  .  . 

Hammond  bloom...                                               j  centre 

I'nhammered  loup,  normal  working  -j  c?n""e 

A.  Phosphorus.     The  proportion  of  phosphorus  elimi- 
nated of  course  increases  with  the  loss  of  iron.      When 
the  loss  of  iron  is  small  and  the  blooms  highly  carbu- 
retted,  most  of  the  phosphorus  of  the  ore  is  found  in  the 
resulting  metal :  but  when  the  loss  is  heavy  and  the  bloom 
holds  but  little  carbon,  it  may  have  only  one-third  of  the 
phosphorus  of  the  ore. 

B.  Carbon.  The  variation  of  0'26$  between  the  differ- 
ent part  of  bloom  3  is  certainly  very  marked.     The  pro- 
portion of  carbon  in  the  bloom  is  said  to  be  well  under 
control ;  but  it  is  probably  only  very  roughly  controll- 
able. 

The  slag  is  said  to  contain  about  62  '46$  of  ferrous  oxide, 
or  40 "8$  of  metallic  iron,  when  the  blooms  are  but  slightly 
carburetted  ;  and  about  9  '91$  of  ferrous  oxide,  or  7'1 5  of 
metallic  iron,  when  the  reduction  is  strong,  highly 
carburetted  blooms  resulting. 

§  323.  ECONOMIC  FEATURES. — Table  160  has  been  cal- 
culated from  Husgafvel's  data  and  from  those  col- 
lected by  Mr.  Garrison.  I  confess  to  doubts  as  to  the 
value  of  certain  numbers,  chiefly  because  one  cannot  be 


TABLE  ICO.— THE  HUBGAFVEL  FUKNACE  AND  ITS  WORK. 


I. 
Petrozavodsk, 

1887. 

II. 
WSrtsilii  furnace, 
1884. 

III. 

Dobrlansky  furnace, 
flg.  183,  1886. 

Dobrlansky  furnace,  1887. 

IV. 

V. 

VI. 

VII. 

Dimensions  — 
Total  hetyht  

>W 

80'  ± 
4' 
5' 
4 
0-5  @1T> 
802°@572° 
ISO  ©300° 

Magnetites. 

estimate  55*  ± 
2     tons  ore 
O'l     "    slag 

21    " 
J-Fir  "very  inferior" 

159@250,  average  190 

3'929@10-477 
405° 
207° 

Haw  magnetite. 
58* 

1-97 
Pine. 

2,899 
945 

2-96 
21*c 

6-5  to  11-T 

446° 
280° 

Kaw  magnetite. 
58* 

1  95 
Pine  and  birch. 

2,899 
145 

8-28 
21*c 

6-5  to  9'8 
437  to  446° 
225  to  280° 

I!.  ill  scale. 

1-85 
Pine. 

2,82B 
116-8 

S'94 

6-5  to  9-8 
302  to  446° 
150  to  230° 

Bull  scale. 
1-64 

Pme. 

2,222 
111-1 

-.» 

"         "  belly  

Tuyeres,  number  

4 

Blast,  pressure,  oz.  per  sq.  in  

•'      temperature.  °F.  ..                                              ...'... 

802"  @  482°  + 
150°  @  250 

/  Lake-ore  and  pud- 
\      dling  slag. 
86*  ± 
1  -64  ore  (3<#  Iron) 
1  02  slag  (49*  iron) 

2-66 
{Fir  and  pine, 
"Medium  quality." 
157 
2,100  ? 
105 

o-oi 

0-12 

0-01 

3  + 

"             C  "... 

Materials  and  Laboi  — 
OEE,  kind.... 

Bog-ore. 

Percentage  of  iron  

Net  ton*  per  net  ton  blooms  

Lbs.  per  net  ton  blooms  (!3-41bs.  per  bushel?) 
"    "    100  of  blooms 

0-017 

4-00 
2'46@3'08 
670@795 
•06©-32 

tr.  @'82 
23$  6 

Limestone     •'      '*      "      "    "         "      

(for  repairs") 

•'       days  per  2.000  Ibs.  blooms  '  

1-52@300 

Composition,  %  carbon  

•12@2'00 
•29@S5 

iii'o 

7'15®40  8 

Slag,  percentage  of  iron  

I.,  II.  and  III.  Krom  data  collected  by  F.  L.  Garrison.    IV.  to  VIT.  From  Husgafvel,  Stahl  und  Kisen,  IX.,  p.  85,  1889. 

a  From  the  data  given  in  this  same  column  the  loss  appears  to  bo  9*  :  but  we  cannot  be  sure  that  the  data  refer  to  the  same  conditions.     Husfrafvcl  states  (Stehl  und  Eisen,  18S9,  p.  40)  that  tna 
loss  at  Wartsilii  In  1885  was  from  K  17  to  12£,  according  to  whether  soft  wrnught-iron  or  steely  blooms  were  made  :  but  that  the  blooms  held  in  some  cases  as  much  as  1S£  of  slag.     If  we  assume 


,  ely 

that  they  held  on  an  average  10£  of  slair.  a  loss  of  12£  from  ore  to  bloom  would,  allowing  for  the  slag  contents  of  the  blooms,  rise  to  21  %. 

6  From  the  data  about  86*  of  blooms  appear  to  bo  recovered  from  100  of  Iron  in  ore.    Assuming  that  the  blooms  contain  90*  of  metallic  iron,  the  loss  would  be  23*. 
f  Assuming  that  the  blooms  contain  90*  of  metallic  Iron. 


274 


THE    METALLUEGY    OF    STEEL. 


sure  that  they  refer  to  the  same  conditions.  The  loss  of 
iron  cannot  be  calculated  with  complete  confidence,  as  we 
do  not  know  how  much  iron  the  blooms  (loups)  contain. 
The  numbers  given  are  based  on  the  assumption  that  they 
hold  on  an  average  90^  of  iron.  Ilusgafvel  states  that 
they  sometimes  contain  15%  of  slag.  The  results  thus  ob- 
tained tally  with  his  further  statement  that  the  loss  at  the 
Konchozersky  works  at  Olnetz  is  20#,  allowing  for  the  slag 
in  the  loups,  while  in  the  old  Finnish  furnaces  it  was  from 
40  to  50%. 

A  Kussian  official  table  appears  to  show  that  the 
cost  of  Husgafvel  blooms  is  the  same  as  that  of  pig-iron 
under  like  conditions  :  but  the  data  have  a  suspicious  look. 
Thus  the  cost  of  pig-iron  is  only  brought  up  to  that  of 
blooms  by  a  charge  of  $2. 65  per  net  ton  for  repairs.  Labor 
costs  but  $0.36  per  ton  diem :  if  we  assume  that  the  cost 
of  given  repairs  in  Finland  and  in  this  country  is  propor- 
tional to  that  of  labor,  this  implies  repairs  such  as  would 
cost  here  about  $11. 00  per  ton  of  pig-iron,  which  is  cer- 
tainly surprisingly  high. 

It  appears  from  this  table  that  less  than  half  as  much  flux, 
but  15%  more  fuel,  27%  more  ore  and  puddle  slag,  and  56% 
more  labor  are  needed  to  make  a  ton  of  blooms  than  a 
ton  of  pig-iron.  This  difference  in  the  quantity  of  flux 
must  be  referred  chiefly  to  the  heavy  scorification  of  iron, 
which  enables  the  bloom-maker  to  dispense  with  much  of 
the  limestone  which  the  pig-iron-maker  needs  ;  but  iron 
ore  is  a  dearer  flux  than  limestone. 

On  these  data  we  might  roughly  put  the  cost  of  bloom- 
making  as  one-quarter  greater  than  that  of  pig-iron  mak- 
ing in  a  42-foot  charcoal-furnace. 

The  Husgafvel  furnace  undoubtedly  gives  much  better 
economy  of  fuel  than  the  American  bloomary,  and  one 
would  expect  it  to  give  better  economy  of  labor.  This 
it  does  not  yet  seem  to  do.  As  to  the  loss  of  iron, 
that  must  ever  remain  proportional  to  the  degree  of  de- 
phosphorization  which  takes  place.  To  cut  down  the  loss 
of  iron  we  must  increase  the  reducing  tendency,  and  we 
thereby  inevitably  diminish  dephosphorization. 

In  so  high  a  furnace  as  the  Husgafvel  there  should  be 
greater  liability  to  excessive  reduction  and  hence  imper- 
fect dephosphorization  than  in  the  low  American  bloomary : 
and  we  may  doubt,  judging  from  the  history  of  like  pro- 
cesses, whether,  even  by  charging  an  excessive  proportion 
of  ore  to  fuel  and  by  rapid  running,  it  would  be  possible 
to  obtain  constantly  so  pure  a  product  from  given  ore  in 
the  former  as  in  the  latter.  But  direct  experiment  alone 
can  answer  this. 

The  use  of  coke  would  probably  yield  a  highly  car- 
buretted  and  correspondingly  impure  product,  indeed 
approaching  cast-iron  in  composition,  and  rich  in  sulphur. 
We  note  that  even  with  charcoal  the  Husgafvel  furnace 
occasionally  yields  iron  with  2%  of  carbon. 

From  reasoning  similar  to  what  has  gone  before  we  may 
infer  that  the  cost  of  coke-blooms  would  be  probably 
about  from  one  quarter  to  one  half  greater  than  that  of 
coke  pig-iron. 

In  order  to  dephosphorize,  the  slag  must  be  basic :  a 
slag  made  basic  by  oxide  of  iron  means  heavy  loss  of  iron. 
One  might  at  first  think  that  we  could  obtain  a  basic  slag 
in  this  furnace  by  replacing  iron-oxide  with  lime,  and  so 
dephosphorize  without  heavy  loss  of  iron.  But  we  must 
remember  that  to  melt  a  basic  lime  slag  demands  a  very 


high  temperature,  and  such  a  temperature  would  not 
only  imply  greatly  increased  fuel  consumption  but  much 
more  strongly  reducing  conditions,  more  strongly  reduc- 
ing both  because  of  the  higher  temperature  and  of  the 
larger  proportion  of  the  reducing  agent  itself,  charcoal. 
But  these  reducing  conditions  oppose  the  dephosphorizing 
action  of  the  basic  slag.  In  short,  if  we  attempt  to  save 
iron  we  turn  the  furnace  into  a  blast-furnace,  and  make, 
if  not  cast-iron,  at  least  a  very  highly  carburetted  steel, 
containing  much  if  not  all  of  the  phosphorus  of  the  ore. 
Now  charcoal  blooms  are  marketable  chiefly  because 
of  their  freedom  from  phosphorus,  and  to  a  consider- 
able extent  on  account  of  t^eir  relative  freedom  from 
carbon. 

This  ingenious  direct  process  is  certainly  one  of  the  most 
successful  yet  devised.  When  we  consider  how  short  a 
time  has  elapsed  since  these  attempts  to  modernize  the 
stiickofen  began,  the  progress  thus  far  made  is  certainly 
most  encouraging.  The  mode  of  dealing  with  the  bloom 
is  ingenious,  but  something  much  better  still  is  needed- 
The  output,  too,  is  very  small.  One  wonders  whether  it 
might  not  be  greatly  increased  without  increasing  the 
tendency  to  carburize,  or  causing  trouble  as  to  the  pene- 
tration of  the  blast,  by  making  the  furnace  oblong  instead 
of  circular  in  plan,  as  in  the  Raschette  furnace,  and  in  the 
Orford  copper  furnaces.  The  Orlord  engineers  increased 
the  output  of  their  furnaces  enormously,  with  some  econ- 
omy in  labor  and  fuel,  by  this  simple  expedient.  In  case  of 
the  Husgafvel  furnace  two  or  more  hearths  would  have  to 
be  provided,  for  the  bloom  formed  in  a  single  long  hearth 
would  be  unmanageable.  Mr.  Garrison  informs  me  that 
Raschette  furnaces  are  still  extensively  and  successfully 
used  in  the  Urals  for  making  charcoal  cast-iron. 

§  324.  THE  NYHAMMAR"  CONTINUOUS  HIGH  BLOOMAKY 
consists  of  a  shaft  1 6'  high  and  18"  wide,  from  the  bottom  of 
which  covered  flues  lead  to  covered  and  closed  charcoal- 
hearths.  Actually  there  seems  to  have  been  but  one 
hearth,  but  the  design  contemplates  several  attached  to 
ach  shaft. 

Ore  and  charcoal  are  charged  in  the  chaft  continuously, 
and  through  this  the  gases  from  the  charcoal-hearths  pass 
to  heat  the  charge.  The  proportion  of  ore  to  charcoal 
barged  in  the  shaft  is  regulated  so  that  the  temperature 
and  reducing  conditions  in  the  shaft  may  be  such  as  to 
deoxidize  the  ore  and  heat  the  resulting  sponge  strongly, 
aut  not  to  carburize  or  to  soften  it.  The  hot  but  not 
sticky  spongy  iron,  together  with  the  residual  charcoal, 
is  raked  from  the  bottom  of  the  shaft  in  o  one  of  the  char- 
coal-hearths, through  one  of  the  flues  already  described. 
In  this  hearth  the  spongy  iron  is  heated  to  the  welding  point 
and  balled,  fresh  lots  of  sponge  apparently  being  raked  in 
as  fast  as  the  iron,  balling,  sinks,  till  enough  for  a  bloom 
tias  reached  the  hearth,  when  raking  ceases  or  is  diverted 
to  another  hearth.  The  melted  slag  is  tapped  from  the 
hearth,  the  iron  worked  into  a  bloom,  drawn  and  ham- 
mered. 

When  it  is  necessary  to  open  a  charcoal-hearth  (e.  <?.,  for 
drawing),  the  flue  which  leads  from  it  to  the  shaft  is 
losed  with  a  damper,  to  prevent  an  inrush  of  air  into  the 
shaft,   and  the  consequent  reoxidation  of    the  spongy 
ron. 

The  following  results  were,  it  is  stated,  obtained  in  five 


fSarnstrSn,  Iron,  XIX.,  p.  467,  188a  :  Oest.  Zeit.,  Aug.  IStb,  1888. 


EDWARD    COOPER'S    PROCESS.      §  326. 


275 


apparently  not  successive  shifts  :  I  deduce  these  numbers 
from  Sarnstron's  data. 

TABLE  161.— P.ESULTS  OBTAINED  is  THE  NTHAMMAP.  BLOOMAP.T. 

Percentage  of  iron  in  ore *"*''    %  ± 

lilooms  per  100  of  iron  in  ore 

Loss  of  iron 8'18j< 

Bnsheii.    Pounds. 

Clmrcoal  per  100  of  iron  in  ore 8'S 

Charcoal  per  100  of  blooms 8'OG  \-io\H 

liliiom.-,  poiuiiN  PIT  furnace  per  shift 

I'lmsplioriis  in  ore 0*91^ 

PhoBpbonis  In  blooms •••• 

i'n. portion  of  initial  phosphorus  removed W'%    @  95-£ 

a  Assumed  at  15  Ihs.  pi-r  liuslii'l  o£  '1M»  enli.  illehrs,  or  1»-:!7  His.  per  cubic  foot. 

The  loss  of  iron  is  certainly  very  small,  especially  in 
view  of  the  dephosphorization  which  occurs  :  indeed  Sarn- 
stron  points  out  that  it  was  probably  greater  than  it 
appeared. 

§  325  A. — GUKLT"  deoxidized  iron  ore  and  carburized  (?) 
the  resulting  sponge  in  the  central  shaft  B  of  the  furnace 
shown  in  Figure  134,  by  passing  through  it  a  stream  of 
hot  producer-gas  from  the  producers  D  D.  Here  the  pro- 
ducer gas  both  heats  and  deoxidizes  the  ore,  which  is  un- 
mixed with  solid  fuel.  The  hot  spongy  iron  was  drawn 
through  a  doorway  at  the  bottom  of  the  shaft,  to  be 


SURLT'S    FURNACE 

Fig.  134. 

balled,  or  if  highly  carburetted  to  be  melted,  in  an  open- 
hearth  furnace  or  in  a  charcoal-hearth.  Apparently  fear- 
ing that  the  producer-gas  would  not  be  hot  enough,  to 
heat  the  ore,  he  would  burn  part  of  it  at  the  points  b  b  by 
means  of  a  carefully  regulated  air-supply.  By  prolonging 
the  passage  of  the  gas  he  would  carburize  the  sponge. 

This  process  was  carried  on  in  Spain  in  a  few  small  fur- 
naces from  about  1865  at  least  till  1884.  In  1884  some 
larger  furnaces  near  Bilbao  were  idle.b  The  process  was 
here  called  Tourangin's.  The  furnaces  were  built  from 
his  design  and  at  first  managed  under  his  direction  :  and 
the  a  r  supply  for  partly  burning  the  gas  before  it  en- 
tered the  ore  column  was  omitted.  Opinions  may  differ 
as  to  whether  this  constituted  a  new  process :  it  seems 
to  me  clearly  Guilt's  process. 

At  the  Alonsotegui  forges  in  Spain,  we  are  told,  hot 
producer-gas  made  from  charcoal  was  passed  through  ore 
in  a  chamber  of  105  cubic  feet  capacity,  and  holding 
about  five  tons  of  ore.  The  sponge  was  drawn  while  hot, 
and  was  immediately  covered  with  cinders.  It  was  drawn 
thrice  daily,  the  total  output  corresponding  to  about  3'2 
tons  of  ore,  so  that  the  ore  remained  in  the  reducing 
chamber  nearly  two  days.  100  pounds  of  ore  containing 
about  56$  of  iron  lost  30  to  34$  in  weight  in  deoxi- 
dizing, and  the  resulting  say  66$  of  sponge  yielded  about 
.r>(>-.:>$  of  blooms  in  a  charcoal  hearth,  with  a  further  con- 
sumption of  25  pounds  of  charcoal :  the  loss  of  iron  from 


a  British  patent  1679,  July  16,  A.  D.  1856  (Dec.  19,  1856;  Jan.  16, 1857). 
b  L.  G.  Laureau,  private  communication,  March  12th,  1889.     The  information 
was  obtained  by  an  agent  sent  to  Spain  by  Mr.  Laureau  to  examine  the  process. 


ore  to  blooms  was  thus  about  10$  of  the  iron  in  the  ore.0 
About  84  pounds  of  charcoal  per  100  of  blooms  were  used 
in  deoxidizing,  so  that  altogether  about  134  parts  of  char- 
coal were  used  per  100  of  blooms. 

The  process  was  tried  at  Ticonderoga,  N.  Y.,  in  1884, 
apparently  with  little  intelligence.  The  reduction  seems 
to  have  beei  complete,  and  neither  reoxidation  nor 
carbon  deposition  seems  to  have  occurred  to  an  important 
extent.  Four  analyses  of  the  sponge  gave  from  0'52  to 
•17$  of  oxygen.b 

B.  Ramdohr*  would  shower  iron  ore  through  a  Stete- 
feldt  furnace  filled  with  carbonic  oxide. 

§  326.  IN  EDWAHD  COOPER'S  PROCESS, "which  was  carried 
out  experimentally  about  the  year  1873,  at  Trenton,  N.  J., 
iron  ore  is  heated  and  reduced  by  a  current  of  hot  carbonic 
oxide,  or  carbonic  oxide  and  hydrogen.  These  gases  are 
oxidized  to  carbonic  acid  and  steam  by  the  oxygen  of  the 
ore :  they  are  then  passed  through  a  regenerator,  in  which 
they  are  highly  heated,  and  thence  through  a  bed  of  coal 
or  other  fuel  in  which  they  are  again  deoxidized  to 
carbonic  oxide  and  hydrogen.  Still  remaining  in  the  same 
losed  circuit,  they  are  then  used  for  reducing  a  fresK 
portion  of  ore,  a  part  of  the  carbonic  oxide  and  hydrogen, 
however,  being  diverted  to  heat  the  regenerator  already 
mentioned. 

To  simplify  matters  let  us  suppose  that  only  carbonic 
oxide  is  used,  and  follow  the  course  of  the  gas.  What  is 
true  of  pure  carbonic  oxide  would  be  true  of  a  mixture  of 
this  gas  with  hydrogen,  mutatis  mutandis. 

In  passing  through  the  ore  column  the  carbonic  oxide 
undergoes  the  reaction 

(1),  3CO  +  Fe2O3  =  3CO2  +  2Fe 
in  which  3  X  12  X  5,607  =  201, 852  calories  are  developed, 
and  2  X  56  X  1,887  =  211,344       "         "   consumed. 

Net  consumption  of  heat,      9,492  calories. 

We  now  return  the  resulting  gas  to  the  producer, 
where  the  reaction 

(2),  3COZ  +  3C  =  6CO  Calories, 

occurs,  developing  -  -  3  x  12  x  2473  =     89,028 

and  consuming  -  -   3  X  12  X  5607  =  201,852 

Net  consumption  in  gas-producer  -  112,824 

Consumption  in  deoxidizing  furnace  9,492 

Total  consumption  of  heat  -    122,346 

We  have  now  six  equivalents  of  carbonic  oxide,  of 
which  we  may  suppose  that  three  are  used  to  repeat  re- 
action (1),  three  more  being  available  for  burning  to  car- 
bonic acid  in  the  regerator, 

where  th«y  would  generate  3  X  12  X  5,607  =  201,852 
as  our  total  deficit  was  -  122.316 

we  now  have  an  excess    of      -  79,536 

calories,  or  65$  of  the  theoretical  heat-requirement  as  a 
surplus  to  make  up  for  loss  of  heat  by  radiation,  to  use  in 
heating  the  ore  to  the  temperature  of  deoxidation,  etc. 

This,  in  Mr.  Cooper's  opinion,  is  not  a  sufficient  surplus. 
Hence  he  introduces  steam  along  with  the  carbonic  acid 
into  the  regenerator  and  thence  into  the  gas-producer, 
thus  making  water-gas,  and  thus  increasing  the  quantity 
of  gas  available  for  burning  in  the  regenerator,  but  with- 

"o^Eitract  from  report  under  oath  by  P.  Villaoz,  manager  of  the  Alonsotegui 
forges,  October  31st,  1883. 

d  Berg  und  Hiitt.  Zeit.,  XXX.,  pp.  67-8,  1871. 

e  R.  \y  Raymond  and  E.  Cooper,  private  communications,  March  30th  »nd 
May  8th,  1889. 


9*6 


THE    METALLURGY    OP1    STEEL. 


out  introducing  nitrogen  into  the  closed  circuit  of  the  solid  fuel  in  the  central  chamber  B,  Figure  135  A,  and 


reducing  system.  It  may,  indeed,  be  regarded  as  a  mode 
of  making  water-gas,  which  is  used  while  still  hot  from 
the  gas-producer  for  deoxidizing  iron-ore.  The  steam  is 
introduced  in  the  form  of  a  jet,  and  incidentally  aids  the 
circulation  of  the  gas  through  the  system. 

His  apparatus  was  actually  much  more  complex  than 
that  which  I  have  sketched.3 


OF-  E-.cooperVj 


through  it  passes  a  stream  of  carbonic  oxide,  generated  in 
the  gas  producers  DD',  which  are  shafts  filled  with  char- 
coal or  coke,  hot  air  being  blown  in  through  the  tuyeres 
a  a.  The  waste  gases  (carbonic  oxide  and  acid  with  nitro- 
gen) escaping  from  the  top  of  B  are  burned  to  heat  the 
blast.  The  ore  is  heated  wholly  by  the  heat  generated  by 
the  combustion  of  the  fuel  burned  in  the  gas-producer  : 


JCHE/AE-  OF 


PK.OC&5.S 


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AlB. 


CHlA/tet 


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i 

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i 

Sz; 

i 

EB- 

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i 

o 

i 

H 

i 

ft 

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CHI/-\/IE-Y 


Figure  185. 


process b  resembles  Cooper's,  except  that 
common  producer-gas  is  used,  and  that,  as  indicated  in 
Figure  135,  the  gas  passes  through  the  regenerator  while 
on  its  way  from  the  gas-producer  to  the  deoxidizing  fur- 
nace. 

It  is  to  be  noted  that  by  reaction  (2),  which  is  repeated 
indefinitely,  we  oxidize  our  carbon  by  oxygen  derived 
from  ore,  not  from  the  atmosphere,  that  is  to  say  by 
oxygen  unaccompanied  by  nitrogen.  At  each  cycle  we 
divert  part  of  our  carbonic  oxide  from  the  circuit  to  the 
combustion  chambers  of  the  regenerators  and  thence 
through  the  chimney  to  the  outer  air,  and  with  this  car- 
bonic oxide  the  accompanying  nitrogen.  We  are  thus 
constantly  eliminating  nitrogen  from  the  system,  and  it 
seems  as  if  this  might  be  taken  advantage  of  to  gradually 
remove  the  whole  of  this  gas,  so  that  we  would  eventually 
have  a  closed  circuit  of  pure  carbonic  oxide  and  hydrogen, 
as  in  Cooper's  process. 

The  course  of  the  gases  is  sketched  in  Figure  135.  • 
§  327.  INTOURANGIN'S  PROCESS"  ore  is  charged  without 


a  Mr.  Cooper  would  pass  the  gas  on  its  way  from  the  deoxidizing  furnace  to  the 
regenerator  through  a  second  gas-producer  or  bed  of  fuel :  indeed,  only  a  part  of 
the  gas  issuing  from  the  gas-producer  shown  in  Figure  135  goes  directly  to  the 
deoxidizing  furnace,  part  joining  the  gas  which  issues  from  the  deoxidizing  fur- 
nace, and  with  it  entering  the  second  gas-producer,  and  passing  thence  to  the  re- 
generator again.  Further,  a  kiln  for  preheating  the  ore  is  projected.  Mr.  Cooper 
thinks  the  continuous  passage  of  the  current  in  a  single  direction  without  reversals 
important. 

b  G.  Westman,  U.  S.  patent  383,201,  May  1st,  1888. 

cU.  S.  Patent  268,840,  Dec.  13th,  1882.  Also  "A  Treatise  on  the  Reduction 
of  Iron  Ore,"  by  E.  Tourangiu,  1881.  The  reader  is  cautioned  to  scrutinize  the 
beat  calculations  and  thermal  data. 


part  of  this  heat  is  communicated  directly  by  the  hot  car- 
bonic oxide,  part  by  conduction  through  the  partitions : 
while  by  heating  the  blast  the  energy  in  the  waste  gases  is 
returned  to  the  apparatus.  In  case  coke  is  used  the  cham- 


Trausverso  Section. 


Longitudiual  Section. 
Flgurn  135A.— Tourangin's  Furnace. 


bers  CC'  are  filled  with  charcoal  and  scrap  iron,  the  latter 
serving  to  desulphurize  the  gas.  The  spongy  iron  is  cooled 
in  the  water- jacketed  legs  F  F  before  drawing. 

We  here  have  a  blast-furnace,  with  carburization  pre- 
vented by  separating  fuel  from  burden,  and  sulphurization 
prevented  by  desulphurizing  the  products  of  the  combus- 
tion of  that  fuel  without  cooling  them  ;  while  compactness 
favors  thorough  utilization  of  heat.  The  project  is  simply 
beautiful:  but  maintenance  of  the  apparatus  may  involve 


CHEN OT' S    PROCESS.       §  332. 


277 


very  grave  difficulties.  If  the  apparatus  be  so  compact 
and  so  well  lagged  that  but  little  heat  radiates,  and  if  the 
blast  be  preheated  in  an  efficient  apparatus,  a  very  high 
temperature  should  be  developed  in  the  gas-producer. 
Compared  with  the  blast-furnace  the  gas-producer  would 
be  cooler  in  that  its  fuel  is  not  greatly  preheated  before 
reaching  the  zone  of  combustion,  but  hotter  in  that  it  is 
not  cooled  by  the  constant  arrival  of  fresh  lots  of  burden 
to  be  heated  and  melted.  Neglecting  the  losses  by  radia- 
tion, and  supposing  the  blast  to  be  cold,  the  gas  should 
reach  the  partitions  EE  at  the  temperature  theoretically 
due  to  the"  combustion  of  carbon  t6  carbonic  oxide,  or  about 
l,i)<)0°  C.  (2, 100°  F.),  the  heat  radiated  away  to  the  sur- 
rounding fuel  being  returned  to  the  region  of  combustion 
when  that  fuel  in  turn  burns.  Add  to  this  the  heat  brought 
in  by  the  blast,  and  the  gas  at  EE  might  reach  2,000°  C. 
(3,600  P.).  If,  on  the  other  hand,  the  temperature  here 
be  kept  down  by  permitting  loss  of  heat  by  radiation,  by 
water-jacketing,  etc.,  we  diminish  the  heating-efficiency  of 
the  apparatus,  and  its  chance  of  successful  competition 
with  the  blast  furnace. 

§  328.  LAUKEAU'S  PROCESS  aims  to  deoxidize  iron-ore 
with  natural  gas,  and  to  prevent  the  deposition  of  carbon 
which  occurs  when  this  fuel  is  passed  directly  through 
hot  ore.  An  application  for  a  United  States  patent  is 
now  pending.  If  the  patent  issues  soon  enough  I  will 
describe  the  process  in  an  appendix. 

§  329.  BULL'S  SO-CALLED  DIRECT  PROCESS*  was  hardly 
a  direct  process  at  all,  but  rather  an  ill-advised  attempt 
to  replace  the  whole  of  the  solid  fuel  of  the  blast-furnace 
with  superheated  water-gas.  Bull  indeed  expected  to 
make  steel  in  the  furnace  :  but  these  expectations  do  not 
deserve  our  notice.  I  may,  however,  point  out  that  in 
the  blast-furnace  we  are  able  to  reach  a  temperature  well 
above  the  melting  point  of  cast-  and  even  of  wrought- 
iron,  while  preserving  a  reducing  atmosphere,  by  the  com- 
bustion of  highly  preheated  solid  carbon  to  carbonic 
oxide :  that  if  we  start  with  hydrogen  and  carbonic  oxide, 
these  gases  can  hardly  be  introduced  into  the  blast-fur- 
nace while  at  a  temperature  above  the  melting  point  of 
cast-iron  by  any  means  of  which  we  now  know.  To  raise 
their  temperature  above  that  of  wrought-iron  or  of  the  slag 
which  accompanies  cast-iron,  they  must  burn,  and  in 
burning  they  must  generate  either  carbonic  acid  or  aqueous 
vapor  or  both,  and  each  oxidizes  metallic  iron  energetic- 
ally :  so  that  the  use  of  unoxidized  carbon  seems  a  neces- 
sity if  we  are  to  obtain  our  iron  and  slag  in  a  molten  state 
without  great  loss  of  iron 

The  results  obtained  with  the  process  seem  to  bear  out 
these  views.  In  a  fourteen-day  run  at  the  John  Cockerill 
works  at  Seraing,  in  an  iron  blast  furnace  21  feet  high  and 
6  feet  in  diameter  at  the  boshes,  which  appears  to  have  used 
the  astonishing  quantity  of  nearly  seven  tons  of  coke  per 
ton  of  white  pig-iron  produced,  or  seven  times  as  much  as 
in  our  best  practice,  part  of  the  coke  was  replaced  by 
water-gas.  Although  the  quantity  of  coke  charged  in  the 
blast-furnace  along  with  the  ore  was  still  enormous,  run- 
ning from  a  little  above  one  up  to  ten  tons  of  coke  per  ton 
of  iron,  and  although  the  total  quantity  of  coke  used  in 
producer  and  blast-furnace  together  was  still  more  than 
four  tons  per  ton  of  iron,  yet  the  partial  substitution  of 


» See  Iron.  XXI.,  p.  89,  1883:  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p. 
838,  1884:  Stahl  und  Eisen,  VI.,  p.  578,  1886. 


water-gas  seems  to  have  chilled  the  furnace.  The  silicon 
fell  from  2'3  to  ()•!.%  the  carbon  from2'27  to  l-45#,  while 
the  sulphur  and  phosphorus  ran  from  1-6  to  0'33%  and 
from  l'7o  to  I'lO  respectively.  The  ore  seems  to  have 
held  about  25%  of  iron. 

The  results  obtained  before  using  Bull's  process  were 
astonishingly  bad,  even  for  an  experimental  furnace.  But 
how  the  promoters  had  the  rashness  to  lay  before  investors 
the  damning  results  which  the  Bull  process  here  yielded  : 
how  journals  of  high  standing  could,  as  they  did,  treat 
them  with  respect,  and  discuss  them  as  if  they  were  of  real 
technical  and  economic  importance,  passes  all  understand- 
ing. Verily,  iron-making  is  the  home  of  the  charlatan." 

§  330.  S.  LUCAS"  in  1792  would  deoxidize  iron  ore  in 
horizontal  retorts  (the  pots  of  a  cementation  furnace),  and, 
apparently  after  allowing  the  sponge  to  cool  within  the 
retorts,  melt  it  in  crucibles. 

Substantially  similar  are  the  processes  of  Hawkins"1  and 
Newton.6 

§  331.  IN  THE  CoNLEy  PKOOESS'  the  ore  is  crushed  to 
pass  a  screen  of  about  twenty  meshes  to  the  linear  inch, 
and  is  then  apparently  dressed  to  remove  gangue  :  then, 
mixed  "with  what  is  chemically  required  to  free"  the 
sulphur,  phosphorus,  "etc.,"  and  enough  charcoal  to  re- 
move the  desired  proportion  of  the  oxygen,  it  is  gently 
heated  and  continually  stirred  in  peculiarly  constructed 
retorts.  The  partially  deoxidized  ore  is  next  run  into  air- 
tight vessels  and  there  cooled :  is  bricked  with  enough 
melted  pitch  "  or  other  carbon  "  to  coke  and  to  remove  the 
remaining  oxygen  but  not  to  melt  on  subsequent  heating, 
and  is  melted  in  a  furnace  or  crucible.  All  conditions  being 
rigidly  fixed,  complete  control  over  the  product  is  claimed. 

Few  experienced  metallurgists  will  entertain  the  claim 
seriously.  The  conditions  are  evidently  not  under  control. 
Important  variations  in  the  composition  and  physical 
condition  of  the  ore,  in  the  temperature  of  the  reducing 
retort,  in  the  degree  of  reoxidation  when  the  partly  re- 
duced ore  runs  from  the  retort  to  the  cooling  vessel,  in 
the  temperature  and  in  the  strength  of  the  oxidizing  con- 
ditions when  the  bricks  are  remelted,  will  arise  and  will 
destroy  the  expected  completeness  of  control.  But  closer 
control  is  not  to-day  a  pressing  need  in  our  Bessemer  and 
open-hearth  practice.  In  the  crucible  process  it  is  indeed 
desirable,  but  here  the  variations  which  arise  are  due 
chiefly  to  variations,  not  in  the  composition  of  the  material 
charged,  but  in  the  temperature  and  strength  of  the 
oxidizing  conditions  in  the  crucible  and  in  the  behavior  of 
the  crucible  itself ;  and,  clearly,  these  variations  would 
not  be  lessened  by  the  Conley  process. 

Beyond  this  one  sees  no  reason  to  expect  merit  in  the 
process,  unless  it  be  in  the  peculiarity  of  the  retorts  and 
in  the  nature  of  "  what  is  chemically  required  to  free" 
the.  phosphorus  and  sulphur.  What  these  are  is  beyond 
our  present  ken. 

§332.  IN  CIIENOT'S  PROCESS"  iron  ore  was  deoxidized 


b  The  published  account  of  the  results  is  so  astonishingly  bad  that  one  wonders 
whether  there  is  not  some  clerical  error,  misprint,  or  obscurity. 

c  British  patents,  April  18,  1793,  No.  1869. 

d  July  4,  1836,  No.  7142. 

e  April  8,  1856,  No.  851. 

t  Iron  age,  XLI.,  p.  722,  1888. 

«  British  patent  1590,  A.  D.,  1866.  My  information  is  taken  chiefly  from  Percy, 
Iron  and  Steel,  1864:  Grateau,  Rev.  Univ.,  VI.,  pp.  1-62,  189:  5Bell,Manuf.  Iron 
and  St.,  p.  34,  1884, and  Hunt,  Kept.  Geolog.  Survey,  Canada,  1860-9,  p.  288.  Bell 
reports  that  the  process  was  used  in  1872  at  only  one  establishment  in  the  world. 


278 


THE    METALLURGY    OF    STEEL. 


by  heating  with  charcoal  in  vertical  retorts,  whose  upper 
part  was  of  fire-brick  and  externally  heated,  the  lower 
part  being  of  sheet-iron  and  water- jacketed,  to  cool  the 
sponge  before  drawing,  and  thus  prevent  reoxidation. 
The  operation  was  continuous.  Chenot  is  said  to  have 
built  a  large  furnace  for  the  direct  process  in  1831. 

In  his  direct-heating  methol  hot  carbonic  oxide  was 
passed  directly  from  a  gas-producer  through  the  column 
of  ore,  as  in  Gurlt's  process. 

TABLE  162.— CIIENOT'S  PROCESS. 


1 

ndirect  heating 

Direct  II  eating 

Per  100  pounds 
ofiron  in  55$ 
ore,  at  Haut- 
mont. 

Per  100  of  iron 
in  60-6£  ore,  at 
Baracaldo. 

Per  100  of 
merchantable 
bar-iron,  at 
Baracaldo. 

Per  100  of 
merchantable 
bar-iron,  at 
Laramede 
(leaner  ore). 

300 

8-75 

Ore  freed  from  fines  

256 

319 

1  Iron  sponge  

38 

160 

220 

Products.  .  K  Blooms  

68-54 

115 

110 

|  Bar-iron  

55-25 

100 

100 

Labor,  days  

0-165 

48 

85 

64 

99 

Coal  for  heating  redueing-furna-e... 

157 

96 

175 
86 

0 
88 

100 

100 

Total  fuel  

825 

287 

Chenot  received  a  gold  medal  at  the  Paris  exhibition 
of  1855,  but  apparently  on  questionable  grounds. 

A.  The  indirect-heating  process. 

I.  The  Furnace  contained  one  or  two  vertical  rectan- 
gular retorts  of  the  following  dimensions, 


Height.  Width.  Length. 

1.  2S'  0-65"         1'  7-69"  6'    6-74" 

l'7-69"  4' 11-06" 

3.  88'  ±  V  4"  4'    9" 


Locality. 
Hautmont. 

H 

Spain.  1872- 


Authority. 
Grateau,  Percy,  Iron  and  Steel,  p.  338. 
'•  '•  "  p.  339. 

Bell,  Manf.  Iron  and  Steel,  p.  84. 


The  upper  parts  were  of  fire-brick,  and  were  heated  by 
means  of  external  flues.  Below  and  forming  a  continua- 
tion of  the  fire-brick  part  of  the  retort  were  rectangular, 
vertical,  water-cooled,  sheet-iron  "refroidissoirs,"  or  cool- 
ers, which  were,  in  the  first  of  the  above  cases,  14'  9 '17" 
long.  The  bottom  of  a  cooler  was  temporarily  closed  with 
removable  grate-bars  0'79"  apart.  To  draw  a  charge  a 
wagon  standing  on  a  lift  beneath  the  cooler  was  raised  to 
the  grate-bars  ;  these  were  drawn,  the  wagon  descended, 
and  the  sponge  dropped  into  it,  the  grate-bars  probably 
being  replaced  as  soon  as  the  wagon  was  full. 

II.  The  Process  — Lump  ore  was  broken  to  about  1  '8- 
cubic-inch  pieces :  fine  ore,  sometimes  mixed  with  reduc- 
ing matter,  was  agglutinated  by  compression.     The  ore, 
now  mixed  with  say  60  pounds  of  charcoal  per  100  of  iron 
present,  was  charged  in  the  retorts  and  there  deoxidized. 
The  daily  withdrawal  of  part  of  the  spongy  iron  from  the 
bottom  of  the  cooler  caused  the  charge  to  descend,  so  that 
it  remained  three  days  in  the  hot  part  of  the  retort,  and 
three  more  in  the  cooler. 

The  sponge  was  worked  into  blooms  in  a  charcoal 
hearth,  or  melted  in  crucibles.  In  the  latter  case  it  was 
first  compressed  into  little  cylinders  occupying  about  one- 
third  of  its  original  bulk,  together  with  deoxidizing  and 
carburizing  matter,  such  as  charcoal,  wood-tar,  resin,  or 
fatty  matter,  and  these  were  melted  in  common  crucibles 
as  in  the  crucible  process.  But  as  the  sponge  cylinders 
were  bulky  and  the  weight  of  a  charge  consequently 
small  (40  to  55  pounds),  the  cost  of  this  fusion  per  pound 
of  ingots  was  excessive. 

While  it  was  thought  possible  to  reduce  the  iron  com- 
pletely, this  took  much  time,  and  it  was  found  better  to 
reduce  it  partially,  and  to  select  by  hand  the  imperfectly 
deoxidized  pieces  for  further  treatment. 

III.  The  Loss. — At  Baracaldo   100  of  iron  in  a  Q()-Q%  ore 


yielded  63*54  of  blooms,  the  loss  being  o6'46$,  and  55-25 
of  bar-iron,  the  loss  being  44'75$. 

IV.  Fuel. — For  reducing  100  of  iron  from  the  ore  about 
48  pounds  of  charcoal  were  used  at  Hautmont  and  about 
35  pounds  at  Baracaldo. 

For  heating  the  retorts  157  and  96  pounds  of  ooal  were 
used  at  these  two  establishments  respectively,  per  100 
pounds  of  iron  in  the  ore. 

V.  The  Labor  in  producing   sponge   was   about  3 -7 
days  per  2  240  pounds  of  iron  in  the  ore,  or  -165  per  100 
pounds. 

Bella  estimates  that  the  loss  of  iron  is  3 -5  times  and  the 
cost  for  fuel  2  3  times  as  great  in  producing  bar-iron  by 
Chenot' s  process  as  in  making  rolled  steel  by  the  blast- 
furnace and  Bessemer  processes.  But  it  is  more  to  the 
point  to  compare  the  cost  of  100  units  of  iron  available  for 
the  open-hearth  process  in  sponge  and  in  scrap-iron. 

B.  In  the  direct-heating  method  the  heating  was  done 
wholly  by  the  hot  reducing  gas,  and  the  total  fuel-con- 
sumption thereby  greatly  lessened :  but  as  the  reducing 
gas  was  made  wholly  from  charcoal,  somewhat  more  of 
this  fuel  was  needed  than  in  the  indirect-heating  method, 
in  which  the  charcoal  had  merely  to  deoxidize  :  so  that  in 
the  direct-heating  method  a  given  weight  of  coal  is  re- 
placed by  a  much  smaller  one  of  charcoal.  It  would  thus 
depend  on  the  relative  prices  of  these  fuels  whether  this 
would  effect  a  saving.  In  the  cases  here  given  one  part  by 
weight  of  charcoal  appears  to  replace  five  of  coal,  which, 
considering  that  a  leaner  ore  was  used  in  the  direct-  than  in 
the  indirect-heating  method,  would  indicate  a  decided  ad- 
vantage for  the  direct-heating  method  :  but  we  cannot  be 
sure  that  other  conditions  were  alike  in  these  two  cases. 

§  333  A.  BLAIR' s  PROCESS." — As  the  success  of  the  open- 
hearth  process  promised  a  demand  for  iron  sponge,  Blair 
made  strenuous  efforts  from  about  1871  to  1878  to  bring 
Chenot' s  process  to  a  commercial  success,  introduced  im- 
portant improvements  in  heating  the  ore,  and  hastened 
the  reduction  by  the  addition  of  lime.  The  process  has 
been  abandoned. 

I.  The  early  furnace,  Figure  136,  like  Chenot' s  in  its 
general  features,    had  three  vertical  retorts  completely 
filled,  above  with  charcoal  and  ore,  below  with  spongy 
iron.   The  upper  parts  were  made  of  tongued  and  grooved 
fire-bricks,    and    heated    externally  by  gas    introduced 
through  the  pipes  OO  ;  their  lower  parts  or  coolers  were 
of   sheet-iron  water-jacketed   (K).      At  the  top  was  a 
cast-iron  thimble  C  heated  internally  by  gas  introduced 
through  a  central  pipe,  and  by  the  carbonic  oxide  gener- 
ated by  the  oxidation  of  the  carbon  of  the  charcoal  by  the 
oxygen  of  the  ore.     At  the  lower  end  was  an  external 
sleeve  LL,  usually  luted,  but  raised  at  intervals  to  allow  a 
little  of  the  sponge  to  slide  out. 

II.  The  Process. — The  ore,  in  lumps  two  inches  thick 
or  less,  mixed  with  33  to  44  parts  of  charcoal  per  100  of 
iron,  was  charged  in  the  four-inch  annulus  between  the 
thimble  and  the  sides  of  the  retort :  here  lying  in  a  thin 
sheet,  it  was  quickly  raised  to  redness  by  the  heat  trans- 
mitted through  the  walls  of  the  thimble  and  those  of  the 
retort.    Thus  one  of  the  great  difficulties, — heating  a  thick 


»  Prin.  Manuf.  Iron  and  Steel,  p.  34,  1884. 

*>U.  8.  patent  126.92S,  May  21st,  1872:  Trans.  Am.  Inst.  Mining  Engineers, 
II.,  p.  175,  1874:  Journ.  Iron  and  Steel  Inst.,  1878,  I.,  p.  47,  1875, 1.,  p.  177: 
Eng.  Mining  Jl.,  XVII.,  June  6th,  1874.  Bell,  Princ.  Manuf.  Iron  and  Steel,  p. 
34,  1884. 


BLAIR'S    PROCESS.       §  333. 


279 


body  of  ore  to  the  middle,  was  met  simply  :  but  some  still 
more  economical  plan  seems  needed,  such  as  preheating  the 
ore  by  direct  contact  with  fuel  in  a  kiln,  whence  it  could 
be  drawn  directly  to  the  reducing  retort  while  still  red-hot. 
As  sponge  was  drawn  from  the  bottom,  the  whole  con- 
tents of  the  shaft  sank,  the  now  hot  ore  from  the  pre- 
heating annulus  into  the  body  of  the  retort,  tbe  sponge  at 
the  bottom  of  the  retort  into  the  cooler.  The  height  and 


capacity  of  GO  tons  of  sponge  per  21  hours  was  estimated 
by  Holley  at  $75,000. 

III.   The  later  Furnace. — Blair  discovered  that  the  adui 
tion  of  say  5%  of  lime  to  the  ore  greatly  hastened  deoxida 
tion — the  alkaline  earth  it  has  been  conjectured  favoring  the 
formation  of  cyanogen.    It  was  now  found  that  the  thimblo 
arrangement  could  not  preheat  the  ore  as  rapidly  as  it 
could  be  deoxidized  in  the  retort  proper :  to  hasten  heat- 


Figure  186.— Blair's  Earlier  Sponge-making  Furnace,  Heating  by  Transmisrion. 

compactness  of  the  column  was  thought  to  prevent  air 

from  entering  beneath  when  the  sleeve  L  was  raised. 
A  retort  4'  G"  in  diameter  and  40'  to  50'  high  turned  out 

about  two  tons  of  sponge  per  24  hours.     This  would  imply 

that  the  ore  remained 

in  the  preheating  annulus  about  0*5  days. 

"      brick  retort     -  "7~        " 

"       cooler    -    -     - -     -     -       4         " 


11  5  days. 
The  cost  of  a  Blair  sponge-making  plant  with  a  daily 


Figure  1  :.<'.— Blair's  Later  Sponge-making  Furnace  with  Direct  Heating. 

ing,  the  single-retort  furnace  shown  in  Figure  137  was  de- 
signed. In  this  the  ore  was  mixed  with  charcoal  as 
before,  but  was  heated  wholly  by  a  stream  of  hot  carbonic 
oxide  and  nitrogen  from  a  coke-burning  gas-producer  C. 
The  gas  passed  up  around  the  retort  ^D,  entering  at  the 
point  E  where,  by  narrowing  the  retort,  an  annular  ring  was 
left,  permitting  the  gas  to  enter  the  ore-column  on  all 
sides.  The  charcoal  was  relied  on  for  the  deoxidation, 
though  doubtless  the  carbonic  oxide  took  up  more  or  less 
oxygen  in  passing  through  the  ore.  The  sponge  was 
cooled  as  before  in  a  cooler,  F. 


280 


THtt    METALLURGY     OF    STEEL. 


Just  how  much  the  presence  of  lime  hastened  operations  I 
cannot  be  readily  determined.  Ireland  stated  that  in  such 
a  retort  1C'  high,  its  inside  diameter  being  i'  above  and 
6'  6"  below,  and  the  total  height  of  the  structure  36',  about 
200  tons  of  ore  could  be  deoxidized  per  week,  which  implies 
that  about  a  day  was  occupied  in  deoxidizing  and  another 
in  cooling,  so  that  the  presence  of  lime  hastens  deoxida- 
tion  sevenfold.  But  Mr.  Morrison  Foster  informs  me  that, 
"  while  the  use  of  lime  was  undoubtedly  an  improvement, 
yet  operations  were  not  carried  far  enough  in  a  practical 
way  to  justify  the  establishment  of  a  basis  for  working."8 
I  am  confident  that  Mr.  Ireland  is  mistaken.  To  increase 
the  cooling  surface  he  would  have  several  narrow  coolers 
instead  of  a  single  wide  one,  beneath  the  brick  part  of  the 
retort. 

Clearly  most  if  not  all  the  sulphur  of  the  coke  must  iii 
this  arrangement  be  absorbed  by  the  iron  sponge :  but  it 
would  seem  possible  to  intercept  it  by  placing  between 
the  gas-producer  and  the  retort  a  thin  column  of  some 
absorbent,  such  as  lime,  or  iron  sponge  itself,  through 
which  the  producer-gas  would  pass. 

In  case  the  producer-gas  heated  the  ore  at  the  point  E 
too  highly,  it  was  cooled  by  diluting  it  with  the  cool  gas 
escaping  from  the  top  of  the  retort  at  G :  clearly  this 
escaping  gas,  owing  to  the  presence  of  the  charcoal  in  the 
ore  column,  would  be  chiefly  carbonic  oxide  and  nitrogen; 
or,  in  other  words,  the  producer-gas  would  be  little  altered 
in  composition  in  passing  through  this  column. 

IV.  TJie  product  was  cold  spongy  iron,  preserving 
roughly  the  shap3  and  size  of  the  original  lumps  of  ore, 
and  apparently  unimpregnated  by  carbon.  The  tempera- 
ture in  the  hot  part  of  the  retort  was  probably  rather  too 
high  to  favor  considerable  carbon-impregnation,  which,  as 
we  have  seen  (p.  120),  almost  ceases  when  the  temperature 
rises  to  bright  redness :  but  in  cooling  the  spongy  iron 
must  pass  very  slowly  through  the  range  at  which  carbon- 
impregnation  occurs  rapidly,  and  it  must  still  be  sur- 
rounded by  an  atmosphere  of  carbonic  oxide.  Yet, 
though  I  conducted  the  process  for  some  time,  I  was 
never  able  to  assure  myself  that  the  sponge  contained 
carbon  left  by  impregnation. 

The  deoxidation  could  be  made  very  thorough  :  accord- 
ing to  Blair  95  to  98^  of  the  iron  was  deoxidized. 


a  Private  communication,  March  22d,  1889. 


V.  Further  Treatment. — The  sponge  when  drawn  from 
the  reducing  furnace  was  quite  cool    so  that  it  did  not 
reoxidize.     It  was  squeezed  under  a  pressure  cf  30,000 
pounds  per  square  inch  into  cylindrical  blooms  C"  in 
diameter  and  from  12"  to  IS"  long.    These  could  be  either 
thrown  direct  into  the  bath  in  the  open-hearth  furnace,  or 
preheated  in  aa  auxiliary  furnace.     In  later  practice  only 
the  fine  sponge  was  compressed,  the  lumps  being  shovelled 
into  the  open-hearth  bath  either  without  previous  prep- 
aration, or  after  balling  in  a  preheating  gas-furnace. 

As  rich  ores  containing  about  C3-6^  of  iron  and  hence 
about  §%  of  gangue  were  used,  the  quantity  of  gangue  to 
be  melted  in  the  open-hearth  furnace  was  not  excess! ve, 
its  heat-capacity  being  probably  about  one-quarter  of  that 
of  the  iron  of  the  sponge.  The  consumption  of  fuel  in 
melting  was  indeed  very  moderate,  only  about 400  pounds 
to  the  ton  of  steel  I  cm  informed  by  Mr.  M.  Foster. 

VI.  Carburization. — Believing  sponge    cheaper   than 
cast-iron,  Blair  would  lessen  the  proportion  of  cast-iron  to 
sponge  used,  in  the  open-hearth  process  by  carburizing 
part  of  the  sponge,  either  by  inclosing  charcoal  or  tar  in 
the  blooms,  perhaps  together  with  some  accelerating  (e.  g. 
cyanogen-yielding)  matter:  or  by  passing  through  the 
reducing  retort  gaseous  hydrocarbons,   which    he    says 
would  carburize  the  sponge. 

In  actual  practice  Blair  used  tar-plugs,  i.  e.  cylinders  of 
sponge  compressed  with  8%  of  their  weight  of  coal-tar,  for 
part  and  sometimes  for  a  large  part  of  the  cast-iron  of  the 
open-hearth  charge.  In  one  case  the  proportion  for  cast- 
iron  was  only  14-05$  for  the  average  of  a  week's  work, 
and  in  two  heats  it  was  only  \Q%  of  the  whole  charge. 

The  loss  chargeable  to  the  sponge-making  process  is  not 
easily  arrived  at.  As  Table  1G2A  shows,  100  parts  of  iron 
in  the  charge  yielded  about  91$  of  ingots  and  scrap  in 
eleven  charges  selected  at  random  by  Bell,  and  about  85$ 
of  ingots  and  scrap  in  428  consecutive  heats.  If,  however, 
we  follow  the  usual  course  and  reckon  the  loss  on  the 
gross  weight  of  cast-iron  and  scrap  charged  without  de- 
duction for  non-ferrous  substances  which  they  contain, 
and  on  the  iron  actually  in  the  sponge,  the  loss  rises  in 
these  two  cases  to  li'62  and  19'90$  respectively. 

In  the  third  schedule  Bell  finds  the  loss  15 '83^  reck- 
oned in  the  former  way :  if  reckoned  in  the  latter  way  it 
would  rise  to  19 '41$.  Without  disputing  Mr.  Bell' s  data 


TABLE  162A..— Loss  IN  THE  OPEN-HEABTU  STEEL  PROCESS,  USINO  IBOM  SPONGE. 


Allowing  for  Impurities  in  pig-iron  and  scrap. 

Reckoned  on  gross  weight  of  pig  nnd  scrap,  but  on  actual  'ron-content  of  Bponge. 

11  heats  sele  ^ted  by  Bell. 

428  consecutive  heats, 
II. 

Data  (riven  by  Bell. 
III. 

11  heats  selected  by  Bell. 

428  consecutive  heats. 
II. 

Data  given  by  Bell 
III. 

Gross 
weight. 

£Fe. 

Weight 

K 

Gross 
weight. 

*Fe. 

Weight 
Fo, 

Gross 
Weight 

*Fe. 

Weight 
Fc. 

Gross 
Weight, 

*Fe 

taken  as 

Weight 
Fo 
taken  us 

Gross 
Weight. 

#Fo 
taken  n> 

Wi-ight 
Fo 
taken  as 

Gross 
Weight. 

£Fo 
taken  as 

Weight 
Fo 
tal.cn  as 

Pig-iron  

23,810 
(   13,255a  ) 
\  10,500b  V 
I     8,116    ) 

14,161 

7,531 

Ui 
83 

90 
60 

22,387 
C6.959 

12,745 
6,025 

1,000,632 

Ill 

940,594 
1,137,090 

759,093 

170,686 
8,110 

SCO 
470 

60 
110 

94 
90 

90 

80 

838 
423 

54 

83 

23,816 
(13,255a  ) 
10.501*  > 
8,1160    ( 

14,161 
7,531 

100 
85 

100 
100 

23,816 
26,959 

14,161 
7,531 

1,000,682 

100 

J  .000,682 
1,137,090 

643,442 

213,858 
15,551 

860 
470 

60 
110 

100 
90 

100 
100 

860 
423 

60 
110 

Scrap-stool  from  pre-  1 
vious  meltings.  ..  ( 
Ppiegeleison  

643,442 

218,853 
15,561 

90 

60 
23 

843,442 

213.858 
15551 

100 

100 

100 

Total  

68,116 

3,010,578 

768 

99 

903 

760 



72.467 
61,870 

3.210,073 
2,571.353 

953 
768 

Loss  

6,246 

439,225 

143 
15-83 



10,597 
14-02 

638,720 
19-90 

185 
19-41 

i  Tar  plugs,  i.  e  ,  cylinders  of  sponge  compressed  with  8£  of  their  weight  of  tar. 

b  Hot  sponge. 

c  Cold  sponge. 

In  case  of  ihe  sponge,  the  loss  hero  given  is  of  course  the  total  loss  from  ore  to  Ingotfl.  .    , 

I.  "  Mr .  I.  Lowthian  Boll  and  the  Blair  Direct  Process,"  Pittsburgh,  1875.    Mr.  Bell  made  tho  loss  20'0«,  apparently  through  omitting  to  allow  for  the  impuritlt  o  sponge,  wl 

II.  °M.  Voster,' Viee-Pri-sidi-nt  of  tho  Blair  Iron  and  Steel  Company.    Private  Communication,  March  22d,  1889,    428  heats,  between  August,  1874,  and  Oct.,  1375, 

III.  Bell,  Principles  of  the  Manufacture  of  Iron  and  Steel,  p.  36,  1884. 


BLAIR    AND     OTHER    DIRECT    PROCESSES.       §  333. 


281 


I  am  at  a  loss  to  find  what  they  refer  to.  The  weight  of 
steel  scrap  is  but  one-sixth  that  of  the  pig-iron  charged, 
while  a  very  different  ratio  exists  in  the  data  previously 
discussed  by  him  and  in  those  given  me  by  Mr.  Foster. 

In  formerly  discussing  this  process  Mr.  Bell  arrived  at 
the  loss  by  adding  to  that  actually  arising  in  the  open- 
hearth  melting  the  loss  previously  experienced  on  tlie  steel 
scrap  charged.  While  doubtless  quite  proper  for  the 
special  conditions  which  he  had  in  mind,  this  is  wholly 
misleading  in  determining  the  loss  between  ore  and  ingots 
by  the  sponge-making  and  open-hearth  processes  com- 
bined. Scrap  steel  charged  represents  runners,  gates, 
fountains,  crop-ends,  sloppings,  skulls  from  previous 
meltings,  scrap  purchased  in  the  market,  and  what 
not.  The  first  group  simply  represents  unmerchantable 
castings.  The  proportion  of  the  castings  which  is  mer- 
chantable should,  with  equally  skillf  ul  founding,  be  the 
same  whether  the  molten  metal  be  made  from  sponge  or 
old  rails  or  pocket-knives.  It  is  dependent  not  on  the 
source  of  the  materijls  charged  in  the  open-hearth  pro- 
cess, but  on  the  mode  of  casting  the  products  of  that  pro- 
cess and  the  skill  of  the  workmen  in  casting. 

In  comparing  the  direct  and  indirect  methods  of  steel- 
making  it  should  be  neglected  quite  as  we  neglect  the  loss 
in  mining  or  in  ore-dressing,  as  foreign  to  the  subject. 
Whether  he  has  included  it  in  the  data  of  Schedule  III. 
I  know  not. 

The  proper  way  to  arrive  at  the  loss  appears  to  be  to 
deduct  from  the  total  loss  that  properly  chargeable  to 
the  cast-iron  and  scrap  used  in  the  process,  and  to  charge 
the  rest  against  the  sponge.  But  it  is  not  easy  to  decide 
how  much  is  chargeable  to  cast-iron  and  scrap,  for  this 
depends  greatly  on  the  skill  with  which  the  open-hearth 
furnace  is  managed,  and,  as  I  know  well,  this  particular 
open-hearth  furnace  (Pranks)  was  not  well  managed. 

The  loss  in  what  I  believe  to  be  the  first  37  heats  made 
in  this  country  (in  1870)  by  the  open-hearth  process,  in 
regular  working,  was  16-63^." 

Blair  claimed  that  the  loss  in  using  scrap,  blooms  and 
cast-iron  was  18  '37$  in  American  practice  at  the  time 
when  the  result  obtained  in  Table  162A  were  obtained. 
M.  Foster  claimed  that  the  loss  by  the  pig  and  ore  pro- 
cess was  then  IS -4$.  According  to  notes  which  I  obtained 
from  Mr.  Holley  the  loss  at  Landore  by  the  pig  and  ore 
process  was  about  22%  in  1874.  The  loss  is  much  less  at 
present.  Bell  took  it  at  Q%  for  comparison  with  Blair' 
work :  but  I  am  sure  that  a  loss  of  6fa  represents  much 
better  open-hearth  practice  than  Blair' s,  and  that  thi 
number  is  not  fair.  Holley  reported  that  the  loss  in  the 
Pernot  open-hearth  practice  was  5  '94$  in  1876  and  4  •"&%  in 
1878 :  and  that  the  loss  at  Terre  Noire  and  Creusot  was  5 
and  6$  respectively  in  1878. 

The  loss  is  usually  heavier  on  the  gross  weight  of  cast- 
than  on  that  of  scrap-iron,  owing  to  the  much  smaller 
proportion  of  iron  initially  present  in  the  former  material. 
From  personal  knowledge  of  the  operations  at  Glenwood 
I  do  not  believe  that  the  loss  on  the  cast-iron  was  less  than 
15$  of  its  g  oss  weight.  If  we  adopt  this  number  and 
assume  that  the  scrap  (which  in  this  case  appears  to  have 
been  especially  impure,  having  by  Bell's  estimate  only  90$ 
of  iron)  also  lost  15$,  then  the  data  given  by  Bell  in 


Schedule  III.  of  Table  162  A  imply  that  the  sponge  lost 
24$.     Thus : 

360  of  cast-iron  at  85$  yielded  -  -  301! 

60  of  scrap-iron  at  85$  51 

110  of  spiegeleisen  at  75$  82 -5 


Total 
Balance  of  yield  to  be  credited  to  sponge 

Total  yield  - 
Sponge  contained 
Loss  on  sponge  =  24 '23$  - 

Yield  of  sponge  as  above 

TABLE  163.— BLAIR'S  Pu- 


439-5 
-  320-5 


760 
-  423 
102-5 


-  320-5 


Indirect  heating 
per  100  Ibs.  of  iron  in  oro. 


Per  centage  of  iron  in  oro 

Ore  used 

Charcoal  for  reducing,  Ibs , 

Coal  or  coke  for  heating  the  retorts 

Labor,  dsiys 

Cost  of  compression 

Output  of  sponge  per  retort  per  week,  tons 


Blair. 
I. 

Bell. 
II. 

Foster. 
III. 

60 

M 

C8 

2(111  lb» 

Id)  Ibs. 

33 

44 

33  ± 

83 

150 

44  ± 

O'l  ± 

1'4 

$0.12  ± 

14 

12  ± 

I.  Hlalr,  Trans.  Am.  Inst.  Mln.  Kng.,  II.,  p.  175.  1S74.    Those  are  expected  results. 

II.  Bell,  Princ.  Man.  Iron  and  Steel,  p  84,  lS8t. 

III.  Report  of  the  Blair  Iron  and  Steel  Company,  January  1st,  1S75.    The  data  are  given  as 
the  actual  working  pesuts  obtained  at  GU-nwood,  near  Pittsburgh. 


a  From  notes  which  I  took  in   1870,  when  attached  as  a  student  to  the  open- 
hearth  plant  of  the  Bay  State  Iron  Company,  during  this  early  practice. 


Comparing  these  numbers  with  those  in  Table  162,  we 
see  that  Blair  lessened  the  consumption  of  fuel  for  heat- 
ing greatly,  but  not  for  deoxidizing.  As  regards  loss  no 
safe  comparison  can  be  made :  for  while  Blair' s  loss  from  ore 
to  ingot  was  much  less  than  Chenot'  s,  we  cannot  tell  how 
much  of  the  difference  was  due  to  better  deoxidation,  and 
how  much  to  the  smaller  opportunity  for  reoxidation  in 
melting  in  the  open-hearth,  in  which  Blair's  sponge  was 
treated,  than  in  the  charcoal-hearth  in  which  Chenot' s  was 
balled. 

The  consumption  of  fuel  and  the  cost  of  installa- 
tion per  unit  of  product  were  not  immoderate.  I  have 
attributed  the  failure  of  the  process  less  to  its  being  in- 
applicable to  existing  conditions  than  to  injudicious 
management,  in  carrying  out  avoidable  experiments  (as  if 
the  unavoidable  ones  were  not  burdensome  enough),  and 
to  certain  misfortunes  for  which  the  management  seemed 
in  no  way  to  blame. 

B.  Yates'  process*  appears  to  be  identical  with  Chenot' s 
indirect-heating  process. 

C.  In   Troscd's  process"  ore  was  reduced  by  contact 
with  carbonaceous  matter  in  externally-heated  vertical 
retorts  :   the  resulting  sponge  was  removed  in  an  air-tight 
buggy. 

D.  In  Clay's*  original  process  walnut-sized  lumps  of 
ore  were  deoxidized  by  heating  to  bright  redness  in  clay 
retorts,  etc.,  with  one-fifth  of  their  weight  of  carbonaceous 
matter  :  the  resulting  sponge  was  immediately  balled  in 
a  puddling  furnace,  with  or  without  some  5%  of  coke, 
hammered,  and  rolled  into  merchant  iron.     The  process 
failed,  chiefly  because  the  reduction  was  very  slow,  and 
because  the  iron  was  often  very  redshort.     We  may  sur- 
mise that  the  gangue  of  the  ore  was  often  imperfectly 


b  Percy,  Iron  and  Steel,  p.  345,  1864. 

c  Berg,  und  Hiitt.  Zeit,  XXV.,  p.  398,  1866. 

dThis  description  is  condensed  from  Percy,  Iron  and  Steel,  p.  330.  Clay's 
British  patent  was  7,518,  Dec.  19th,  1837.  Percy's  description  indicates  that  the 
sponge  was  taken  hot  to  the  puddling  furnace:  according  to  Kerl  it  was  cooled 
before  the  transfer.  (Grundriss  der  Eisenhiitteukunde,  p.  266.) 


282 


THE    METALLURGY    OF     STEEL. 


fluxed,  so  that  it  formed  a  slag  which  was  difficultly 
fusible,  hence  was  expelled  with  difficulty,  and,  present 
in  excess,  made  the  iron  redshort  or  rather  slag-short. 
Heavy  waste  of  iron  doubtless  weighed  against  the  pro- 
cess. 

E.  In  Rento'it?  s  process*  ore  was  deoxidized  by  heating 
in  contact  with  coal  in  a  vertical  retort,  at  the  end  of  a 
puddling  furnace,  by  whose  waste  gases  the  ore  was  heated, 
and  in  which  the  spongy  iron  was  balled  prior  to  shingling. 
To  make  a  ton  of  blooms  required, 

2-5  tons  of  ore  at  $4  -  $10.00 

About  2-5  tons  of  coal  -  10.13 

Welding,  working,  $5,  shingling,  $1.50,  labor,  $3         9.50 


$29.63 

P.  In  Wilson's11  process  coarsely  pulverized  ore  with 
20$  of  charcoal-  or  coke-dust  is  heated  to  800°@1,000°  F. 
(427°@538°  C.)  for  twenty- four  hours  in  vertical  retorts 
(C,  Figure  138)  at  the  end  of  a  puddling  furnace,  by 


Transverse  Section 

through  Stack 
Part  Section. 
through  a  Retort 


B,  Central  TJp-tatoflue 

C,C,  Relorta 

D,  Chute  from  Retort  to  Balling  Furnace 

E,E,  External  Down:take-£lue>  to  Chhruray 


Figure  138.— Furnace  for  Wilson's  Direct  Process. 


whose  waste  heat  they  are  heated  externally.  The  par- 
tially deoxidized  ore  is  then  dropped  into  a  second  hearth 
of  the  puddling  furnace,  and  after  twenty  minutes  more 
is  pushed  into  the  hearth  proper,  where  it  is  balled. 

G.  Rogers*  would  heat  ore  with  coal  in  a,  rotating  retort 
above  a  puddling  furnace,  into  which  he  would  drop  the 
resulting  sponge. 

§  334.  ScnMiDiiAMMER,d  apparently  following  out  the 
idea  of  the  Nyhammar  furnace,  §324,  proposes  the  continu- 
ous stiickofen  shown  in  Figure  140.  The  shaft  is  charged 
continuously  with  ore  and  enough  charcoal  for  dt  oxidation: 
the  ore  is  deoxidized  during  its  descent:  the  temperature  is 


a  Condensed  from  Percy,  Iron  and  Steel,  p.  334.     The   process  was  patented  in 
1851  in  this  country. 

b  W.  P.  Ward,  Trans.  Am.  Inst.  Mining  Engineers,  XII.,  p.  52S,  1884. 
cBnrgund  Hiitt.  Zeit..  1863,  p.  341. 
dStahl  und  Eisen,  VI.,  p.  465,  1886. 


raised  to  the  welding  point  by  hot  blast  and  hot  water- 
gas  blown  through  the  tuyeres :  the  spongy  iron  is  balled 
through  working  openings,  and  the  balls  are  drawn  from 
the  fore -hearth  A  on  lifting  the  door  B. 

The  distinctive  features  are  substitution  of  hot  gas  and 
air  for  part  of  the  more  costly  charcoal;  the  fore-hearth  A, 
and  the  door  B,  which  permit  forming  and  drawing  the 
balls  without  allowing  the  superincumbent  charge  to  slide 
down  as  in  Husgafvel's  furnace. 


Figure  140.— Schmidhammer's  Continuous  High  Blooinury  (Stuckofen). 

§  335.  THE  Du  PUY  PROCESS®  uses  a  thin  sheet-iron 
instead  of  a  clay  retort.  The  sheet-iron  conducts  heat  to 
the  charge  much  more  readily  than  fire-clay,  but  of  course 
lasts  but  a  single  heat.  It  welds  to  the  spongy  iron  and 
is  hammered,  rolled,  or  melted  with  it  as  the  case 
may  be. 

About  116  pounds  of  ground  iron  ore,  mixed  with  carbon- 
aceous matter  for  reduction  and  with  suitable  fluxes  to 
scorify  the  gangue,  is  inclosed  in  annular  sheet-iron  (No.  26 
gauge  =0'018"  thick)  canisters  about  13"  high,  15"  in  diam- 
eter outside,  6"  in  diameter  inside,  and  weighing  0  pounds. 
The  charged  canisters  are  heated  to  bright  whiteness  (a 
welding  heat)  for  from  5f  to  10  hours  on  the  coke-covered 
hearth  of  a  common  open  reverberatory  furnace.  The 
reduced  metal,  still  in  its  canister,  may,  according  to  Du 
Puy,  be  converted  into  muck-bar  by  hammering  or  squeez- 
ing and  rolling,  then  cut  up  and  treated  by  the  crucible 
process  ;  may  be  charged  at  once  in  the  open-hearth  pro- 
cess with  or  without  (?)  cast-iron :  or  maybe  melted  down 
with  cast-iron  in  the  furnace  in  which  it  has  been  re- 
duced. 

In  a  table  of  results  given,  from  71  to  86  or  on  an  aver- 
age 78 '5  pounds  of  muck-bar  or  blooms  were  recovered  per 
100  pounds  of  iron  contained  in  the  ore :  so  that  a  116- 
pound  charge  of  67$  ore  would  yield  61  pounds  of  blooms : 
or,  deducting  the  six  pounds  of  canister,  56  pounds.  Thus 
for  every  100  pounds  of  blooms  we  have  to  sacrifice  10 
pounds  of  thin  sheet-iron  on  which  has  been  put  the  ex- 
pense not  only  of  rolling  down  to  No.  26  gauge,  but  of 
working  into  canisters.  The  cost  of  the  canisters  alone, 
judging  from  Mr.  Du  Puy's  data,  should  have  been  at 
least  $7  @  $8.50  per  ton  of  muck-bar. 

If  charcoal  were  used  the  cost  for  reducing  fuel  would 
be  considerable :  if  either  anthracite  or  coke  the  sulphur 
of  the  fuel  would  contaminate  the  iron. 

The  phosphorus  of  the  ore  of  course  remained  within 


eMetallurg.  Rev.,  I,  p.   486,1878.    Journ.  Frank.  Inst.,  CIV,  p.  377,  1877; 
CV£.,  p.  404,  1878;  July,  1881. 


EAMES'     OR    CARBON    IRON    COMPANY'S    DIRECT    PROCESS.       §  340. 


283 


the  canister.  If  the  mass  were  rolled  to  muck-bar  and  if 
the  slag  were  sufficiently  basic,  owing  to  scorification  and 
loss  of  iron,  some  of  the  phosphorus  would  be  eliminated 
as  the  slag  was  squeezed  out  in  roiling  or  hammering. 
But  this  rolling  or  hammering  involved  expenseand  further 
waste  If  the  canisters  wer.3  charged  direct  into  an  acid 
open-hearth  furnace,  the  phosphorus  of  the  ore  would  enter 
the  iron.  Metcalf  gives  the  following  composition  of  ex- 
tremely redshort  vvrought-iron  made  by  this  process." 
Silicon.  Sulphur.  Phosphorus.  Oxide  or  cinder. 

•460  -027  -010  '796 

Later,  dispensing  with  canisters,  Du  Puy  moulded 
ground  iron  ore  with  charcoal,  clay  and  lime  into  pipes, 
18"  x  8",  which  he  heated  and  balled  in  open  reverbera- 
tories,  with  prohibitory  loss  of  iron,  40  to  50%. 

§  337.  MUSIIET"  would  deoxidize  iron  ore  with  carbon- 
aceous matter  in  crucibles,  and  immediately  melt  the 
deoxidized  iron.  His  process  has  already  been  discussed, 
(§  315,  C.  II). 

§  338  A.  SIEMENS,  in  one  of  his  early  direct  processes, 
would  suspend  two  cast-iron  retort -i  or  hoppers  A  A,  with 
fire-clay  ends,  above  the  laboratory  of  an  open-hearth 
steel-melting  furnace,  Figure  141. 


FIG.  141. — AN  E.utLY  L>IRE<  r-I'uui  ESS  Fi:it.\A(K  OF  C.  \V.  SIEMENS. 


Around  each  hopper  is  a  space  heated  by  a  regulated 
supply  of  flame  from  the  open-hearth  furnace  :  within  it 
a  wrought-iron  pipe  supplying  producer-gas  for  deoxidiz- 
ing the  ore. 

About  28  pounds  of  charcoal  is  charged  through  each 
hopper,  and  on  this  sufficient  ore  to  fill  the  hopper  com- 
pletely. Producer-gas  is  then  injected  through  the  pipes 
in  the  center  of  the  hoppers,  and  deoxidizes  the  ore  which 
has  meanwhile  been  raised  to  redness  by  the  heat  con- 
ducted through  the  walls  of  the  hoppers.  About  half  a  ton 
of  pig-iron  is  charged  on  the  open-hearth :  melting,  it  dis- 
solves the  lower  end  of  the  columns  of  more  or  less  com- 
ple  t  ely  deoxidized  iron,  with  a  rapidity  which  is  only  limited 
by  the  time  needed  to  deoxidize  the  ore  in  the  hopper. 
Sufficient  sponge  having  been  thus  melted  off  in  three  or 
four  hours,  charging  ceases,  the  remaining  ore  in  the 
hoppers  sinks,  a  clay-coated  cast-iron  cover  suspended  by 
strong  wire  descending  with  the  ore-column,  so  that  the 
flame  may  not  enter  the  empty  hoppers.  On  this  cover  is 
placed  the  charcoal  and  ore  of  the  subsequent  charge, 
eventually  lowered  by  cutting  the  wire.  The  charge 
already  melted  is  brought  to  the  right  degree  of  carburiza- 
tion,  and,  after  an  addition  of  spiegeleisen,  is  tapped. 

To-day  we  wonder  that  a  man  of  Siemens'  genius  and 
judgment  could  have  seriously  entertained  so  crude  a 


a  Trans.  Eng.  Soc.,  W.  Penn,  p.  318,  Mch.  16th,  1883. 

b  British  patent,  Nov.  13,  1800,  No.  8,447. 

?•  Lecture  before  Fellows'  Caem.  Soc.,  May  7tb,  1868. 


project  even  twenty-one  years  ago.  To  maintain  these 
hoppers,  exposed  thus  in  an  open-hearth  furnace  ;  to  heat 
these  thick  bodies  of  ore  through  and  to  deoxidize  them 
at  their  necessary  low  temperature  in  any  reasonable  time; 
to  keep  this  open-hearth  furnace  waiting  while  the  charge 
of  ore  was  deoxidizing  ; — well,  well !  To-day's  folly  is 
wiser  than  yesterday's  wisdom. 

B.  PonsardA  in  like  manner  would  place  several  fire- 
clay retorts  8"  in  diameter  and  40"  high  in  a  reverbera- 
tory  gas-furnace,  their  mouths  being  fitted  into  openings 
in  the  roof,  their  lower  parts  open  or  perforated  and  rest- 
ing on  the  hearth,  which  had  gutters  leading  to  a  central 
sump.  In  the  retorts  is  charged  ire  with  flux  and  about 

%  (!)  of  carbon  for  deoxidation  and  carburizatiou.  The 
reduced  iron,  melting,  runs  through  the  holes  in  the 
bottoms  of  the  retorts  and  collects  in  the  sump. 

Ponsard  claimed  that  for  producing  one  ton  of  cast- 
iron  in  this  apparatus  one  ton  of  coal  sufficed  for  deoxida- 
tion, carburization,  and  melting.  This  process  is  open  to 
the  same  fatal  objections  as  Siemen's.  Indeed  they  seem 
identical.  Which  was  the  prior  invention  I  know  not. 

§  339  A.  FOR  PRECIPITATING  COPPER"  from  its  solutions 
spongy  iron  was  used  as  early  as  1837,  and  has  been  used 
in  later  years.  I  am  informed  that  its  use  is  now  aban- 
doned. Three  tons  of  "purple  ore"  (the  residue  from 
leaching  copper  from  roasted  cupreous  pyrites),  with  18 
cwt.  of  coal  which  has  passed  a  screen  of  eight  meshes  to 
the  linear  inch,  is  heated  to  bright  redness  in  a  6"  layer  on 
the  22'  X  8'  hearth  of  an  open  reverberatory  furnace  with 
tightly  fitting  doors  and  a  very,  say  4'  8",  deep  fire-box  (to 
yield  a  so-called  reducing  flame),  for  from  9  to  24  hours, 
during  which  the  ore  is  turned  twice  or  thrice.  The  spongy 
iron  is  then  drawn  through  holes  in  the  hearth  into  tightly 
closed,  wheeled  sheet-iron  boxes  of  12  cubic  feet  capacity, 
where  it  cools  for  two  days.  For  heating,  15  cwt.  of  coal 
are  needed  per  ton  of  ore,  or  altogether  say  159  pounds  of 
coal  per  100  of  iron  in  ore.  The  composition  of  the  copper 
precipitated  by  this  sponge  is  given  as  67'5^  copper,  5'15$ 
ferric  oxide.  If  this  is  the  usual  composition,  it  would 
indicate  that  the  spongy  iron  was  surprisingly  well  deoxi- 
dized, probably  90$  of  its  iron  being  in  the  metallic  state. 

B.  Harvey  heated  coarsely  powdered  ore  with  charcoal 
on  inclined    steatite    shelves    connected  with  a  balling 
furnace,  and  heated  by  a  passing  flame.     The  deoxidized 
ore  was  transferred  to  the  hearth  of  the  balling  furnace 
and  balled.     The  process  failed. 

C.  Gerhardt  bricked  ore,   flux  and  carbonaceous    de- 
oxidizing matter  with  tar,  heated  these  bricks  in  a  pud- 
dling furnace,  and  there  balled  the  resulting  iron,  using 
330  pounds  of  coal  per  100  of  finished  iron.* 

§  340.  Iv  THE  EAMES15  or  Carbon  Iron  Company's  pro- 
cess iron  ore  is  deoxidized  on  the  carbonaceous  hearth  of 
an  open  reverberatory  furnace,  by  means  of  graphitic 
anthracite  or  "retarded  coke," h  with  which  it  is  mixed. 


d  British  Patent  2,334,  July  34,  1868;  T.  8.  Hunt,  Geologr.  Survey  Canada, 
1866-69,  p.  398;  Comptes  Rendus,  LXIX,  p.  177,  July  19tb,  1868.  Berg  und 
Hiitt  Zeit  ,  XXVIII.,  p.  415,  1869.  The  numbers  here  given  are  Ponsard's. 

e  Lunge,  Sulphuric  Acid  and  Alkali,  I.,  pp.  615-81, 1879,  gives  drawings  of  the 
apparatus  and  details  of  the  treatment. 

'Berg und  Hiitt.  Zeit.,  XXXIII .,  p.  183,  1874. 

« Trans.  Am.  Inst.  Min.  Eng.,  XVI.,  p.  708,  1888.  Iron  Age,  XLI.,  p.  349, 
1888.  A.  E.  Hunt,  private  communication.  U.  S.  patents  318,551  to  318,554, 
318,605  to  318,607,  318,609,  May  36th,  1885  :  396.992,  Jan.  29,  1889. 

t>  "  Retarded  coke  "  is  coke  mixed  with  milk  of  lime,  so  that  It  offers  very  little 
surface  for  oxidation. 


284 


THE    METALLURGY    OF    STEEL. 


These  reducing  agents,  in  that  they  themselves  become 
oxidized  only  very  slowly,  indeed  reduce  the  iron  less 
rapidly  than  charcoal  or  common  coke ;  but  after  re- 
duction is  effected  they  resist  oxidation  and  so  persist  and 
remain  to  protect  the  reduced  iron  from  reoxidation  :  and 
as  the  difficulty  in  direct  processes  is  not  so  much  in  the 
reduction  as  in  preventing  reoxidation,  the  idea  is  reason- 
able. Indeed,  I  think  it  likely  that  the  substitution  of 
graphite  for  charcoal  has  diminished  the  loss  of  iron.a 

I.  The  furnace  now  used  is  an  open    reverberatory 
measuring  about  18"  from  roof  to  hearth,  and  fired  with 
natural  gas  at  both  ends,   the  products  of  combustion 
escaping  through  a  flue  in  the  middle  of  the  roof.     The 
hearth  is  about  six  feet  wide  and  fifteen  feet  long,  and  has 
a  layer  of  graphite  from  four  to  six  inches  thick  on  its 
upper  surfa'e.     Eames  recommends  a  graphite-iron  bot- 
tom prepared  as  follows  :b 

Lumps  about  one  foot  thick  of  the  graphitic  anthracite  of 
Cranston,  R.  I.,  are  set  in  a  single  layer  on  the 
hearth  ;  the  interstices  are  filled  with  ground  iron  ore  ; 
the  whole  is  covered  with  a  layer  (2"  to  4"  thick  in  the 
middle,  3"  to  6"  at  the  side)  of  wheat-grain  sized  anthra- 
cite :  this  is  dried  by  gentle  heating ;  on  it  is  placed  a 
half-inch  or  inch-thick  layer  of  ground  iron  ore;  the 
temperature  is  gradually  raised  during  from  three  to 
five  hours  to  1,371°  C.  (2,500°  F.  bright  whiteness)  to 
deoxidize  the  ore  and  later  to  soften  the  mass.  The 
hearth  is  then  rammed  solid  witha  heavy  dolly.  The  iron 
ore,  or  the  iron  reduced  from  it  by  the  surrounding  carbon, 
is  said  to  strengthen  the  hearth  greatly.  A  graphite-clay 
hearth  is  said  to  be  readily  indented,  a  pure  graphitic-an- 
thracite hearth  to  flake  and  get  mixed  with  the  sponge-balls. 

II.  Reduction. — 2,240  pounds  of  dry  rich  ore  (say  62% 
of  metallic  iron)  and  550  pounds  of  graphitic  anthracite 
containing  78$  of  carbon,  are  ground  to  pass  a  screen  of 
sixteen  meshes  to  the  linear  inch,  mixed  with  enough 
water  to  render  the  mass  slightly  plastic,  and  spread  in  a 
four-inch  layer  on  this  hearth.     The  carbon  is  not  quite 
enough  to  deoxidize  the  whole  of  the  iron  by  the  reaction 

Fe2O;i  +  3  C  =  2Fe  +  3  CO, 

so  that  some  of  it  appears  to  be  oxidized  to  carbonic  acid 
by  the  ore.  The  doors  are  closed  and  luted,  and  the  fur- 
nace is  now  heated  with  a  so-called  reducing  flame. 

20  m.  :  The  charge  has  shrunk  to  a  thickness  of  2"  ; 
temperature  incipient  redness,  say  538°  C.,  1,000°  F. 

1  hr. :  the  charge  has  shrunk  to  1'3"  :  beads  of  Iron  are 
seen  on  its  surface. 

1  Jir.  30  m.  :  the  charge  has  shrunk  to  1" :  begin  working 
into  balls  say  20"  in  diameter,  and  weighing  from  85  to 
185  pounds  each.  Temperature  not  above  moderate  red- 
ness, 816°  C.,  1,500°  F. 

If  the  balls  are  for  the  open-hearth,  balling  takes  but 
30  to  40  minutes ;  if  for  rolling,  an  hour,  as  in  this  case 
they  must  be  brought  to  a  welding  heat.  Thus  the  last 
ball  is  drawn  at  2  h.  40  m.  and  3  h.  in  charges  for 
the  open-hearth  and  for  rolling  respectively.  Repairs, 


a  This  f-ubstituUon  teems  to  auout  balance  ine  excess  of  the  oxidizing  tendencies 
of  Eames1  open  reverberatory  over  those  <  f  the  charcoal-hearth  and  shaft-furnace, 
for  the  loss  of  iron  is  about  the  same  as  in  the  American  bloomary  and  in  Hus- 
gafvel's  lurnace.  (Of.  Table  154,  p.  S68.)  Eames'  loss,  21$,  is,  indeed,  from  ore 
to  ingots,  that  of  these  other  processes  only  from  ore  to  blooms,  in  remelting 
which  a  further  loss  would  result  But  these  blooms  have  been  made  at  a  high 
welding  heat,  and  hence  with  greater  Io«s  than  if,  as  in  Eames'  process,  the  heat 
merely  sufficed  for  making  loose  balls  for  the  open-hearth  furnace.  If  graphite 
has  real  advantage-,  a  shaft-furnace  like  Schmidhamtuer's  seems  better  for  using 
it  than  an  open  reverberatory. 

•>  U.  8.  Patent  306,993,  Jan.  29, 1889. 


fettling  and  charging  take  20  minutes  more,  so  that  the 
total  length  of  the  operation,  when  balls  for  the  open- 
hearth  furnace  are  made,  is  three  hours,  and  six  1, 600- 
pound  heats  are  made  per  reducing  furnace  per  24  hours. 

III.  Further  Treatment — The  sponge  balls,  like  those 
produced  in  other  processes,  may  be  hammered  or  squeezed 
and  rolled  to  muck-bar  for  use  in  the  open-hearth  or  the 
crucible  process ;   or  they  may    be  charged  while  still 
white-hot  into  a  bath  of  molten  cast-iron  in  the  open-hearth 
furnace. 

IV.  Loss.— From  Hunt's  data  I  calculate  the  loss  in  one 
reducing  heat  as  follows  : 

Iron,  pounds. 

Ore  charged  in  reducing  furnace,  2,973 

pounds,  at  62$  =  -  1,818  at  9:10  A.  M. 

2,010  pounds  of  sponge-balls  resulting 
were  charged  in  the  open-hearth  fur- 
nace at  10:45  to  11:45  A.  M. 
The  open-hearth  charge  further  contained 
Of  pig-iron  -  870  at  9:30  A.  M. 

Of  f  erromanganese  of  70$  manganese        24  at  1:10  p.  M. 

27712 

Ingots  produced  2,150,  scrap  191  -  2,341  at  1:20  p.  st. 

Loss  -      -      371 

ll$c  of  loss  is  chargeable  to  pig  and 
ferromanganese  -  98 

Loss  chargeable  to  sponge  process,  from 

ore  to  ingot  -  273  pounds, 

which  is  15$  of  the  iron  contained  in  the  ore.  This 
way  of  calculating  the  loss,  I  think,  gives  us  the  most 
valuable  results,  since  what  we  seek  to  know  is,  "Assum- 
ing that  the  pig  and  ferromanganese  lose  the  same  amount 
when  meltel  with  sponge  balls  as  when  melted  with  scrap, 
how  does  the  loss  on  the  sponge-balls  themselves  compare 
with  the  loss  on  scrap  ?" 

The  loss  reckoned  on  ore, pig  and  ferromanganese  is  13*7$ 
here,  but  in  regular  working  the  loss  seems  to  be  rather 
higher  than  this.  With  two  15-ton  open-hearth  furnaces 
using  about  50  parts  of  pig-iron,  10  of  scrap  (both  taken  at 
their  gross  weight  and  without  reduction  for  non-ferrous 
matter  which  they  contain),  and  40  parts  of  iron  contained 
in  sponge-balls,  or  altogether  100  parts  reckoned  in  this 
way,  87  parts  of  ingots  and  scrap  result,  implying  a  loss  of 
13$.d  If,  now,  we  assume  that  the  pig-iron  and  scrap  lose 

o 

8$  by  weight  or  60  X  — —  =  4-8  parts,  we  have  to  charge 

100 

against  the  40  parts  of  iron  in  sponge  a  loss  of  13  —  4'8  = 
8-4  parts  of  iron,  or  §  °  =  21$  of  the  iron  in  the 

sponge.  That  is  to  say,  in  the  sponge-making  and  open- 
hearths  processes  combined  the  loss  from  ore  to  ingots  is 
21$.  This  is  decidedly  more  than  in  the  combined  blast- 
furnace and  open-hearth  processes,  in  which  the  total  loss 
probably  does  not  exceed  10  per  cent. 

In  making  muck -bar  the  loss  is  still  greater,  as  at  the 
higher  welding  heat  to  which  the  balls  must  be  raised 
oxidation  is  very  rapid.  Hunt  reports  that  in  one  week 
three  reducing  furnaces  made  collectively  50  heats : 

Receiving  altogether  of  ore 112,000  pounds 

This  contained  ofiron 69,440 

There  was  produced  of  muck-bar 44,810 

Implying  a  loss  of  85*o£a 
a  The  original  contains  an  error,  giving  the  loss  as  2 


c  The  loss  on  pig  and  scrap  charges  in  this  same  furnace  is  1 1#» 
d  A.  E.  Hunt,  private  communications,  April  9th  and  SJSd,  1889. 


SIEMENS    DIRECT    PBOCESS.      §  341. 


He  further  gives  the  loss  as  follows  : 

100  of  Iron  in  ore  yields  of  blooms  6"  X  0"  X  20" So •(>  loss  =  19'4# 

of  billets  4"  X  4"  X  24" Ti-M  "  !  .'7  I''.: 

ofnmck-barS}"  X  j" t^'"'l  "  =  Sl'49* 

100  of  mnrtv  -bar  curtains O'Ol.j  of  phosphorus. 

Ore  for  making  100  of  imlek-bar  contains O'Ms  ' 

100  of  ore  contains O'OIW  " 

In  a  heat  described  to  me  by  a  very  trustworthy  witness, 
of  100  parts  of  iron  in  the  ore  charged  in  the  reducing 
furnace,  15-6  were  removed  in  the  slag  of  the  same  fur- 
nace, (this  slag  contained  51%  of  iron),  and  19 -7  more  ex- 
isted in  the  sponge-balls  as  oxide,  so  that  only  6  .'7  of 
metallic  iron  in  sponge-balls  was  recovered  from  loo  of 
iron  in  ore,  a  loss  of  35-3$.  The  sponge-balls  contained 
about  62-61$  of  iron  as  metal  and  19-7$  as  oxide:  but 
these  numbers  are  only  rough  approximations,  owing  to 
the  heterogeneousness  of  the  sponge-balls.  Had  these 
balls  been  for  the  open-hearth  furnace,  part  of  this  iron- 
oxide  would  have  been  deoxidized  by  the  carbon  and  sili- 
con of  the  bath. 


TABLE  1C3B. — EAMKS  OR  CARBOH  IRON  COMPANY'S  PROCESS. 


Dimensions  of  reducing  furnace. 


15' 


Length  of  hearth 

Width  of  he.li  tli 6' 

Height  frotn  hearth  to  roof 18" 

Length  of  campaign  without  serious  repairs One  year. 

Charge  for  one  heat. 

Ore,  kind Minnesota  T 

*'     percentage  of  iron 65 

"     weight 2,240  Ibs. 

"     percentage  of  phosphorus  0*04 

Length  of  one  heat 8  hours 

Number  i  if  heats  per  24  hours 6 

Men  c  mployed  per  furnace  per  shift 2 

Shifts  per  '24  hours 2 

Output  per  furnace  per  heat. 

Pounds  of  balls  ].er  heat 1,600 

"           "        per24hours 12,800 

Outlay  in  reducina-furnacefor  2,00  >  pounds  of  iron  recovered  as  ingots  in 
subsequent  open-hearth  melting. 

Ore,  pounds 3.896 

Labor,  days I  •  17 

Loss  from  ore  to  ingots , 21* 


Composition  of  sponge  balls. 
Inm 

Coko  <ir  tfrapliiti- 

Carbmi  cmnbintMl  with  iron.    .... 


90* 

6' 

0-15 




Sulphur  and  phosphorus 0'05 


These  data  are  communicated  by  Mr.  A.  E.  Hunt,  of  the  Carbon  Iron  Company. 

V.  Dephosphorization. — Open-hearth  steel  made  from 
these  sponge-balls  contains  nearly  the  whole  of  the  phos- 
phorus of  the  ore:  but  muck-bar  made  from  them  is 
nearly  free  from  phosphorus,  having  according  to  Hunt 
less  than  0-015$  of  phosphorus  from  an  ore  holding  0-063$. 
The  muck-bar,  were  there  no  dephosphorization,  would 
contain  0'148$  of  phosphorus,  so  that  0-133  of  phosphorus 
is  removed  per  ]  00  of  iron  recovered,  or  0'09  per  100  of 
iron  in  ore. 

The  difference  between  the  dephosphorization  in  ingot. 
and  in  muck-bar-making  is  clearly  due  to  the  general 
principle  that  in  the  direct  process  dephosphorization 
and  loss  of  iron  usually  go  hand  in  hand.  Balls  for  the 
open-hearth  are  made  at  a  low  temperature,  with  a  flame 
but  slightly  oxidizing,  and  with  rapid  balling :  little  iron 
is  oxidized,  the  mechanically  inclosed  slag  is  chiefly  an 
earthy  silicate,  difficultly  fusible,  pasty,  and  hence  but 
little  of  it  runs  out  from  the  balls  :  most  of  it  goes  with 
the  balls  to  the  open-hearth  furnace,  whose  siliceous  walls 
give  rise  to  an  acid  slag,  and  the  phosphorus  of  the  slag 
within  the  balls  is  reduced  by  the  carbon  of  the  bath  as 
fusion  proceeds. 

In  making  muck-bar,  however,  the  higher  temperature 
and  the  more  oxidizing  flame  which  it  entails  in  the  reduc- 
ing furnace,  as  well  as  the  longer  heating,  oxidize  much 
iron :  the  slag  becomes  basic  and  hence  dephosphorizing, 


ferruginous  and  hence  fusible :  it  melts  and  runs  away 
from  the  balls  both  in  the  reducing  furnace,  in  shingling 
and  in  rolling,  and  in  running  away  remove.s  the  phos- 
phorus. The  slag  from  the  blooms  contains,  according  to 
Hunt: 

Iron  ...from    30  to  50  % 

Silica "      24  I- 

Phosphorus "    O'l  to  O'la-t 

and  is  thus  probably  between  a  singulo-  and  a  subsilicate 
in  composition.  This  composition  tallies  fairly  with  1  lie 
actual  loss  of  iron  and  removal  of  phosphorus  :  thus,  it 
iron  and  phosphorus  are  removed  in  the  ratio  50  to  0-in, 
the  removal  of  0*09  of  phosphorus  per  100  of  iron  in  the 
ore,  which  as  we  have  seen  occurs,  implies  a  loss  of  30$ 
of  the  iron  of  the  ore,  which  is  very  close  to  the  actuaJ 
loss  of  31-49$. 

The  statements  on  page  59  imply  that  the  silica  should 
be  near  thu  lower  of  the  above  limits,  24$,  to  permit 
thorough  dephosphorization. 

Condition  of  the  Process.— The  Carbon  Iron  Company 
has  eight  reducing  furnaces,  which  are  running  double 
turn  all  the  time,  and  two  15-ton  open-hearth  furnaces 
running  steadily,  with  a  charge  of  about  50$  of  cast-iron, 
10$  of  scrap  and  40$  of  sponge-balls.  A  considerable  part 
of  the  spongy  iron  is  rolled  into  muck-bar,  not  for  use  as 
wrought-iron,  but  as  a  material  for  the  crucible  and  open- 
hearth  processes.  The  process  has  clearly  passed  to  the 
commercial  stage,  and,  with  the  cheap  fuel  of  Pittsburgh 
and  under  the  very  skillful  superintendence  which  it  is  so 
fortunate  as  to  have,  apparently  to  the  profitable  stage. 

The  success  of  the  process  in  Pittsburgh,  where  the 
Blair,  the  DuPuy  and  the  Siemens  processes  have  failed, 
would  be  chiefly  attributable  to  the  supply  of  a  very  cheap 
heating  fuel,  natural  gas  ;  but  still  I  think  in  some  part 
to  the  use  of  special  reducing  agents,  which  lessen  the  loss 
of  iron.  The  loss  from  ore  to  ingots  is  probably  less  than 
that  in  the  DuPuy  and  Siemens  processes  from  ore  to 
blooms :  while  over  the  Blair  process  the  Eames  has  the 
advantage  of  utilizing  the  sensible  heat  of  the  sponge  when 
the  balls  are  plunged  into  the  open-hearth  bath. 

§  341.  A.  IN  THE  LATE  SIEMENS  DIRECT"  or  "pre- 
cipitation" process  fine  ore  was  reduced  by  coal,  with 
which  it  was  mixed  and  heated  in  a  rotating  furnace 
like  a  Danks  puddler,  the  coal  precipitating  metallic 
iron  from  the  molten  ore.  The  resulting  metal  .was 
balled  as  in  puddling,  squeezed  to  expel  slag,  and  either 
used  as  material  for  the  open -hearth  process  or  worked 
into  merchantable  wrought-iron.b  Some  details  are  con- 
densed in  Table  165. 

I.  The  plant  for  furnaces,  crusher,  hammer,  etc.,  was 
estimated  by  Holley  to  cost  $40,000  per  125  tons  weekly 
capacity. 

II.  The  furnace,  Figure  144,  differed  from  the  common 
rotary  puddler  chiefly  in  being  gas-fired  and  regenerative, 
the  gas  from  the  producer  d,  passing  through  a  flue  g,  en- 
closed between  the  regenerators  h  7i,  direct  to  the  rotator 


a  Tunner,  Metallurg.  Rev..  I.  P.,  573, 1873  ;  Holley,  Trans.  Am.  Inst.  Min.  Eng., 
VIII.,  p.  321, 1880 ;  Maynard,  Idem,  X.,  p.  274, 1881 ;  Siemens,  Jour.  Iron  and  E 
Inst.,  1873,  I.,  p.  37 ;  1877,  II.,  p.  345. 

b  Mr  J  Head  informs  me  that  the  process  was  practically  abandoned  during  the 
life  of  Sir  William  Siemens.  The  deoxidation  was  successful,  but  the  reoxidation 
fatal.  Private  communication,  Nov.  7th,  1888. 


286 


THE    METALLURGY    OF     STEEL. 


Section  N  O  P  Q. 


T 


M 


Half  section  through  H  I. 
If  W 


Half  section  through  L.  M. 
* 


Figure  144.— Rotary  Gas  Furnace  for  Siemen's  Direct  Process.    (Holley.) 

a  Rotator  in  which  deoxidation  occurs,    b  Gas-port,    c  Entrance-port  for  air  and  exit-port  for  products  of  combustion,    d  Gas-producer. 
«  Reversing  valve.    /  Slag  buggy,    g  Gas-flue.    A  Regenerator. 


a,  the  air  alone  being  preheated.  The  entrance  for  gas  (5) 
and  air  (c)  and  the  exit  for  products  of  combustion  were 
at  the  same  end  of  the  rotator,  leaving  the  other  end  free 
for  charging  and  working.  The  ports  were  small,  so  that 
the  velocity  of  the  entering  gas  and  air  should  suffice  to 
throw  the  flame  well  towards  the  working  end. 

The  three  inch  brick  lining  (which  lasted  months)  was 
glazed  by  heating  with  roll- scale,  and  fettled  (say  2|  to  6 
inches  deep)  with  iron  ore  and  a  little  coal,  which  reduces 
the  ore  slightly  to  a  very  refractory  state.     The  ends  ex- 
posed to  the  basic  slags  were  sometimes  lined  with  bauxite  ; 
thorough  lining  occupied  from  24  to  48  hours,  fettling  three 
to  four  hours.     To  make  the  charge  roll  rather  than  slide ' 
the  lining  was  roughened,  e.g.,  by  ridges  of  fettling  hold- ! 
ing  a  water  pipe,  which  cooled  and  maintained  them  ;  or! 


by  ridges  of  ore-lumps  placed,  after  drawing  the  charge, 
in  the  still  liquid  slag,  which  was  then  chilled  with  water. 

III.  The  operation  was  divisible  into  two  periods  (1) 
heating  and  partial  reduction ;  (2),  complete  reduction  and 
balling.  In  the  first  the  temperature  was  relatively  low  to 
avoid  fusion  before  reduction,  and  the  rotation  slow.  In 
the  second  the  temperature  gradually  became  high  enough 
for  balling,  and  the  rotation  faster.  In  both  the  atmos- 
phere was  necessarily  strongly  oxidizing  to  iron  and  its 
low  oxides. 

Pea-sized  ore,  basic-slag-yielding  flux  (actually  lime- 
stone) and  small  coal  were  heated  in  the  slowly  revolving 
rotator  with  a  pretty  full  air-supply.  After  2.5  hours, 
reduction  being  well  advanced,  the  temperature  and  rate 
of  rotation  were  raised,  the  slag  began  to  form,  accumulat- 


SIEMENS'     DIRECT    PROCESS.      §  341. 


287 


ing  till,  after  another  hour,  it  was  tapped.  After  four 
hours,  reduction  being  completed,  the  temperature  was 
again  raised  and  the  rotation  accelerated,  then  temporarily 
arrested  to  permit  balling  by  hand,  and  later  to  draw  the 
balls  successively.  This  done,  the  furnace  was  charged 
afresh.  The  balls  contained  about  fO%  of  metallic 
iron,  the  blooms  made  from  them  it  is  said  99.7  per  cent. 
I  deduce  the  following  from  Tunner  : 

TABLE  164.— DIARY  OF  SIEMENS  DIRECT  PROCESS:  TOWCESTER, 


HOURS. 

MINUTES. 

0 

0 

riiart-e  introduced  :  furnace  stationary. 

0 

5 

Eotate  at  12  to  15  revs.  per.  miu.  (?)a    Full  air  supply  to  heat 

quickly. 

2 

0 

Heat  bright  red.  Charge  still  dry.  Much  coal  yet  unconsumed. 

Ore  hard,  magnetic,  partly  metallic. 

2 
3 

30 
0 

The  charge  partly  pasty.    Heat  raided.    Some  slag  appears. 
Heat  raised  more.    More  liquid  slag  appears. 

3 

30 

The  pasty    mass    begins  balling.      More  slag  forms.    Rotate 

quicker.    Tap  slag,  for  first  time,  completely. 

3 

45 

Tap  again.    Less  slug. 

4 

0 

Heat  raised  to  whiteness.    Rotate  quicker,   stopping  momen- 

tarily to  ball. 

4 

8 

First  ball  drawn.    Shape  and  draw  remaining  balls. 

4 

30 

All  drawn.    Charge  anew. 

u  This  implies  a  circumferential  speed  of  320  to  400  feet  per  miuute,  or  of  a  mile  in  13  min- 
utes. Maynard  reports  that  the  speed  of  the  Tyrone  11-foot  rotators  was  one  revolution  in  15  to 
18  minutes,  or  a  circumferential  velocity  of  about  2  feet  per  minute. 


charge  occupied  nine  hours.  Thus,  although,  there  was 
clearly  an  endeavor  to  shorten  the  operation,  it  seems  to 
have  lengthened  greatly,  and  unavoidably. 

The  loss  of  iron  was  actually  heavy,  probably  at  least 
20$.  As  the  material  was  melted  and  subsequently 
balled  in  the  necessarily  strongly  oxidizing  atmosphere 
of  the  rotator,  this  was  probably  absolutely  unavoidable. 
The  rich  slags  given  in  columns  I  and  II  of  Table  165 
tally  well  with  this  loss.  The  data  in  column  VII 
indeed  indicate  a  very  slight  loss,  for  no  less  than  60.5 
pounds  of  blooms  were  recovered  from  100  of  ore  and 
scale.  But  this  loss  does  not  tally  with  the  extremely 
small  quantity  of  fuel  used  for  reducing,  only  23  parts 
per  100  of  blooms,  and  I  think  that  there  must  be  some 
error.  The  heavy  loss  of  iron  of  course  permits  dephos- 
phorization ;  note  the  large  proportion  of  phosphoric 
acid  in  the  slags  of  Table  165. 

The  loss  here  given  is  from  ore  to  blooms :  that  from  ore 
to  ingots  would  probably  be  at  least 


TABLE  166.    DETAILS  OF  T::»  SIEMENS  DIRECT  PROCESS. 


I. 

71. 

III. 

IV. 

V. 

VI. 

VII. 

Place                                  

Towcester. 

Tyrone. 

Pittsburgh. 

Lfcndor*. 

Date                                             

18T6 

1S77 

1877 

1887 

1879 

1881^ 

1881 

Authority  

Tunner. 

Siemens. 

Siemens. 

Siemens. 

HoUey. 

Maynard. 

llolley. 

HOT  A  TOR. 

8'  6" 

11' 

11'  4" 

9'  6" 

9' 

11' 

12' 

Tbickiif^-of  l>r'k  lining  

3" 

4t" 

Thickness  of  fettling 

5"@6" 

2' 

820'  @  400' 

12@15 

.56  @  .67 

CHARGE, 
Ore,  ^Fe  

44-29  d 

40± 

60 

Lbs.  per  charge,  mv  
niill-.scale  

1,960 
504° 

3,360 

578 
1,008 

500 
1,003          1 

4,000 
800 

6,023 

2,240 
1,344 

slag  

2,464 

8,528 

2,370 

8,287 

4,800 

6,023 

8,684 

868  a 

1,31211 

1,274  h 

2,156 

Limestone  

280 

168 

112 

95 

250 

271 

Eeducing  coal  

896 

1,008 

723 

728 

600  @  700 

1,382 

604 

6,103 

2,7*4 

6,744 

0,74-1 

1,051 

1,006 

5,480 

486 

2,818 

1,784 

339 

8,268 

8,596 

1,086 

1.888 

8,478 

7,083 

4,809 

4,682 

6,516 

$701 

963 

689 

204 

191 

889 

285 

8,083 

2.082 

1,824 

1,465 

882 

7.200 

621 

4,592  t 

4,480  e 

3,800 

6,302 

2,824 

2J2  j  Coal,  total  pounds  

7,675 

6,512 

4,682 

6,602 

3,845 

5-6 

Laboi%  $ 

ID.  00 

8.68 

10.00 

9.241 

w       1  Repairs,  etc  t  $  

2.00 

^       \Total  cost,  $     .... 

16.45 

(?) 

25.00 

(?) 

B(?) 

6f 

58  f 

T  ? 

8-5  ± 

2-V± 

6'2 

4  hr.  30  m. 

4  'or.  21  m. 

4  hr.  8m. 

8hr.  12m. 

7hr.  ± 

9hr.  -f 

4  hr.  80  m.  ± 

Pr.nmrcT. 

a.        b.         c. 
47         56       46 

a.        b. 
47        56 

%  P2  OB  

5-2       8-5      ]-9 

52       8'5    .. 

%  rt       

1  0        0-4      OS 

98       19 

%  Si  <>2 

28-1      188     12-5 

99-71 

98'8  @  99  9 

87  ± 

%c... 

0.12 

tr.  @  0-23 

*P  .. 

•074 

.02  @  .128 

Us;:::::::;;::::::::::::::::::::::::: 

027 

tr.  @  0-27 

65] 

1,111 

1,282 

1,118 

1,600®  1,700 

2,579 

2,168 

8,225? 

5,555 

6,580 

7.791  ? 

5,600  ±  @  5,950  ± 

6,075  ± 

11,290 

Loss*  of  iron  

25*  d 

193  I 

6-07  1  hj 

12-611 

15  @  20  d 

20-15 

p. 

I.  Tunner,  Metallurg.  Rev.,  I.,  p.  673,  1878. 
II.  Siemens,  18  charges  at  Towcester,  Jour.  Iron  and  St.  lest.,  1877,  11.,  p.  882. 

III.  Idem,  p.  857:  Average  of  27  charges, 

IV.  Idem,  p.  358:  Average  of  40  charges. 

V.  HoUey,  Trans.  Am  Inst.  Mining  Eng.,  VIII.,  p.  321,  1880. 
VI.  G.  W.  Maynard,  Idem,  X.,  p.  274,  1881. 
VII.  Data  quoted  from  Holley  by  Maynard,  Loo.  Cit. 

a  First  tapping. 

b  Second  tapping 

c  Reheating. 

(1  Excluding  mill  scale  used 

e  Producer  coal  only. 

t  Producer  and  steam  coal. 

g  Special  charges  only:  does  not  Delude  rolling  the  hammered  blooms. 

h  Including  scale,  etc. 


1  Apparently  including  scale,  etc. 

J  This  number  is  incredible 

k  The  actual  loss  of  iron,  assuming  that  the  blooms  contained  87^  of  iron.  It  is  stated  that 
they  contained  10  @  15#  of  cinder. 

1  $9.24  per  ton  of  blooms  of  87#  of  iron:  $10.62  per  100  of  iron  in  the  blooms.  The  latter 
seems  more  nearly  comparable  with  other  numbers  in  the  same  line,  as  in  the  other  columns 
blooms  apparently  of  98  to  9ff'9£  of  iron  are  referred  to.  The  sum,  $10.62  appears  to  include 
labor  for  heating,  for  shipping,  and  for  receiving. 

m  Tap-cinder. 

n  Undescribed  cinder. 

o  Reh eating-furnace  slag. 

p  If,  as  the  context  suggests,  the  ore  contained  about  53#  of  iron  and  the  scale  about  72,  tke 
weight  of  blooms  would  exceed  that  of  iron  charged,  so  that  the  loss  would  be  represented 
by  the  slag  inclosed  in  the  blooms. 


The  most  important  variation  in  the  process  seems  to 
have  been  in  its  length.  In  1873,  Siemens  reported  that 
"the  time  occupied  in  working  one  charge  rarely  exceeds 
two  hours."  In  1880,  Holley  reported  that  the  output  at 
Tyrone  had  been  increasing  gradually,  having  now  reached 
about  five  heats  a  day."  In  1881  Maynard  reported  that  a 


D  In  1877  Holley  reported  that  "  a  charge  "  "  has  been  made  in  two  hours  twenty  minutep. 
The  tim«  of  the  shortest  operation  I  witnessed  was  294  hours.  At  Newton,  two  years  ago, 
the  time  waa  4  to  4J4  hours." 


The  fuel-consumption  was  heavy,  and  probably  un- 
avoidably, as  the  heating  was  indirect,  and  as  the 
strongly  oxidizing  atmosphere  of  the  reducing  furnace 
both  directly  oxidized  the  reducing  fuel  and  continually 
reoxidized  the  iron,  to  re-deoxidize  which  demanded  a 
further  excess  of  reducing  fuel.  It  should  hardly  be 
possible  to  bring  the  fuel-consumption  much  below  200 
pounds  per  100  of  blooms. 


288 


THE    METALLURGY    OF    STEEL. 


In  addition  to  the  compositions  given  in  Table  1(J5  we 
have  the  following  from  Metcalf,  of  very  redshort 
wrought-iron  made  by  this  process1 : 


Carbon, 
.0)3 


Silicon, 


Manganese, 
0 


Phosphorus, 
tr. 


Snlphur, 
.016 


Copper,      Dissolved  Oxide. 
.030  .30 


B.   The  Cascade  Furnace. — Instead  of  a  rotator  Siemens 
at  one  time  used  a  "  Cascade  "  furnace,  Figure  145.    A  lake 


SIEMENS 


nj.  i«. 
CASCADI 


E  FURNACE. 


of  fused  ore  was  formed  on  the  upper  hearth,  and,  by 
piercing  the  intervening  bank  of  unmelted  ore,  was  run 
at  intervals  upon  the  lower  hearth,  upon  which  meanwhile 
a  layer  of  equal  parts  of  powdered  anthracite  or  coke  and 
ore  had  been  spread.  On  stirring,  the  mass  foamed  and 
became  pasty  ;  in  from  40  to  50  minutes  the  iron,  precipi- 
tated by  the  carbon,  was  balled,  to  be  melted  in  the  open- 
hearth  furnace  or  squeezed.  In  Siemens'  published  re- 
sults the  loss  was  less  than  1% ;  but  as  the  slag  rarely  held 
less  than  15  and  sometimes  as  much  as  40$  of  iron,  I  doubt 
whether  such  results  could  be  obtained  regularly.  In- 
deed, Siemens  abandoned  this  method  because  of  liability 
to  heavy  loss  of  iron,  and  because  "a  certain  degree  of 
manual  skill  and  labor"  was  needed.0  Truly,  it  is  hard 
to  understand  on  what  kind  of  information  Siemens  and 
others  based  their  statements  concerning  both  this  and 
the  rotator  process. 


Fig.  146. 
FURNACE  FOR  F.  SIEMENS  CONTINUOUS  DIRECT-PROCESS. 

§  342.  LECKIE  '  would  brick  ore  with  coal  or  peat,  heat 
the  bricks  in  chambers  adjoining  an  open-hearth  steel 
melting  furnace,  and  when  deoxidation  has  progressed 
well,  push  them  into  the  bath  of  molten  cast-iron  on  the 


j  Trans.  Eng.  Soc.  W.  Perm.,  March  16, 1883,  p.  217. 

c  Journ.  Iron  and  Steel  Inst.  1873,  I,  pp.  43,  51. 

1 T.  8.  Hunt,  Kept.  Geolog.  Survey  Canada,  1866-9,  p.  296. 


open-hearth, 
here. 


The  objections  stated  in  §  315,  C,  I,  apply 


§343.  IN  F.  SIEMENS'*  DIRECT  PROCESS  ore,  coal  and 
fluxes  are  charged  continuously  through  a  slit  at  the  end 
of  a  regenerative  gas-furnace,  Figure  146,  which  is  rectan- 
gular in  plan,  with  the  entrance  and  exit  ports  at  the 
same  end,  the  opposite  end  AB  being  strongly  inclined. 
The  heat  is  so  high  that  the  ore  melts  immediately  on  en- 
tering the  furnace,  and  so  coats  over  and  protects  the 
coal  from  the  action  of  the  flame  of  the  furnace.  The 
melting  ore  trickles  down  the  incline  A  B,  its  iron  being  re- 
duced by  the  coal,  partly  during  its  descent,  partly  after 
reaching  the  bath  at  the  bottom  of  the  incline.  Basic 
additions  are  made  to  the  molten  slag,  to  permit  dephos- 
phomation  and  the  reduction  of  the  iron.  The  slag  runs 
out  continuously,  the  metal  is  tapped  from  time  to  time. 

For  reasons  given  in  §  b!5,  C,  I,  the  plan  is  less  promis- 
ing than  striking. 

§  344,  A.  EUSTIS™  would  coke  fine  ore  with  coking 
bituminous  coal,  and  melt  the  coked  lumps  in  a  cupola 
furnace,  thinking  that  the  phosphorus  would  escape 
deoxidation  both  in  the  coking  and  the  fusion. 

It  would  be  necessary  to  have  a  great  quantity  of  car- 
bon present.  If  the  product  were  not  itself  carburized, 
it  would  be  so  extremely  infusible  that  an  enormous 
quantity  of  fuel  would  have  to  be  present  in  order  to  melt 
it,  and  this  quantity  of  fuel  would  probably  make  the 
deoxidizing  conditions  so  strong  that  the  phosphorus 
would  enter  the  iron.  If,  on  the  other  hand,  the  product 
were  carburized,  and  therefore  fusible,  enough  carbon 
would  have  to  be  present  to  prevent  its  decarbnrization 
by  any  small  quantity  of  reoxidized  spongy  metal,  and  to 
keep  the  slag  quite  free  from  iron-oxide,  as  this  of  course 
would  react  rapidly  on  the  carburetted  bath  and  remove 
its  carbon.  But  in  this  case  the  slag,  being  free  from 
iron-oxide,  would  not  hold  phosphorus  unless  made  basic 
with  lime  or  magnesia,  and  to  melt  a  lime  or  magnesia 
slag  would  require  so  high  a  temperature,  and  hence  so 
much  fuel  (the  reducing  agent),  that  here  too  the  phos- 
phorus would  be  deoxidized. 

In  short  we  have  the  difficult  if  nob  impossible  task  of 
dephosphorizing  under  the  necessarily  strongly  deoxidiz- 
ing conditions  of  shaft-furnace  smelting. 

For  the  rest,  if  cast-iron  is  to  be  made,  the  process  is 
more  costly  than  the  blast-furnace ;  if  ingot  metal,  the 
problem  of  melting  it  in  a  shaft-furnace  is  no  easy  one.  To 
melt  it  in  the  open-hearth  we  have  to  preheat  gas  and  air 
tremendously  ;  to  melt  it  in  a  shaft  furnace  would,  I  fear, 
need  very  hot  blast  and  an  abundance  of  highly  preheated 
fuel  ;  in  short  the  conditions  of  the  blast-furnace  exagger- 
ated, for  the  temperature  must  be  much  higher  than  that 
reached  in  cast-iron  making. 

B.  IRELAND. — The  same  objections  apply  to  Ireland's 
plan  of  melting  sponge  in  a  cupola  furnace.11 


m  Trans.  Am.  Inst.  Min.  Eng.,  IX.,  p.  274,  1881. 
"Jour.  Iron  and  Steel  Inst.,  1878, 1.,  p.  52. 
e  Wagner's  Jabresberieht,  xxxiii.,  p.  305,  1887. 


CHARCOAL    HEARTH     PROCESSES.       §  346. 


289 


CHAPTER  XVI. 
CHARCOAL-HEARTH  PROCESSES. 


When  steel  is  made  from  cast-iron,  this  material  maybe 
used  without  preparatory  treatment,  as  in  the  Bessemer 
process,  or  it  may  undergo  some  preparatory  process. 
The  chief  and  normal  use  of  some  of  these  preparatory 
processes,  such  as  pig-washing  and  mechanical  puddling, 
is  to  prepare  material  for  steel-making  ;  that  of  others, 


conditions  are  brought  about,  chiefly  (1)  by  melting  the 
metal  down  in  drops  before  the  tuyere,  repeatedly  if  need 
be,  so  that  it  passes  in  a  state  of  minute  subdivision  and 
with  great  surface  exposure  through  a  part  of  the  hearth 
where  the  atmospheric  oxygen  is  in  excess  ;  and  (2)  by 
the  action  of  the  basic  ferruginous  slag  with  which  the 


SECTION    ON    CENTRE. 

-  --3-6- 


SECTION  ON   CENTRE. 


§Fore-  or  workinp-plate. 
Shell  for  preheating  cast- 


iron. 

1     roper, 
-tuyere. 

oled  east-iron  bot- 
tom-plate. 

pOut-lroD  side-plates. 
Ca-st  iron  rear  plate. 
Tap  hole  for  slag. 
Cast-irun       water  -  cooled 

lioslirs. 
K    Cast  iron  water-cooled  roof 

and  sides. 
L    Lattice-door. 
M   Hot  tila.st  stove. 
O   Blast-pipe  leading  to  hot- 

blnst  stove. 

p  Dampers  regulating  the 
admission  ot  air  to  the 
hot-blast  stove. 


AMERICAN    LANCASHIRE   HEARTH 
COLUMNS  XI  AND  XIV  OF  TABLE  171. 


SECTION    ON    LINE   *   A  A. 


§    Blast-main 
Pan  for 


etting  the  char- 
coal. 

T    Hook. 

U  Li  tslit  bar  for  working  the 
rge. 

V  Opening  for  detaching  iron 
rrumthe  rear-plate. 

W  Heavy  bar  for  pry.ng  up 
the  ball. 

X    Working  doorway. 


e.  ff.,  hand -puddling,  charcoal-hearth  refining,  etc.,  is  to 
make  wrought-iron  to  be  used  as  such,  and  their  use 
as  preparatory  to  steel-making  is  only  subsidiary. 

§  346.  IN  GENERAL. — Charcoal-hearths  for  refining 
cast-iron  are,  roughly  like  the  Catalan  and  bloomary 
heartlis  for  reducing  iron  from  the  ore,  low,  rectangular 
chambers,  Figure  149,  sometimes  roofed,  Figures  147, 148, 
and  with  one  or  more  tuyeres.  The  chief  difference  is 
that  in  refining  cast-iron  much  more  strongly  oxidizing 


metal  is  mixed  during  the  earlier  stages,  and  with  which 
it  is  covered  during  the  later  stages,  to  ward  off  the 
strongly  carburizing  tendency  of  the  charcoal. 

Material. — As  this  process  is  a  very  expensive  one,  and 

hence  only  used  for  making  iron  of  excellent  quality,  and 

as  the  quality  of  the  product  depends  to  a  considerable 

!  extent  on  that  of  the  material,  «,  e.,  on  its  freedom  from 

1  phosphorus  and  sulphur,  so  only  pure  cast-iron  is  used, 

j  and  preferably  charcoal  cast-iron.     As  the  length  and  cost 


290 


THE    METALLURGY    OF     STEEL. 


of  the  operation  increase  with  the  proportion  of  carbon 
and  still  more  with  that  of  silicon  in  the  metal,  so  closi 
gray  or  preferably  mottled  or  white  cast-iron  is  habitually 


SWEDISH  WALLOON 
CHARCOAL-HEARTH 


fig.  U9. 

used  ;  and,  in  case  open  gray  iron  is  used,  it  is  well  to  re 
move  part  of  its  silicon  by  a  partial  refining  in  a  prelim 
inary  process. 

Silicon  not  only  greatly  retards  the  operation  by  being 
oxidized  in  preference  to  carbon,  but  more  especially  be 
cause  the  silica  formed  by  its  oxidation  makes  the  slag 
less  basic,  and  so  less  strongly  decarburizing  ;  and  the  re- 
moval of   phosphorus  and  carbon  occurs  in  large  parl 
through  the  action  of  the  basic  slag.     Not  only  does  a 
less  basic  slag  remove  phosphorus  and  carbon  less  rapidly, 
but   it  devours  iron-oxide    the  more  readily,   and  thu 
increases  the  loss  of  iron.     Indeed,  we  must  make  up  oui 
minds  to  a  loss  of  over  two  parts  by  weight  of  iron  foi 
every  part  of  silica,  or  of  about  one  part  by  weight  of  iron 
for  each  part  of  silicon  that  enters  the  slag.     Moreover, 
a  very  considerable  outlay  of  labor  and  time  is  needed  to 
work  the  iron-oxide  into  the  slag. 

The  pigs  are  in  many  cases  cast  in  cast-iron  mould 
("chills");  if  cast  in  sand,  much  of  this  would  adhere 
to  them  and  silica  would  thus  be  introduced. 

The  presence  of  manganese  in  the  cast-iron  is  thought 
undesirable,  not  only  because  it  is  oxidized  in  part  in 
preference  to  the  carbon  and  silicon,  and  because  the 
manganese  slags  are  less  strongly  fining  than  the  iron 
slugs — thanks  to  the  higher  affinity  of  manganese  than  of 
iron  for  oxygen,  and  to  the  fact  that  manganese  does  not 
slide  up  and  down  in  its  degree  of  oxidation  as  iron 
does,  carrying  oxygen  from  atmosphere  to  metal— but 
also  for  another  important  reason.  The  manganese  Blags 
are  unduly  fluid,  and  do  not  adhere  to  the  sides  and  upper 
part  of  the  lump  of  iron  and  exert  their  fining  influence 
over  its  whole  surface  like  the  relatively  pasty  iron  slags, 
but  run  down  and  collect  beneath,  leaving  the  iron  in 
contact  with  the  charcoal,  from  which  it  rapidly  takes  up 
' carbon. 

For  fuel  charcoal  is  used,  not  only  because  free  from 
suJphur,  bat  because  it  has  less  ash  than  solid  mineral 
fuels,  and  so  introduces  less  silica  into  the  slag.  To  re- 
move sand,  pebbles,  etc.,  serious  sources  of  silica,  the 
charcoal  shortly  before  use  is  washed  in  large  tanks 
which  stand  hard  by  the  charcoal-hearths  themselves. 

The  hearths  are  usually  of  naked,  unlined  cast-iron 
plates,  at  least  in  part  water-cooled.  Brick-work  or  other 


clayey  lining  i,->  to  be  avoided,  because  its  silica  would 
enter  the  slag. 

§  347.  PRODUCT— THE  REASONS  FOR  THE  EXISTENCE 
OF  THE  PROCESS. 

From  given  cast-iron  the  charcoal-hearth  process  yields 
better  wrought-iron  than  puddling,  perhaps  in  part  be- 
cause the  charcoal  lacks  the  sulphur  which  the  mineral 
fuel  of  the  puddling  furnace  contains,  and  of  which  a  little 

TABLE  167.— COMPOSITION  AND  PROPERTIES  OF  CHARCOAL-HEARTH  IRON. 


c 

y. 

0. 

Si. 

Mn. 

P. 

s. 

Tensile  strength, 
Ibs.  per  sq.  in. 

<-     — 

'i  =• 

»£ 
•£ 

w~ 

Elonga- 
tion. 

Reduction  of  1 
urea,  per  cout  (I 

Percent. 

Meas- 
ured on 

1 

2 

a 

4 

5 
6 

7 
8 
9 
10 

11 
13 
13 
14 
15 
16 
17 

18 

in 

20 
21 
32 
23 
21 
X, 
2li 

Aryd,  Srnaland,  Sweden  (Rolled). 

Hallstalmmmer,  Westman  land, 
Sweden  (.Rolled)  

0.07 
0.18 

0  07 

O.-Mt 

ILMHKI 

50,916 

45,014 
47,553 
44,603 

44,877 
51,053 
56,199 

37,3(17 
40,485 

27,104 
34,360 

14.1 
16.7 

•>a.o 
ig!6 

39.0 
17.2 

5.3" 

40. 
18. 

M. 

77. 
74. 
68. 
65. 
65. 
59. 

Lesjoforss,    Wermland,    Sweden 
(Boiled)  
Hallstahanimer  
Lesjoforss   

0.07 
0.07 
0.08 
0.07± 
0.08 
0  07 

0.022 

From  Daunemora  Ore  
Swedish  a  

0.087 
0,054 
0.087 
.040 
.200 
.01 
.18 
.06 
.11 
.06 
.05 
.06 
.05 
.08 
.03 
.06 
.12 

0.115 
0.028 
0.050 
nil. 
.100 
.005 
.005 
.016 
.021 
.02 
.02 
.0-33 
.02 
.10 
.25 
.21 
.19 

'tr'.' 

nil. 
.050 
.005 
.02 
.01 
.07 
.005 
nil. 
.008 
nil. 
tr. 
.008 
.009 
.01 

0.034 
tr. 
0.005 
0  005 
.100 
.016 
.04 
.03 
.05 
.02 
.04 
.017 
.02 
.05 
.01 
.01 
.01 

0.220 
0.055 
O.(i32 
nil. 
.025 
.002 
.002 
.01 
.08 
nil. 
.009 
nil. 
.01 
.09 
.01 
.03 
.008 

"       a  

(i 

it 

t 

4 

« 

t 

1 

American  

t 

1        

(a)  Made  from  cast-iron,  containing  carbon,  4.00  to  4.50  f,  silicon,  0.30  to  0.50  %,  manganese, 
trace  to  1.80  %,  phosphorus,  0.01  to  0.15  %,  sulphur,  0.01  to  0.03  %. 
\  to  9,  Styffe,  Iron  and  Steel,  pp.  133,  13d,  140,  1869. 
10  to  1 2,  1'ercy,  Iron  and  Steel,  p.  73li,  1864. 


1 3  and  1 4 ,  Bell,  Princ.  Manuf .  Iron  and  Steel,  p.  345,  1884. 
15  to  26,  G.  H.  Billings,  Piivate  Communication,  April  7, 1889. 


may  enter  the  metal,  but  chiefly  for  the  following  reason. 
In  both  processes  we  can  decarburize  the  pasty  metal 
throughout  its  mass  only  by  stirring  it  vigorously,  expos- 
ing fresh  surfaces  to  the  action  of  the  atmosphere  and  of 
the  strongly  decarburizing  basic  slag,  and  this  stirring 
intentionally  mixes  slag  with  metal  to  effect  decarburiz- 
ation.  We  thus  get  a  ball  of  stiff,  pasty  wrought-iron 
mixed  with  much  slag.  In  some  of  the  charcoal  hearth 
processes  we  get  rid  of  most  of  this  slag  by  remelting 
this  ball ;  holding  it  aloft  we  allow  its  metal  to  fall  drop 
by  drop,  and  collect  it  in  a  new  ball,  which  we  carefully 
avoid  touching,  and  which  is  thus  relatively  free  from 
slag.  In  the  puddling  process  we  cannot  do  this,  and 
must  content  ourselves  with  squeezing  out  as  much  of  the 
slag  as  we  can  in  hammering  or  rolling. 

Charcoal-hearth  iron,  then,  is  in  a  manner  intermediate 
setween  common  wrought-iron  and  ingot-iron  in  that  it  is 
•emelted  and  cast  while  molten  into  a  malleable  mass  ; 
jut  instead  of  being  cast  into  a  si agl ess-mould  as  in  true 
ngot-metal-making  processes,  it  is  poured  upon  a  bath  of 
slag  of  which  a  very  little  inevitably  becomes  mixed  with 
;he  metal. 

But  while  it  is  clear  why  charcoal-hearth  iron  is  tougher 
;han  puddled  iron,  it  is  not  so  easy  to  see  why  it  is 
rougher  than  ingot-iron,  unless  we  hold  that  the  small 
quantity  of  slag  in  charcoal-hearth  iron  promotes  tough- 
ness while  the  larger  quantity  in  puddled  iron  opposes 
onghness.      The  conditions  under  which  the  charcoal- 
learth  iron  is  melted  and,  as  it  were,  cast  within  the 
earth,  are  very  different  from  th'>se  which  attend  the 
asting  of  ingot-iron.     Charcoal-hearth  iron  is  raised  but 


PRODUCT  OF  CHARCOAL  HEARTH.   §  347. 


291 


slightly  above  its  melting  point,  and  for  a  few  moments 
only  ;  is  cast  drop  by  drop  through  an  atmosphere  rich  in 
carbonic  oxide  and  carbonic  acid  into  a  white-hot  bath  of 
slag,  falling  in  all  bat  a  few  inches  :  ingot-iron  is  held  for 
a  very  considerable  length  of  time  far  above  its  melting 
point,  is  cast  in  a  thick  stream,  through  a  cold  atmosphere 
of  oxygen  and  nitrogen,  usually  into  a  cold  cast-iron 
mould,  often  falling  several  feet.  In  the  charcoal -hearth 
drop  of  metal  follows  drop  in  such  a  way  that  neither 
pipe  nor  blowhole  nor  microscopic  cavity  seems  to  form  ; 
ingot-metal  is  so  cast  that  pipes  or  blowholes  or  micro- 
scopic cavities  or  all  three  arise.  Charcoal-hearth  iron  is 
purposely  kept  as  free  as  possible  from  slag,  ingot-metal 
is  purposely  kept  practically  absolutely  free  from  slag. 
I  will  not  attempt  to  say  to  which,  if  to  any,  of  these 


Here  is  a  case  which  exemplifies  the  curious  :md 
anomalous  facts,  or  at  least  beliefs,  touching  the  proper- 
1  ties  of  charcoal-hearth  and  ingot-iron.  For  making  screws 
charcoal  hearth  iron  is  used  because,  so  it  is  said,  ingoi 
iron  is  not  tough  enough  to  endure  the  upsetting  which 
arises  in  forming  the  head  of  the  screw.  But  the  char- 
coal-hearth iron  used  is  purposely  rather  brittle,  is  in- 
tentionally made  from  rather  phosphoric  cast-iron,  so  that 
the  shaving  formed  in  cutting  the  thread  may  break  off 
short,  and  not  interfere  with  the  cutting  tool.  Now  we 
are  told  that  charcoal-iron  endures  upsetting  better 
than  ingot-iron,  and  at  the  same  time  its  shavings  break 
off  more  aptly  ;  in  brief,  it  is  tougher  in  the  head  but 
shorter  in  the  thread  !  Some  of  these  paradoxical  beliefs 
turn  out  on  investigation  to  be  mere  superstitions,  others 


fig.  W.    AMERICAN-SWEDISH-LANCASHIBE  HEARTH. 


differences  the  apparently  very  considerable  difference  be- 
tween the  properties  of  ingot-iron  and  of  those  of  cliarcoal- 
hearth  iron  is  due,  nor  even  that  it  is  due  to  any  of  these 
rather  than  to  other  and  unnoticed  differences.  I  will  not 
even  insist  that  there  is  a  real  difference  in  quality.  We 
know  that  the  properties  of  tough-pitch  copper  are  in- 
fluenced very  greatly  and  obscurely  by  the  conditions 
preceding  and  attending  casting. 

The  apparent  superiority  of  charcoal-hearth  to  ingot- 
iron  can  hardly  be  attributed  to  greater  freedom  from 
carbon,  silicon,  phosphorus,  etc.,  if  we  may  judge  by  the 
analyses  in  Table  167. 

Uncertain  whether  the  conditions  of  the  charcoal-hearth 
give  better  quality  than  we  can  obtain  in  ingot-metal,  we 
may  not,  like  so  many  superficial  observers,  predict  the 
early  disappearance  of  the  process. 


to  be  true,  due  now  to  simple  now  to  obscure  conditions. 
How  it  is  with  this  one  I  know  not. 

It  is  doubtful  whether  the  charcoal-hearth  removes 
phosphorus  as  thoroughly  as  the  puddling  process,  for  its 
atmosphere  seems  much  less  powerfully  oxidizing.  This 
appears  to  more  than  outweigh  the  usually  greater  basicity 
of  its  slag,  and  the  more  thorough  removal  of  the  slag 
from  which,  as  long  as  it  is  present,  the  iron  may  reabsorb 
phosphorus  at  high  temperatures,  as  in  reheating. 

Thanks  to  the  excellence  of  its  product  charcoal-hearth 
refining  seems  to  hold  its  own  pretty  well,  at  least  if  we 
include  the  balling  of  scrap  wrought-iron  in  charcoal- 
hearths.  The  output  of  charcoal  blooms  from  cast-iron 
and  scrap  together  in  this  country  was  greater  in  1887  than 
in  any  of  the  years  from  1874  to  1878  ;  the  output  of  the 
Swedish  charcoal-hearths  increased  by  about  60  per  cent. 


202 


THE    METALLURGY    OF    STEEL. 


between  1860  and  1880.  In  South  Wales  the  charcoal- 
licarth  has  been  used  very  extensively  for  making  iron  for 
tin  plates,  but  there  mild  steel  is  now  driving  it  out  of 
the  field. 

In  the  Austrian  Alps  and  in  Russia  it  is  still  used  ex- 
tensively, I  understand.  The  following  table  gives  data 
concerning  the  extent  to  which  it  is  used  : 

TABLE  168.  —  PRODUCTION  or  BLOOMS  BY  REFINING  CAST-IRON  IN  CHARCOAL-HEARTHS. 


As  the  data  in  Table  171   show,  important  economies 


TEAR. 

UNITED  STATES, 
(Blooms  from  Cast-iron  and  Scrap.) 

SWEDEN. 

Number  of 
Hearths. 

Output. 

Net  Tons. 

Number  of 
Hearths. 

Output. 
Net  Tons. 

1860. 
1874. 
1877. 
I8» 
1882. 

l,260b 

124,223 

25,220 
83,073 
38,987 

-12,939 
27.210 

21,813 
28,818 
25,787 

729b 

198,915 

1884. 

18-'5. 
1887 

53a 

1888. 

aTliis  does  not  include  charcoal-hearths  which  make  blooms  for  use  in  the  plate,  sheet 
and  wire-making  mills  with  which  they  are  connected. 

b  Hearths  and  furnaces. 

United  States,  from  Ann.  Statistical  Kept.  Am.  Iron  and  Steel  Ass.,  1838,  p.  37,  and  J.  M. 
Swank,  private  communication. 

Sweden,  from  Ehrenwerth,  Das  Eisenhuttenwesen  Schwedeus,  p.  99, 1885,  from  Akerman. 

Table  169  shows  that  some  of  the  American  charcoal- 
hearth  establisments  existing  and  even  running  at  present 
are  extremely  old,  and  that  the  development  of  the  indus- 
try, as  judged  from  the  number  of  establishments  built, 
was  most  rapid  between  1870  and  1880. 

TABLK  169.— AGE  OF  THE  CHARCOAL-HEARTHS  EXISTING  NOW  OR  LATELY  IN  THE 
UNITED  STATES. z 


Of  those  built  in  the  several  periods  of  Column  1,  the 
following  numbers  were 

Tears. 

No.  Bnilt. 

No.Eebnilt. 

Abandoned  appa- 
rently between  1H83 
and  1888. 

Idle  in  1887,  bnt 
apparently  not 
abandoned. 

Running  in  1887. 

1755.       1 
1799. 
1800. 
1819. 
1820. 
1829 
18JO. 
1839. 
1810. 
1849. 
1850. 
18  9. 
I860.        1 
J809.        f 
1870.        i 
18T9.       f 
JH80 
1883.       .. 
188J 
18«5.       .. 
1887. 
1888. 

6 
6 
4 
6 
6 
0 
7 

10 

1 
1 
1 
1 
1 
0 

4 
3 
3 
2 
3 

2 
2 
1 
4 
2 

1 

1 

0 
2 
2 

3 

6 

8 

4(!) 

1 

1 
1 

1 
1 

1 

1 

0 

x  Oi.e  may  not  safely  infer  that  the  original  hearths  still  exist  in  these  establishments  ; 
they  may  have  been  built,  rebuilt  or  replaced,  but  at  least  the  original  establishments 
eii-t. 


Bell  estimates  the  cost  of  making  2,240  pounds  of  char- 
coal hearth  bar  iron  in  Sweden  as  follows  : 

TABLE  170. — COST  op  MAKING  CHARCOAL-HEARTH  IRON  IN  SWEBDEN.     7,WM> 

2,912  pounds  Cast-iron  @  $14.52  per  2,240  Ibs $18  82 

3.0SO       "       Charcoal  @  $4.84    "      "      "    668 

Labor 5  57 


Total $3107 


b  Princ.  Manuf.  Iron  and  Steel,  p.  347,  1884. 


The  data  in  Table  171  indicate  that  the  cost  of  the 
manufacture  of  blooms,  assuming  Bell's  prices,  is  much 
less,  to  wit : 

2,575  pounds  of  Cast-iron  @  $14,53  per  ton $1669 

1,120        "  Charcoal  @  $4.84     "      "    242 

Labor,  2 days®  $1.25  d 2  50 


$21  61 


d  Bell  does  not  give  the  rate  of  wages. 


of  the  process.     Thus  we 

see 

that   the  output  of  the 

a  This  is  the  consumption  per  2,000  Ibs.  of  burs,  not  blooms, 
b  It  is  assumed  that  a  bushel  of  2,500  culrc  in.  weighs  11  Ibs.:  then  l»»3_24  bushels. 
The  original  gives  the  measure  of  charcoal,  but  not  the  weight, 
c  There  seems  to  be  a  slight  discrepancy  between  the  output,  the  charee,  and  the  loss, 
d  The  same  assumption  us  in  b  :  the  weight  of  charcoal  is  given,  but  not  the  measure, 
e  This  is  the  loss  from  cast-iron  to  bars,  not  blooms. 

Loss  — 
From  cast-iron  to  blooms,  per  / 
100  of  cast-iron  f 

o             o          t^e-1  o 

d               e-            >  «    -i 

3        5      g«  g. 
£2355   3  -.gz^af  "•  o 
|ls|'«'g^2aBia    ar 

2  -•  r,  ?f  cTO  °J5'K  =M            n    H. 

}  I 

i|i  *;  ji  *  lr&  ;  i 

DIMENSIONS  or  HEARTH— 

Width  and  length 
Height  to  tuyere  

"  above  tuyere. 
"  total  " 
BLAST— 

Pressure,  ounces  per 
Temperature  p  !•  ... 
Size  of  tuyere,  nozzle 
Inclination  of  tuyere. 
Number  of  tuyeres... 

"8  K;  s 

"<      P*. 
o  . 
tr     n  • 
g      3  • 

i  i  1 

;  ^^A^- 

8 

K 

i|  1 

:    ~ 

ijw 

«  g 

||| 

8 

W. 

S!  f 

CO 

White  or 
mottled. 

as'aacK 

x  I 

r*  P- 

itfl 

:  :  ©xg 

^    !    co      *: 

:  :  1   * 

1      cr? 

iSS  - 

£o  c.t~ 

Swedish  Walloon. 

|  Double-smelting  process. 

@©  p 

£g      § 

B  *           ? 

o-0" 

white  or  n 
tied. 

in. 

Sweden, 
Dannemora, 
about  1873. 

| 

8 

Sfe-     g   s    ^ 
m.  »    »  je    :  ; 

trcr 

f 

gx   8    £ 

°i-    P1    •" 

|H 

IV. 

Sweden. 
Dannemora 
about  1884. 

CO 

i 

W*-1               to 

f 

cr 

V 

3" 

In  Sweden. 

Swedish  Lancashire  hearth. 

d^spr 

;   ? 

)'@lhr.3C/ 

SP 

Kerl,  Grundiss  der  Eisenbttttenkunde,  p.  340,  1875. 
Percy,  Iron  rand  Steel,  p.  599,  1864. 
,  Kerl,  op.  cit.,  p.  838. 
,  Ehrenwerth,  das  EisenhQttenwesen  Schwedens,  p.  32,  1885. 
Percy,  op.  cit.,  p.  591. 
,  Kerl,  op.  cit.,  p.  338. 

CO 

SI 

Ss:    |  • 
"|i    |  ! 

S     :  : 
»     :  : 

mottled 

a 

u*  ^^  o 
o    o 

VI. 
Before  1875. 

•nc 

.h.    1  1 

a               00 

I      EB-M 
H-3 

D-  :    , 

c 

«3 

C 

III! 

4  \  H 

H-  1"  •" 

1 

VI.           CJt        C*O* 

?      8    » 

half  white,  half 
mottled  to  gray 
1  hr.  2V 

S 

Ipl 

to     tc 
*i    *« 

\nn. 

HamnSs,  1884. 

tO                 ii  -^                 •-        *, 

*».       b     crcr 

i           tO 
•           i—        *O 

i* 

II 

-3SX8 

IX. 
Domnarfvet 
1882. 

~   5    ^  1 

to 

© 

CO 

: 

;ll 

W 
2. 

i"j« 

VII.,  VIII.  and  IX.,  Ehrenwerth,  op.  cit.,  pp.  27,  68,  45. 
X.,  Bell,  Princ.  Manuf.  Iron  and  Steel,  p.  346,  1884. 
XI..  From  the  author's  Notes. 
XII.  XIII.,  Kerl,  op.  cit.,  pp.  334,  a36. 
XIV.,  From  the  author's  Notes. 

CO           *O«0:      •              O        Z 

*"•      co    :  ; 

1 

»           it*.        tO 

U!?£ 

| 

« 

pa 

United  States. 

to     „        to     c 

8        "S-S-     "    ° 

E 
©  n 

3   ' 

ii= 

A 

Q 

Triple-smelting  Process. 

8 

2  hours  2y 

14.2  to  16.1 
112°@125C 
233.  6°  ®  257°  F 
1"X1.5" 

« 

XIII. 
Before  1875. 

Franche- 
ODBM. 

I  -te  »  ' 

8_ 

9 

|? 

^ 

» 

ill 

B          f 
g.         f 


CLASSIFICATION  OF  CHARCOAL- HEARTH  PROCESSES.     §  348. 


293 


§  848.  CLASSIFICATION. — The  charcoal- hearth  processes 
are  classified  according  to  the  number  of  times  that  the 
metal  is  melted  down  before  the  tuyere  into  the  single-, 
the  double-  and  the  triple-smelting  classes  (Einnial- 
schmelzerei,  Zwelmalschmelzerei,  and  Dreimalschmelzerei 
or  German  or  breaking  up  [AufbrechschmiedeJ  class). 

The  number  of  smeltings  needed  depends  chiefly  on  the 
proportion  of  carbon,  silicon  and  manganese  to  be  removed, 
arid  also,  but  to  a  smaller  extent,  on  the  desired  thorough- 
ness of  decarburization,  etc.  Hence  the  single  smelting  is 
chiefly  applicable  to  white  cast-iron  and  to  iron  already 
partly  refined  :  the  double  smelting  to  mottled  iron,  or  to 
white  or  previously  parti}7  refined  iron  when  an  extremely 
pure  product  is  sought :  the  triple  smelting  to  mottled  or 
to  gray  iron. 

The  processes  are  also  divided  into  the  Walloon  and  non- 
Walloon  classes.  The  ground  of  this  distinction  seems  to 
be  a  little  in  dispute.  Tanner  classes  as  Walloon  all  those 
processes  in  which  the  bloom  is  reheated  in  a  separate 
hearth,  an  arrangement  which  leads  to  a  smaller  consump- 
tion of  charcoal,  as  mineral  fuel,  sawdust,  etc.,  may  be 
used  for  reheating.  But  this  is  not  true  of  the  Swedish 
Walloon  process.  Kerl  appears  to  class  all  double-smelt- 
ing processes  as  Walloon. 

Tanner  recognizes  no  less  than  fourteen  kinds  of 
wronght-iron  making  types  of  charcoal-hearth  refining 
processes,  and  five  moiM  steel  making:  but  we  need  con- 
cern ourselves  only  with  those  given  in  Table  171,  which 
are, 

Single  smelting. 

\  Swedish  Walloon. 
Double  Smelting.  •<  (Lancashire. 

|  English  Walloon. - 

/  Somh  Wales. 
Triple  melting,  e.  (j.  Franche-C'omte 

Of  these  the  Swedish.  Walloon  (called  in  Sweden,  plain 
"  Walloon")  is  used  in  Sweden  solely  and  exclusively  for 
making  bars  from  Dannemoru  cast-iron  which  are  to  be 
converted  into  blister  steel.  Changes  in  the  procedure 
have  long  been  and  I  believe  are  still  prohibited  by 
contract  with  the  English  consignees,  lest  the  quality  of 
the  product  be  injured.  However  faithfully  the  spirit  of 
this  contract  may  be  kept,  the  data  in  columns  II.  to  IV. 
of  Table  171  indicate  that  its  letter  has  been  violated,  for 
the  output  per  hearth  per  24  hours  has  increased  greatly, 
while  the  consumption  of  fuel  has  fallen  off,  since  Percy's 
great  work  was  written. 

This  process  is  more  expensive  than  the  Lancashire, 
using,  say,  four  times  a*s  much  charcoal  and  much  more 
labor.  One  would  naturally  suppose  that  the  excellence 
of  the  Dannemora  iron  was  due  rather  to  the  excellence 
of  the  ore,  notably  its  remarkable  freedom  from  phos- 
phorus, and  to  the  thorough  roasting  whicli  it  undergoes, 
than  to  the  use  of  the  Swedish  Walloon  instead  of  the 
Lancashire  process.  The  vastly  greater  fuel-consumption 
of  the  former  should  indeed  be  detrimental  as  opposing 
the  removal  of  phosphorus,  of  which  a  little  is  reported 
even  in  the  Dannemora  iron  (see  Table  167).  Moreover, 
the  Swedish  Walloon  iron  is  probably  much  less  homo- 
geneous than  the  Lancashire-hearth  iron. 

Nearly  if  not  quite  all  the  charcoal-hearth  iron  made  in 
Sweden,  other  than  Dannemora  iron  for  cementation,  is 
made  by  the  Lancashire  process,  and  much  Danne- 
mora iron  not  intended  for  cementation  is  thus  made. 
This  process  is  also  used  extensively  in  this  country. 


Whether  it  has  ever  been  used  in  Lancashire  I  know 
not.  It  was  brought  to  Sweden  by  Welsh  workmen, 
and  to  this  country  by  Swedes.  The  South  Wales  process 
was  used  extensively,  and  actually  in  South  Wales,  not- 
ably for  making  plates  for  tinning.  But  it  has  been 
driven  out  of  that  district  to  a  great  extent,  if  not 
altogether,  by  the  Bessemer  and  open-hearth  processes. 

§  349.  EXAMPLE  OF  THE  SINGLE-SMELTING  PROCESS.— 
The  white-iron  pigs,  much  as  shown  at  the  right  of  Figure 
149,  are  gradually  pushed  forward  towards  the  tuyere  as 
their  hotter  ends  melt  away,  and  the  iron  is  almost  com- 
pletely decarburized  as  it  trickles  past  the  tuyere.  It 
collects  as  a  ball  on  the  oxide-bottom.  Imperfectly  re- 
fined parts  are  broken  off  and  melted  again :  the  ball 
is  drawn  and  hammered  :  the  billets  from  the  preceding 
charge  are  heated  in  the  same  fire. 

§  350.  IN  THE  LANCASHIRE-HEARTH  PROCESS*  three 
periods  are  distinguished : 

1,  the  preheated  cast-iron  is  melted  down  before  the 
tuyeres  (say  15  minutes) ; 

2,  the  pasty  mass  which  the  collecting  drops  form  is 
constantly  broken  up  by  prying  from  beneath,  and  the 
slag  is  thereby  mixed  with  it  (20  to  30  minutes) ; 

3,  the  almost  decarburized  mass  is  raised  above  the 
charcoal  and  gradually  melted  down,  collecting  beneath 
in  a  ball  which  is  drawn  and  hammered  (25  to  30  minutes). 

The  hearth  is  wholly  lined  with  naked,  unprotected, 
cast-iron  plates,  the  bottom  and  preferably  the  sides  being 
water-jacketed.  In  American  practice  a  bottom-plate 
lasts  about  four  weeks,  and  the  others  about  twice  as 
long. 

In  some  American  Swedish  Lancashire-hearths,  Figures 
147,  148,  whose  work  is  given  in  column  XI.  of  Table  171, 
the  whole  of  the  roof  and  sides  are  formed  by  one  or  two 
heavy  castings,  K  K,  Figure  148,  which  are  full  to  the  top 
with  water.  Figure  148,  which  is  from  a  photograph  of 
the  hearths  represented  in  Figure  147,  further  shows  the 
tools  used,  and  the  actual  form  of  double-elbowed  blast- 
pipe,  which  enables  us  to  withdraw  the  tuyere  readily.  The 
products  of  combustion  pass  first  into  the  fire-brick  ells 
M  M,  in  which  they  heat  the  blast,  whose  entrance  is  ef- 
fected through  the  pipe  O,  and  regulated  by  the  dampers  P. 
By  shifting  these  dampers  we  can  send  the  blast  through 
the  blast-heating  pipes,  or  directly  to  the  tuyeres  without 
preheating,  or  in  readily  variable  proportion  through  both 
paths  simultaneously.  From  these  ells  the  products  of 
combustion  pass  beneath  the  boilers,  which  stand  behind 
and  beneath  the  blast-main  R.  The  lattice  L,  designed 
to  hold  in  the  charcoal  and  to  protect  the  workmen 
in  some  measure,  was  not  in  use  at  the  time  of  my 
visit. 

The  charcoal  is  added  and  nearly  all  the  work  is  done 
through  the  wide-open  doorway  X  X,  through  which  an 
enormous  excess  of  air  rushes,  greatly  lessening  the  heat- 
ing power  of  the  products  of  combustion. 

a  According  to  Percy  this  is  a  misnomer,  as  the  process  was  imported  into  Sweden 
from  South  Wales  in  1829.  (Iron  and  Steel,  p.  598,  A.D.  1864.) 


294 


THE    METALLURGY    OP    STEEL. 


Description  of  Process.— I  will  now  describe  the  prac- 
tice which  I  have  seen  in  this  country ;  it  corresponds 
closely  to  the  Swedish. 

Preparatory. — 275  pounds  of  pig-iron  in  lumps  up  to 
one  foot  long  are  preheated  on  the  shelf  B,  while  the  pre- 
ceding charge  is  working.  The  ball  being  drawn,  the 
hearth  is  cleaned,  and  the  quantity  of  slag  present  ascer- 
tained. If  there  is  not  enough  to  cover  the  bottom-plate 
E  thoroughly,  slag  is  added.  It  is  essential  that  there 
should  be  enough  for  this  purpose,  lest  the  molten  iron 
should  strike  and  attach  itself  to  this  plate. 

1st  Period. — The  hearth  is  next  filled  to  about  one  foot 
above  the  tuyeres  with  charcoal,  and  on  this  the  now  red- 
hot  pigs  are  drawn  from  the  shelf  B.  The  blast  is  turned 
on ;  the  pigs  are  covered  with  charcoal.  During  the 
whole  operation  charcoal  is  added  every  few  minutes,  and 
on  it  is  thrown  water  by  the  pan  S,  partly  that  the  work- 
man may  work  at  the  hearth  without  excessive  discom- 
fort, partly  that  the  charcoal  and  carbonic  oxide  may  not 
burn  uselessly  at  the  top  of  the  fire,  and  that  the  carbonic 
oxide  may  be  preserved  to  burn  beyond,  in  the  flue  under 
the  boiler.  The  melting  pigs  tend  to  sink  down  as  the 
charcoal  beneath  them  burns  away  ;  they  must  therefore 
be  lifted  a  little  every  few  minutes,  so  that  the  drops 
which  trickle  from  them  may  pass  through  the  oxidizing 
core  of  the  region  of  combustion.  But  for  this  they 
would  soon  sink  down  to  the  bottom  of  the  hearth,  and 
the  fusion  would  lose  its  oxidizing  character,  which  is  due 
wholly  to  the  passage  of  the  molten  metal,  drop  by 
drop,  throug  h  the  most  strongly  oxidizing  part  of  the 
hearth. 

As  the  mass,  now  considerably  decarburized,  collects  at 
the  bottom  of  the  hearth,  it  is  so  far  cooled  by  the  neigh- 
borhood of  the  water-cooled  bottom-plate  that  it  becomes 
decidedly  pasty  ;  thus  any  given  particle  of  metal  is  only 
fluid  during  the  brief  period  when  it  is  dropping  from  the 
still  unmelted  portion  above  to  join  the  previously  melted 
but  now  partly  resolidified  mass  beneath. 

If  too  much  slag  be  present,  the  gradual  accumulation 
of  metal  on  the  bottom  raises  the  slag-level  so  high  that 
the  entrance  of  the  blast  is  impeded  ;  this  may  be  recog- 
nized by  a  peculiar  fluttering  noise  which  the  blast  makes. 
In  this  case  the  excess  of  slag  must  be  tapped  out  through 
H  ;  but  as  it  is  not  easy  to  judge  just  how  much  is  excess, 
the  whole  of  the  molten  part  of  the  slag  may  be  tapped  out, 
and  enough  slag  returned  to  cover  the  bottom  fully  when 
the  second  fusion  occurs. 

Up  to  this  point  one  man  only  works  at  the  hearth, 
but  two  are  at  work  during  the  whole  of  the  second 
period. 

%d  Period. — When  the  whole  charge  seems  to  have 
melted  down  and  collected  thus  at  the  bottom  of  the 
hearth,  the  workman  feels  about  in  the  charcoal  with  the 
hook  T,  to  find  any  still  unmelted  lumps.  He  now  be- 
gins lifting  up  the  pasty  lump  with  the  light  bar  U,  run- 
ning its  point  along  the  face  of  the  bottom-plate  so  that 
no  scattered  pieces  may  escape  him,  and  from  now  on 
throughout  the  second  period  this  lifting  is  continued 
with  but  brief  interruptions  ;  indeed,  during  part  of  the 
time  both  workmen  are  prying  simultaneously,  one  at 


each  side  of  the  hearth.  Running  the  point  of  his  bar 
beneath  the  mass  the  workman  bears  down,  using  the 
inner  edge  of  the  fore-plate  A  as  a  fulcrum,  and  raises 
the  mass  by  from  three  to  five  inches  from  the  bottom- 
plate.  Into  the  space  thus  left  falls  some  charcoal,  runs 
some  molten  slag,  and  pierces  the  blast.  As  the  workman 
moves  his  bar  from  this  point  to  another,  the  pasty  mass 
(gradually  sinks  back  again,  and  must  soon  again  be 
raised. 

In  prying  the  mass  up  the  workman's  bar  cuts  deeply 
into  it,  carrying  some  of  the  slag  which  had  collected  be- 
|  neath  the  metallic  lump ;  thus  slag,  cooled  to  pastiness  by 
1  the  bottom -plate,  and  pasty  metal  are  intimately  mixed, 
and  thus  the  fining  action  of  Blag  on  metal  is  promoted. 
The  iron-oxide  of  the  slag  gives  up  oxygen  to  the  carbon, 
silicon  and  phosphorus  of  the  metal,  and  when  the  blast 
again  penetrates  again  absorbs  oxygen  from  the  atmos- 
phere, to  be  again  given  up.  The  pasty  mass  is  not  only 
1  indented  from  beneath  by  this  prying,  but  broken  up 
here  and  there.  It  is  reunited  not  only  by  the  same  pry- 
ing from  beneath,  but  also  as  the  workman  pries  the 
metallic  lumps  horizontally  from  around  the  tuyeres 
towards  the  centre  of  the  hearth,  for  pains  must  be  taken 
at  all  times  that  the  tuyeres  are  clear  and  that  the  blast 
issues  freely.  At  first  the  metal,  soft  and  barely  pasty, 
is  lifted  readily ;  as  fining  progresses  it  becomes  stiffer 
and  stiffer,  and  soon  a  powerful  pressure  is  needed  to 
raise  it. 

Towards  the  end  of  this  period  the  carbonic  oxide  comes 
off  so  rapidly  that  the  fine  charcoal  lying  above  the  metal 
seems  to  boil,  so  energetically  is  it  stirred  by  the  escap- 
ing gas. 

The  indications  of  progress  are  chiefly  the  consistency 
of  the  metal  just  noted,  and  the  color  and  consistency  of 
the  slag.  At  first  the  coating  of  slag  seen  on  the  bar  as  it 
is  drawn  from  the  fire  is  sluggish  an'd  reddish,  sluggish 
because  silicious  and  relatively  cool ;  reddish  because 
relatively  cool  and  apparently  because  sluggish,  the  outer 
air-cooled  layer  remaining  outside  and  concealing  the 
hotter  interior.  Later  it  grows  ever  thinner  and  whiter ; 
thinner  because  more  basic  (with  decreasing  proportion 
of  carbon  and  silicon  in  the  metal,  iron  oxidizes  more 
readily  and  is  less  readily  deoxidized),  and  because  hotter 
(the  oxidation  of  carbon,  silicon  and  iron  as  well  as  of  the 
charcoal  ever  raising  the  temperature) ;  whiter  because 
hotter  and  probably  because  thinner,  moving  quickly 
with  shifting  positions  of  the  bar,  so  that  the  hotter  in- 
terior comes  readily  to  the  surface. 

When  the  metal  appears  from  these  indications  to  have 
"  come  to  nature,"  i.e.,  to  be  almost  wholly  decarbuvized, 
the  third  period  begins. 

3d  Period. — The  lump  is  now  broken  into  several 
pieces,  which  are  lifted  above  the  tuyere,  much  of  the 
metal  indeed  reposing  on  top  of  the  charcoal.  A  bar  U 
is  introduced  through  the  opening  V,  behind  one  of  the 
tuyeres,  to  break  off  any  lumps  adhering  to  the  back  of 
the  hearth.  This  is  the  first  time  that  the  metal  has  been 
visible  since  charging,  having  meanwhile  been  covered 
with  charcoal.  From  this  point  till  the  ball  is  to  be  pried 
out  of  the  hearth,  only  one  man  is  at  work. 

This  period  is  essentially  a  remelting,  and  the  work  is 


FRANCHE-COMTE  AND  OTHER  PROCESSES.   §  351. 


295 


similar  to  that  in  the  first  period.  As  fast  as  the  lumps 
which  are  to  be  melted  sink  down  owing  to  the  burning 
away  of  the  charcoal  beneath,  they  must  be  pried  up  so  as 
to  keep  them  well  above  the  mass  which  is  collecting  at 
the  bottom  as  fusion  proceeds  (call  this  the  lower  mass), 
and  so  that  the  metal  in  melting  may  as  before  drop 
through  the  current  of  air  thrown  in  by  the  tuyeres.  The 
workman  is  very  careful  not  to  touch  the  lower  mass  with 
his  bar,  lest  he  force  slag  into  it,  and  so  defeat  the  chief 
object  of  this  period,  the  elimination  of  the  slag. 

During  the  first  part  of  this  second  fusion  the  lower 
mass  is  so  small  that  the  molten  slag  protects  it  from  the 
carburizing  action  of  the  charcoal ;  but  by  the  time  that 
say  two-thirds  of  the  metal  has  reached  it,  it  has  outgrown 
the  covering  capacity  of  the  slag,  and  more  slag  must  be 
added.  That  actually  added  is  hammer-slag  from  ham- 
mering the  charcoal-hearth  blooms.  It  is  thrown  on  the 
shoulders  of  the  lower  mass,  and,  thanks  to  its  high  state 
of  oxidation  (which  the  blast  maintains),  it  is  so  pasty 
that  it  does  not  all  run  down,  but  a  layer  of  it  remains 
and  covers  the  shoulders  of  the  lower  mass,  and  wards  off 
the  carburizing  action  of  the  charcoal. 

During  all  this  time,  be  it  remembered,  the  workman  is 
occasionally  prying  up  the  upper  mass,  to  keep  it  out  of 
contact  with  the  lower. 

The  upper  mass  being  nearly  all  melted,  the  scattered 
lumps  are  raked  together  and  welded  to  the  lower  mass 
witli  light  taps  of  the  hook  T.  The  blast  is  slackened, 
and  the  glowing  bloom  is  pried  out  from  the  hearth  by  both 
workmen,  who  bear  down  on  the  heavy  bar  W.  Nearly 
the  whole  of  the  slag  comes  out  with  the  ball,  in  a  layer 
whose  lower  side  is  nearly  smooth,  showing  the  shape  of 
the  bottom-plate,  but  whose  thickness  is  naturally  very 
irregular,  being  on  an  average  perhaps  three  inches.  The 
slag  does  not  adhere  so  strongly  but  that  it  could  be  pried 
off  in  large  lumps  ;  this  is  not  done,  however.  All  of  the 
slag  falls  off  when  the  bail  is  hammered.  In  hammering, 
all  imperfectly  refined  parts  are  cut  off,  and  returned  to 
the  hearth. 

The  hammered  ball  is  reheated  in  another  furnace  ;  we 
need  not  follow  it  further. 

Here  is  the  diary  of  an  operation  which  I  saw  in  March, 
1889: 

DIARY    OF    A   LANCASHIRE  HEARTH    REFINING. 

Preceding  ball  drawn lib.  57m. 

Hearth  cleaned  till —  lib.  58m. 

lit  Period.  Redhotpigs  drawn  from  the  Hue  from llh.  58m.  till  12h.  00m. 

Blast  turned  on  :  pigs  covered  with  charcoal ;  pigs  lifted  occasionally ;  charcoal 

added  and  water  thrown  on. 

td  Period.  All  melted  at 12h.  14m. 

Both   men    pry  lump    almost  constantly  ;    charcoal   added    frequently ;    water 

thrown  on  occasionally. 

Metal  has  come  to  nature 12h.  33m. 

3d  Period.   The  lump  is  broken  up  and  lifted  above  the  tuyeres,  protruding  far 

above  the  charcoal 12b..  37m. 

Begins  melting  again 13h.  44m. 

Bar  introduced  by  one  workman  horizontally,  to  keep  upper  mast*  up  ;  charcoal 

charged  occasionally  ;  water  added  ;  hammer-slag  charged. 

Small  pieces  raked  together 12h.  59m. 

Loose  pieces  balled  to  main  mass 111.  00m. 

Blast  stopped  Ih.  Olm. 

Ball  pried  up  and  drawn Ih.  Olm.  to  In.  02m. 

Begin  hammering Ih.  03m. 

End  hammering Ih.  05m. 

§  3~>1.  IN  THE  SOUTH  WALES  PROCESS  the  cast-iron  is 
first  melted  down  in  a  coke  refinery  or  run-out  fire,  and 
there  part  of  its  silicon  and  carbon  are  removed  by  the 
action  of  the  blast.  It  is  then  tapped  out  into  a  pair  of 
charcoal -hearths,  the  relatively  acid  slag  being  held  back, 


and  any  which  runs  into  the  charcoal-hearth  being  care- 
fully removed.  The  partly  solidified  metal  is  broken  up 
and  piled  near  the  tuyere.  After  melting  down  it  is  re- 
peatedly raised  slightly  from  the  bottom,  apparently  as 
in  the  Lancashire  process.  The  slag  is  tapped  off  from 
time  to  time.  As  soon  as  the  metal  has  "come  to 
nature,"  i.e.,  is  thoroughly  decarburized,  it  is  withdrawn 
and  hammered. 

This  process  thus  lacks  the  descorifying  final  melting 
of  the  Lancashire  process. 

I  have  met  no  late  description  of  the  South  Wales  pro- 
cess. Greenwood,  indeed,  states  that  the  charge  in  the 
coke  refinery  is  from  5  to  6  cwts.  of  cast-iron,  and  that 
a  charge  lasts  a  little  over  an  hour.q  These  agree  with 
Percy's  statements  made  in  1864  ;  whether  (hey  are  simple 
copies,  or  whether  the  process  has  remained  stationary,  I 
know  not. 

§352.  IN  THE  SWEDISH- WALLOON  PROCESS  one  or  two 
very  long  pigs  of  white  or  mottled  cast-iron  (a,  Figure 
149),  are  melted  down  drop  by  drop,  being  pushed  for- 
ward as  fast  as  their  ends  melt  off,  till  enough  to  yield  a 
bloom  of  from  say  84  to  93  pounds  has  been  melted. 
This  may  take  some  twenty  minutes,  during  which  the 
pasty  metal,  gradually  reaching  the  bottom  of  the  hearth, 
is  worked  constantly.  The  pasty  mass  is  now  broken  up, 
raised  above  the  tuyere,  and  melted  a  second  time,  appar- 
ently much  as  in  the  Lancashire  method.  During  this 
time  the  bloom  from  the  preceding  charge  is  heated  in 
this  same  hearth,  held  steeply  inclined  as  shown  in  Fig- 
ure 149. 

This  process  differs  chiefly  from  the  Lancashire  process 
in  that  the  bloom  is  reheated  in  the  hearth  in  which  it  is 
made,  in  that  the  charge  is  very  small,  and  that  the  cast- 
iron,  instead  of  being  introduced  all  at  once,  is  gradually 
pushed  forward.  From  this  last  it  happens  that  the  in- 
terval between  the  melting  of  the  first  and  that  of  the  last 
part  of  a  given  charge  bears  a  much  greater  proportion  to 
the  total  length  of  the  heat  in  the  Swedish-Walloon  than 
in  the  Lancashire  process.  Indeed,  from  printed  and  oral 
descriptions  of  the  former  process,  I  infer  that  the  pasty 
mass  is  broken  up  for  remelting  immediately  after  the 
last  of  the  cast-iron  has  melted.  Hence  the  first-melted 
part  of  the  metal  is  much  further  decarburized  when  the 
remelting  begins  than  the  last-melted  part;  and  I  am  in- 
formed that  the  heterogeneousness  thus  introduced  sur- 
vives the  remelting  to  a  very  considerable  extent,  i.  e.,  that 
the  product  is  decidedly  heterogeneous. 

§  353.  IN  THE  FRANCHE-COMTE  PROCESS  the  pigs  of 
gray  cast-iron  are  melted  down  as  in  the  Swedish-Walloon 
process,  Figure  149,  i.  e.,  are  gradually  pushed  forward 
as  their  ends  melt  off.  This  continues  for  about  90 
minutes  or  less,  during  which  the  bloom  from  the  pre- 
ceding charge,  having  been  cut  in  two,  is  reheated  in  the 
same  hearth  and  forged,  three  heatings  and  forgings 
being  needed  for  each  half  bloom.  The  pasty  mass  which 
has  meanwhile  accumulated  on  the  hearth  bottom,  is  now 
lifted  above  the  tuyeres  and  gradually  melted  down,  fall- 
ing drop  by  drop  past  the  tuyere.  This  occupies  some  20 
to  25  minutes  more.  Those  parts  of  the  mass  resulting 
from  this  second  fusion  which  are  still  imperfectly  de- 
carburized, must  be  raised  up  and  melted  down  a  third 
time. 


<j  Steel  and  Iron,  p.  33!>,  1884, 


290 


THE    METALLURGY    OP    STEEL. 


The  hearth  is  usually  covered,  and  the  sensible  heat  of 
the  products  of  combustion  is  utilized  somewhat  as  in  the 
Lancashire  hearth. 

The  distinctive  features  of  this  process,  then,  are  that 
the  bloom  from  the  preceding  heat  is  reheated  in  the  refin- 
ing hearth ;  that  gray  cast-iron  is  used  ;  that  the  pigs  are 
pushed  forward  in  melting  instead  of  being  charged  all  at 
once  ;  that  the  metal  or  part  of  it  is  melted  thrice;  that 
the  hearth  is  covered,  and  its  waste  heat  utilized. 

§  354.  MELTING  SCRAP-IRON  IN  THE  LANCASHIRE 
HEARTH  (Of.  Table  171,  Col.  XIV.).— Owing  to  the  rela- 
tive prices  of  scrap  malleable  iron  (steel  and  wrought  iron) 
and  of  pure  cast-iron,  most  of  the  American-Lancashire 
hearths  now  treat  the  former  material  exclusively. 

The  process  is  practically  the  third  period  of  the  cast- 
iron  refining  process  already  described.  The  ball  from  the 
previous  operation  being  drawn,  the  hearth  is  cleaned  and 
partly  filled  with  charcoal,  and  cold  malleable-iron  scrap 
is  thrown  on  it.  If,  as  often  happens,  much  light  scrap  is 
used,  such  as  sheet-iron  clippings,  broken  wire  from  wire- 
drawing establishments,  etc.,  this  is  charged  first,  and 
after  a  few  minutes  whatever  heavy  scrap  is  at  hand. 
The  charge  is  covered  with  charcoal  as  before  and  melted 
down,  the  chief  work  being  to  raise  the  upper  mass  (the 
still  unmelted  part)  occasionally,  so  that  the  blast  may 
enter  between  it  and  the  lower  mass  (i.  e.,  the  metal 
which  has  melted,  dropped,  and  accumulated  on  the  bot- 
tom), and  care  is  taken  not  to  touch  the  lower  mass  with 
the  tools,  lest  slag  become  mixed  with  it.  As  soon  as  all 
the  material  has  reached  the  lower  mass,  this  is  pried  out 
and  hammered,  quite  as  in  the  case  of  cast-iron. 

In  the  last  six  months  of  1888  the  loss  from  scrap  to 
cropped  billets  at  an  American  mill  was  22.75%,  of  which 
the  croppings  formed  0.66$,  and  9.20$  occurred  in  the 
two  reheatings  and  hammerings  which  followed  the  ham- 
mering of  the  ball,  so  that  the  loss  from  scrap  to  ham- 
mered bloom  was  12.89%-  As  most  of  the  scrap  was  thin, 
with  niuch  surface,  this  loss  is  certainly  small.  Column 
XIV.,  Table  171,  represents  practice  at  this  mill. 

As  the  scrap  is  nearly  free  from  silicon  and  silica,  the 
slags  are  more  basic  than  in  treating  cast-iron.  There 
is  thus  a  considerable  fining,  and  I  am  informed  that 


about  10  to  \5%  of  the  phosphorus  present  is  removed, 
that  the  sulphur,  even  if  initially  as  high  as  0.10$,  falls 
to  a  mere  trace,  and  that  the  carbon,  even  if  initially  as 
high  as  0.40$,  usually  falls  to  about  0.03$. 

The  operation  is  of  course  much  more  rapid  than  fining 
cast-iron,  and  fourteen  heats  are  made  per  shift  instead 
of  seven,  by  two  workmen. 

The  cast-iron  plates  which  line  the  hearth  last  much 
longer,  three  or  four  times  as  long,  as  when  cast-iron  is 
treated.  The  difference  is  probably  due  to  the  fact  tliat 
in  the  latter  case  the  product  of  the  first  fusion,  being 
much  more  fusible,  and  hence  remaining  fluid  lunger, 
penetrates  to  the  lining-plates  to  a  greater  extent.  Fur- 
ther, the  energetic  prying  and  scraping  along  the  bottom 
during  the  second  period  of  the  treatment  of  cast-iron 
probably  tend  to  wear  the  bottom  plate  out. 

As  the  plates  are  less  attacked,  and  as  the  addition  of  a 
little  silica  to  the  very  basic  slags  formed  in  treating 
scrap-iron  is  less  to  be  dreaded  than  in  treating  cast-iron, 
so  the  rear  lining-plate  is  usually  omitted,  the  brick-work 
of  the  rear  wall  being  exposed  to  the  heat. 

§  355.  STEEL. — It  is  much  harder  to  make  weld-steel 
than  wrought-iron  in  the  charcoal-hearth,  for,  instead  of 
carrying  decarburization  as  far  as  it  can  go,  we  have  to 
interrupt  it  at  a  given  point,  and  there  is  little  to  indicate 
when  this  point  is  reached.  Here,  as  in  making  puddled 
steel,  the  decarburization  must  proceed  slowly  in  order 
that  we  may  interrupt  it  with  more  certainty.  Further, 
in  limiting  the  final  action  which  removes  the  carbon,  we 
also  limit  the  removal  of  phosphorus  ;  hence,  and  because 
phosphorus  is  more  hurtful  to  weld-steel  than  to  wrought- 
iron,  especially  pure  cast-iron  should  be  used  for  making 
charcoal-hearth  steel. 

In  order  to  retard  the  decarburization  we  use,  when 
making  weld-steel,  an  abundance  of  a  liquid  and  less 
strongly  fining  slag  than  when  wrought-iron  is  aimed  at, 
less  strongly  fining  through  carrying  less  iron-oxide,  and 
instead  carrying  more  silica  or  more  manganese.  The  slag 
is  made  manganiferous  either  through  the  direct  addition 
of  oxide  or  silicate  of  manganese,  or  by  using  manganif- 
erous cast-iron.  Manganese  silicate  is  less  strongly  fining 
than  iron-silicate  for  reasons  already  given. 


CHAPTER  XVII. 
THE  CRUCIBLE  PROCESS. 


§  356.  THE  CRUCIBLE  STEEL  PROCESS  in  its  broadest 
sense  consists,  1st,  in  melting  iron  of  like  or  unlike  car- 
bon-content, and  with  or  without  carburizing  or  decarburiz- 
ing  additions,  in  crucibles ;  2d,  in  tranquilizing  the 
molten  mass  so  that  it  may  yield  compact  castings,  either 
by  holding  it  molten  so  that  it  may  absorb  silicon  from  the 
crucible  walls,  or  by  the  addition  of  ferro-aluminium  or 
other  quieting  substance;  3d,  in  casting  or  "teeming" 
into  ingots  or  other  forms. 

Of  this  process  the  most  important  varieties  are  : — 
1,  Huntsman's,  the  original  method,  in  which  small 
pieces  of  blister  or  other  highly  carburetted    steel  are 
melted  alone,  or  with,  a  slag-making  flux  (e.  g.,  glass). 


2,  Josiah  Marshall  Heath' 3*  modification  of  adding 
manganese,  either  previously  reduced  by  heating  its  oxide 
with  carbonaceous  matter,  or  reduced  in  the  process  itself 
by  the  action  of  charcoal  on  oxide  of  manganese. 

Huntsman's  method  thus  modified,  it  is  said,  is  now  the 
prevalent  one  in  Sheffield. 

3,  The  carburizinq -fusion  (or  cementing-f usion)  method, 
in  which  the  percentage  of  carbon  in  the  product  is  regu- 
lated by  the  addition  of  carbonaceous  matter  (practically 


a  For  an  account  of  Heath's  invention  and  litigation,  Cf.  Percy,  Iron  and  Steel, 
p.  840.  Percy  concludes,  apparently  quite  justly,  that  Heath's  invention  virtually 
covered  the  present  method  of  using  a  mixture  of  charcoal  and  oxide  of  manganese, 
though  the  courts  held  otherwise, 


CRUCIBLE    AND    OTHER    PROCESSES    COMPARED.      §  357. 


297 


charcoal),  is  said  to  have  been  used  in  the  last  century  by 
Chalut  and  Clouetb,  and  is  the  prevalent  method  in  this 
country. 

4,  Uchatius1 ,  or  the  pig  and  ore  method,  of  melting 
granulated  cast-iron  with  iron  ore,  till  lately,  if  not  now, 
practiced  at  Wykmanshyttan  in  Sweden. 

5,  The  pig  and  scrap  method  of  melting  wrought-iron 
or  steel,  or  both,  raising  the  proportion  of   carbon  by 
adding  cast-iron. 

In  all  the  above  methods  the  molten  metal  is  tranquilized 
by  killing,  i.  e.,  holding  it  molten,  so  as  to  yield  sound  in- 
gots. 

6,  The  Mitis  method,  in  which  the  charge  originally 
constituted  in  any  of  the  above  ways,  is  tranquilized  by  the 
addition  of  ferro-aluminium  immediately  after  fusion,  and 
is  teemed  a  few  minutes  later. 

7,  TJie  basic   method,  or  fusion   in  basic    instead  of 
silicious  crucibles,  while  it  has  not  been  worked  out  so  far 
as  I  know,  is  likely  to  be  tried  in  the  near  future. 

TABLE  173.— COMPOSITION  OF  SLAO  or  THE  CRUCIBLE  PROCESS. 


sm,  rac>5 

FeO.  FeaO3 

MnO 

A]aOs 

CaO. 

MgO 

S 

,  • 
Ca 

1  . 
8 

Alkalies 

1... 

2  
3  
4  
5  

L. 
M. 
M. 
B. 
B. 

ii.  in  ... 

41.24  .... 

40.86  

t.n  "  .w 

1 

s'.ao  '.'.'.'.'.'.'. 

4.00  
4.41  3.66 
34.10;  1.51 

34.04 
18.45 
30.58 
17.43 
6.40 

28.80 
35.85 

is!o5 

tr. 

0.87 

'i'.74 
25.79 

tr. 
W!  43 

.89 

.23 

"i'.ii" 

1.  Bochum,  Ledebur,  Ilandbnch,  p.  856.    Slag  present  during  teeming. 

2.  Slag  accompanying  steel,  No.  40  of  Table  179.    Lumps,  gray  ;  powder,  nearly  white. 
Insoluble  in  hydrochloric  acid.  Miiller,  Stahl  mid  Eisen,  VI.,  p.  6<J8,  1886. 

3.  Slag  of  steel  41,  Table  1T9;  color,  gray.    Idem,  p.  CM. 

4*  Slag  of  steel  7'A  in  Table  ISO  ;  dark,  uruwn  yray,  translucent ;  very  brittle  •  vitreous  •  Sp 
Gr.  3.1t.     Insoluble  in  nci.ls,     Hnimi,  K.  r<r  mid  Ilittten,  Xcit.,  XLIV.,  p.  105,  1885. 

'».  Sl:i£  from  No.  b8.  Table  180  (hash-).  Har  Uy  melted,  brown-jrray  with  violet  sheen,  porous, 
with  shots  of  iron  ;  powder  light  brown.  Sp.  Gr.,  4.11,  Idem,  p,  119. 

§  857.  THE  CRUCIBLE  AND  OTHER  PROCESSES  COM- 
PARED.— The  crucible  process  is  on  the  one  hand  very  much 
more  costly  than  the  Bessemer  and  open-hearth  processes, 
both  as  to  material  and  cost  of  conversion,  as  to  labor, 
fuel  and  refractory  materials.  On  the  other  hand,  its 
product  is  apparently  justly  thought  much  better  than 
that  of  these  other  processes,  even  for  like  composition. 
Its  costliness  limits  it  to  the  production  of  steel  of  high 
quality,  designed  for  cutting-tools,  springs,  fire-arms, 
etc.  It  affords  less  control  over  the  percentage  of  carbon 
in  the  product  than  either  the  Bessemer  or  the  open-hearth 
process.  Hence,  when  making  large  castings  by  pour- 
ing together  the  contents  of  several  crucibles,  to  insure 
homogeneousness  we  should  observe  certain  precautions, 
which  are  needed  to  a  much  smaller  degree,  if  at  all,  in 
the  Bessemer  and  open-hearth  processes.  When  a  very 
great  number  of  crucible-fuls  are  poured  together,  the 
differences  in  composition  probably  nearly  offset  each 
other  :  this  should  be  the  case  with  Krupp's  guns,  which 
are  said  to  be  made  wholly  of  crucible  steel ;  but  when  a 
smaller  number  of  crncible-fuls  are  poured  into  a  single 
casting,  it  would  seem  desirable  to  mix  them  thoroughly, 
e.  g.,by  pouring  into  a  common  mixing  ladle,  from  which 
the  casting  is  teemed. 

It  is  not  easy  to  see  why  crucible  should  be  better  than 
Bessemer  and  open-hearth  steel  of  like  composition.  The 
crucible  differs  from  the  open-hearth  process, 

1,  In  treating  smaller  charges  ; 


*Cruner  (Smith),  the  Manufacture  of  Steel,  p.  127. 


2,  In  usually  treating  material  which  is  not  only  purer 
but  less  liable  to  occasional  serious  impurity  ; 

3,  In  nearly  completely  excluding  the  fire-gases  ; 

4,  In  exposing  the  charge  to  a  clay  instead  of  a  silica 
lining  ; 

5,  In  being  under  less  perfect  control  as  to  temperature, 
additions,  time,  etc.     This  sounds  heretical,  but  I  am  con- 
vinced that,  it  is  true.     In  the  open-hearth  furnace   the 
charge  is  ever  open  to  easy  inspection,  so  that  we  readily 
determine  what  additions  and  what  changes  in  temperature 
are  needed  at  agiven  instant.     The  closed  crucible  cannot, 
as  the  process  is  usually  carried  out,  be  thus  examined 
readily  at  short  intervals,  and  practically  we  are  confined 
to  a  single  examination ;  though  if  is  not  absolutely  neces- 
sary that  we  should  be  so  restricted.    Tlie  Bessemer  pro- 
cess is  under  as  good  control  as  the  open-hearth. 

Of  these  differences  we  summarily  reject  the  first, 
fourth  and  fifth,  as  wholly  improbable  causes  of  superi- 
ority. 

The  second  does  not  bear  on  the  question  of  the  rela- 
tive merits  of  crucible  and  other  steel  of  given  compo- 
sition. 

The  exclusion  of  the  fire-gases,  in  that  it  prevents  the 
absorption  of  sulphur  from  them,  is  in  the  same  way  be- 
side the  present  point.  But  it  may  well  be,  as  Metcalf  con- 
jectures (§  174,  p.  109),  that  the  greater  opportunity  which 
the  open-hearth  and  especially  the  Bessemer  process  offers 
for  the  absorption  of  nitrogen  (and  hydrogen  he  might 
add)  injures  their  product.  Whatever  be  the  reason, 
there  seems  to  be  little  doubt  that  crucible  steel  is  better 
than  Bessemer  and  open-hearth  steel  of  like  composition 
as  actually  made.  However,  as  its  superiority  is  unex- 
plained, we  cannot  now  tell  whether  it  is  due  to  conditions 
unattainable  in  the  competing  processes,  or  to  conditions 
which,  though  as  yet  overlooked,  are  still  attainable.  If 
to  the  latter,  we  may  expect  that,  once  the  needed  condi- 
tions are  known,  the  improvement  of  our  dephosphor- 
izing processes,  basic  open-hearth  and  Bessemer,  Bell- 
Krupp  washing,  etc.,  will  gradually  bring  the  quality  of 
the  product  of  these  cheaper  processes  up  to  that  of 
crucible  steel,  and  thus  remove  the  reason  for  the  existence 
of  the  crucible  process. 

The  belief  in  the  superiority  of  crucible  steel  of  like 
composition  rests  rather  on  general  observation  than  on 
conclusive  direct  evidence,  and  it  must  be  confessed  that 
the  quality  of  much  of  this  evidence  is  not  of  the  best : 
this,  however,  from  the  nature  of  the  case  is  almost  un- 
avoidable ;  but  the  quantity  of  evidence  goes  far  to  make 
up  for  its  quality.  Some  of  the  evidence,  however,  can- 
not be  simply  ignored.  Thus,  eminent  steel-makers 
assure  us  that  Bessemer  and  open-hearth  steel  remelted 
in  crucibles  is  little,  if  at  all,  better  than  before.  A  very 
distinguished  maker  of  both  crucible  and  Bessemer  steel 
assures  me  that  he  finds  much  of  the  Bessemer  and  open- 
hearth  tool -steel,  of  which  great  quantities  are  actually 
sold,  almost  as  pure  as  the  best  crucible  steel,  yet  hardly 
as  good  as  the  much  less  pure  common  grades  of  spring 
crucible  steel.  I  am  informed  that  the  only  American 
open-hearth  tool-steel  plant  has  lately  been  sold  to  a 
maker  of  springs. 

Bessemer' s  assertion'  that  half  the  crucible  steel  in 


•Mourn.  Iron  and  Steel  Inst.,  1884, 1,,  p.  397 ;  Cf.  Stajil und  Eieen,  V.,  1885,  p.  HI, 


298 


THE    METALLURGY    OF    STEEL. 


Sheffield  is  simply  Bessemer  or  open-hearth  steel  remelted 
in  crucibles,  helps  not,  for  we  do  not  know  that  this  half 
contains  any  of  the  most  excellent  steel :  if  it  does,  this 
excellence  may  still  be  due  to  the  remelting  in  crucibles. 

If  the  foregoing  be  true  we  may  conclude  that,  if  we 
are  to  bring  the  quality  of  Bessemer  and  open-hearth  up 
to  that  of  crucible  steel,  while  equal  purity  of  product  is 
surely  necessary,  the  first  step  is  to  discover  the  cause  of 
the  inferiority  of  the  former  classes  for  given  composition, 
the  next  to  provide  a  remedy. 

But,  granting  that  there  is  little  doubt  of  the  superi- 
ority of  crucible  steel  of  given  composition,  we  see  causes 
which  have  probably  given  us  an  exaggerated  idea  of  it. 
First,  in  the  Bessemer  and  open-hearth  processes  we 
actually  use,  in  large  part,  the  crude  product  of  the  blast 
furnace,  which  is  not  only  usually  less  pure  but  less  uni- 
form in  purity,  more  subject  to  the  occasional  presence  of 
serious  quantities  of  impurities  (phosphorus,  sulphur) 
than  the  material  used  for  the  crucible  process,  cast-iron 
purified  by  puddling,  etc.,  the  pure  iron  of  the  bloomary 
fire,  etc.  Again,  relatively  little  effort  has  been  made  to 
produce  in  the  Bessemer  and  open-hearth  processes  the 
tool-steels  to  which  the  crucible  process  chiefly  owes  its 
high  standing.  From  the  fact  that  in  the  Bessemer  and 
open-hearth  processes  we  habitually  and  intentionally 
aim  at  a  product  much  poorer  (because  cheaper  and,  all 
things  including  cost  considered,  better  suited  to  its 
habitual  uses)  than  the  habitual  product  of  the  crucible 
process — from  this  fact  we  easily  and  loosely  infer  that 
the  habitual  great  inferiority  is  necessary.  In  the  Besse- 
mer and  open-hearth  process  we  wisely  habitually  avoid, 
in  the  crucible  process  we  habitually  adopt,  those  expen- 
sive precautions  which  give  great  excellence.  It  is  not 
wise,  it  is  casting  pearls  before  swine,  to  demand  for  a 
given  purpose  material  better  than  the  conditions  of  the 
case,  cost  included,  warrant :  to  insist  that  rails  shall  have 
no  more  than  0.02$  of  phosphorus,  taking  an  extreme 
case.  While  it  is  better  to  err  on  the  side  of  superiority 
if  at  all,  while  such  errors  spring  from  the  better  side  of 
our  nature,  to  err  is  still  to  err. 

§  358.  CRUCIBLES  are  of  two  chief  kinds,  graphite  and 
clay.  The  graphite  crucibles  last  much  longer,  endure 
much  rougher  usage,  at  least  as  to  changes  of  temperature, 
and  hold  a  heavier  charge  than  the  clay  ones,  and  are 
thus  much  more  convenient  and  more  economical  of  labor  : 
they  cost  rather  less  per  pound  of  ingots,  but  give  up 
carbon  and  silicon  to  the  metal  to  a  much  greater  extent, 
and  probably  more  irregularly  than  clay  ones.  Finally, 
the  loss  of  iron  is  less  in  graphite  than  in  clay  crucibles. 

In  making  steel  of  the  best  quality  care  is  taken  that 
the  cover  of  the  crucible  fits  tightly  ;  this  is  thought  less 
important  in  making  steel  of  common  grades.  The  cover 
of  a  European  crucible,  according  to  Ledebur,  has  a  round 
hole  through  which  a  rod  is  introduced  for  examining  the 
charge.  The  hole  is  closed  with  a  clay  plug  during  melt- 
ing". In  the  Mitis  process  the  crucible  cover  has  such  a 
round  hole,  never  closed,  through  which  the  ferro-alumin- 
ium  is  introduced ;  but  with  this  exception,  American 
crucible  covers,  so  far  as  my  observation  goes,  are  always 
holeless. 

Graphite  crucibles,  almost  always  used  in  this  country, 


Handbuch  der  Eisenhuttenkujjde,  p.  843. 


usually  hold  a  charge  of  from  60  to  90  pounds.  Heavier 
charges  are  occasionally  used  ;  in  one  establishment  the 
charge  was  at  one  time  200  pounds.  The  objection  to  large 
crucibles  is  that,  in  order  that  they  may  be  strong  enough 
to  hold  the  heavy  charge  and  to  endure  the  pressure  of 
the  tongs  in  drawing  from  the  furnace  while  intensely  hot, 
their  walls  must  be  made  thick  ;  this,  beside  increasing 
the  difficulty  of  making  aul  drying  them,  lengthens  the 
time  of  melting,  the  thicker  walls  conducting  heat  more 
slowly  to  the  charge.  The  \  ery  heavy  charges  possible 
in  a  cool  operation  like  brass  founding,  running  up  to  500 
and  occasionally  even  to  700  pounds,  are  hardly  to  be 
hoped  for  ;  yet  the  attempts  to  increase  the  weight  of  the 
charge  have  met  with  a  certain  measure  of  success.  The 
200  pound  charges  above  referred  to  were  melted  at  the  rate 
of  three  per  shift  like  the  80  pound  ones;  they  have,  how- 
ever, been  abandoned,  not  because  of  technical  failure,  but 
because  opposed  vigorously  by  the  labor  union.  As  they 
should  effect  a  very  considerable  economy,  we  may  expect 
further  efforts  to  employ  them.  At  the  Mitis  works,  al- 
ready referred  to,  charges  running  up  to  130  pounds  are  used. 

Tlie  average  life  of  graphite  crucibles,  in  this  country,  is 
from  four  to  six  heats  whether  in  gas,  anthracite  or  petro- 
leum furnaces.  It  is  shorter,  naturally,  when  making  soft 
than  making  hard  steel.  Thus, in  making  softMitis  castings 
in  the  Noble  petroleum-furnace,  crucibles  last  but  three 
heats. 

From  the  fact  that  crucibles  last  no  longer  when  making 
hard  steel  in  the  Noble  furnace  than  in  others,  although 
this  furnace  is  used  only  for  the  Mitis  process,  in  which 
the  heat  is  much  shorter  than  the  common  heat  of  other 
furnaces,  killing  being  omitted,  one  might  infer  that  the 
Noble  furnace  was  exceptionally  trying  to  the  crucibles. 

European  graphite  crucibles  usually  last  only  from  one 
to  three  heats.  But  the  crucibles  made  by  Muller  of  Paris, 
have  in  some  works  an  average  life  of  from  seven  to  nine 
heats  in  case  of  hard,  and  from  five  to  six  in  case  of  soft 
steel.  They  contain  about  50%  carbon. 

Use. — Graphite  crucibles  are  usually  charged  quite  cold 
in  the  white-hot  melting  furnace  and  are  cooled  off  after 
each  heat  without  care,  being  thrown  out  on  the  cold  ground 
while  white-hot,  even  in  the  dead  of  winter.  At  Mitis  works, 
however,  they  are  hastily  refilled  while  still  hot,  and  im- 
mediately returned  to  the  furnace.  They  are  examined, 
usually  after  each  heat,  to  learn  whether  they  can  be  used 
again  safely. 

In  many  works  the  charge  is  lessened  slightly  from  heat 
to  heat,  so  as  to  lower  the  slag-level,  since  the  crucible 
corrodes  more  deeply  here  than  beneath,  where  it  is  simply 
in  contact  with  molten  metal.  The  successive  charges 
may  be  say  85,  80,  78,  75,  72  pounds,  etc.,  in  case  of  gra- 
phite crucibles.  The  reduction  is  heavier  for  clay  cru- 
cibles, successive  charges  weighing  say  50,  44  and  38 
pounds.  But,  in  many  other  establishments  using  graphite 
crucibles,  the  crucible  is  packed  full  at  each  heat,  without 
attempt  to  regulate  the  slag-level. 

At  the  Wayne  works  the  crucibles  are  clay-washed  within 
after  each  heat,  as  soon  as  they  begin  to  show  serious  wear; 
this  is  said  to  increase  their  life  to  from  5  to  8  heats". 

Manufacture.  — G rap  1 1 i t e   crucibles    are   made"  from  a 


a  Jour.  Iron  and  St.  Inst,  18S7,  I.  P.,  418,  from  Iron  Age,  XXXVIII,  No.  18. 

b  My  description  of  graphite-crucible  making  is  based  chiefly  on  information! 
given  by  Mr.  W.  F.  Downs,  of  the  Dixon  Crucible  Company,  private  communica- 
tion, Jan.  la,  1889,  and  on  an  article  by  Dr.  J.  C.  Booth.  Jouru.  Am.  Chem.  Soc., 
VI.,  p.  283,  1884,  and  VII.,  p.  4,  1885,  ' 


MANUFACTURE    OF    CRUCIBLES.      §  358. 


299 


mixture  of  gniphifc,  liiv  rhiy  and  sand,  say  in  the  follow- 
ing proportions  by  weight. 

TABLE  174.— PROPORTIONS  BY  WEIIIBT  USED  IN  MAKINO  GRAPHITE  CRUCIBLES. 


Graphite. 

Air-dried  Clay. 

Band. 

Li>ss  on  Burning. 

Authority. 

60 

45 

5 

5* 

Booth. 

50 

i;i 

7 

W,t 

50 

41 

9 

10* 

» 

50 

33 

1? 

Downs. 

The  burnt  crucible  pretty  constantly  contains  about  50 
to  55$  carbon.  The  proportion  of  clay  to  sand,  however, 
differs  according  to  the  experience  of  the  maker  and  the 
details  of  the  method  of  manufacture  (Cf.  Table  180,  §368). 

Ceylon  graphite  is  generally  used,  though  some  Amer- 
ican graphite  has  given  good  results.  The  Ceylon  graphite 
is  nearly  pure,  containing  (Booth)  about  6%,  but  sometimes 
not  more  than  1$,  of  pyrite  and  quartz.  The  elastic-scaly 
or  laminated  variety,  or  the  elastic-fibrous,  only  should  be 
used,  not  the  amorphous  ;  the  first  two  bind  the  matrix 
of  clay  firmly. 

The  graphite  is  crushed  in  "  bark  mills,"  then  pulverized 
between  common  mill-stones,  to  from  40  to  100  "  mesh, " 
the  coarser  part  being  bolted  out  in  a  common  flour-bolter  ; 
Booth  recommends  that  none  slunild  be  coarser  than  -fa" 
to  Ty  diameter.  If  the  graphite  be  too  coarse  the  crucible 
is  apt  to  become  porous,  and  to  be  weakened  by  cleavage 
planes  ;  if  too  fine,  the  crucible  is  too  dense  and  is  apt  to 
crack  under  the  extreme  changes  of  temperature  to  which 
it  is  exposed,  and  conducts  heat  slowly. 

The  clay  is  usually  of  the  best  German  "Klingenburg" 
or  "Crown  "  brand.  It  is  at  once  very  fat,  refractory  and 
wholly  free  from  grit. 

The  sand  should  be  rather  coarse,  passing  a  screen  of 
about  40  meshes  to  the  lineal  inch,  and  not  liable  to  fly  on 
heating.  Burnt  infusible  fire-clay  has  been  found  as  good, 
but  not  better:  its  action  is  mechanical,  making  the  air- 
drying  uniform,  and  acting  as  a  skeleton  to  resist  the  pres- 
sure of  the  tongs. 

Mixing. — The  clay  is  made  into  a  thin  paste  with  water, 
the  sifted  sand  and  graphite  are  stirred  in  with  a  shovel, 
and  the  mass  is  then  mixed  thoroughly  by  repeated  passage 
through  a  pug-mill ;  it  is  then  tempered  by  a  few  days',  or 
better  weeks',  repose  in  a  damp  place,  covered  with  cloths 
which  are  moistened  occasionally.  During  this  repose  any 
little  bubbles  of  air  are  gradually  squeezed  out  by  the  sink- 
ing together  of  the  soft  mass. 

Moulding. — A  weighed  lump  of  the  tempered  mass  is 
slapped  and  kneaded,  thrown  into  the  bottom  of  a  thick, 
strongly  banded,  plaster-of-paris  \or  more  rarely  wooden) 
mould,  whose  interior  has  the  shape  of  the  exterior  of 
the  crucible,  and  centered  on  a  potters  wheel.  While 
this  revolves,  a  cast-iron  or  steel  profile  of  the  interior  of 
the  crucible  is  lowered  into  the  mass.  As  in  moulding 
pottery,  so  here  the  clayey  mass  is  pressed  against  the 
sides  of  the  mould  and  raised  gradually  to  its  top,  jointly 
by  the  revolution  and  by  the  moulder's  hand.  The  very 
slight  excess  which  protrudes  above  the  top  of  the  mould 
is  pared  off,  and  the  inside  of  the  lip,  if  any,  is  cut  out. 

This  method  of  moulding  on  a  potter's  wheel  is  said  to 
give  much  better  results  than  simple  pressing  into  shape, 
not  only  through  its  kneading  action,  but  especially  be- 
cause it  arranges  the  graphite  flakes  tangentially,  so  that 
they  bind  the  mass  very  effectively. 


Drying. — The  crucible  is  left  in  the  plaster  mould 
about  three  hours,  the  plaster  absorbing  its  moisture,  and 
thus  partly  drying  and  stiffening  it  so  that  it  can  be 
handled.  The  mould  loses  during  the  night  part  of  the 
moisture  thus  taken  up,  but  by  the  end  of  a  week  or  so 
it  has  become  so  wet  that  it  must  be  specially  dried  to 
regain  its  bibulousness. 

Burning. — The  crucible  thus  partly  dried  is  removed 
from  the  mould,  and  air-dried  on  racks  in  a  warm  room, 
say  at  70°  to  80°  F.,  for  about  a  week.  Each  crucible  is 
then  inclosed  in  two  seggars,*  one  inverted  over  the  other, 
the  joint  being  sometimes  luted  for  better  exclusion  of 
air. 

The  seggars,  with  their  contents,  are  closely  packed  in 
a  common  pottery-kiln,  which  has  many  fire-places  to 
insure  uniform  heating.  In  this  country  it  is  fired  with 
anthracite,  and  towards  the  end  of  the  firing  with  long- 
flaming  pine  wood,  to  fully  heat  the  extreme  upper  parts 
of  the  kiln.  To  limit  the  oxidation  of  the  graphite,  as 
little  excess  of  air  as  practicable  should  be  admitted. 
Booth  would  further  enclose  a  little  coal  or  coke  within 
the  seggars  themselves,  to  take  up  any  oxygen  which  en- 
tered them. 

Burning  takes  a  week,  of  which  one  day  is  occupied  in 
charging,  three  days  in  firing,  and  two  and  a  half  days  in 
cooling  down.  Some  kilns  lately  built  burn  much  more 
rapidly,  but  perhaps  not  so  well.  The  temperature  reaches 
a  strong  but  not  dazzling  white  heat,  say  1,350°  C.  (2,463° 
F.),  but  is  much  lower  in  the  cooler  part  of  the  kiln. 

Indications. — In  burning,  the  graphite  of  the  very  skin 
is  removed,  leaving  the  crucible  drab.  But  the  graphite 
should  not  be  burnt  out  to  a  considerable  depth,  as  the 
strength  of  the  crucible  at  low  temperatures  depends  on 
it.  Hence  in  well  burnt  crucibles  the  black  interior  re- 
gion, in  which  the  graphite  still  remains,  should  lie  so 
near  the  surface  that  it  can  be  exposed  by  rubbing  with 
the  fingers.  A  thick  drab  coating  means  a  heavy  burning 
out  of  graphite  and  a  worthless  crucible.  A  black  skin 
may  be  due  to  remarkably  perfect  exclusion  of  air.  More 
commonly  it  means  that  the  crucible  is  soft  because  not 
burnt  enough. 

The  cost  of  graphite  crucibles  in  this  country  is  given 
approxima  tely  in  the  following  table : 

TABLE  1"5. — SIZE  AND  COST  OF  AMERICAN  GRAPHITE  CRUCIBLES. 


Height 
Outside. 
Inches. 

Diameter  Outside. 

Weight. 

Capacity. 

Price  per 
Crucible. 
Nominal. 

Actual  for 
large  lots. 

Top. 

Bilge. 

Bottom 

13 

w* 

WX" 

TH" 

249>s. 

M>   11,-. 

$1  20 

(1  00 

IOM" 

11  /if" 

glx" 

3S   ii 

100    ll 

1  50 

1  30 

16 

u»» 

1% 

9" 

45   ll 

130   ll 

1  80 

These  dimensions  are  given  by  the  Joseph  Dixon  Crucible  Company.    They  seem  to  me  to 
be  more  stumpy  than  ihuse  of  most  crucibles. 

The  designation  numbers  used  by  different  makers  for 
a  given  size  of  crucible  are  far  from  constant. 

Very  poor  graphite  crucibles  (number  4,  Table  176), 
lasting  only  one  heat,  cost  23  cts.  in  Styria  about  the 
year  1878.  In  France  graphite  crucibles  now  cost  about 
four  cents  per  pound  of  steel  which  their  normal  charge 
contains. 

Figure  150  shows  an  American  100- pound  steel-crucible 
for  anthracite  shaft-furnaces.  For  gas-furnaces  the 


a  Conical  or  cylindrical  fire-clay  vessels,  which  protect  the  crucible  from  the  air, 
prevent  sudden  changes  of  temperature,  and  prevent  the  soft  crucibles  from  crush- 
ing each  other  by  their  own  weight. 


aoo 


THE    METALLURGY    OF     STEEL 


crucible-walls  are  thicker  towards  the  top,  where  the 
flame  is  sharpest,  and  thinner  near  the  bottom  than  in 
this  figure. 


Flg.  ISO.    CRUCIBLES. 

Clay  crucibles,  though  decidedly  tough  while  hot  (in- 
deed, they  are  thought  tougher  than  graphite  crucibles 
at  a  steel-melting  heat),  grow  very  brittle  when  cooled. 
They  are  therefore  used  continuously  without  cooling, 
being  returned  to  the  white-hot  furnace  immediately 
after  teeming  and  inspection.  Further,  on  account  of 
their  tendency  to  crack  under  abrupt  changes  of  tem- 
perature below  bright  redness,  they  are  heated  very 
gradually  for  their  first  heat.  They  last  three  heats  or 
less,  while  American  graphite  crucibles  last  five  or  six 
heats. 

The  clay  crucibles  always,  I  believe,  contain  a  little 
coke,  say  5$,  which  hastens  drying,  probably  strength- 
ens the  crucible  when  hot,  and  hastens  killing  by  pro- 
moting the  absorption  of  silicon  by  the  steel. 

For  the  preparation  of  clay  crucibles  let  two  examples 
suffice. 

Swedish  Practice. — A  20-crucible  batch  of  540  pounds 
of  finely-ground,  sifted,  dried  clay,  and  13  pounds  of 
coke,  is  mixed,  moistened  and  worked,  rests  for  about 
twelve  hours,  is  trodden  and  worked  again  with  extreme 
care,  and  divided  into  20  weighed  lumps.  Each  is  worked 
thoroughly  to  expel  air-bubbles  and  to  make  it  homo- 
geneous, solid  and  tough.  After  pressing  to  shape,  the 
moist  crucible  is  dried  first  at  20°  to  30°  (C.)  then  at  50°  to 
70°,  for  three  or  even  four  months,  and  is  then  gradually 
heated  for  18  hours  to  incipient  redness.  A  handful  of 
chamotte  (powder  of  old  crucibles)  is  thrown  in,  and  the 
crucible  is  placed  in  the  barely  red-hot  melting  furnace, 
whose  temperature  is  gradually  raised  till  the  chamotte 
partly  sinters,  when  the  crucible  is  filled  with  metal." 

British  Practice. — The  almost  impalpably  pulverized 
and  carefully  weighed  meterials  are  wetted  and  thor- 
oughly mixed,  usually  in  a  mill,  sometimes  still,  and  it 
is  thought  with  better  results,  by  treading  systematically 
under  men' s  bare  feet  for  several  hours,  with  periodical 
cutting  and  turning  by  spade.  The  mass  is  then  cut  into 
balls  each  sufficing  to  make  one  crucible.  The  ball  is 
further  hand-worked,  thrown  into  the  smooth  well-oiled 
mould  b,  Figure  151,  and  squeezed  macaroni-like  into 
shape  by  forcing  down  the  oiled  plug  a,  centered  by  the 
pin  e,  the  clay  rising  into  and  filling  the  annular  space 
between  mould  and  plug.  In  hand-manufacture  a  is  al- 
ternately raised  and  pressed  down,  the  last  time  being 
driven  down  by  a  mallet,  and  is  then  withdrawn  twist- 
ingly.  In  machine-manufacture  it  is  driven  down  and 
withdrawn  by  mechanism,  the  centering  pin  e,  now  un- 


necessary, being  dispensed  with.       Its  upper  edge  now 
being    trimmed,  the  nucible  and  mould  are  placed  on  a 

post  Tc ;  the  mould 
is  dropped;  the 
crucible  is  thus 
bared,  and  its  top 
is  forced  inward  to 
the  barrel-shape  m 
shown,  by  pressing 
on  it  a  conical-frus- 
tum shaped  mould. 
The  crucible  is  lifted 

,  l|ii:         \  with     well     fitting 

I"     I  sheet-iron   plates   to 

*        -'  a    shelf  in   the  pot- 

house  ;  dried  here  for 
one  or  two  days ; 
further  dried  in  the 
melting-house  on  a 
shelf  next  to  the 
flues  for  at  least 
ten,  but  preferably 
for  30  to  40  days ; 
heated  to  incipient  redness  with  others  during  some  four 
teen  hours,  mouth  downward,  on  a  bed  of  burning  coke, 
and  surrounded  with  fine  coke,  in  a  tightly  luted  anneal- 


Fig.  151.    BRITISH  CLAY  CHUCIBLKS  AND  TUKIK 
MANUFACTURE.    GREENWOOD. 


Fig.  US.    SHEFFIELD  COKK  CRUCIBLE  FURNACE.    GREENWOOD. 

ing  furnace  Z,  Figure  152,  which  permits  but  very  slow 
combustion.  It  is  now  placed  on  its  stand  (d,  Figure  151), 
in  the  melting  hole  which  has  previously  received  a  little 
live  coal,  and  which  is  now  filled  with  coke  to  the  tops  of 
the  crucibles.  These,  on  reaching  redness  in  some  thirty 
minutes,  are  filled  with  metal,"  if  hand-made  first  re- 
ceiving a  handful  of  sand,  which  frits,  closes  the  hole  left 
by  the  centering-pin,  arid  cements  crucible  to  stand. 

Clay  crucibles  cost  in  Sheffield  about  $0.15  (8d.),  in 
1864,b  and  about  23  to  29  cts.  at  present  (I  sh.  to  1  sh. 
3d).  Their  present  cost  is  thus  about  20  cents  in  Sheffield 


a  Practice  at  Osterby,  Sweden.     Hermelin,  Stahl  und  Eisen,  VIII.,  p.  340, 1888, 
from  Jernkont,  Aim.  XLIII.,  pp.  338-343. 


a  Greenwood,  Steel  and  Iron,  pp.  36,  430. 
b  Percy,  Iron  and  Steel,  p.  835.    ' 


CRUCIBLE    FURNACES. 


359. 


801 


per  100  pounds  of  ingots,  or  about  the  same  as  that  of 
graphite  crucibles  in  this  country.  But  as  clay  crucibles 
would  doubtless  cost  more  here  than  in  Sheffield,  they 
would  be  more  expensive  per  pound  of  ingots  than  graph- 
ite crucibles. 

As  they  are  corroded  more  by  the  slag  than  graphite 
crucibles  are,  it  is  important  to  change  the  slag-level  by 
lessening  the  weight  of  successive  charges. 

TABLE  176. — COMPOSITION  OFSTEEL-MKLTING  CHUCIBLES.    (Sec  also  Tables  179,  180.) 


A.— GRAPHITE  CRUCIBLES. 


Proximate. 

Ultimate. 

Graphite. 

Coke. 

* 

Raw 

Clay. 
% 

Cha- 
motte 
etc. 
% 

C 

% 

SiO,. 
% 

A1.0, 

FeOx 

% 

Alka- 
lies. 
% 

Other 
bases. 
% 

1.  Usual       composi 
tion,  Ledebur.. 
2.  Weddinc 

)20  @ 
/      75 
44 
30a 

83 
51 

33  @ 
6G 
121) 
30a 

1 

15@60 

44 

40a 

,  ' 
7 

3.         "        

5.  American,  the  au- 
thor... 

B.— 

12 
21  a 
4 

7@9 

CLAY 

80b 
31a 

88 

DRUCII 

8 
48a 
8 

LES. 

14.  Wedding            .  ..Charcoal. 

15   Wedding... 

16   Sheffield,  Percy. 

than  Sheffield  ones.  On  the  other  hand  the  great  depth 
of  the  Sheffield  ash-pit,  which  permits  easy  removal  of 
clinkers  during  a  heat  and  gives  access  to  the  crucibles 
from  beneath  for  stopping  leaks,  is  unnecessary  in  Amer- 
ican furnaces,  the  clinkers  forming  more  slowly  with  the 
slower  burning  anthracite,  and  the  greater  depth  of  fuel 
beneath  the  crucible  preventing  access  from  below.  Indeed 
I  do  not  know  that  it  would  be  possible  to  stop  a  leak  in 
a  graphite  crucible  even  if  it  were  accessible. 


AMERICAN   FOUR-POT  ANTHRACITE^ 
CRUCIBLE  FURNACE. 

I 


1.  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  844. 

2.  Wedding,  Darstellung  des  Schmiedbaren  Eisens,  p.  611. 

3.  Dohlen  Cast-steel  Works,  idem.  p.  617. 

4.  Eibiswald  (xvii..  Table  172);  last  1  to  2  heats;  cost  23  cents  (0  48  florins);  hand-made; 
dried  at  77  to  104°  F.,  85  to  SO  days.    Met.  Rev.,  I.,  p.  584,  1878. 

5.  A  piece  cut  from  an  American  HO  Ib.  steel-melting  crucible,  after  long  drying  at  a  tem- 
peramre  well  above  100°  C.,  lost  51.17S6  by  weight,  on  ignition  in  a  platinum  crucible  over  a 
blast  lamp,  Jan.,  1889. 

13.  The  mixture  nse<l  l>y!Musliet  Greenwood,  Steel  and  Iron,  p.  20.    It  is  not  stated  ex- 
plicitly that  the  proportion*  are  by  weight. 

14.  Used  at  Snllinger  Htttte,  Wedding,  Darstelhing  des  Schmiedbaren  Eisens,  p.  616. 

15.  Wedding,  Idem.  p.  511.  The  proportion  of  raw  clay,  "  Rohem  Thon,"  seems  excessive. 

16.  Percy.  Iron  nnd  Steel,  p.  834. 
a  Proportions  by  volume. 

b  It  is  not  stated  explicitly  that  all  this  clay  was  raw. 

§  3f)9.  FURNACES. — In  nearly  all  cases  either  direct- 
firing  shaft-furnaces  or  Siemens  regenerative  gas-furnaces 
are  used.  Gas  furnaces  of  other  types  and  direct-firing 
reverberafory  furnaces  have  been  used  to  a  certain  ex- 
tent, and  Nobel's  petroleum  furnace  is  now  used  with 
success  for  the  Mitis  process." 

The  Sheffield  %-pot  coke  shaft-furnaces  or  melting-holes, 
Figure  152,  consist  of  oval  chambers  three  feet  high  from 
the  bars,  by  26"xl9",  and  three  feet  from  center  to  center, 
arranged  in  rows  along  one  or  both  sides  of  the  melting- 
house,  and  lined  with  about  six  inches  of  fire-brick  or  of; 
ganister,  the  latter  rammed  around  a  wooden  core.  In 
older  works  each  hole  has  its  own  chimney -flue  F,  the 
flues  of  five  or  six  holes  being  built  into  a  single  flat, 
block-chimney :  but  in  many  modern  works  the  little  flues 
E  from  each  hole  unite  in  a  common  flue  and  square 
chimney.  The  draft  is  regulated  by  bricks  inserted  in 
the  flues  E  and  M.  Full  access  is  given  to  the  grate  B  by 
the  deep  cellar  D,  so  that  leakage  from  the  crucibles  can 
be  detected,  and,  it  is  said,  even  stopped. 

Tlie  American  4-pot  anthracite  shaft-furnaces  (usually 
standing  in  long  rows  on  either  side  of  boilers,  which  run 
lenthwise  of  the  melting-house  and  are  heated  by  the  waste 
gases),  have  closed  and  luted  ash-pits,  into  which  three- 
inch  pipes  deliver  low-pressure  blast  from  a  fan-blower. 
The  compact  slow-burning  anthracite  offers  so  little  sur- ' 
face  that  it  is  necessary  to  have  a  much  thicker  bed  of  it 
than  of  coke  ;  hence  American  furnaces  are  much  deeper 


•  For  notices  of  old  aud  rare  furnaces  see  Kerl,  Grundriss  der  Eiseuhiittenkunde,. 
p.  409. 


Fig.  153. 

It  were  vain  to  seek  fuel- economy  by  prolonging  the 
shaft-furnace,  so  as  to  make  the  descending  column  of 
fuel  intercept  the  escaping  heat.  This  would  lower  the 
temperature  by  causing  reduction  of  carbonic  acid  to 
oxide ;  further,  the  crucible  must  be  near  the  top  of  the 
fire  for  examination  and  drawing. 

Shaft-furnaces  are  usually  run  by  day  only,  and  every 
other  day  at  that. 

The  Siemens  crucible-furnace,  Figure  154,  is  of  the 
common  Siemens  regenerative  type,  with  a  pair  of  regen- 
erators aaaa  (section  N  P)  on  either  side  of  the  melting- 
chamber  6,  which  is  cut  up  by  cross-walls  p  p  p  (section 
A  B),  into  from  two  to  ten  melting-holes,  each  of  which 
usually  holds  six  crucibles.  The  flame  travels  so  short  a 
distance  in  the  melting-hole  or  laboratory  that  gas  and  air 
must  be  mixed  intimately,  so  as  to  shorten  the  flame.  To 
this  end  the  gas  for  each  melting-hole  is  shot  up  through 
three  small  orifices  c  c  c  (plan  and  section  N  P)  into  the 
horizontally  moving  stream  of  air,  while  the  velvetry  d 
probably  eddies  and  thus  further  mixes  the  streams, 
beside  deflecting  the  flame  downward  so  as  to  warm  the 
bottoms  of  the  crucibles. 

Each  melting-hole  has  a  single  opening  above  for  draw- 
ing and  charging,  closed  with  clamps  e  e  e  (section  A  B), 
each  of  which  covers  two  crucibles,  and  is  hung  by  a  chain 
to  an  overhead  telegraph,  or  is  lifted  by  a  hook  supported 
by  the  axle  of  a  small  two-wheeled  buggy,  Figure  157. 

The  bottom  of  the  melting-hole  has  an  eight-inch  layer 
of  coke-dust,  and  beneath  this  a  hole  f  (section  N  P), 
temporarily  closed  with  an  old  crucible-cover.  Should  a 
crucible  break,  a  hole  is  forced  through  this,  letting  the 
molten  steel  run  through  into  the  vault  g  beneath.  This 
hole  is  generally  opened  each  Saturday  afternoon,  and  all 
melted  matter,  clinker,  etc.,  run  through.  The  coke  bot- 
tom is  usually  made  up  afresh  after  each  shift. 

The  Siemens  furnace  is  run  continuously  from  Monday 
morning  till  Saturday  afternoon.  The  consumption  of 
fuel  is  indicated  in  Table  172.  In  one  Pittsburgh  mill 
only  half  a  pound  of  slack  coal  was  used  per  pound  of 


803 


CRUCIBLE    FURNACES. 


359. 


steel  made,  in  a  test-run  of  one  week  ;  an  accurate  account 
of  a  year's  work  showed  that  with  Wellman  steam-blown 
producers  0.75  pounds,  and  with  common  Siemens  pro- 
ducers one  pound  of  slack  coal  was  used  per  pound  of 
steel. 

It  is  very  important  that  the  flues  s,  s,  s'  beneath  the 
regenerators,  shown  in  section  N  P,  should  be  very  large, 
especially  in  the  long  42  and  60-pot  furnaces.  The  gas 
and  air  must  travel  through  these  flues  the  whole  length 
of  the  furnace  ;  the  travel  for  the  first  melting-hole  is 
much  shorter  than  for  the  further  ones,  and  unless  these 
flues  be  very  large,  so  as  to  supply  the  ports  t  and  c 
with  more  air  and  gas  than  they  can  transmit,  an  undue 
proportion  of  the  gas  and  air  will  enter  the  nearer  melting- 
holes  and  the  further  ones  will  work  cold.  The  dimen- 
sions given  in  section  N  P  are  standard  ones,  but  they 
would  be  better  if  somewhat  larger,  so  that  the  sectional 
area  of  the  {§£}  flue  should  be  50$!  larger  than  the  sum  of 
minimum  areas  of  all  the  ||'sr3}  ports  on  one  side  of  the 
furnace,  or  so  as  to  make 

2s  —  9<  x  1.5 
s'— 9c-xl.5 

s,  s',  t  and  c  being  the  sectional  areas  of  the  passages  s, 
s',  t  and  c  shown  on  section  NP  of  Figure  154. 
For  larger  furnaces  the  ratios  -  and  -  should  be  still 

larger,  on  account  of  the  longer  travel  through  the  flues. 
Here,  if  we  let  N  =  the  number  of  gas  or  air  ports  on 
each  side  of  the  furnace,  it  is  well  to  make 

2s  —  2N« ;  s'  —  2Nc. 

In  one  admirable  60-pot  furnace  s' 
=  60"  x  27"  so  that 

2s  —  N  x « x  2  —  GOt. 
«'  —  Nxcx2  — 60c. 

The  Nobel  liquid-fuel  furnace?  Figure  15~),  has  two 
chambers,  a  and  «',  each  containing  two  crucibles,  and  a 
third  a",  originally  intended  to  hold  a  pair  of  crucibles, 

Fig-  166. 

NOBEL'S  PETROLEUM    FURNACE 


60"  x  18"  and  s 


Sectlon-C-D. 


but  not  utilized.  The  fuel  is  a  somewhat  refined  petro- 
leum, costing,  I  am  told  5  cents  per  gallon,  while  crude 
Pennsylvania  petroleum  costs  about  1.6  cents  per  gallon. 
At  one  works  attempts  to  use  crude  oil  failed.  I  am  in- 
formed that  crude  oil  has  been  successfully  used  at 
another  works,  but  I  have  been  unable  to  verify  this 
statement  to  my  satisfaction. 

The  petroleum  is  fed  from  an  over-head  tank  through 
the  pipe  h,  on  the  upper  of  a  series  of  pans  f.  An  over- 
flow from  each  pan  carries  any  excess  of  oil  to  the  next 
lower  pan,  and  from  the  lowest  back  to  an  underground 
tank,  whence  it  is  pumped  at  intervals  to  the  overhead 
tank.  Air  is  admitted  between  the  pans,  through  the  slot 
m  (regulated  by  the  plate  n),  and  through  the  passage  p 

«U.  S.  Patent  321,  840,  L.  Nobel,  July  7th,  1885. 


in  the  side  and  bridge-walls.  We  thus  cool  and  preserve 
them,  while  preheating  the  air  somewhat.  The  flame 
passes  staggeringly  through  the  passage  d,  the  ports  c.  s, 
t,  s,  and  the  chambers  a,  a'  a"  to  the  chimney  •?/;.  The 
draft  is  regulated  by  the  slide-valve  x.  Each  chamber  is 
covered  with  a  large  tile  u,  having  a  peep-hole  »,  tempor- 
arily stopped,  above  each  crucible.  When  drawing  and 
charging  crucibles  the  tile  is  slid  lengthwise,  uncovering 
half  a  chamber  at  a  time,  while,  to  protect  the  puller-out, 
the  flame  is  drawn  straight  to  the  chimney  through  the 
flue^?  by  opening  the  valve  g. 

The  staggering  path  of  the  flame,  in  that  it  impinges 
well  on  the  crucibles,  makes  the  furnace  efficient  as  to 
fuel-consumption  ;  in  that  it  impinges  sharply  on  the 
bridge-walls,  it  shortens  the  life  of  the  furnace  and  in- 
creases the  cost  of  repairs.  Actually,  the  hottest  bridge- 
wall  is  rapidly  cut  out  by  the  flame. 

A  layer  of  coke  is  arranged  at  the  bottom  of  the  furnace 
quite  as  in  the  Siemens'  furnace,  for  running  the  steel 
from  broken  crucibles  into  the  flue  p  beneath.  It  would 
be  well  if  there  were  a  vault  beneath  this  flue  into  which 
molten  steel  could  be  run  ;  it  should  be  hard  to  remove  a 
mess  of  steel  from  the  little  flue  p,  without  tearing  the 
furnace  to  pieces." 

Repairs. — The  Sheffield  coke  furnaces  are  relined  with 
gannister  every  four  weeks  ;  their  walls  are  rebuilt  once  a 
year ;  and  after  about  five  or  seven  years  thorough  repairs 
are  needed. 

Anthracite  shaft-furnaces  at  one  American  works  are 
repaired  about  every  four  months,  with  an  outlay  of  one 
day's  time  of  a  bricklayer  and  helper,  and  388  fire-bricks. 
American  gas-furnaces  are  repaired  about  once  in  six 
months,  with  an  outlay  of  about  $350  in  case  of  a  60-pot 
furnace. 

A  Nobel  furnace  runs  probably  about  18  days ;  the 
longest  run  at  one  American  Mitis  works  has  been  27 
days. 

From  these  data  I  estimate  the  cost  of  repairs  per 
pound  of  steel  roughly  as  follows  : 


Furnace.    Pota.  Output  per  month. 

pots,  heats,  days.  Ibs.      Ibs. 
Anthracite..  4          4X3X12X75-  10,800 
pots,  hts.shfts.wkis.lb". 

Gas 60    60X3X11X4X75-594,000       594,000x6-3,564,000    $350.00 

heats,  days.  Ibs. 
Nobel 2  2X9X20X110-     39,600      $40.00 


Output  per  campaign.  Repairs  Repairs  per 

Ibs.       total.      Ib.  steel. 
10,800X4=     43,200      $25.00         0.06. 

0.01 


0.10 


Comparison. — Gas-furnaces  have  great  advantages  over 


a  P.  Ostberg,  Trans.  Am.  Inst.  Min.  Eng.,  xiv.,  p.  775,  1886,  states  that  wrought- 
iron  is  melted  in  this  furnace  at  the  rate  of  11  meltings  in  12  hours,  the  last  taking 
only  about  fifty  (exceptionally  forty)  minutes,  while  in  common  furnaces  to  melt 
steel,  which  is  more  fusible,  it  takes  four  to  six  hours.  Actually  a  heat  occupies 
from  three  to  four  hours  in  common  furnaces.  As  only  two  of  the  four  crucibles  in 
the  Nobel  furnace  are  drawn  at  a  teeming,  the  true  length  of  a  heat  is  double  the 
interval  between  successive  teemings.  Actually  the  crucible  remains  in  the  furnace 
at  American  Mitis  works  about  2  hours  and  15  minutes,  or  just  about  the  time  re- 
quired for  melting  in  good  American  practice.  Remembering  that  on  the  one  hand, 
the  time  of  killing  is  saved  in  the  Mitis  process,  and  that,  on  the  other,  the  charge 
is  less  fusible  than  in  the  common  crucible  practice,  the  Nobel  furnace  seems  to 
melt  rather  more  rapidly  than  is  usual  with  Siemens'  furnaces.  But  the  tempera- 
ture in  a  properly  designed  Siemens'  furnace  is  limited  only  by  the  refractory 
nature  of  the  brickwork  and  crucibles  ;  and  it  may  be  owing  to  an  excessively  high 
temperature  employed  in  the  Nobel  furnace,  but  avoided  in  good  Siemens'  prac- 
tice, that  the  Mitis  crucibles  are  used  only  about  one-half  as  many  heats  (hotter  but 
shorter  heats)  as  those  in  American  Siemens'  furnaces ;  and  that  there  are  only  as 
many  days  in  a  Nobel  furnace  campaign  as  weeks  in  the  campaign  of  a  Siemens' 
furnace.  Mr.  Ostberg  indeed  states  that  in  common  furnaces  crucibles  are  only 
exceptionally  used  more  than  thrice,  while  in  Nobel  funiaces  they  last  six  or  seven 
heats.  Actually  it  seems  to  be  just  the  other  way.  In  common  American  practice 
the  crucibles  last  five  or  six  heats  ;  in  the  Nobel  furnace  at  the  Mitis  works  of  whose 
practice  I  have  direct  information,  they  last  but  three. 


THE    METALLURGY    OP    STEEL. 


303 


shaft-furnaces  in  that  they  are  much  more  convenient, 
the  crucibles  being  always  readily  accessible ;  use  less 
than  half  (sometimes  less  than  one-quarter)  as  much  fuel, 
and  usually  much  cheaper  fuel  at  that ;  and  avoid  the 
corrosion  of  the  crucible  by  the  ash  of  the  fuel  which 
occurs  in  shaft- furnaces,  which  probably  shortens  the  life 
of  the  crucible  appreciably.  On  the  other  hand,  their 
first  cost  is  much  greater,  and,  strangely  enough,  the 
Sheffield  steel-makers  think  that  they  afford  less  control 
over  the  temperature  than  shaft-furnaces.  It  is  further 
objected  that  the  crucibles  next  the  walls  in  gas-furnaces 
heat  more  slowly  than  those  in  the  middle  ;  but  the  dif- 
ference is  probably  unimportant.  In  this  country  gas- 
furnaces  are  habitually  used,  and  are  fast  driving  the 
shaft-ftirnaces  out  of  existence.  But  I  am  informed  that 
only  one  Sheffield  firm  of  importance,  Sanderson  Brothers, 
uses  the  gas-furnace. 


CROSS-SECTION    OP 

PITTSBURGH    60-POT    IWELTING'  HO.OSE 
Scale  ll)i— i" 


Fir/.  150. 


The  Nobel  furnace  uses  as  much  if  not  more  fuel  per 
ton  of  product  than  the  best  gas-furnaces,  and  of  a  more 
powerful  and  usually  more  expensive  fuel  at  that,  and  it 
requires  more  labor.  Its  repai  rs,  moreover,  are  exceedingly 
expensive.  It  is  said  to  yield  a  higher  temperature  than 
other  furnaces  ;  but,  while  one  may  not  estimate  these 
high  temperatures  confidently,  the  Nobel  furnace  did  not 
seem  to  me  materially  hotter  than  a  Siemens'  crucible 
furnace,  and  certainly  not  hotter  than  an  open-hearth 
furnace.  Nor  can  I  readily  believe  that  we  cannot  de- 
velop in  a  well-designed  Siemens'  furnace,  as  high  a  tem- 
perature as  in  this  furnace.  Indeed,  the  temperature 
attainable  in  the  Siemens'  furnace  seems  to  be  limited  only 
by  the  melting-point  of  our  refractory  materials. 

In  comparing  the  Nobel  with  the  Siemens'  furnace  we 
must  recollect  that,  on  the  one  hand,  its  usual  product, 
almost  carbonless  steel,  demands  a  higher  temperature 
than  the  high -carbon  steel  usually  made  in  Siemens' 
crucible  furnaces ;  and  that  the  Nobel  furnace  is  run 
intermittently,  the  Siemens'  continuously.  On  the  other 
hand,  a  Nobel  furnace  heat  is  much  shorter,  killing  being 
omitted,  than  that  of  a  Siemens'  furnace.  Considering 
these  facts,  and  considering  that  the  design  of  the  Nobel 
furnace,  allowing  the  products  of  combustion  to  pass  to 
the  chimney  very  hot,  would  not  lead  us  to  expect  any- 
thing like  the  economy  of  a  Siemens'  furnace,  its  fuel- 
consumption  is  surprisingly  low,  if,  indeed,  this  has  been 
trustworthily  determined.  The  Nobel  furnace  is  certainly 
much  cheaper  to  build  than  the  Siemens',  and  it  uses  less 
fuel  than  the  shaft-furnace.  It  therefore  commends 
itself  for  small  establishments,  in  which  castings  are  made 
only  on  a  few  days  in  each  week  ;  for  these  the  Siemens' 
furnace  is  unsuited,  as  it  must  run  continuously  to  be 
economical. 

It  is  only  fair  to  add  that  my  direct  information  about 


Fig.  157 

PLAN  OF  PITTSBURGH 
60-POT    MELTING    HOUSE 

Scale-lO-a'' 


TUtcfc  for  smoking'Moulds 


304 


MELTING    AND    KILLING.       §  361. 


the  Nobel  furnace  is  chiefly  confined  to  the  practice  of  a 
single  mill,  which  I  am  credibly  informed  is  much  less 
intelligently  managed  than  several  others  in  which  the 
furnace  is  used.  In  spite  of  several  endeavors,  I  have 
failed  to  obtain  information  in  detail  and  sufficiently 
direct  to  be  accepted,  touching  the  practice  in  these  other 
works. 

§  360.  CHABGING. — In  Sheffield  the  charge  is  introduced 
through  a  sheet-iron  funnel  into  the  red-hot  (usually  clay) 
crucible,  resting  on  its  stand  in  the  melting-hole. 

In  the  United  States  the  graphite  crucible  is  carefully 
filled  by  hand  while  cold.  The  larger  pieces  of  metal  are 
packed  at  the  bottom,  on  these  is  poured  the  carburizing 
charcoal,  usually  with  a  little  oxide  of  manganese,  and 
often  with  a  little  "physic,"  such  as  salt,  ferrocyanide  of 
potassium,  etc.  Above  the  .charcoal  are  packed  the 
smaller  and  closer  fitting  pieces  of  metal,  probably  inter- 
cepting during  melting  nearly  all  the  free  oxygen  and 
carbonic  acid  which  enter  from  above,  and  thus  protect- 
ing the  charcoal  from  oxidation.  The  crucible  is  then  in- 
troduced, without  any  stand,  either  into  the  anthracite 
shaft-furnace,  here  resting  directly  on  the  glowing  coal, 
the  several  crucibles  in  actual  contact  with  each  other,  or 
into  the  white-hot  melting-hole  of  the  Siemens'  furnace, 
resting  on  the  coke  bottom. 

The  usual  practice  is  to  introduce  the  whole  charge  into 
the  crucible  at  the  same  time  ;  but  at  Osterby,  in  Sweden, 
the  spiegeleisen  or  ferromanganese  is  added  (apparently 
shortly)  "before  the  charge  is  wholly  melted."  This 
doubtless  gives  better  control  over  the  proportion  of  man- 
ganese in  the  product,  and  diminishes  the  loss  of  this 
metal. 

§361.  THE  HEAT  consists  of  two  periods,  "melting" 
and  "killing." 

Melting. — The  crucible  introduced  and  its  cover  placed, 
gas  and  air  are  turned  on,  in  case  of  gas-furnaces,  while 
in  case  of  shaft  furnaces  the  anthracite  or  coke  is  piled 
up  to  a  little  above  the  top  of  the  crucible,  which  is  nearly 
level  with  the  bottom  of  the  flue  E,D,  Figures  152  and  153. 
The  bulky  coke  burns  so  rapidly  that  it  is  necessary  to 
add  more  after  about  45  to  55  minutes,  that  hanging  to 
the  sides  of  the  pots  being  first  poked  down  so  that  we 
may  have  a  solid  bed  of  fuel  next  the  bars,  and  so  avoid 
cooling  the  lower  part  of  the  pots ;  and  this  is  repeated 
at  least  once  during  the  heat,  so  that  we  have  at  least 
three  firings  to  each  heat.  The  compact  anthracite  both 
burns  away  and  heats  up  so  slowly  that  this  is  neither 
necessary  nor  practicable.  An  anthracite  fire  is  not  replen- 
ished during  the  heat,  for  the  addition  of  cold  fuel  would 
chill  and  retard  the  operation  unduly.  It  is  probably  at 
least  partly  due  to  this  that  the  crucibles  in  anthracite 
practice  rest,  not  on  stands  and  through  these  on  the  grate 
bars,  but  directly  on  a  bed  of  anthracite  so  deep  as  to 
last,  without  replenishing,  through  the  four  hours  of  a 
heat. 

When  it  is  thought  the  charge  is  melted,  the  crucibles 
are  uncovered  and  examined  to  ascertain  the  progress  of 
the  fusion.  Care  must  be  taken  that  no  coke  or  anthracite 
falls  into  the  crucible ;  it  is  said  that  if  this  happens  the 
steel  becomes  very  hot-short  and  "stares,"  i.  e.,  has  a 
splendent  fracture.  The  carbon  of  a  pound  of  coal  (say 


34  cubic  inches,  a  lump  3.25  inches  cube),  if  absorbed  by 
the  metal,  would  raise  the  carbon- content  of  a  50-pound 
charge  by  two  per  cent.  ;  were  the  charge  initially  highly 
carburetted,  this  would  change  it  to  cast-iron. 

In  the  six-pot  melting  hole  of  a  gas-furnace  only  the 
two  middle  pots  are  examined. 

The  melter's  eye  at  once  recognizes  by  the  temperature 
whether  the  charge  is  but  partially  melted  and  therefore  at 
the  melting  point,  or  superheated  much  beyond  that  point. 
In  the  former  case  it  is  necessary  to  learn  how  much  metal 
is  still  unmelted  ;  to  this  end  the  melter  feels  about  in  the 
pot  with  a  thin  iron  rod,  a  course  which  is  unnecessary 
and  often  dispensed  with  if  the  temperature  is  clearly 
above  the  melting  point.  If  the  temperature  be  very  high, 
no  steel  adheres  to  the  rod.  According  to  Ledebur", 
European  melters  judge  from  the  appearance  of  slag  and 
metal  as  to  the  progress  of  operations.  At  first  the  slag 
is  highly  ferruginous,  and  hence  black  ;  later  it  grows 
lighter.  American  melters  are  rather  close- mouthed  as  to 
the  indications  which  they  watch  for  ;  but  I  have  never 
detected  them  in  examining  the  slag  removed  by  the  rod. 

This  examination  occurs  at  the  time  of  the  third  firing 
in  case  of  coke  furnaces.  In  anthracite  furnaces  the  cru- 
cible has  by  this  time  sunk  some  distance  toward  the 
bars,  thanks  to  the  burning  away  of  the  fuel  beneath  it. 
It  is  therefore  lifted  up  a  short  distance  (say  5"  or  6"), 
through  the  fuel  by  the  puller-out,  just  before  removing 
its  lid  for  examination,  the  melter  simultaneously  pack- 
ing the  coal  down  beneath  the  pot  with  a  bar. 

The  charge  now  looks  like  slowly  boiling  porridge,  and 
bright  specks,  probably  of  metallic  iron,  may  be  seen  on 
the  upper  surface  of  the  slag. 

Kitting. — Were  the  charge  teemed  as  soon  as  melted, 
the  steel  would  be  full  of  blowholes.  By  Trilling  it,  /.  e. 
holding  it  molten  in  the  crucible,  which  still  remains  in 
the  melting-hole,  some  change  occurs  which  removes  the 
tendency  to  form  blowholes,  and,  on  teeming,  sound, 
deeply  piping  ingots  or  other  castings  are  now  obtained. 
Killing  probably  acts  chiefly  through  enabling  tlie  metal 
to  absorb  silicon  from  the  walls  of  the  crucible,  thus  in- 
creasing its  solvent  power  for  gas,  and  thus  enabling  it  to 
retain  in  solution  during  solidification  the  gas  which  it 
contains  when  molten.  The  common  belief  is  that  killing 
expels  the  gas  which  is  present,  so  that  less  remains  to 
escape  during  solidification.  But,  in  the  first  place,  we 
find  that  silicon  is  absorbed  rapidly  during  the  killing, 
and  we  have  already  seen  that  silicon  seems  to  prevent 
blowholes  by  increasing  the  metal's  solvent  power  for  gas. 
In  the  second  place,  when  the  conditions  are  such  that  the 
metal  cannot  absorb  silicon,  holding  the  metal  molten  in 
this  way  does  not  kill  it,  i.  e.,  does  not  cause  it  to  solidify 
without  blowholes.  Thus  in  numbers  14,  38,  43  to  45  and 
47  of  Table  179,  we  find  that  only  from  0.006  to  0.06  %  of 
silicon  is  absorbed,  and  here  in  each  case  the  steel  con- 
tains blowholes.  In  number  57  the  metal  (after-blown 
basic  steel),  though  held  molten  for  three  hours,  yet  took 
up  but  0.012  %  of  silicon  ;  it  then  scattered  and  rose  more 
on  teeming  than  that  which  had  not  been  thus  killed". 
It  is,  moreover,  the  experience  in  Mitis  works  that  when 


a  Handbuch  der  Eisenhiittenkunde,  p.  851. 

b  This  case  should  pretty  effectually  dispose  of  the  belief  that  the  escape  of  gas 
during  solidification  is  due  to  a  protracted  reaction  between  carbon  and  oxygen. 


THE    METALLURGY    OF    STEEL. 


305 


the  charge  is  wrought-iroq,  the  resulting  metal,   being; 
nearly  free    from    silicon    and  carbon,  is    not  rendered 
tranquil  by  being  held  molten,  or,  as  they  put  it,  will  not 
kill. 

On  the  other  hand,  it  is  but  fair  to  point  out  that  in 
numbers  35  and  45  of  Table  179,  the  product  is  relatively 
free  from  blowholes,  though  the  metal  absorbs  but  0.09 
and  0.11  %  of  silicon,  or  but  little  more  than  in  some  of 
those  cases  in  which  blowholes  form.  Again,  in  numbers 
18  and  22,  in  which  wrought  iron  is  melted,  0.29  and  0.28  % 
of  silicon  is  absorbed,  yet  porous  ingots  result. 

If  killing  be  unduly  prolonged,  the  metal  becomes  hard 
and  brittle,  teems  "dead,"  i.  e.,  very  tranquilly,  and  yields 
very  solid  ingots.  This,  again,  may  be  due  to  excessive 
absorption  of  silicon.  It  is  very  doubtful  whether 
moderate  over-killing,  say  of  15  or  20  minutes  more 
than  is  actually  necessary,  produces  an  appreciable  effect. 
Steel  of  only  common  grade  is  usually  made  on  Mon- 
days, because,  as  the  furnace  is  not  up  to  its  normal  tem- 
perature then,  the  proper  length  of  time  for  killing  cannot 
be  readily  determined. 

The  melter  practically  predetermines  the  length  of  the 
killing  period,  judging  from  the  appearance  of  charge 
and  furnace  at  the  time  of  the  examination  already  de- 
scribed, and  from  the  known  proximate  composition  of  the 
charge,  how  soon  it  will  be  ready  for  teeming.  As  soon 
as  this  predetermined  period  (modified,  of  course,  in  case 
the  temperature  of  the  furnace  should  be  changed  ab- 
normally during  killing)  has  passed,  the  charge  is  drawn 
and  teemed  without  second  examination. 

Killing  usually  lasts  from  30  to  60  minutes  ;  sometimes 
it  does  not  last  more  than  15  minutes,  and  sometimes  as 
long  as  an  hour  and  three  quarters.  In  general  the  hotter 
the  furnace  the  shorter  may  killing  be.  It  is  the  nearly, 
if  not  quite  universal,  belief  of  steel-melters  that  the  bet- 
ter the  steel,  i.  e.,  the  freer  from  phosphorus,  etc.,  the 
longer  killing  does  it  need.  It  is  said  that,  if  the  charge 
consists  wholly  of  Bessemer  or  open-hearth  steel  scrap, 
no  killing  is  needed. 

Just  what  the  elements  are  whose  presence  hastens  kill- 
ing is  not  known.  We  can  understand  that  manganese 
might  have  this  effect,  since  we  see  in  §  368,  D.  E.,  that  it 
increases  the  absorption  of  silicon.  Or  the  presence  of 
oxide  of  manganese  in  the  slag  may  here,  in  some  imper- 
fectly understood  way,  promote  soundness. 

In  the  Mitis  process,  killing  is  dispensed  with.  A  little 
of  what  is  said  to  be  ferro-aluminium  is  added  as  soon  as 
the  charge  is  melted,  and  the  metal  teemed  a  very  few 
minutes  thereafter. 

Teeming. — The  moulds  for  the  small  ingots  usually 
made  in  the  crucible  process  are  split  (Figure  158),  and  held 
together  with  a  pair  of  rings  and  keys.  Before  use  both 
halves  of  the  mould  are  laid  flat,  with  their  inner  faces 
down,  and  smoked  from  beneath  by  holding  a  pan  of  burn- 
ing resin  (used  in  many  American  works),  coal-tar  (British 
works),  or  birch-bark  (Osterby),  under  them  (Figures 
156-7).  Some  American  steel-makers  report  that  coal-tar 
yields  a  rather  wet  coating,  which  roughens  the  surface  of 
the  ingot. 


Scale  X'  to  1 
Fig.  158.    AMERICAN  SPLIT  MOULD  FOB  CRUCIBLE-STEEL  INQOTS. 


Killing  ended,  the  clamps  over  the  melting  hole  are  re- 
moved, e.  g.,  by  a  chain  and  telegraph  as  in  Figure  156,  or 
by  a  little  buggy  as  in  Figure  157 ;  and  the  blast,  or  draft, 
or  gas  and  air,  as  the  case  may  be,  shut  off.  In  case  of  an 
anthracite  shaft-furnace  the  fire  by  this  time  has  burnt 
down  so  that  most  of  the  crucible  projects  above  it.  The 
puller-out,  his  arms  and  legs  thickly  wrapped  with  sack- 
ing, wet  to  prevent  ignition,  and  at  Mitis  works  with  his 
head  covered  with  a  thick  cloth  and  his  eyes  protected 
with  dark  blue  glasses,  now  grasps  the  crucible  with  his 
tongs,  Fig.  160,  straddles  the  melting-hole,  and  with  a 
single  motion  lifts  the  pot  and  swings  and  rests  it  on  the 
melting-house  floor8,  then  swings  it  across  to  the  teeming- 
hole,  close  to  the  ingot  mould  to  be  filled.  It  is  now 
grasped  by  the  teenier  with  the  tongs,  Figure  161.  The 
puller  out  or  one  of  the  moulders  pries  off  the  cover  with 
his  tongs,  the  slag  is  swabbed  up  by  means  of  a  mop, 
i.  e.,  a  light  iron  rod  with  a  ball  of  slag  from  previous 
operations  attached  to  it.  This  chills  the  slag,  and  by  a 
dexterous  twisting  motion  is  made  to  take  up  most  of  it. 


Fig.  159.    PULL-ODT'S  Tones  FOR  130-potrHD  CRUCIBLES. 


Fig.  160.    PULLEB-ODT'S  TONGS. 


Fig.  161.    TEEMEB'S  TONGS. 

The  teemer,  his  right  hand  and  arm  thickly  enveloped 
in  cloth,  and  standing  with  crucible  and  mould  at  his  right, 
rests  the  tongs  about  midway  of  their  length  on  his  bent 
left  knee  as  a  fulcrum  ;  raises  the  crucible,  partly  by  throw- 
ing his  weight  on  the  left-hand  end  of  the  tongs,  partly  by 
lifting  with  his  right  hand,  and  pours  the  metal  gently 
into  the  mould,  whose  top  is  but  a  few  inches  above  the 
floor-level,  taking  care  that  the  stream  is  continuous,  and 
that  it  does  not  strike  the  sides  of  the  mould  ;  to  prevent 
this  the  mould  may  be  slightly  inclined  toward  the  teemer 
(Figure  156).  If  the  stream  were  interrupted,  the  surface 
of  the  metal  would  crust  over  and  a  cold-shut  would  form  ; 
if  it  struck  the  side  of  the  mould  the  metal  would  freeze 
there,  and  an  unsound  spot  on  the  ingot's  surface  would 
result.  It  is  that  he  may  guide  the  stream  more  accur- 


a  At  an  American  Mitis  works  the  puller-out's  tongs  (Figure  159}  weigh  27  pounds, 
the  crucible  35,  and  the  charge  occasionally  130,  or  altogether  192  pounds.  This, 
while  a  light  load  under  favorable  conditions,  here  clearly  demands  considerable 
strength.  Actually  it  is  swung  without  apparent  difficulty. 


306 


TEEMING. 


301. 


ately  that  the  teemer  bears  the  weight  of  the  crucible  on 
his  knee,  and  does  not  at  first  allow  the  crucible  to  rest 
on,  or  even  touch,  the  mould ;  but  later,  when  the  ingot 
is  nearly  teemed  and  the  stream,  having  but  a  little 
distance  to  fall,  is  easily  guided,  the  teemer  rests  the 
weight  of  the  crucible  in  part  on  the  top  of  the  mould. 


Pulling  the  crucible  from  the  melting  hole  by  hand  is 
certainly  very  crude.  As  he  straddles  the  hole  the  puller- 
out  is  exposed  to  almost  intolerable  heat,  which,  should 
a  crucible  break  while  he  is  pulling  it  out,  must  become 
simply  agonizing,  if  not  indeed  dangerous.  Fortunately 
he  is  only  exposed  to  the  very  intense  heat  for  from  two 


OT 


OX" 


<  s'e" 


TEEMING  TONGS  FOB  130-pooND  CBUCIBLES. 


Fig.  162. 


If  the  weight  of  the  ingot  is  to  exceed  that  of  a  single 
crucible-charge,  part  or  even  the  whole  of  the  charge  of  one 
crucible  is  poured  into  another  ;  or  two  teemers  keep  up 
a  continuous  stream  of  metal ;  or,  finally,  the  contents  of 
many  crucibles  are  emptied  into  a  single  loam-lined 
wrought-iron  teeming-ladle,  from  which  the  metal  is 
teemed. 

In  Britain  the  crucible  is  carried  from  the  melting  to 
the  teeming-hole  with  "a  pair  of  tongs,  forming  a  barrow 
mounted  on  a  central  pivot  fixed  to  the  axle  of  a  pair  of 
wheels,  whereby  the  pot  can  be  inclined  for  teeming,  and 
also  raised  from  the  ground  so  as  to  be  run  along  the  iron- 
elated  floor.  "a 

The  crucibles  from  all  the  melting-holes  of  a  given 
furnace  are  teemed  in  rapid  succession,  the  teemer  indi- 
cating which  in  his  judgment  are  ripest  for  teeming.  If 
a  pot  is  too  hot  when  drawn  from  the  melting-hole, 
it  is  allowed  to  stand  by  the  teeming-hole  till  sufficiently 
cooled. 

The  moulds  for  the  usual  small  ingots  are  unkeyed 
as  soon  as  the  ingot  within  has  set,  say  six  or  eight 
minutes  after  teeming,  and  after  teeming  two  or  three 
later  ingots. 

Graphite  crucibles  are  immediately  thrown  out  and 
dragged  away,  for  examination  after  cooling.  Clay  cruci- 
bles are  examined  while  hot,  and,  if  sound,  immediately 
returned  to  the  melting-hole  and  refilled. 

During  teeming  the  metal  in  the  crucible  is  quiet,  a 
very  few  bubbles  escaping  from  it,  and  is  said  to  be  quite 
transparent  to  the  practiced  eye  ;  this,  however,  I  venture 
to  doubt.  I  have  never  found  a  credible  witness  who 
would  affirm  without  hesitation  that  he  was  sure  that  he 
had  seen  through  it.  I  have  always  found  it  quite  opaque. 
A  very  little  pale  flame  curls  slowly  across  the  crucible. 
In  the  mould  the  metal  gives  out  a  very  pretty  shower  of 
sparks,  solidifies  tranquilly,  and,  if  highly  carburized, 
pipes  deeply. 

If  the  metal  be  soft  it  may  be  desirable  to  stop  the 
mould  with  sand,  so  as  to  chill  the  ingot-top  and  prevent 
rising.  In  American  practice  the  mould  is  either  not 
stopped  at  all,  or  a  cast-iron  plate  is  placed  on  the 
top  of  the  mould,  several  inches  above  the  ingot-top, 
whose  chilling  it  probably  hastens. 


a  Greenwood,  Steel  and  Irou,  p.  432. 


to  three  seconds,  as  nearly  as  I  have  been  able  to  measure 
it,  or  for  perhaps  three  minutes  collectively  in  a  whole 
shift. 

The  200  pound  crucibles  already  described  were,  in- 
deed, pulled  out  by  a  crane,  and  by  it  swung  to  the 
teeming-hole. 

Like  most  hand-work,  hand-pulling  is  surer  than  ma- 
chine-pulling. The  crucible  must  be  grasped  so  firmly 
that  it  will  not  slip,  but  not  so  tightly  that  it  crushes, 
as  it  readily  may  at  this  exalted  temperature.  The  grip 
is  more  readily  adjusted  by  hand,  the  feeling  insensibly 
guiding.  Indeed,  it  is  said  that  the  puller-out,  in  grasp 
ing  an  old  weak  pot,  feels  for  the  strongest  points  ;  but 
so  rapid  is  he  and  so  intense  the  glare,  that  an  on-looker 
cannot  detect  this. 

Grading. — The  ingot  after  cooling  is  "topped,"  i.  e., 
has  the  piped  upper  part  broken  off  (about  10  to  20$  by 
weight  in  case  of  mild  steel  ingots,  and  about  20  to  35^  in 
case  of  those  of  hard  steel ,  Table  78,  p.  153),  and  is  graded 
by  the  appearance  of  the  fresh  fracture.  It  is  said  that  a 
difference  of  0.10$  of  carbon  is  readily  distinguished,  at 
least  between  the  limits  of  \%  and  1.5%,  and  that  an 
experienced  eye  detects  even  a  difference  of  0.05$. 

Labor. — The  number  of  men  per  gang  and  their  respec- 
tive duties  naturally  vary  much.  Let  a  few  examples 
from  current  practice  suffice. 

Works  A. — The  gang  for  each  24-pot  anthracite  shaft 
furnace  consists  of  seven  men:  1  melter,  1  puller-out,  1 
setter-in,  1  mould-tosser,  1  coal-wheeler,  1  pot-packer,  1 
pot-packer's  helper. 

The  melter  is  in  general  charge  of  the  furnace,  examines 
the  charge  when  melted,  decides  the  length  of  killing, 
teems  the  steel,  examines  the  emptied  crucibles,  and  de- 
cides whether  to  use  them  again. 

The  puller -out  raises  the  crucibles  at  examination  time, 
pulls  them  from  the  melting-hole  for  teeming,  and  unclink- 
ers  the  melting-holes  which  are  not  running. 

The  setter-in  places  the  already  filled  crucibles  in  the 
melting-hole,  charges  the  coal  around  them,  and  cleans 
the  fires  after  drawing  and  teeming.  He  follows  the 
puller- out  closely,  charging  the  first  melting- hole  while 
the  puller-out  is  drawing  from  the  third,  etc. 

The  mould-tosser  smokes  the  moulds,  sets  them  up  and 
removes  them,  and  draws  the  ingots  from  the  teeming-hole. 


TIME    OF    OPERATION,    LOSS,    MATERIALS.      §  362. 


307 


TJie  coal-wheeler  brings  coal  to  the  melting-holes. 

The  pot-packer  and  his  helper  fill  the  crucibles,  swab  up 
the  slag  at  the  time  of  teeming,  drag  away  the  emptied 
pots  for  examination,  and  bring  new  ones  from  the  store- 
house. 

Works  O. — Each  12-pot  anthracite  furnace  has 

1  melter  who  teems,  cares  for  the  fire  and  takes  all  the 
labor  on  contract,  at  $6.00  per  ton  of  steel ;  1  puller-out 
and  1  moulder ;  total,  3  men. 

Works  E  and  F.—  Each  42-pot  Siemens  furnace  has  1 
melter,  1  helper,  3  pullers-out  and  4  moulders  ;  total,  9. 

The  melters  duties  are  the  same  as  at  Works  A,  except 
that  he  teems  only  half  the  pots,  the  helper  teeming  the  rest. 

The  three  pullers-out  lift  the  pots  from  the  melting- 
holes,  relieving  each  other. 

The  moulders  ^moke,  set  and  remove  the  moulds,  re- 
move the  ingots,  and  fill  the  crucibles.  During  teeming 
one  moulder  removes  and  replaces  the  clamps  above  the 
melting  hole ;  a  second  pulls  off  the  pot-lids ;  a  third 
swabs  out  the  slag ;  a  fourth  drags  away  the  emptied  pots. 
This  is  the  common  Pittsburgh  arrangement.  Charging  does 
not  begin  till  all  the  crucibles  have  been  drawn  and  emptied. 

With  60-pot  Siemens  furnaces,  drawing  and  teeming  are 
done  by  two  gangs  working  simultaneously,  one  under 
the  melter,  the  other  under  the  teenier. 

In  Sheffield  (III.,  Table  172),  the  gang  for  twelve  two-pot 
coke  melting-holes  is,  to-day,  1  melter,  1  teemer,  2  pull- 
ers-out, 1  or  2  cellar-boys,  1  odd  man,  1  yardman  ;  total,  7. 

Mitis  Works. — Two  Nobel  furnaces,  each  holding  four 
crucibles,  of  which  two  are  drawn  at  a  heat,  are  worked 
by  one  melter  and  one  puller-out,  the  engineer  lending  a 
hand.  In  addition  there  are  the  casting  gang  and  the 
moulders.  The  labor  is  clearly  heavier  than  in  case  of 
Siemens'  and  shaft  furnaces,  owing  to  greater  care  re- 
quired in  feeding  the  fuel  and  regulating  the  temperature, 
and  to  the  necessity  of  transferring  the-  crucibles  from  the 
middle  to  the  hot  chamber,  which  increases  the  puller- 
out's  labor  by  at  least  half;  but  no  accurate  comparison  is 
possible,  because  more  labor  is  needed  to  prepare  and  teem 
into  the  numerous  small  moulds  for  the  Mitis  castings 
than  when,  as  in  usual  crucible  practice,  common  ingots 
are  made.  I  give  a  rough  estimate  in  Tables  172  and  178. 

The  labor  in  the  crucible  process  is  excessively  costly. 
The  melter  usually  provides  all  the  labor  on  contract,  re- 
ceiving on  the  eastern  seaboard  of  this  country  about 
$6.00  and  in  Pittsburgh  $5.50  to  $6.50a  per  2,000  pounds 
of  ingots,  though  here  the  use  of  gas  furnaces  lightens  the 
labor  greatly.  From  data  at  hand  I  estimate  that  the 
melter' s  gangs  in  Pittsburgh  receive  on  an  average  about 
$3.00  to  $3.00  apiece  per  eight-hour  shift.  The  melter  and 
puller-out  must  have  strength  and  judgment,  butit  seems 
to  me  that  the  price  paid  is  wholly  out  of  proportion  to 
to  the  intrinsic  needs  of  the  case.  It  is  rarely  wise  to  dis- 
pense wholly  with  skilled  men,  but  that  one  may  get 
along  after  a  fashion  without  them  is  shown  by  the  expe- 
rience of  an  American  crucible  steel  works  whose  mana- 


a  Of  two  thoroughly  trustworthy  correspondents  in  Pittsburgh,  one  assures 
me  that  he  pays  his  melting  gang  $5.50;  the  other  that  he  pays  his  $6.50  per 
2,000  pounds  of  ingots.  The  difference  is  probably  due  to  a  slight  difference  in  the 
range  of  duties,  the  higher  price  including  topping,  weighing,  etc.  We  note  in 
Table  172  that  the  labor  in  American  mills  using  shaft  and  gas  furnaces  is  much 
less  per  100  pounds  of  ingots  than  in  British  and  continental  mills— 0.09  to  0.13  days 
against  about  0.20.  The  difference  is  too  great  to  be  wholly  referred  to  the  some- 
what heavier  charges  and  shorter  heats  of  American  practice. 


ger,  discharging  imported  steel  men  in  disgust,  hired  a 
sailor  and  a  butcher,  neither  with  any  knowledge  of  steel- 
making,  as  melter  and  as  puller-out.  He  certainly  keeps  his 
works  running,  though  with  much  waste  of  his  own  issue. 

§362.  TIME  OF  OPERATION. — Shaft  furnaces  run  one 
shift  at  a  time,  every  alternate  day,  i.  e.,  one  shift  out  of 
four.  While  not  running  they  are  uncliukered.  Three 
heats  per  shift  is  the  usual  stent. 

Gas  furnaces  run  continuously  from  Monday  morning  till 
Saturday  afternoon,  with  two  gangs  working  alternate  shifts 
of  three  heats  apiece,  each  gang  beginning  work  as  soon 
as  the  third  heat  of  the  preceding  shift  is  ended,  no  matter 
at  what  hour  this  happens.  Thus  they  sometimes  work 
twelve  shifts  between  Monday  morning  and  Saturday  noon. 

Melting  may  take  45  minutes  or  even  an  hour  longer  for 
a  very  soft  than  for  a  hard,  i.  e.,  highly  carburetted 
charge.  The  usual  time  is  from  2  hours  15  minutes  to 
2  hours  45  minutes.  Kill  ing  usually  lasts  from  30  min- 
utes to  1  hour  in  this  country.  At  Osterby,  in  Sweden, 
it  is  said  to  last  only  from  10  to  30  minutes.  The  dis- 
crepancy may  be  due  in  part  to  a  different  estimate  of  the 
time  when  killing  begins,  which  is  not  accurately  define- 
able.  Charging  and  drawing  usually  take  about  15  to  20 
minutes  collectively.  With  graphite  crucibles  and  gas-fur- 
naces, weight  of  charge  and  initial  temperature  of  cruci- 
ble and  of  furnace-walls  being  nearly  constant,  there  is 
no  very  great  difference  between  the  length  of  successive 
heats,  unless  the  degree  of  carburization  of  the  charge 
changes  considerably.  But  with  clay  crucibles  and  coke- 
shaft-furnaces  the  first  heat  of  the  day  takes  much  longer 
than  the  later  ones,  in  which  the  furnace  walls  are  hotter ; 
the  crucible,  returned  to  the  melting  hole  immediately 
after  teeming,  is  much  hotter  initially ;  and  the  charge 
much  lighter.  Thus  the  first  charge  may  take  from  four 
to  five  hours,  the  second,  according  to  Greenwood,  about 
2  hours  30  minutes. 

§  363.  THE  Loss  is  generally  very  small,  less  than  two 
per  cent,  and  sometimes  inappreciable.  It  is  probably 
rather  less  with  graphite  than  with  clay  crucibles,  the  car- 
bon of  the  former  not  only  lessening  the  oxidation  of  iron, 
but  by  causing  a  marked  absorption  of  carbon  and  silicon, 
offsetting  the  loss  of  iron.  The  loss  is  doubtless  relatively 
heavy  when  the  charge  consists  of  small  and  rusty  pieces. 
In  the  Mitis  process  the  loss  sometimes  rises  to  10%  when 
very  rusty  small  pieces  are  used. 

At  Works  A  an  85-pound  charge  yields  84  pounds  of  in- 
gots and  about  66  pounds  of  rolled  bars,  so  that  1.2%  is 
lost  in  melting  and  2\%  is  removed  by  topping  and  in  fur- 
ther oxidation  during  heating  and  rolling.  At  Osterby 
100  of  charge  yields  96.3  of  ingots  and  1.8  of  scrap,  with 
1.9  of  loss, 

§  364.  THE  MATERIALS  used  in  this  country  are  chiefly 
puddled  and  bloomary  iron,  and  wrought-iron  and  steel 
scrap.  There  is  a  belief  that  for  the  very  best  quality  of  steel 
nothing  butDannemora  Swedish  iron  is  suitable,  and  even 
that  the  employment  of  blister-steel  of  uniform  carbon- 
content  made  from  Dannemora  iron  is  essential.  Certain  it 
is  that  relatively  little  blister-steel  is  made  or  used  in  this 
country.  In  1886  only  2,651,  and  in  1887  only  6,265  net 
tons  of  blister,  puddled,  patented  and  apparently  certain 
other  minor  classes  of  steel  were  made  collectively  in  this 


308 


THE    METALLURGY    OF    STEEL. 


country,  while  80,609  and  84,421  tons  respectively  of  cru- 
cible steel  were  made  in  these  two  years".  Of  this  probably 
nine-tenths  was  made  from  American  iron,b  so  that  im- 
ported blister-steel  cannot  have  been  an  important  com- 
ponent. 

The  only  apparent  explanation  of  the  siiperiority  of 
Dannemora  iron  is  its  almost  complete  freedom  from 
phosphorus,  of  which  it  is  reported  to  contain  from  trace 
to  0.034  %.°  Akerman  reports  that  the  ore  contains  about 
0.003  %  of  phosphorus." 

In  Sheffield,  however,  blister-steel  seems  still  to  be 
generally  used.  While  we  may  have  better  control  over 
the  percentage  of  carbon  in  the  cast-steel  when  using 
blister-steel  than  when  using  wrought-iron  and  charcoal, 
it  is  extremely  hard  to  believe  that,  starting  with  a  given 
wrought-iron,  it  should  make  any  difference  whatsoever 
in  the  excellence,  apart  from  carbon -percentage,  of  the 
product  whether  carburization  be  effected  by  charcoal  in 
the  large  crucible  of  a  converting-furnace,  or  by  charcoal 
in  the  small  crucible  of  a  melting-furnace.  The  crucible 
process  seems  to  delight  in  and  to  generate  an  atmosphere 
of  superstition  and  empiricism. 

Bell-Krupp  washed  metal  is  bought,  and  therefore  pro- 
bably used,  by  several  crucible -steel  makers.  If  thoroughly 
dephosphorized  it  should  be  an  excellent  material. 

In  using  scrap,  especially  high-carbon  steel  scrap,  there 
Is  much  uncertainty  as  to  its  quality,  and  hence  as  to 
that  of  the  product,  since  it  is  absolutely  impossible  to 
make  good  steel  from  phosphoric  or  sulphurous  materials 
in  acid  crucibles.  By  selecting  scrap  of  classes  for 
which  good  materials  are  habitually  used  (clinch-nails, 
screws,  etc.),  the  uncertainty  is  greatly  diminished,  but 
is  not  removed.  When  really  excellent  material  is  need- 
ed, we  must  use  scrap  of  known  and  guaranteed  phos- 
phorus-content, such  as  shearings  of  boiler-plate  from 
some  of  the  few  most  careful  mills,  etc. 

The  size  to  which  the  pieces  of  bar-iron  are  cut  may  be 
6"xl"x3".  That  of  pieces  of  scrap  is  usually  from  this 
size  down,  but  of  course  varies  greatly,  sometimes  reach- 
ing 6"x2£"x2i".  For  making  very  hard  steel,  chromium, 
tungsten  and  manganese  are  added  (cf.  pp.  48,  75,  81). 

The  only  evident  objection  to  the  use  of  cast-iron  and 
iron  ore  is  that  they  usually  hold  much  more  phosphorus 
and  sulphur  than  the  wrought-iron  and  steel  made  from 
them.  Where  this  objection  disappears,  as  with  some 
very  pure  Swedish  material,  the  percentage  of  carbon  of 
crucible- steel  may  be  advantageously  and  very  cheaply 
governed  by  using  them. 

There  is  a  common  belief  that,  for  given  composition, 
crucible-steel  made  from  open-hearth  or  Bessemer  steel  is 
not  nearly  as  good  as  that  made  from  wrought-iron  or 
blister-steel  (§  357). 

Additions. — Besides  the  charcoal  for  carburizing  the 
metal,  a  little  ferromanganese  or  spiegeleisen  is  usually 
added  to  prevent  blowholes  and  promote  forgeableness  ; 
about  a  struck  teaspoonful  of  oxide  of  manganese,  to 
form  a  thin  slag  (it  also  increases  the  absorption  of  silicon 
and  carbon);  and  often  physics,  not  to  say  nostrums,  such 


a  Ann.  Statistical  Kept.  Am.  Iron  and  Steel  Ass.,  p.  30,  1888. 
b  Testimony  of  Wm.  Metcalf,  Kept.  Select  Committee  on  Ordinance  and  War- 
ships, p.  318, 1886. 
c  Percy,  Iron  and  Steel,  p.  736. 
d  The  State  of  the  Iron  Manufacture  in  Sweden,  Stockholm,  1876,  p.  18. 


as  salt  (it  may  thin  the  slag),  ferrocyanide  of  potassium, 
(it  should  promote  carburization),  sal  ammoniac,  etc. 
Without  direct  experimental  evidence  we  cannot  tell 
whether  these  physics  have  any  valuable  action,  or  whether, 
as  one  strongly  suspects,  they  are  mere  gingerbread  pills. 
The  crucible-steel  maker  is  very  secretive  about  his  mix- 
tures ;  it  is  doubtful  whether  we  would  be  much  wiser 
than  now  if  he  told  us  frankly  all  he  certainly  Jcnew 
about  them. 

As  regards  the  quantity  of  charcoal  to  be  added  to  pro- 
duce steel  of  given  carbon-content,  I  can  give  no  sure 
rules.  Probably  from  60  to  75  %  of  the  carbon  of  the  char- 
coal is  taken  up.  The  charge  may  take  up  probably  not 
more  than  0.25  %  of  carbon  from  the  walls  of  a  new  com- 
mon graphite  crucible,  and  probably  not  more  than  0.15  % 
from  those  of  an  old  one.  In  a  coke-clay  crucible  the 
charge  may  gain  a  little  carbon  (say.  06  %}  from  the  cruci- 
ble, but  usually  loses,  say  up  to  0.23  %.  Spiegeleisen, 
ferromanganese  and  oxide  of  manganese,  and  long  and  hot 
killing,  increase  the  absorption  of  carbon:(see  §  369). 

§  365.  UNIFORMITY. — Clearly,  the  percentage  of  carbon 
in  the  ingot  depends  not  only  on  that  in  the  charge,  but 
on  the  proportion  of  rust  and  scale ;  on  the  tightness  of 
the  crucible ;  on  the  degree  to  which  the  graphite  or  coke 
of  its  walls  are  exposed  to  the  charge,  and  thus  on  the 
age  of  the  crucible  and  the  amount  of  corrosion  which  it 
undergoes  during  melting  ;  on  the  temperature  ;  and  on 
the  length  of  melting  and  killing.  So  great  is  the  un- 
certainty thus  introduced  that  a  well-known  steel-maker 
informs  me  that,  with  like  charges,  the  percentage  of 
carbon  in  the  ingot  may  vary  from  0.80  to  1.50  %.  This 
seems  to  me  rather  an  exaggeration,  and  the  statement  of 
another  and  very  eminent  crucible  steel-maker,  that  the 
carbon  of  the  ingot  may  vary  by  from  0.15^  to  0.20$ 
either  way  from  the  point  aimed  at,  seems  nearer  the 
mark. 

Taking  considerable  numbers  of  heats  at  random,  I 
found  that,  in  the  Bessemer  process,  the  greatest  deviation 
of  the  carbon-percentage  from  the  average  was  usually 
from  0.01  to  0.03  %  for  soft  steel,  and  only  0.04  %  even  for 
rail  steel  made  from  remelted  pig.  For  open-hearth  steel 
the  maximum  deviation  was  about  0.07  %  to  0.08  %.* 
Doubtless  the  deviations  would  be  somewhat  greater  in 
making  highly  carburized  steel  such  as  the  crucible  pro- 
cess usually  produces :  but,  allowing  for  this,  it  is  prob- 
able that  the  variations  between  the  different  ingots  of  a 
single  heat  in  the  crucible  process  is  considerably  greater 
than  that  between  different  heats  of  either  the  Bessemer 
or  the  open-hearth  process. 

With  regard  to  silicon  the  crucible  process  stands  at  a 
still  greater  disadvantage,  to  judge  from  the  experiments 
of  Table  179,  and  from  our  general  knowledge  of  the  sub- 
ject. I  found  the  range  of  variation  of  silicon  in  Bessemer 
steel  in  no  one  series  over  0.015  f0,  and  in  one  series  it  was 
only  0.009  %. 

§366.  IN  THE  MITIS  PROCESS  Nobel's  petroleum  fur- 
nace (Figure  155)  is  used.  It  runs  only  one  shift  at  a  time  ; 
four  crucibles  are  placed  in  the  furnace,  two  in  the  mid- 
dle and  two  in  the  hottest  chamber.  As  actually  practiced 
at  one  works,  the  charge  consists  solely  of  wrought-iron 


a  Trans.  Am.  Soc.  Mining  Eng.,  XV.  p.  347,  1887. 


MITIS     PROCESS.       §  366. 


309 


scrap,  when  the  softest  product  is  sought,  mixed  with 
more  or  less  steel  scrap  and  even  cast-iron  for  harder 
products. 

The  furnace  is  fired  the  night  before  melting:  by  seven 
the  following  morning  the  first  heat  of  two  pots  in  cham- 
ber a  is  melted.  This  ascertained  by  inserting  a  rod 
through  the  cover  of  the  orucible,  a  cold  ingot  said  to 
be  of  ferro-aluminium  (say  enough  8$  ferro-aluminium  to 
introduce  .05  to  .10  %  of  aluminium)  is  introduced  through 
this  same  hole,  the  lid  of  the  melting-hole  having 
for  this  purpose  alittlehole  immediately  above  the  crucible, 
usually  closed.  After  about  three  minutes  the  metal  is 
stirred  vigorously  with  a  little  iron  rod.  After  two  or  three 
minutes  more  the  cover  of  the  melting-hole  is  removed, 
one  crucible  is  drawn,  then  the  cover  is  replaced ;  the 
crucible  uncovered  ;  the  abundant  black  glassy  slag,  full 
of  shots  of  metal,  swabbed  up  (I  am  told  that  sometimes  a 
quart  of  it  is  removed),  and  the  metal  teemed.  Then  the 
second  crucible  is  drawn  in  like  manner.  Then  the  two 
crucibles  from  the  middle  are  transferred  to  the  hot 
chamber  a,  and  two  cold  ones  previously  filled  placed  in 
the  middle  chamber  a'.  From  this  time  on  a  pair  of  cruci- 
bles is  drawn  about  every  75  minutes  till  say  5  P.  M., 
making  9  heats  per  shift.  Table  172,  and  §§  359,360  give 
further  data.  Table  177  gives  the  actual  time  of  certain 
parts  of  the  operation  by  my  own  observation. 

TABLE  177.— TIMS  or  OPERATIONS  IN  THE  MITIS  PROCESS. 


i. 

II. 

III. 

IV. 

V. 

—  y  35" 

ty  7" 

Charge  examined.  

4'  10" 

y  3" 

Melting-hole  uncovered  * 

<y  o" 

V  0" 

V    0" 

<y  6" 

Crucible  out.  

V  5" 

Melting-hole  closed  

(X  10" 

0/  7« 

Crucible  in  teeming  tongs.  ..  . 

<y  12" 

V  30" 

&  20" 

<y  20" 

<y  so" 

(y  50" 

(y  45" 

ty  54" 

Teeming  ends  

1'  40" 

1'  45" 

1'  55" 

1'  47" 

g 

5 

12 

Watch  in  hand,  I  noted  that  this  transferring  the  cruci- 
bles from  one  chamber  to  the  other,  and  charging  fresh 
ones,  occupied  60  to  65  seconds  for  each  furnace,  ex- 
cluding the  time  occupied  in  getting  ready.  To  transfer 
a  crucible  from  one  chamber  to  the  other  took  fifteen 
seconds,  counting  from  the  time  of  uncovering  the  first 
to  that  of  covering  the  second  chamber.  The  sliding 
covers  of  the  melting-chambers  permit  very  rapid  move- 
ment. 

Though  it  was  nearly  two  minutes  from  the  time  of  leav- 
ing the  furnace  to  teeming  into  the  last  flask,  the  whole 
charge  seemed  to  run  out,  leaving  the  crucible  surpris- 
ingly clean  and  not  badly  corroded. 

The  quieting  effect  of  the  ferro-aluminium  is  very 
marked,  and  more  sudden  than  that  of  ferro-silicon  in  the 
open-hearth  process.  Watch  in  hand,  two  and  a  half 
minutes  after  adding  ferro-aluminium  to  a  charge,  which 
was  boiling  gently,  I  found  it  almost  absolutely  quiet. 
Poured  within  three  or  four  minutes  of  this  observation 
it  lay  perfectly  quiet  in  the  crucible  and  mould,  much 
like  cast-iron.  Examining  it  later  I  found  it  extremely 
tough. 

But,  while  the  addition  of  ferro-aluminium  quiets  an 
almost  carbonless  charge  effectively,  there  has  been  great 
trouble  in  getting  solid  castings  of  steel  of  about  0.25  per 
cent,  of  carbon,  and  the  use  of  ferro-silicon  for  this  pur- 
pose is  contemplated.  This  accords  with  Davenport's 


observation  (p.  87,  foot  note0),  that  the  addition  of  ferro- 
aluminium,  while  itthinnednon-carburetted  iron,  seemed 
to  stiffen  molten  carburetted  steel. 

Hatchets  cast  by  this  process  and  wholly  unforged  are 
now  selling  in  this  country.  Their  polished  surfaces 
show  only  a  moderate  number  of  blow-holes.  But  the  very 
soft  Mitis-castings  are  indeed  remarkable.  The  neck  of 
one  of  these,  which  contained  0.14  per  cent,  of  carbon  and 
0.24  per  cent,  of  silicon4,  which  had  not  been  annealed,  and 
which  was  said  to  have  been  made  from  horse-shoe  nails, 
was  Ty '  x  f"  and  about  2£  inches  long.  Fastening  one  end 
in  a  vise,  I  twisted  the  neck  two  complete  revolutions  (of 
360°)  before  it  broke.  Nicked  and  broken  with  a  sledge 
without  heating,  its  fracture  was  fine  crystalline  ;  forged, 
cooled,  nicked  and  broken,  its  fracture  was  extremely, 
indeed  extraordinarily,  silky,  more  like  that  of  copper 
than  that  of  iron.  In  both  cases  serious  blowholes  ap- 
peared. 

The  natural  field  for  Mitis  castings  is  to  replace  castings 
of  common  malleable-iron. 

They  are  necessarily  more  costly,  and  actually,  so  far 
as  my  observation  goes,  much  more  liable  to  contain 
serious  blowholes  than  malleable  castings  are.  My 
inquiries  among  those  who  have  used  Mitis  castings 
corroborates  my  own  experience,  that  they  are  as  yet 
very  untrustworthy.  Besides  the  serious  and  often  fatal 
blowholes,  there  is  much  variation  in  shrinkage,  so  that 
the  castings  often  fall  short  in  finishing,  and  many  of 
them  have  hard  spots.  On  the  other  hand,  they  are  in- 
comparably tougher  than  malleable  castings. 

Thus  the  Mitis  process  has  gone  a  step  beyond  the 
forms  of  the  crucible  and  open-hearth  processes  hitherto 
used,  in  producing  extremely  tough  castings,  almost  free 
from  carbon:  but  it  does  not  seem  to  have  overcome  the 
chief  obstacles  which  the  production  of  castings,  hard  or 
soft,  by  these  processes  has  met,  the  liability  to  blowholes, 
uncertainty  as  to  contraction,  and  heterogeneousness, 
whether  from  segregation  or  imperfect  mixing.  Nor  do 
I  see  that  it  is  more  likely  to  overcome  these  difficulties 
than  the  processes  with  which  it  competes,  while  the  very 
nature  of  the  castings  which  it  habitually  produces  tends 
to  exaggerate  them. 

Mitis  castings,  then,  seem  to  commend  themselves  for  pur- 
poses where  extreme  toughness  is  so  necessary  as  to  com- 
pensate for  greatly  increased  first  cost,  and  where  failure 
owing  to  presence  of  large  cavities  will  not  lead  to  serious 
consequences.  They  are  used  for  the  armatures  and  field- 
magnets  of  dynamo-electric  machines,  thanks  to  their 
extremely  low  magnetic  retentiveness,  due,  of  course,  to 
their  purity. 

Their  price,  depending  greatly  on  their  size,  shape  and 
number,  is  not  of  ten  much  below  12  cents  per  pound  in  this 
country  ;  that  of  small  malleable-iron  castings  of  usual 
simple  shapes  is  commonly  between  4  and  6  cents  per 
pound. 

On  pages  87  and  88  I  gave  reasons  for  doubting  that 
soft  Mitis  castings  contained  any  appreciable  quantity 
of  aluminium ;  none  had  been  found  in  them,  and  it 
seemed  likely  to  oxidizeand  scorify  instantly.  If  aluminium 
remained  unoxidized  in  any  of  these  castings  it  would  be 


a  I  have  to  thank  Messrs.  Hunt  &  Clapp,  of  Pittsburgh,  for  kindly  analyzing  this 
casting  for  this  work. 


310 


THE    METALLURGY    OP    STEEL. 


in  those  which  are  highly  carburetted,  the  carbon,  of 
course,  tending  to  prevent  the  oxidation  of  other  elements 
present,  aluminium  included.  But  a  careful  analysis  in 
Brown's  laboratory,  by  a  method  which  this  eminent 
chemist  has  devised  and  believes  trustworthy,  failed  to 
detect  more  than  0.02  per  cent,  of  aluminium  in  a  tool- 
steel  high-carbon  Mitis  casting,  to  which  the  usual  dose 
of  ferro-aluminium  had  been  added.  The  analytical 
method  is  of  such  a  nature  that  this  result  indicates  that 
not  more  than  0.02  percent,  of  aluminium  was  present; 
while  it  is  not  unlikely  that  a  considerable  part  of  this  0.02 
per  cent,  consisted  of  substances  other  than  aluminium. 

I  am  informed  that  the  Mitis  process  is  in  actual  use  in 
five  American  works,  in  four  different  States  ;  in  Sheffield, 
in  France,  and  in  Belgium*. 

§  367.  THE  COST  of  the  crucible  process  is  roughly 
estimated  in  Table  178.  The  cost  of  the  materials  varies  so 
widely,  according  to  their  purity,  that  any  assumed  cost 
would  be  more  likely  to  mislead  than  to  instruct.  It  is, 
therefore,  left  blank. 


TABLE  178.— ESTIMATED  COST  OF  MAKING  100  LBS.  or  STEEL  BY  THE  CBDCIBLE  PROCESS. 
SPECIAL  CHARGES  ONLY. 


Pittsburgh 
gas 
furnaces. 

New  Jersey 
anthracite 
furnaces. 

Mitis 
process  a. 

Material,  102  fcs.  of  iron,  according  to  qualily.  .  . 

Fuel.     100  tts.  slack  coal  @  3  cts.  per  76  Ibs 

$0.04 

230  tbs.  anthracite  @  $4.25  per  2,240  tts. 

$0.43 

87  Ibs.  petroleum  @  5  cts.  per  gal  

JO  60  ($0  19)b 

Labor  

28 

27 

33a 

Repairs  

.01 

.06 

10 

Crucibles  

22 

22 

45 

Moulds,  charcoal,  sundries  

.03 

.03 

03 

Total,  excluding  material  

$0.58 

$1.01 

$1  51  ($1  10)b 

a  For  comparison  with  the  other  processes  the  steel  is  supposed  to  be  cast  in  common  in- 
eot-monlds.  I  assume  that  the  puller-out's  labor  is  half  greater  than  in  anthracite  and  gas 
furnaces,  but  that  in  other  respects  the  labor  requirement  is  the  same  for  all.  To  allow  for 
moulding,  and  for  teeming  many  small  castings  by  the  Mitis  process,  the  cost  of  labor  should 
be  increased  considerably. 

b  Supposing  that  crude  oil  at  $0.016  per  gallon  is  used. 


THE  CHEMISTRY  OP  THE  CRUCIBLE   PROCESS. 

§  368.  The  following  sketch,  while  partly  speculative, 
is  in  large  part  based  on  and  in  harmony  with  the  results 
of  practice  and  of  the  experiments  detailed  in  Tables  179 
and  180. 

The  charge  contains  initially  a  moderate  quantity  of 
oxygen  as  rust,  scale,  and  the  slag  of  weld-iron.  This,  as 
well  as  the  trifling  quantity  of  atmospheric  oxygen 
initially  present,  and  free  oxygen  and  the  oxygen  of  any 
carbonic  acid  or  aqueous  vapor  which  may  enter  by  leak- 
age or  diffusion,  should  tend  to  form  oxide  of  iron  and  (if 
the  charge  contain  spiegeleisen  or  ferro-manganese)  of 
manganese.  This  tendency  is  opposed  by  the  carbon  of 
the  crucible-walls,  which,  especially  in  case  of  new  gra- 
phite crucibles,  tends  to  take  up  the  free  oxygen  and  to 
red  uce  the  carbonic  acid  present. 

The  metallic  oxides,  melting  first  to  a  very  basic,  cor- 
rosive, oxidizing  slag,  should  collect  at  the  bottom  of  the 


a  Private  comiDunicatiou,  The  U.  3.  Mitis  Co.,  Jan.  7th,  1889. 


crucible  and  react  on  its  walls,  and  later  on  the  gradually 
accumulating  bath  of  molten  metal.  The  first  action  of 
this  slag  on  the  metal  should  be  strongly  fining,  tending 
to  oxidize  carbon,  silicon  and  manganese.  As  the  slag- 
level  is  gradually  raised  by  the  accumulation  of  the  molten 
metal  beneath,  the  sl&g  corrodes  ring  after  ring  of  the 
crucible- walls,  exposing  their  graphite  or  coke  to  the 
rising  underlying  metal,  which  absorbs  carbon  voraciously. 
The  fining  action  should  thus  weaken  rapidly  as  the  slag 
grows  acid,  through  absorption  of  silica  from  the  crucible, 
and  through  the  reduction  of  its  oxides,  partly  by  the 
metal's  carbon  and  silicon,  partly  (incase  of  strongly 
graphitic  crucibles  chiefly)  by  the  carbon  of  the  crucible. 
Thus,  fining  probably  soon  gives  way  to  carburization, 
the  carburized  metal  reducing  and  absorbing  silicon*  from 
the  now  acid  slag,  and  from  the  acid  crucible-walls,  from 
these  probably  the  more  readily  the  more  silicious  the 
clay  which  composes  them. 

The  net  result,  under  usual  conditions,  as  indicated 
by  our  experimental  data,  is  that  in  graphite  crucibles, 
the  metal  gains  in  carbon  (usually  by  from  0.  to  0.25$), 
and  in  silicon  (usually  by  from  0.05  to  0.20%)  ;  that,  if 
spiegeleisen  or  ferro-manganese  is  charged  before  melt- 
ing, much  of  its  manganese  is  slagged,  and  the  absorption 
of  carbon  is  increased  very  greatly,  rising  even  to  nearly 
2%  (numbers  31  and  41),  and  that  of  silicon  greatly,  rising 
sometimes  to  nearly  0.50$  (numbers  30  and  39),  when 
about  3.5%  of  ferro-manganese  is  added  ;  and  that  if  oxide 
of  manganese  is  charged,  part  of  its  manganese  is  some- 
times if  not  usually  reduced  and  absorbed  by  the  metal. 
The  more  highly  carburetted  the  crucible- walls,  the  greater 
will  be  the  net  absorption  of  carbon,  manganese  and  sili- 
con. 

In  clay  crucibles  the  charge  either  loses  carbon  (say 
up  to  0.23$)  or  gains  but  slightly  (say  up  k>  0.06%),  while, 
if  we  may  trust  our  scanty  data,  gaining  but  slightly  in 
silicon,  unless  manganese  or  its  oxide  be  present. 

If  the  charge  contains  charcoal  or  graphite,  this  both 
carburizes  the  metal  during  heating  to  the  melting  point 
(probably  most  of  its  carbon  is  absorbed  by  the  steel), 
and  greatly  shortens  and  weakens  if  it  does  not  eliminate 
the  fining  period,  by  protecting  iron  and  manganese 
from  oxidation,  and  by  reducing  at  least  a  part  of  their 
oxides. 

If,  on  the  other  hand,  oxide  of  manganese  is  charged, 
it  tends  to  intensify  and  prolong  the  fining,  to  post- 
pone and  enfeeble  the  carburization,  opposing  the  action 
of  the  charcoal. 

Risking  repetition,  let  us  now  take  up  the  behavior 
of  silicon,  carbon  and  manganese  separately. 

THE  ABSORPTION  OF  SILICON.— Unless  basic  crucibles  be 
used,  the  steel  always  takes  up  silicon,  the  proportion 
absorbed  in  general  increasing, 

A,  with  the  proportion  of  graphite  or  coke  in  the  cruci- 
ble walls ; 

a  From  a  basic  slag  iron  may  be  reduced,  as  is  indicated  by  numbers  82-4.  of  Table 
180.  The  fusion  in  this  case  occurred  in  limeless  magnesia  crucibles.  Ferric  oxide 
and  lime  were  added  to  the  charge  in  the  proportions  225  ferric  oxide  to  100  of  lime. 
The  iron  remaining  in  the  resulting  slag  corresponded  to  only  153  of  ferric  oxide  to 
100  of  lime.  The  slag  can  hardly  have  received  lime,  and  it  can  hardly  have  lost  iron 
except  by  reduction  to  the  metallic  state.  This  view  is  favored  by  the  presence  in 
the  slag  of  many  globules  of  iron,  some  visible  to  the  naked  eye,  others  microscopic. 
There  is,  unfortunately,  a  possibility  that  the  apparent  reduction  of  iron  may  be 
due  to  heterogeneousness  of  slag,  as  Brand  states  that  the  slag  was  sintered  rather 
than  molten,  and  that  its  color  was  not  uniform. 


CHANGE  OF  COMPOSITION  IN  CRUCIBLE-MELTING. 


311 


TABLE  179. — CHANGE  OP  COMPOSITION  IN  CRUCIBLE-MELTING. 


Description  of  Crucible 
used. 

Change  of  composition  during  melting. 

Description  of  charge  and  product. 

Time  of 
killing. 

Remarks. 

^  Prox  mate  composition 
.£  of  miztureforcrucihles 

Percentage 
of  carbon. 

Initial  composi- 
tion. 

Final. 

Gain  (-)-)  or  Loss  (  —  ). 

Charge. 

Product. 

o    , 
•3  -^ 
S  «2 

3  |a 

Ji 

O 

t> 

sf 

P  *•> 
I* 

a| 

oa 

O.X. 

isi 

to 

Mn.*. 

C.%. 

Si.  *. 

vi 

a 

C.f 

SI.*. 

Mn.  %. 

ll 

is 

Description. 

Description. 

R 

Ban 

g 

14 

I  Like  charges,  of  3W  weld-steel. 
j  70*  wrought-iron. 

J-  Weld-steel. 

Weld-steel  and  ferro-manganese. 
Steel  only. 
Steel  and  0.4,<  oxide  of  manganese. 

V  White  cast-iron,  melted  thrice. 

Weld-Btecl,  melted  twice. 
!•  Wrought-iron,  melted  twice  

Many  blowholes. 
Solid. 

Crucible  pierced, 
n            n 

Clay  added. 
No  clay  added. 

Clay  added. 

j  Crucible  very  little 
1     eaten. 

Crucible  mnch  eaten. 

tt            ii         ti 

Crucible  little  eaten. 

Crucible  much  eaten. 
it           it         n 
j  Ferro   charged   be- 
1     fore  melting, 
t  Ferro  charged  after 
1     melting. 

1st  melting. 
2d         ii 
3d         n 
1st        ii 
2d         n 
3d         ii 

Melted  in  7  hours. 

R  Cla 

R        1! 

L    ... 

y  an 
tt 

dgr 

1! 

aph 

ite. 
11 

28 
40 
28 
39 
39 
40 

27 

.39 

1.29 
1.29 
1.31 

.01 
.01 

.05 

.12 
.12 
1.01 

1.14 
1.24 

1.86 

.23 
.24 

.49 

.10 
.15 
.75 
101 

—  .15 
—  .05 
+  .52 

+  .22 
+  .23 
+.44 

—.02 
+  .03 
—.26 

n 

R 

R 

40 

211 

M    48 
it      it 
n      it 
n      It 
tl      it 
n     n 
ii     n 
ii    83 
ii     n 
n     n 
M     n 
n     n 
n     n 
ii     n 
n     11 
ti  

:::: 

^—  •—> 

52 

tt 

!1 

,-•—.' 

40± 

3.  59 
3.71 
3.77 
94 

.07 
.58 
.76 
0? 

2.04 
1.91 
1.80 
.24 

3.71 

3.77 
3.64 
1.19 

.58 
.76 
1.07 
.36 

1.91 
1.86 
1.86 

•4-  .12 
+  .06 
—  .13 
+  .25 
-f  .08 
+  .20 

+  .10 

4-  .22 

-|-    .32 
4-  .67 
—  .05 
+  .40 
+  .31 
•f    63 

+  .51 

+  .18 
1.31 
+  .34 
+  .27 
+  .06 
+  .18 
+  .28 
+  .31 
+  .29 
+  .33 
+  .15 
+  .15 
+  28 

—  .13 
—.05 
.0 

[-.02 

(-.«" 
-.«, 

fca 

75.0 
1.7 

32!6 
1.1 
32.0 
1.1 
24.3 
38.0 
1.1 
24.3 

19.8 
46.3 
19.8 
38.6 
2.2 

'i'.s 

64.4 

'i'.s 

64.4 
.9 
32.0 

19!8 
46.3 

6i!4 
1.8 

66!  i 

2.2 

55!  i 

55.1 
55.1 
55.1 
55.1 
55.1 
49.6 
5.5 

M 

11 

1  19 

36 

1.27 
.25 
.35 
1.13 
1.45 
.72 
.67 
1.31 
1.62 
07 

.63 
.08 
.26 
.31 
.62 
.29 
.62 
.20 
.35 
.30 

.22 

'  J9' 

'.09 
.56 

.74 

M 

.05 
.25 
.91 

.02 
.08 
.03 

.08 
'"2i' 

17 

ro± 

Weld-steel,  melted  twice  

It 

.05 

tr. 

.11 

Wrought-iron,  melted  twice  •! 

Porous  1 

It 
n 

.91 

1.31 
04 

.05 
.20 

o-> 

.14 
.56 

1  Weld-eteel,  melted  twice,  with  Ijf  of 
f     oxide  of  manganese. 

Porous. 
Solid. 

3h. 
lh.± 

11 

it 

50  ± 
50  ± 
50— 
•SO— 

.67 

1.12 
1.15 
.09 
.32 

.30 
.02 
.35 
.02 
90 

'".is 

'".M 

1.34 

1.15 
1.11 
.32 
.39 

1.47 
1.50 
2.4(i 

2.92 
2.57 
2.21 
2.30 
1.21 

1.61 

1.54 

1.04 

1.36 
1.27 
2.60 

1.29 

.49 
.14 

.66 
.35 
.61 
.20 

.39 

.37 
.69 
.44 

.35 
.61 
.53 
.61 

.14 
23 

.24 

.19 

.64 
.84 
.36 

.33 

.11 
046 

'  .'ii' 
"io' 

.88 
.89 
1.52 

1.80 
1.51 
1.28 
1.81 

.19 

.42 

.35 

1.82 

.83 
.94 
1.17 

1.60 

4-  .67 

-f  .03 
-  .04 
+  .23 
+  .07 

+  .69 
+  .03 
+1.47 

+1.93 
+  .H 
+1.25 
+  .06 

—  .01 
+  .12 

-|-  .05 

+  .01 

+  .33 
+  .22 
+1.50 

+  .18 
—  .45 

+  .36 
+  .33 
+  .26 
+.18 
+.19 

+  .27 
+  .31 
+  .39 

+.30 
+.17 
+.48 

+  .08 

+.09 
+  .18 

+  .19 
+  .05 

+  .49 
+  .65 
+  .16 

+  .13 

+.04 
+  .006 
+  .08 
+.11 
+  .04 

+.04 
+.02 

+.29 

[-•«" 

[•+.01 

-.20] 
+.01 
-.56] 

-.28] 
—.01 
—  .80] 
-.07 

-,j 
-J 

- 

—  .63J 

-1.62 
—  .89 

-i.os] 
ni 

Weld  steel,  melted  twice  ;  new  crucible 

j  Wrought-iron,  melted  twice  ;  old  cra- 
ft    cible. 

!•  Weld-steel,  with  ferro-manganese. 

ii 

ii    48 

52 

.78 
1.47 
.99 

.99 
2.46 
.99 
2.24 

1.22 
1.49 

1.49 

1.03 

1.03 
1.04 
1.10 

1.10 
.94 

.10 
.37 
.05 

.05 
.44 
.05 
.53 

.05 
.05 

05 

.14 

.14 
.19 
.20 

.20 

.06 
01 

1.08 
.88 
2.08 

2.08 
1.52 
2.08 
1.28 

.45 

.80 

.80 

2.45 

2.45 

1.82 
2.22 

2.22 

40 

40 
40 
28 

28 

25± 
25± 

0 

n 
ii 
n 
tl 

Weld-steel  1 

Ferro-manganese  ( 
Weld-steel  i 

Ferro-manganese  ) 
No.  30  remelted. 
Weld-steel  1 

ti  

Ingot  from  No.  33. 

Absolutely  solid.. 

n             ii 

n             it 

Rather  porous  — 
Solid  

Ih.  45m 
2h. 

"     15 
n      11 

M        II 

II        II 

II        It 
II        11 
II 

35 
tt 

!1 

(1 

1! 

GO 

ti 

it 

tt 

ii 
n 

Spiegel  of  8.74*  Mn  

Cast-iron  
Dannemora  iron  
Spiegel  of  8.74:*  Mn  

15m. 

Ih.  45m 
3h.  15m 
15m. 

Weld  steel                           f 

)  Ferro-manganeee  1 

Ferro-manganeee  I 

Ferro-manganese  i 

n      0 
II     II 
11     II 
11     II 

11     II 

11 
11 

It 

..    II 
..     II 
L 

0 
n 

ti 

tt 

5 

tl 

ti 
ti 
ti 

i5T~ 

t! 
tt 
It 

95 
n 

1! 
tl 
II 

\ 

-.31] 
-.05 

-,99±] 
—.58 
....       ] 

Weld-steel  f 
Weld-steel             

Blowholes. 
Many  blowholes. 
n              ii 
Compact  

45m. 
7h. 

lh.45m. 
3h. 

.96 
.77 

1.22 

.78 
.45 

1.26 

.oa 

.15 
.05 

.11 
.08 

.20 

.77 
.55 

1.20 

.70 
.34 

l.*6 
1.03 
.84 

.15 
.26 

.09 

.15 
.10 

.SO 
.48 
.12 

.14 
.12 

1.41 
.83 
.82 

19 

—  .22 
-  .02 
—  .08 
—  .11 

—  .23 

Ingot  from  No.  45  

.45 

.17 
.11 

2.4± 
1.41 

Weld-steel. 
Cast-steel. 
Weld-steel. 
Ferro-manganese. 
Ingot  from  No.  50. 
Non-manganiferous  steel. 
Manganese  oxide. 
Weld-steel, 
Weld-steel  and  ferro-manganese. 
Weld-steel. 
Weld-eteel  and  ferro-manganese. 

25± 
it 
it 

.73 
.92 
.94 
1.14 
.015 
60 

.02 
.04 
.10 
.12 
.01 

.13 
2.63 
.26 
2.76 
P.  02 

.75 
2.81 
.74 
2.86 
.02 
70 

.08 
.37 
.10 
.47 
.02 

.18 
1.32 
.26 
1.53 
P.03 

+  .02 

+1.89 
—  .20 
+1.72 
+  .005 
T     10 

+.06 
+.33 
0 
+.35 
+  .01 

+0.5 
-1.31 
0 
—1.23 
P+  .01 

ii 

n   .... 

n 
M 

:{i 

M     .... 

II 

1  3  like  charges  (steel  and  iron),  melt-  1 
V    ed  successively  in  the  same  graph-  -< 
i     ite  crucible.                                     ( 
3  like  charges  (steel  and  iron),  melt-  | 
v    ed  successively  in  the  same  coke-  ^ 
}     clay  crucible. 
Wrought-iron. 
Spiegeleisen. 
Same  as  No.  64. 
Wrought  iron  

•• 

60 

66 

+    06 

" 

60 

60 

0 

f  ^ 

]:::::::::::: 

.60 
.60 
60 

.66 
57 



+  .06 
03 

56 

04 

4 

55 

43 

.12 

') 

I 

i!    35 

H      0 
tt      tl 
11      tl 
tt   

55 

88 

+    33 

1 

0 
tt 
it 

f  £ 

,100 

11 
II 

50 

41 

09 

i 

50.1 
5.0 

.50 
.58 
.74 

.74 

.74 

1.50 
1.60 
.80 
.75 
.57 

+1.00 
11.02 
.06 
.01 
—  .17 

1 

Spiegeleisen  

Same  as  No.  66,  with  0.55  Ibs.  graphite. 
Steel,  iron  and  graphite. 
j  3  like  charges,  melted  successively  in 
)     the  same  crucible. 
Steel,  iron  and  spiegel. 
Wrought-iron. 
White  cast-iron. 
Steel. 
Spiegeleisen. 
Ixide  of  manganese. 

I 

;p 

,,jc 

lay 
cr 

lay 
cr 

(and  coke  f)  1 
ucible.         ( 

(and  coke?)  1 
ucible.          f 

.72 
.30 

.... 

1.20 
.89 

+  .48 
+  .59 

i 

40.2 
14.9 
63.4 
.6 
.6 

1 

1  to  3.  Like  charges  are  melted  in  crucibles  containingdifferent  proportions  of  carbon,  other  conditions  being  constant.    Reiser. 
4  to  6.  In  4  and  5  like  steel  is  melted  in  crucibles  made  with  different  proportions  of  graphite.     In  5  and  6  the  same  steel  is  melted  in  crucibles  made  with  like  proportions    of 
aphite,  but  2%  of  ferro-manganese  is  added  in  No.  6,  while  none  is  added  in  No.  5. 
7-8.  Apparently  like  charges  melted  in  7  without,  in  8  with  addition  of  0.4£  of  oxide  of  manganese.    Reiser. 

12  and  13.  Weld-steel  (gefrischter  Hohstahl)  is  melted  once  (No.  12)  and  twice  (No.  13). 

14  and  15.  Wrouaftt-iron  (gefrischtes  Schmiedeisen)  melted  once  (No.  14)  and  twice  (No.  15).    The  ingot  from  No.  14  was  full  of  blowholes,  that  from  No.  15  was  "  perfectly  solid." 

16-17.  Weld-steel  melted  once  (No.  16)  and  twice  (No.  17).    The  crucible  became  perforated  above  the  level  of  the  steel. 

18-19.  Wrought-iron  melted  once  (No.  18)  and  twice  (No.  19).    The  fir  st  melting  yielded  a  porous,  the  second  a  compact  ingot.    The  crucible  was  perforated  above  the  level  of  the 

20-21 .  Weld-steel  melted  once  (No.  20)  and  twice  (No.  21),  each  time  with  If  of  oxide  of  manganese.    The  crucible  was  not  perforated,  the  part  above  the  steel-level  being  made  with 
the  usual  mixture  of  equal  parts  of  graphite  and  clay. 

22-23.  Wrought-iron  melted  once  (i2)  and  twice  (No.  23),  yielding  in  the  first  case  a  porous  and  in  the  second  a  solid  ingot.    The  crucible  was  not  perforated. 

24-25.  Weld-steel  melted  once  (No.  24)  and  twice  (No.  25),  each  time  in  a  previously  unused  crucible. 

26-27.  Wrought-iron  melted  once  (No.  26)  in  a  once  used  crucible,  and  a  second  time  (No.  27)  in  the  same  crucible. 

28-29.  Weld-steel  and  ferro  manganese  are  melted  once  (No.  28)  and  then  a  second  time  (No.  29),  and  now  held  molten  at  the  highest  heat  for  three  hours. 

30-3 1 .  Weld-steel  and  ferro-mauj.-anese  are  melted  once  with  the  addition  of  a  little  fusible  clay  (No.  30)  and  once  without  it  (31).     In  30  the  steel  was  killed  for  about  an  hour.    In  32  tie 


312 


CHANGE  OF  COMPOSITION  IN  CRUCIBLE-MELTING. 


crucible,  where  in  contact  with  the  steel,  was  corroded  to  a  depth  of  about  .31  inches  (8mm).    Tho  graphite  thus  set  free  should  contain  about  1.15  IDS.  of  carbon  (520  grammes),  or  more  thac 
enough  to  account  for  the  carbon  taken  tip  by  the  steel. 

32.  24.25  pounds  of  the  ingot  resulting  from  No.  30  were  remelted  in  a  similar  crucible. 

33.  31.96  pounds  ofweld-steel  and  1.10  pounds  of  ferro-manganese  are  melted  with  clay  in  a  graphite  crucible. 

34.  24.25  pounds  of  the  ingot  from  33  are  remelted  in  a  like  crucible. 

35.  Regular  Duisburg  practice  :  19.84pounds  of  Swedish  cast-iron  and  46.3  pounds  of  wronght-iron  melted  in  3  hours  45  minutes,  then  killed  for  1  hour  45  minutes,  yielding  an  absolutely 
solid  ingot.    The  crucible  was  very  slightly  corroded,  and  very  little  slag  formed. 

36.  19.84  pounds  Swedish  cast-iron  and  3S.58  pounds  Dannemora  wrougut-iron,  with  2.2  pounds  of  charcoal-spiegeleisen  containing  8.74*  of  manganese,  were  melted  in  2  hours  40 
minutes  and  killed  at  a  high  temperature  for  3  hours.    The  crucible  was  much  eaten,  and  much  slag  formed. 

37.  The  same  as  36,  except  that  the  crucible  was  lined  with  clay.    The  clay  lining  was  destroyed  and  the  crucible  much  eaten. 

38.  64.4  pounds  of  weld-steel  with  1.8  pounds  of  ferro-mauganese  of  81.3$  of  manganese  melted  in  3  hours  30  minutes,  killed  for  15  minutes.    The  ingot  had  some  blowholes;  the 
crucible  was  little  eaten. 

39.  The  same  mixture  melted  in  the  same  way,  but  killed  1  honr  45  minutes.    Much  slag  formed,  crucible  much  eaten,  steel  solid. 

40.  Half  of  the  ingot  from  38  was  remelted  in  the  crucible  used  in  No.  39  in  2  hours  30  minutes,  then  killed  for  8  hours  15  minutes  at  a  high  heat.    The  crucible  much  eaten. 

41.  1.8  pounds  of  ferro-mangane«e  and  64.4  pounds  of  weld-steel  melted  together,  killed  only  15  minutes.    3.3  pounds  of  slag  formed  and  the  crucible  eaten  .39  inches  deep. 

42.  Charge  of  composition  like  that  of  41.  but  the  ferro-manganese  was  stirred  into  the  steel  after  melting. 

43  to  47  were  carried  out  in  crucibles  so  lined  with  clay  that  the  charge  was  completely  protected  from  the  action  of  the  graphite  of  the  crucible. 

43.  Weld-steel:  the  molten  metal  was  wild,  rose  and  gave  an  ingot  with  blowholes. 

44.  Wrought-iron  with  0.04$  of  silicon  gave  a  very  porous  ingot. 

45.  Weld-steel:  the  gradual  heating  of  steel  and  crucible  occupied  9  to  12  hours;  killing.  45 minutes.    The  resulting  molten  metal  scattered,  rose,  and  formed  a  very  porous  in»ot. 

46.  The  ingot  from  45  remelted;  killed  7  hours  at  the  highest  heat.    A  compact  ingot  resulted,  with  much  slag. 

47.  The  frame  charge  as  No.  35,  19.8  pounds  of  Swedish  cast-iron  and  46. 3  pounds  of  Dannemora  wrought-iron.    It  was  melted  and  treated  in  the  same  way  as  No.  35,  except  that 
the  crucible  of  No.  47  was  lined  with  clay.    The  steel  was  restless,  and  formed  a  porous  ingot. 

48  to  51.  Fusions  in  clay  crucibles  containing  only  5*  of  coke. 

.12.  66.2  pounds  of  weld-steel,  poor  in  manganese,  are  melted  with  2.2  pounds  of  calcined  oxide  of  manganese. 

53-56.  Weld-steel  is  melted  in  clay-graphite  crucibles,  in  53  and  55  alone,  in  54  and  56  with  ferro-manganeae  of  73.76*  of  manganese. 

57.  After-blown  basic  metal,  unrecarburized,  poured  into  a  glowing  crucible,  placed  at  once  in  the  crucible  furnace,  and  held  molten  for  three  hours;  on  teeming,  it  now  scattered 
and  rose  more  than  before  killing. 

59  to  63.  Acharge  of  33  pounds  of  steel,  of  0.92*  of  carbon,  22  pounds  of  wrought-iron,  of  0.10*  of  carbon,  was  melted  in  three  successive  fusions  in  the  same  graphite  crucible;  then 
in  three  successive  fusions  in  the  same  coke-clay  crucible.  It  is  reasonably  but  not  absolutely  certain  from  the  description  that  a  new  charge  was  taken  for  each  fusion. 

66.  7  hours  needed  to  melt  the  charge. 

67.  The  same  charge  as  No.  66  with  250  grammes  of  graphite.    If  we  suppose  that  the  whole  of  the  graphite  was  taken  up  by  the  steel,  this  does  not  account  for  the  gain  of  carbon. 
The  initial  carbon,  .50*,  does  not  include  the  graphite. 

68.  33  pounds  of  steel  with  0.9£  of  carbon,  and  23  pounds  of  wrought-iron  with  0.1W  of  carbon  and  .83  pounds  of  graphite  are  melted  together.    The  initial  carbon  given,  0.58*,  does 
not  include  the  graphite. 

69-7 1 .  Like  charges  of  41.34  pounds  of  steel,  11.57  pounds  of  iron  and  1.7  pounds  of  spiegeleisen,  are  melted  successively  in  the  same  coke-clay  crucible. 

REFERENCES.  1  to  8.  Ledebur,  Handbuch  der  Eisenhuttenkunde,  p.  854;  Stahl  and  Eisen,  III.,  p.  603,  1883. 

9  to  27,  also  5  7.  Muller,  Stahl  und  Eisen,  V.,  p.  179, 1885. 

88  to  52.  Idem,  VI.,  p.  695,  1886. 

63  to  56,  Ledebur,  Stahl  nnd  Eisen,  V.,  p.  370,  1885. 

In  numbers  32,  34,  42  and  53, 1  have  taken  the  liberty  of  correcting  what  appear  to  be  errors  in  subtraction  in  the  originals. 


TABLE  180.— CHANGE  op  COMPOSITION  IN  CRUCIBLE-MELTING,  BRAND. 


Number. 

Description  of  Crucibles  Used. 

Change  of  Composition. 

C 

Si 

Mn 

S 

P 

1 

Proximate 
Composition. 

Ultimate  Composition. 

Graphite. 

o 
O 

Fat  Clay. 

Burned  Clay. 

Old  Pots. 

Bauxite. 

C 

o 

O 

3 

& 
& 

1 

Other  Bases. 

* 

f 

' 

• 

t 

71 
72 

73 
74 
75 

20 

•M 

50 

18.60 

12.78 

34.71 

1.24 

.37 

1.23 

The  charge  contained  originally  
Immediately  after  complete  fusion  
Loss  or  gain  
45  minutes  after  fusion  
Loss  or  gain  
90  minutes  after  fusion  

.23 
.38 

"!44 
"!50 

'+.is 

'+.06 
+  06 

.12 
.10 

'".iii 
'"25 

'—.bit 

+:62 

.74 
.36 

-.as 

.03 
.04 

"!6i 
'.'046 

'+'.6i 
'"!6 

+"66o 

.223 
.223 

'!824 
'.'224 

...„ 

+!66i 
...„ 

•• 











135  minutes  after  fusion 

53 

30 

38 

224 

Lops  or  gain  

+.03 

+  05 

+  02 

+  005 

0 

76 

77 

78 

40.43 

24.63 

27.89 

6.78 

The  charge  contained  originally  

.23 

.119 

029 

Very  slightly  inclined  to  rise 
Perfectly  quiet. 

One  hour  after  complete  fusion  
Loss  or  gain  
3^  hours  after  complete  fusion  

.84 
95 

'+.6i 

.211 

296 

+1692 

.035 
039 

+'.006 

LOPS  or  cain  

+  11 

+  085 

+  664 

79 
80 

81 

0 

53.92 

40.57 

6.28 

•'••• 

The  charge  contained  originally  

36 

143 

028 

Strong  tendency  to  rise. 
Slight  tendency  to  rise. 

.... 

" 

.. 

One  hour  after  fusion  
Loss  or  gain  

.33 

28 

—'.03 

.13 

178 

—  !6is 

.037 

'  'oil 

+:669 

Loss  or  gain  

—  05 

+  048 

+  004 

81.6 
82 

83 
84 

0 

4.80 

2.49 

MgO 
92.62 

s 
.099 

The  charge  contained  originally  

.23 

tr 

.119 
0 

.74 

.029 
063 

.223 
090 

Loss  or  gain  
45  minutes  after  melting  

tr. 

—  .23 

"6" 

—.119 

'  Vr'.  ' 

—.74 

'  .'065 

+  .034 
+  002 

'.'050 

—.133 

-!6or 

1  hour  and  30  minutes  after  melting.  .  . 
Loss  or  gain  

.018 

+  .018 

0 

0 

.077 

.043 





... 

A  mixture  of  puddled  iron  and  spiegeleisen,  95*  of  the  former  with  5*  of  the  latter  in  the  first,  second  and  fourth  sets;  92*  of  the  former  and  8*  of  the  latter  in  the  third  set,  was  melted 

n  crucibles  ot  four  different  compositions.    In  the  first  set,  coke-clay ;  in  the  second,  graphite  clay;  in  the  third,  pure  clay;  in  the  fourth  magnesia  crucibles  were  used.    In  the  first  three 

s  the  molten  steel  was  held  in  the  crucible,  samples  being  removed  from  time  to  time  through  a  two-inch  hole  in  the  lid,  to  learn  the  changes  in  the    metals'  composition.    In  the  first, 

:ond,  and  third  sets  the  crucibles  bad  a  capacity  of  60  pounds  each.    The  magnesia  crucibles  of  the  fourth  set  were  inclosed  in  60  pound  graphite  crucibles,  the  space  between  them 

ng  rammed  with  graphite.    These  magnesia  crucibles  were  cemented  with  tar,  which  was  burnt  out  by  a  five  days  heating  in  the  oxidizing  flame  of    an  annealing  furnace.    Three 

XLIV  81"  cn  were  u       *or  tnl8  set' one  for  eacl1  ot  toe  8amPles  Nos.  82  to  84,  and  to  each  two  parts  of  ferric  oxide  and  one  of  lime  were  added.    Brand,  Berg  und  Htttt   Zeit 


THE     CHEMISTRY     OF     THE     CRUCIBLE     PROCESS.      §368. 


313 


B,  probably  with  the  proportion  of  carbon  in  the  metal 
itself ; 

C,  with  the  length  of  killing  ; 

Z>,  with  the  proportion  of  metallic  (i.e.,  tmoxidized) 
manganese  present ; 

E,  the  addition  of  oxide  of  manganese,  however,  prob- 
ably usually  diminishes  the  absorption  of  silicon. 

A.  The  Influence  of  the  Proportion  of  Carbon  in  the 
Crucible-  Walls. — In  the  perfectly  carbonless  crucibles, 
43  to  47,  and  in  the  clay  crucibles  with  only  5$  of  coke, 
48  to  52,  wrought-iron  takes  up  almost  no  silicon,  and 
steel  relatively  little ;  with  28%  of  carbon  or  more  in  the 
crucible  walls  the  absorption  of  silicon  is  rmich  more 
marked,  amounting  on  an  average  to  something  like 
0.30$  in  the  usually  manganiferou^  charges  of  Table  179. 
Further  increase  in  the  proportion  of  carbon  present  in 
the  crucible- walls  seems  to  increase  the  absorption  of 
silicon  very  much  more  when  the  charge  itself  contains 
but  little  than  when  it  contains  much  carbon.  Thus  we 
find  relatively  little  increase  in  the  silicon-absorption  by 
high-carbon  steel  as  the  carbon  content  of  the  crucible- 
walls  rises  from  28%  to  39$  in  numbers  4  and  5  ;  from  about 
40  to  about  50$  and  arain  to  about  70$  in  numbers  12-13, 
24-25  and  16-17.  Yet  these  same  increments  in  the 
carbon-content  of  the  crucible-walls  increase  the  silicon- 
absorption  greatly  when  the  charge  is  wrought-iron,  as 
Table  181  shows : 

TABLE  181.—  ABSORPTION  OF  SILICON  AS  AFFECTED  BY  THE  PROPOBTION  OF  CARBON  IN  THE 

CRUCIBLE-WALLS. 


Carbon  content  of  crucible-walls,* 

Absorption  of  Silicon  by  wronght-iron,  %. 
Number  in  Table  179 


0.006 
44 


40± 


0.08 
14 


50±       70± 


0.18 
26 


0.29 
18 


0.28 
22 


The  following  explanation  seems  to  cover  the  ground 
fairly.  The  reduction  of  silicon  is  probably  effected  by 
the  carbon  of  the  metal  and  that  of  the  crucible-walls 
jointly,  but  chiefly  by  the  latter,  thanks  to  the  much 
more  intimate  and  extended  contact  of  the  graphite  with 
the  acid  and  easily  reduced  silicates  of  the  walls,  than  of 
the  steel  with  the  supernatant  slag.  (Needless  to  say,  the 
presence  of  the  molten  steel  is  essential  to  this  reduction 
of  silicon:  cf.  §  61,  p.  36.)  Thus  we  note  that  when  even 
highly  carburetted  steel  is  melted  in  carbonless  crucibles 
(Nos.  43-7)  the  absorption  of  silicon  is  very  slight,  from 
.04  to  .11$.  But  in  order  that  the  silicon  reduced  from 
the  walls  and  absorbed  by  the  metal  should  remain  in  the 
metal,  the  latter  must  contain  a  fair  proportion  of  carbon. 

Now,  the  metal  takes  up  carbon  from  the  crucible  walls 
to  a  degree  which  probably  increases  rapidly  with  their 
proportion  of  carbon.  But  a  given  absolute  absorption  of 
carbon  from  the  crucible- walls  has  a  vastly  greater  rela- 
tive effect  on  the  carbon-content  and  consequent  silicon- 
reducing  power  of  metal  initially  almost  carbonless,  say 
wrought-iron,  than  on  those  of  initially  highly  carbur- 
etted metal :  e.g.,  an  absorption  of  0.25%  of  carbon  in- 
creases by  400%  the  carbon-content  of  metal  holding 
initially  but  0.05$  of  carbon,  but  that  of  metal  with  1.00 
of  carbon  by  only  25%.  Add  to  this  the  fact  that  the  ab- 
solute absorption  of  carbon  seems  in  general  to  be  de- 
cidedly greater  with  charges  of  wrought-iron  than  with 
those  of  steel. 

Probably  more  silicon  is  absorbed  from  the  walls  of  new 
than  of  old  and  partly  decarburized  ones  (cf.  §  Absorption 
of  Carbon,  369  A). 


B.  The  influence  of  the  proportion  of  carbon  in  the 
metal  on  the  absorption  of  silicon  is  illustrated  in  Table 
182.  Here  we  note  that  a  charge  of  steel  in  general  takes 
up  much  more  silicon  than  one  of  wrought-iron  ;  and  that 
when  the  carburetted  ingot  resulting  from  the  fusion  of 
wrought-iron  (in  which  much  carbon  is  always  absorbed) 
is  again  melted,  more  silicon  is  absorbed  than  in  the 
fusion  of  the  wrought-iron  itself.  This  for  reasons  given 
in  A.  An  exception  seems  to  occur  in  numbers  16  and 
18.  Whether  this  is  due  to  the  fact  that  in  these  experi- 
ments the  crucibles  were  perforated,  thus  introducing 
the  oxidizing  fire-gases,  probably  to  different  degrees  in 
the  two  cases,  or  to  some  other  and  unnoticed  factor,  I 
cannot  say.  In  a  Mitis  casting,  said  to  be  made  from 
melted  horse- nails,  Hunt  and  Clapp  found  0.24$  of  silicon 
with  0.14  of  carbon  ;  but  how  much  of  this  came  from  the 

TABLE  182.— INFLUENCE  OF  CARBON-CONTENT  os  SILICON-ABSORPTION. 


Steel  

j 
1 

First 
Fusion  . 

JG-iinof  Si.*  
)  Number  

.34 

13 

.38 

16 

.33 

24 

| 

First 
Fusion. 

,GainofSi.*  
(Number  

.06 

14 

.29 

18 

.18 

36 

"l 

~\  Gain  of  Si.  % 

18 

33 

19 

| 

15 

19 

27 

crucible-walls  and  how  much  was  introduced  with  the 
ferro-aluminium,  I  know  not. 

C.  The  influence  of  the  length  of  killing  is  illustrated 
in  Tables  180  and  183.  In  the  first  and  third  sets  of  the 
latter  table  there  is  an  actual  loss  of  silicon  in  melting 
down,  but  the  gain  during  killing  is  invariably  continu- 
ous (except,  of  course,  in  case  basic  crucibles  are  used). 
This  may  be  referred  to  the  progressive  acidification  of 
the  slag,  already  pointed  out,  which  makes  the  reduction 
of  its  silicon  more  easy ;  and  to  the  higher  temperature 
during  killing,  which,  raising  the  affinity  of  carbon  for 
oxygen  relatively  to  that  of  silicon,  favors  the  reduction 
of  silicon  from  slag  and  crucible  by  the  carbon  of  crucible 
and  steel. 

TABLE  183.— INFLUENCE  OF  LENGTH  OF  KILLINO  ON  SILICON-  ABSORPTION. 


No  in  Table  179  ..  ;  

38 
15  min. 
4-.M 

+  .05 

39 

1  hr.  45  min. 
+  .33 
+  .49 

40 
3hr.  15  min. 
-f  .22 
+\65 

45 
45  min. 
—  .19 

+  .063 

46 

7hr. 
.23 

Length  of  killing  

Gain  of  silicon,  %  

+  -11 

Graphite  crucible.                      Pure  clay  crucibles. 

Z>,  E.  The  influence  of  manganese  is  shown  in  Table 
184 ;  here  in  each  case  the  addition  of  ferro-manganese 
increases  the  absorption  of  silicon,  and  in  two  cases  very 
greatly.  The  addition  of  oxide  of  manganese,  however, 
diminishes  the  absorption  of  silicon.  Thus,  in  numbers 
20  and  21  (Table  179),  in  which  1%  of  oxide  of  manganese 
is  added  to  a  charge  of  weld-steel,  only  0.15$  of  silicon  is 
absorbed  :  while  0.28  and  0.31$  respectively  are  absorbed 
in  the  parallel  cases  numbers  15  and  17,  in' which  oxide  of 
manganese  is  omitted  ;  indeed,  in  cases  12,  13,  24  and  25 
of  Table  170,  in  which  like  steel  is  melted  without  oxide 
of  manganese,  the  minimum  silicon-absorption  is  0.26$, 
in  spite  of  the  lower  carbon-content  of  the  crucible  walls. 

TABLE  184.— ISFLUENCE  OF  MANGANESE  os  THE  ABSORPTION  OF  SILICON  AND  OF  CARBON. 


4 

33 

5 

6 

12 

30 

Absorption  of 
Silicon,  %.. 

Weld-steel  alone  
"  with  ferro-man^anesc  

+.22 

'+"48 

+.23 

+.44 

+.34 

'+".39 

Absorption  of 
Carbon,  %.  . 

'*  alon?  
"  with  ferro-mangunese  

—.15 

+1.25 

—.05 

'+"53 

+.25 

+'i;47 

Absorption  of 

"  alone  

—.03 

—'so 

+.03 

—  ~2R 

—.02 

'—  '56 

Carbon  in  cru< 

38± 

39± 

40± 

314 


THE    METALLURGY    OF     STEEL. 


Ledebur,  with  hardly  his  usual  acuteness,  believes  that 
manganese  increases  the  absorption  of  silicon  by  increas- 
ing the  steel's  affinity  for  this  metalloid,  pointing  out 
that  if  the  excess  of  silicon  in  number  6  over  that  in 
number  5  were  due  to  the  deoxidation  of  silicon  in  6 
(Table  179)  by  the  reaction 

2Mn  +  SiO2  =  2MnO  +  Si 

then  (0.44—  Q.23)5^-5 =.825%  more  of  manganese  should  be 
oxidized  in  6  than  in  5,  while  actually  only  0.26  -+-  0.03  = 
0.29$  is.  Soa,  too,  if  the  manganese  simply  protected  the 
silicon  from  oxidation  by  itself  taking  up  the  oxygen 
present,  .825%  of  manganese  would  be  needed  to  lessen  the 
oxidation  of  silicon  by  .44 — .23  =  .21%. 

Without  denying  that  manganese  may  have  such  a 
tendency  to  attract  silicon  to  iron,  I  may  point  out  that 
the  manganese-content  of  6  exceeds  that  of  5  by  an  amount 
which  seems  hardly  large  enough  to  attract  so  much  more 
silicon ;  and,  further,  that  simpler  explanations  are  at 
hand. 

Unoxidized  manganese  may  affect  silicon-reduction  in 
several  ways : 

1,  favorably,  by  directly  reducing  silicon  from  slag  or 
crucible- walls  by  the  reaction  just  given  ; 

2,  favorably,  by  combining  with  oxygen  which  would 
otherwise  have  attacked  silicon  ; 

3,  favorably,   by  increasing  carbon-absorption.      The 
fusible  ferromanganese,   melting  early,   gives  rise  to  a 
highly  manganiferous  corrosive  slag.     This  eats  deeper 
into  the  crucible  walls  and  exposes  their  carbon  more 
fully  to  the  rising  molten  steel,  which  thus  absorbs  more 
carbon  than  in  case  of  non-manganiferous  charges  with 
their  less  corrosive  slags.    Note  that  in  each  case  in  Table 
184  the  carbon-absorption  is  very  much  increased  by  the 


Of  these  actions  (of  which  the  last  is  probably  relatively 
unimportant)  the  fourth  should  be  strong  relatively  to  the 
others  when  the  proportion  of  manganese-oxide  is  very 
large. 

While  one  could  hardly  foretell  confidently  the  net 
effect  of  manganese  under  new  conditions,  it  is  not  sur- 
prising that  the  first  three  outweigh  the  fourth  considera- 
tion, and  lead  to  a  net  increase  of  silicon- absorption  when 
a  moderate  quantity  of  ferromanganese  is  charged  in 
carburetted,  well-closed  crucibles,  in  which  only  a 
moderate  quantity  of  manganese  is  likely  to  be  oxidized  ; 
and  it  is  very  natural  that,  when  manganese-oxide  is 
charged  as  such,  the  first  two  actions  being  thus  elimi- 
nated, and  the  fourth  pronounced,  the  silicon-absorption 
should  be  diminished,  as  in  numbers  18  to  21  of  Table 
179. 

§  369.  THE  ABSORPTION  OF  CAKBON,  much  more  variable 
than  that  of  silicon,  increases 

A,  with  the  proportion  of  carbon  in  the  crucible-walls ; 

B,  with  the  proportion  of  metallic  manganese  present ; 

C,  probably  with  the  proportion  of  oxide  of  manganese 
present ; 

D,  usually  slightly  with  the  length  of  killing,  in  case 
graphite  crucibles  are  used ; 

E,  probably  with    the  temperature    reached,   in    case 
graphite  crucibles  are  used  ; 

F,  the  carbon  of  charcoal  or  graphite  added  is  in  large 
part  absorbed  by  the  metal. 

A.  TJie  influence  of  the  proportion  of  carbon,  in  tlie 
crucible-walls,  often  masked  by  that  of  other  variables, 
can  be  traced  in  a  rough  way  in  Table  185.  It  needs  no 
explanation. 


TABLE  185.— INFLUENCE  of  THB  PROPORTION  OF  CARBON  IN  THE  CRUCIBLE  WALLS  ON  THE  ABSORPTION  OF  CARBON  BY  TUB  METAL. 


stool          I  Number  in  Table  179  
eel  7  Gain  of  Carbon  

45 
from  —  .19 

43 
to  —.45 

48 
from  —  .08 

81 
to—    23 

40 

+  22 

53 
+  02 

4 

34 

to  +  06 

13 

12 
to  +  25 

25 

24 

to  -r-  03 

16 

17 

Wrought-  1  Number  in  Table  179  

44 

15 

14 

27 

26 

22 

33 

Iron.      J  Gain  of  Carbon  

+.008 

to  -j-  30 

from  +  07 

to  -f-  23 

from  -f-  03 

to  -{-  67 

Percentage  of  Carbon  in  Crucible-walls 

0 

5 

15 

25± 

2, 

1 

40 

t 

5 

0 

70 

± 

addition  of  manganese.  Now,  this  excess  of  carbon 
naturally  reduces  silicon  vigorously  from  both  slag  and 
crucible  walls.  In  harmony  with  this  view  is  the  fact 
that,  in  numbers  41-2  of  table  179,  the  absorption  of  carbon 
is  very  much  and  that  of  silicon  decidedly  greater  when 
the  ferromanganese  is  charged  before,  than  when  it  is 
charged  after  melting.  In  Ledebur' s  view  one  might  ex- 
pect the  reverse,  since,  when  the  manganese  is  charged 
after  melting,  the  resulting  steel  is  the  more  mangan- 
iferous and  should  attract  silicon  the  more  vigorously. 

4,  unfavorably,  the  oxide  of  manganese  charged  as 
such,  or  formed  during  fusion,  directly  increases  slag- 
basicity,  thus  opposing  the  reduction  and  favoring  the 
oxidation  of  silicon. 

5,  favorably,  the  corrosive  oxide  of  manganese,  attack- 
ing the  crucible  walls,  increases  the  quantity  of  slag,  so 
that  a  given  reduction  of  silicon  per  100  of  slag  means  a 
greater  silicon-absorption  per  100  of  steel. 


a  The  numbers  which  I  give  here  differ  slightly  from  Ledebur's,  but  not  enough 
to  affect  the  argument, 


Very  experienced  steel  makers  assure  me  that  the 
charge  may  take  up  0.25%  of  carbon  from  a  new  pot,  but 
not  more.  This  agrees  with  the  data  for  normal  condi- 
tions in  Table  179.  Here  0.25%  is,  with  one  exception,  the 
greatest  carbon  absorption  when  the  final  proportion  of 
manganese  is  below  0.83$,  and  when  the  crucible  walls 
contain  less  than  about  70%  of  graphite. 

Thanks  to  the  progressive  decarburization  of  its  walla 
(which  doubtless  extends  for  an  appreciable  distance  be- 
yond their  inner  faces),  the  crucible  naturally  imparts 
more  carbon  to  the  steel  (and  hence  more  silicon)  during 
the  first  than  during  later  fusions.  This  effect  is  readily 
traced  in  numbers  58  to  60,  61  to  63,  and  69  to  71  of  Table 
179,  and  is  well  known  in  practice.  It  is,  perhaps,  inten- 
sified, as  Boker  a  points  out,  by  the  fact  that  in  teeming 

a  Wedding,  Darstellung  des  Schmiedbaren  Eisens,  p.  678.  Boker  further  points 
out  that,  thanks  to  this  protection  of  the  crucible-walls,  the  slag  formed  in  a  sec- 
ond and  third  melting  is  less  able  to  take  up  silica  from  the  walls,  hence  is  more 
ferruginous  and  hence  tends  the  more  to  oxidize  the  carbon  and  silicon  of  the  un- 
derlying metal.  While  one  may  not  speak  positively  without  experimental  evi- 
dence, he  seems  to  me  to  exaggerate  this  protective  action  of  the  residual  elag. 


CHEMISTRY    OF    THE    CRUCIBLE    PROCESS.      §  370. 


818 


some  of  the  slag  adheres  to  the  crucible  walls.  During 
the  following  heat  this  slag  to  a  certain  extent  protects 
them,  if  not  after  fusion  is  complete,  at  least  during 
fusion,  from  the  action  of  the  early-formed  corrosive  slag. 

B.  TJie  influence  of  the  presence  of  manganese  is  shown 
in  Table  184.  It  is  probably  due  chiefly  to  the  corro- 
sive action  of  the  oxide  of  manganese  formed  during 
and  after  fusion,  which  exposes  the  carbon  of  the  crucible- 
walls  more  fully  to  the  molten  metal ;  in  part  to  the  pres- 
ence of  this  oxide  of  manganese,  which,  by  its  affinity  for 
silica,  favors  the  oxidation  of  silicon  instead  of  carbon  by 
what  oxygen  is  present,  and  opposes  the  reduction  of 
silica  at  the  expense  of  carbon  ;  and  in  part  to  the  fact 
that  the  manganese  unites  with  oxygen  which  might 
otherwise  have  attacked  carbon. 

G.  Oxide  of  manganese,  charged  as  such,  should  for  the 
first  two  of  these  reasons  favor  the  absorption  and  reten- 
tion of  carbon,  while  favoring  decarburization  by  tending 
to  be  reduced  at  the  expense  of  the  carbon.  We  note  that 
from  0.11  to  0.42  %  of  manganese  is  reduced  from  the 
oxide  of  manganese  charged  in  numbers  8,  20,  21  and  52 
of  Table  179. 

D.  Influence  of  the  length  of  killing. — Prolonging  the 
killing  should,  on  the  one  hand,  tend  to  increase  the  car- 
bon-absorption by  prolonging  the  period  of  contact  of 
steel  with  the  carbon  of  the  crucible-walls  ;  on  the  other 
hand,  the  rise  of  the  temperature  during  killing  should 
favor  the  oxidation  of  carbon  at  the  expense  of  silica  and 
oxide  of  manganese.    The  former  action  should  be  most 
powerful  in  strongly  graphitic  crucibles,  the  latter  in 
crucibles  holding  but  little  carbon.     Further,  the  pro- 
gressive increase  in  the  silicon-content  diminishes  the 
steel's  solvent  power  and  probably  its  affinity  for  carbon. 

We  seem  to  find  these  expected  results  in  a  rough  way. 
Thus,  in  the  Mitis  process,  in  which  killing  is  extremely 
brief,  I  am  informed  that  only  about  0.05  %  of  carbon  is 
taken  up  from  a  new  crucible  and  less  from  old  ones.  I 
have  already  stated,  however,  that  a  casting  selected  at 
random  and  made  from  horse-nails  held  0.14  %.  In  current 
American  practice  (in  which,  however,  more  highly  gra- 
phitic crucibles  are  used)  we  have  seen  that  as  much  as 
0. 25  %  of  carbon  may  be  taken  up.  Again,  in  Table  183,  with 
our  graphite  crucible  105  minutes'  killing  increases  the 
carbon-absorption,  but  when  the  killing  is  prolonged  to 
195  minutes,  the  carbon- absorption  again  falls  off.  In 
Table  180  the  carbon-absorption  in  carboniferous  crucibles 
slackens  as  killing  is  prolonged,  while  in  carbonless  cru- 
cibles we  have  a  continuous  loss  of  carbon.  Number  84 
forms  an  exception :  some  coke  fell  into  the  crucible 
probably. 

Finally  in  numbers  9  to  11,  in  which  the  metal  is  initally 
nearly  saturated  with  carbon,  as  the  silicon  rises  from 
.58  to  .76  and  to  1.07  ^,  the  absorption  of  carbon  first  dim- 
inishes, then  turns  to  a  loss,  and  at  least  part  of  this  loss 
very  probably  occurs  during  killing. 

E.  A  high  temperature  during  killing,  in  that  it  in- 
creases the  affinity  of  carbon  for  oxygen  relatively  to  that 
of  silicon  and  of  manganese,  should  lessen  the  absorption 
of  carbon  ;  in  that  it  increases  the  action  of  the  slag  on 
the  crucible-walls,  and  thus  the  exposure  of  graphite  to 


steel,  it  should  increase  carbon-absorption.  The  experi- 
ence of  crucible  steel  makers  who  use  highly  graphitic 
crucibles,  indicates  that  the  second  influence  outweighs 
the  first.  The  higher  the  killing  temperature  the  greater, 
so  it  is  said,  is  the  absorption  of  caroon. 

F.  TJie  proportion  of  the  carbon  added  as  charcoal  or 
graphite  which  is  absorbed  by  the  metal,  varies  with  the 
strength  of  the  factors  which  favor  carbon  absorption, 
e.  ff.,  probably  declining  as  the  proportion  of  carbon  pres- 
ent from  other  sources  (crucible-walls,  initial  carbon-con- 
tent of  the  metal,  etc.),  increases,  and  as  the  quantity  of 
oxygen  from  rust,  manganese,  oxides,  leakage,  etc.,  in- 
creases. A  distinguished  crncible-steel  maker  thinks  that 
usually  about  75  %  of  the  carbon  of  the  charcoal  charged  is 
taken  up  by  the  steel. 

Comparing  numbers  66  and  67  of  Table  179,  we  find  that 
the  addition  of  250  grammes  of  graphite  to  one  of  two 
like  charges  increased  the  carbon  in  the  resulting  steel  by 
about  272  grammes,  which  certainly  goes  to  show  that  a 
very  large  part  of  the  carbon  of  the  graphite  was  ab- 
sorbed, though  especially  as  commercial  graphite  is  usually 
very  impure,  some  unnoted  variation  doubtless  exagger- 
ated the  carbon  absorption  in  number  67. 

§  370.  THE  ABSORPTION  OP  MANGANESE. — In  Table  179 
we  find  that,  while  the  manganese  of  ferromanganese  or 
spiegeleisen  is  slagged  to  a  considerable  extent ;  yet  when 
highly  carburetted  crucibles  are  used,  manganese  initially 
present  in  steel  containing  even  as  much  as  1.52  %  o± 
manganese  is  but  slightly  affected  (numbers  29,  32,  34  lose 
from  nothing  to  .07  %  of  manganese);  finally  oxide  of  man- 
ganese charged  as  such  is  in  part  reduced.  This  harmonizes 
fully  with  the  role  of  manganese  in  influencing  the  absorp- 
tion of  carbon  and  silicon  already  given.  First,  metallic 
manganese  promotes  the  retention  of  silicon  and  carbon 
in  part  by  being  oxidized  in  their  stead,  and  the  absorp- 
tion of  silicon  by  being  oxidized  at  the  expense  of  this 
metalloid  ;  next,  oxide  of  manganese  in  part  lessens  the 
net  gain  of  these  elements  by  being  reduced  at  their 
expense. 

When  the  charge  contains  spiegeleisen  or  ferro-man- 
ganese,  as  these  substances  are  much  more  fusible  than 
the  rest  of  the  charge,  the  first  formed  bath  of  molten 
metal  may  contain  60  %,  70  %,  or  even  more  manganese. 
Its  richness  in  manganese  favors  the  rapid  oxidation  of 
this  metal,  whose  oxide  is  greedily  devoured  by  the 
acid  slag.  But  when  we  charge  simply  manganiferous 
steel,  even  if  the  manganese-content  reckoned  on  the 
whole  charge  be  the  same,  we  do  not  get  this  early  highly 
manganiferous  metal  bath  and  resulting  oxidation  of 
manganese,  because  the  manganese  and  iron  of  the  charge 
melt  par ipassu.  When  we  charge  oxide  of  manganese,  in 
that  we  make  the  slag  both  basic  and  manganiferous,  we 
favor  the  reduction  of  manganese  at  the  expense  of  car- 
bon and  silicon,  and  its  transfer  from  slag  to  metal. 

Table  186  illustrates  the  very  rapid  slagging  of  manga- 
nese when  a  highly  manganiferous  iron  is  melted.  In  the 
first  line  we  have  the  loss  of  manganese  on  melting  a 
mixture  of  ferromanganese  and  weld-steel.  The  loss 
when  the  resulting  ingot  is  remelted,  given  in  the  second 
line,  falls  below  the  original  loss  by  a  far  greater  amount 


816 


THE    METALLURGY    OF    STEEL. 


than  can  readily  be  referred  to  the  difference  in  the  Initial 
manganese  content. 

TABLE  186.— A  MIXTU«E  op  FERROMANGANESE  AND  STEEL  LOSES  MUCH  MORE 
MANGANESE  THAN  A  SIMPLE  MANOANIFKHOUS  STEEL  MELTED  ALONE. 


LOBS  of     (On  Melting  Steel  and  Ferro-manganese  
Manganese!  On  Remelting  the  Resulting  Ingot  

—  99 

—.58 

—.80 
—.07 

—  .20 
+  .01 

Number  in  Table  179 

60-1 

33-4 

28-9 

So,  too,  in  numbers  41-2  of  Table  179  we  note  that  when 
ferrotnanganese  is  charged  before  melting,  1.05$  of 
manganese  is  lost,  against  0.62$  when,  all  other  conditions 
apparently  remaining  constant,  it  is  charged  after  melting. 
Numbers  30-31  of  Table  179  show  that  the  slagging  of 
manganese  is  increased  by  acidifying  the  slag.  Other  con- 
ditions being  constant,  a  little  fusible  clay  was  added  in 
30  but  not  in  31  ;  in  the  former  this  addition  exactly 
doubled  the  loss  of  manganese  from  the  metal. 

Naturally,  the  oxidation  of  manganese  charged  in  the 
metallic  state  will  be  less  and  the  reduction  of  oxide  of 
manganese  greater  in  highly  graphitic  than  in  clay 
crucibles  ;  because  the  carbon  of  the  crucible  walls  directly 
tends  to  reduce  manganese,  because  it  increases  the  steel's 
carbon-content  and  its  tendency  to  take  up  manganese  and 
part  with  carbon,  and  because  the  abundance  of  carbon 
tends  to  reduce  silicon  from  the  slag,  which  thus  becomes 
the  more  basic  and  the  readier  to  permit  the  reduction  of 
its  oxide  of  manganese.  These  are  but  three  different 
faces  of  the  same  tendency.  Table  187  illustrates  the  in- 
fluence of  the  carbon-content  of  the  crucible-walls  on  the 
loss  of  manganese. 


carbon  from  the  crucible-walls  favor  the  reduction  of 
manganese  at  the  expense  of  carbon  in  highly  carbonifer- 
ous crucibles  ;  with  a  high  temperature  the  manganese 
may  return  from  slag  to  metal  (this  occurs  in  number  75 
of  Table  180,  even  though  the  crucible  is  not  highly 
carburetted).  With  crucibles  relatively  free  from  carbon 
and  with  other  conditions  favoring,  the  slagging  of 
manganese  may  continue  during  killing,  as  occurs  in  38-9 
of  Table  179. 


During  killing  the  loss  of  manganese  should  be  much 
less  than  during  melting,  the  molten  metallic  bath,  if  at 
first  highly  manganiferous,  being  constantly  diluted  by 
the  fusion  of  the  rest  of  the  charge  ;  while  both  the  higher 


The  effect  of  increasing  the  length  of  killing  on  the  loss 
of  manganese  cannot  be  readily  traced  in  the  data  at  hand, 
being  masked  by  that  of  other  variables.  In  38-9  of 
!  Table  179  lengthening  the  killing  nearly  triples  the  loss 
of  manganese  ;  in  numbers  72-5  of  Table  180  it  turns  a 
loss  into  a  slight  gain.  One  would  expect  that  prolong- 
ing killing  would  diminish  the  loss  of  manganese  when 
highly  carburetted  steel  is  melted  in  highly  carburetted 
crucibles,  and  increase  it  under  the  opposite  conditions. 

Sulphur,  in  the  cases  given  in  Table  180,  increases 
gradually  but  constantly,  being  taken  up  perhaps  from 
the  pyrite  of  clay  or  graphite,  perhaps  from  that  of  the 
fuel,  very  small  quantities  of  sulphurous  anhydride  enter- 
ing the  crucible. 

Copper  increases  very  slightly  in  numbers  71-5  and  81.5-84 
of  Table  180,  as  shown  below,  doubtless  because  concen- 
trated in  a  slightly  smaller  mass,  owing  to  slight  removal 
of  other  elements. 


TABLE  187.—  INFLUENCE  OP  THIS  PROPORTION  OF  CARBON  IN  THE  CRUCIBLE  WAILS 
ON  THE  LOSS  OF  MANGANESE. 

No.  in 

Table. 
180. 

72.      Initial  Composition  

Nickel.         Cobalt. 

Copper. 

0.092 
0.094 
0.092 
0.097 

Phosphorus. 

0.823 
0.224 
0.223 
0.043 

0.049 
0.047 
0.049 
0.050 

c*«.i    !  Loss  of  Manganese  .  . 
Steel  jNnmber       B 

—  .99± 
50 
5 

—.63 
38 
15 

-.80 
33 
28 

-.26 
6 
39 

28 

—.20 
28 
40± 

1  75.      Final         n              
81.5    Initial       n 

31 

40 

84.      Final         n              

%  Carbon  in  Crncible-walls..  .  . 

Phosphorus,  in  like  manner,  increases  slightly  when 
clay  or  graphite  crucibles  are  used,  but  is  eliminated 
gradually  in  basic  crucibles. 

Nlcltel  and  cobalt  once  increase  slightly,  once  decrease 


temperature  of  the  killing  period  and  the  accession  of '  slightly. 


CHAPTER  XVIII. 
APPARATUS  FOR  THE  BESSEMER  PROCESS." 


§  371.  THE  ARRANGEMENT  OF  BESSEMER  PLANTS. — 
According  to  their  size  these  may  be  divided  arbitrarily 
into  the  great  and  the  small  plants,  or  into  the  "  big  " 
and  the  "baby  Bessemer." 

The  arrangement  of  large  plants  is  a  matter  of  the 
greatest  importance,  in  view  of  the  usually  enormous 
quantity  of  material  to  be  handled,  and  of  the  necessity 
of  handling  it  not  only  cheaply  but  very  rapidly  :  and  it 
should  therefore  be  studied  carefully.  The  arrangement  of 
small  plants  is  much  less  important,  and  only  deserves 
passing  notice. 

To  fix  our  ideas,  let  us  note  the  arrangement  of  the 
Joliet  plant,  Figure  163,  and  the  path  followed  by  the 
materials.  We  have  to  melt  the  cast-iron  which  is  to  be 


Bessemerized  or  "  blown :"  to  blow  it,  removing  its  carbon 
and  silicon :  to  re-carburize  it  in  order  to  remove  the 
iron-oxide  taken  up  in  blowing,  and  usually  also  in  order 
to  give  it  the  desired  proportion  of  carbon :  to  cast  it  in 
the  form  of  ingots  :  and  finally  to  remove  these  ingots. 
We  will  here  follow  the  metal  no  farther. 

The  melting  occurs  in  the  cupola  furnace  I.  Thence 
the  cast-iron  is  tapped  through  the  runner  R  into  the 
iron  ladle*  F,  and  from  this  a  weighed  quantity  (say  ten 
tons)  of  it  is  poured  through  the  short  runner  below  and 


s  This  chapter  treats  of  certain  apparatus  for  the  acid  Bessemer  process. 
The  hydraulic  apparatus  and  the  cupolas,  as  well  as  the  modifications  of  the 
apparatus  which  the  basic  process  calls  for,  will  be  treated  of  in  the  second 
volume  of  this  work. 

t  This  ladle  is  called  the  iron-ladle  to  distinguish  it  from  the  casting-ladle  L. 


APPARATUS    FOR    THE    BESSEMER    PROCESS.       §  371. 


!U7 


to  the  left  of  F,  into  one  of  the  already  highly  heated 
converters  or  vessels  Co,  which  for  that  purpose  is 
turned  about  the  axis  of  the  trunnion  t  by  means  of  the 
rack  G,  so  that  its  length  lies  horizontally,  and  that  its 
nose  comes  under  this  short  runner. 

The  vessel  being  thus  charged  with  cast-iron,  the  blast 
is  let  on  through  the  tuyeres  Q,  Figures  202  and  204,  and  the 
vessel  is  turned  upright,  so  that  the  blast  is  forced  through 
the  bath  of  molton  cast-iron,  throwing  it  into  violent 
ebullition,  and  removing  its  carbon  and  silicon  rapidly. 
The  escaping  gases  pass  through  the  chimney  or  "  hood  " 
T. 

As  soon  as  the  appearance  of  the  flame  issuing  from 
the  converter's  nose  indicates  that  decarburization  is  com- 
plete, the  vessel  is  again  rotated  about  the  trunnion-axis, 
but  this  time  in  the  opposite  direction,  so  that  its  nose  is 
brought  close  to  the  runner  d,  and  the  blast  is  now 
stopped.  Through  this  runner  the  spiegeleisen  used  for 
recarburizing  is  now  ntn  into  the  vessel,  having  mean- 
while been  melted  in  the  one  of  the  cupolas  S,  and  col- 
lected in  the  spiegel-ladle  K. 

A  violent  reaction  occurs  between  the  spiegeleisen  and 
the  decarbnrized  and  oxygenated  metal  in  the  vessel, 
which  i  <  :iow  turned  so  as  to  pour  the  molten  steel  within 
it  into  I  he  casting-ladle  L,  which  rides  on  the  jib  of  the 
casting  crane  C.  This  crane  now  swings  the  casting-ladle 
successively  over  the  cast-iron  ingot-moulds  N,  standing 
in  the  casting-pit  P,  the  steel  being  poured  into  the 
moulds  through  the  nozzle  in  the  bottom  of  the  ladle  by 
raising  an  internal  stopper  lifted  by  the  stopper-rod 
shown. 

The  ingot-moulds  are  next  lifted  from  the  partly  solidi- 
fied ingots  by  the  ingot-crane  i  c,  and,  by  means  of  tongs 
or  "dogs"  hanging  from  these  same  cranes,  the  ingots 
themselves  are  now  lifted,  placed  on  cars  and  carried 
while  still  molten  within  to  th;  heating  furnaces  in  the 
rolling  department.  The  removal  of  the  moulds  is  termed 
"  stripping." 

But  meanwhile,  after  discharging  its  steel  into  the 
casting-ladle,  the  vessel  has  besn  i.iverted  to  pour  out  its 
slag,  inspected  rapidly  to  see  what  repairs  are  needed,  and 
turned  back  into  position  for  receiving  another  charge  of 
cast-iron,  or  as  it  is  called  another  "heat."  The  oxide  of 
iron  formed  by  the  excess  of  blast  in  immediate  contact 
with  the  ends  of  the  tuyeres  gradually  scorifies  and  cor- 
rodes these,  and  heat  by  heat  the  tuyeres  grow  shorter 
and  the  bottom  thinner,  so  that  after  from  15  to  30  heats  it 
becomes  necessary  to  remove  the  bottom  and  .replace  it 
with  a  fresh  one,  i.  e.  to  "change  bottoms." 

In  case  "direct-metal"*  is  used,  it  is  brought  from  the 
blast-furnace  by  a  ladle  like  F,  and  running  on  the  same 
track,  and  is  poured  through  the  same  runner  into  the 
vessel. 

The  vessels  must  stand  at  such  a  height  that  their 
steel  pours  readily  into  the  casting  ladle,  and  that  the 
debris  which  they  drop  when  inverted  can  be  readily  re- 
moved :  the  casting- crane  so  that  it  may  receive  the 
steel  from  the  vessels  and  deliver  it  to  the  moulds:  the 
moulds  so  that  they  are  readily  placed,  and  that  they  and 
the  ingots  cast  within  them  are  readily  removed :  the 

s  "Direct-metal"  is  cast-iron  brought  while  still  molten  direct  from  the 
blast  furnace  and  poured  into  the  converter.  In  distinction  from  it,  cast-iron 
which  has  been  cast  into  pigs  at  the  blast  furnace  and  remelted  in  cupolas 
before  being  run  into  the  Bessemer  vessels  is  known  as  "  cupola-metal."  I 


cupolas  so  that  the  molten  metal  is  readily  transferred 
from  them  to  the  vessels,  and  that  their  debris  is  leulily 
removed  by  rail. 

There  are  many  modifications  of  the  arrangement  I  have 
sketched  ;  >'.  ;/.  in  the  position  of  the  cupolas  and  the 
arrangement  of  the  runners,  both  cast-iron  and  spiegel- 
eisen being  in  some  mills  introduced  through  the  runner  >l : 
in  the  number  of  vessels,  of  which  there  are  usually 
two,  yet  sometimes  three  or  even  four,  while  in  small 
plants  there  is  occasionally  but  one  :  in  the  number  of 
casting-cranes,  usually  one,  sometimes  two,  rarely  three: 
in  the  shape  of  the  casting-pit,  which  is  very  deep  in  old 
British  mills,  shallow  in  most  modern  mills,  and  occa- 
sionally wholly  dispensed  with,  the  moulds  standing  on 
the  gea:  :M!  level :  in  the  number  and  arrangement  of  the 
ingot-cranes,  etc.,  etc.  Again,  while  in  most  mills  th<» 
ingots  are  stripped  in  the  casting-pit,  in  some  they  are 
removed  with  their  moulds  to  another  place  before  strip- 
ping. The  value  and  object  of  these  modifications  we 
will  consider  later. 

§  372.  CLASSIFICATION  OF  OPERATIONS. — The  operations 
above  outlined  may  be  divided  into  four  groups  : 

1.  Melting  and  transferring  the  molten  metal  to  the 
converter. 

2.  Blowing. 

3.  The  pit-work,8  casting,  stripping  and  removing  the 
ingots. 

4.  Repairs,    especially    those  to  bottoms,    ladles    and 
moulds. 

The  following  movements  of  materials  are  to  be  made, 
and  for  them  tracks,  runners,  cranes,  hoists,  etc.,  are  to 
be  provided. 

A.  Taking  cast  iron,  coke  and  spiegeleisen  to  the  cu- 
polas. 

B.  Removing  cupola-slag  and  "  dump." 

C.  Conducting  the  molten  cast-iron  and  spiegeleisen  to 
the  vessels. 

D.  Carrying  the  molten  steel  to  the  moulds. 

E.  Removing  the  ingots  for  rolling,  hammering,  etc. 

F.  Removing  the  moulds  that  they  may  cool,  and  re- 
turning them. 

Gr.  Bringing  and  removing  ladles. 

H.  Bringing  and  removing  vessel-bottoms. 

L  Bringing  and  removing  vessel-  and  pit-slag  and  scrap. 

In  addition  to  the  above,  which  are  of  the  nature  of 
transportations,  the  following  motions  must  be  provided 
for : 

J.  Rotating  the  vessels. 

K.  Lifting  the  ingots  from  the  pit.* 

L.  Setting  the  moulds  and  lifting  them  from  the  pit. 

In  designing  a  plant  for  small  output  it  is  usually  very 
important  that  the  cost  of  installation  be  kept  very  low, 
as  the  interest  charges  fall  heavily  on  the  small  tonnage, 
and  as  powerful  and  hence  costly  machinery  can  be  oc- 
cupied but  a  fraction  of  the  time,  i.  e.,  to  poor  advantage. 
Thus  a  small  and  hence  compact  plant  is  sought;  the  con 
verting  building  itself  is  small ;  cupolas,  vessels,  pit  and 
perhaps  heating  furnace  stand  close  to  each  other  ;  some 
of  the  above  movements  are  suppressed  or  combined,  and 
several  of  them  are  effected  by  the  same  machine. 

t  Though  in  certain  mills  there  io  no  true  pit,  it  is  still  more  convenient  to  spea'i, 
of  those  classes  of  work  which  in  most  works  cccur  in  the  pit,  as  "  pit-work." 


THE    METALLURGY    OF    STEEL. 


But  when  a  large  output  is  aimed  :it,  e.  g.,  when  rail- 
ingots  are  to  made,  and  where  operations  are  necessarily 
hurried,  it  is  best  to  separate  the  places  where  the  above 
four  groups  of  operations  are  to  be  carried  out,  so  that  the 
workmen  engaged  in  each  group  may  not  hinder  those  of 
another,  and,  sufficiently  oppressed  in  hot  weather  with 
the  heat  necessary  to  their  own  group,  may  not  have  their 
working  power  further  diminished  by  the  heat  from  the 
other  groups.  Clearly  this  is  more  important  in  case  of 
a  large  than  in  that  of  a  small  output,  since  in  the  former 
case  more  workmen  are  employed  in  each  group,  their 
operations  and  motions  are  quicker,  and  more  in  need  of 
free  working-space,  and  the  evolution  of  heat,  (whether 
from  running  streams  of  molten  metal  or  the  presence 
of  hot  ingots)  is  more  constant,  and  its  effects  consequently 
more  intense  and  far  more  trying  than  in  the  latter. 
Moreover,  as  in  the  case  of  large  output  there  are  more 
men  in  each  group,  so  it  is  expedient  to  put  in  charge  of 
each  group  a  workman  of  exceptional  powers  of  direction, 
and  it  is  less  important  to  have  all  the  groups  immediately 
under  the  eye  of  a  single  foreman.  In  case  of  large  out- 
put the  superintendent  delegates  his  authority  to  a  num- 
ber of  bosses  (the  head  vessel-man,  the  head  pit-man, 
etc.),  and  holds  each  of  them  responsible  for  results.  In 
case  of  a  small  output  bosses  of  such  responsibility  can- 
not be  employed,  for  their  wages  would  form  too  seri- 
ous a  charge  per  ton  of  the  small  product ;  hence,  great 
compactness  is  further  desirable  here,  in  order  that  the 
superintendent,  or  rather  in  this  case  foreman,  may  be 
within  sight  and  earshot  of  all. 

Again,  if  we  thus  scatter  the  different  groups  we  must 
have  locomotives  or  other  costly  means  of  transporting 
the  material  from  point  to  point ;  their  absolute  cost  is  rela- 
tively little  larger  in  case  of  large  than  in  that  of  small 
output,  and  thus  forms  a  relatively  light  charge  per  ton 
of  the  greater  product. 

These  considerations,  of  course,  apply  with  more  or  less 
force  to  industries  in  general  ;  but  to  iron  manufacture 
with  especial  force,  for  here  undue  condensation  not  only 
impedes  the  many  and  rapid  movements  of  heavy  and 
often  difficultly  handled  and  white-hot  objects,  but  leads 
to  oppressive  heat,  which  lowers  the  workman' s  efficiency, 
to  say  nothing  of  increasing  his  sufferings.  Here  mercy 
pays. 

But  though  it  is  thus  desirable  to  separate  the  four 
groups,  it  is  best  that  the  operations  of  each  group  be 
carried  on  in  a  small  space,  so  that  the  men  of  each  may 
have  but  short  excursions  to  make,  may  communicate 
and  co-operate  quickly  with  each  other,  and  that  they 
and  the  objects  in  their  charge  may  ever  be  well  within 
sight  and  speaking  distance  of  their  boss. 

§  873.  THE  POSITION  OF  THE  CUPOLAS  must,  as  already 
stated,  be  such  that  the  molten  cast-iron  can  be  conveyed 
readily  from  them  to  the  vessels,  and  that  their  own  debris 
can  be  readily  removed. 

A.  Their  debris  is  not  only  very  considerable,  but  a 
very  large  quantity  is  thrown  out  suddenly  when  they 
dump.  In  order  that  they  may  dump  (and  dumping  is 
by  far  the  easiest  way  of  removing  their  contents  at  the 
end  of  their  campaign),  and  that  the  debris  dumped  may 
be  readily  removed,  they  should  stand  well  above  the 
ground  level,  not  less  than  8  or  9  feet ;  in  close  proximity 


to  a  broad-gauge  track  ;  and  either  apart  from  the  con- 
verting-room proper,  or  along  one  of  its  sides,  so  that 
their  debris  may  be  delivered  into  an  open  space  as  free 
as  practicable  from  walls  and  pillars,  as  these  interfere 
with  breaking  it  up,  or,  indeed,  quarrying  it  as  must 
sometimes  be  done. 

In  the  older  Bessemer  plants,  e.  g.,  Joliet  (Figure  163), 
a  chute  U,  beneath  the  cupolas,  throws  their  debris  com- 
pletely out  of  doors.  In  most  of  the  later  plants  the 
cupolas  stand  hardly  high  enough  for  this,  but  they  are 
either  removed  from  the  converting-room  (Bethlehem, 
Harrisburg)  ;  or  their  debris  is  carried  from  beneath  them 
by  a  similar  but  shorter  chute,  and  falls  into  a  space  en- 
cumbered only  with  short  and  smooth  division  walls  ;  or 
both  these  plans  are  combined. 

B.  Transferring  the  molten  cast-iron.  In  order  that  the 
cast-iron  might  run  by  gravity  to  the  vessels,  the  cupolas 
in  the  older  Holley  plants  stood  close  to  and  higher  than 
the  vessels,  nearer  even  than  in  the  Joliet  type,  figure 
163.  The  cast-iron  was  tapped  from  the  cupolas  into 
stationary  tipping  ladles,  resting  on  scales,  and  close  to 
the  cupolas ;  by  tipping  these  ladles  a  given  weight  of 
cast-iron  was  run  through  long,  loam-lined  runners  to  the 
vessels.  The  runners  in  this  and  similar  mills  have  a  fall 
of  about  one  in  four  or  one  in  five.  They  are  forked  at 
the  lower  ends  so  as  to  deliver  into  either  of  two  vessels, 
and  pivoted  so  as  to  be  pushed  well  into  the  vessel's 
mouth  when  delivering  iron,  and  again  withdrawn  before 
the  vessel  is  turned  up  (Figures  171  and  173). 

But  here  a  very  serious  difficulty  arose.  The  cupola 
tappers,  much  of  whose  time  was  necessarily  spent  on  the 
side  of  the  cupolas  nearest  the  vessels,  were  completely 
hemmed  in  by  heat.  In  front  of  them  were  the  hot 
cupolas,  from  whose  shells  much  heat  radiated  ;  by  their 
feet  were  large  ladles  full  of  molten  cast-iron;  while  be- 
hind them  rushed  in  a  torrent  of  hot  air,  heated  by  the 
ingots  in  the  pit  and  by  the  flame  of  the  vessels.  Their 
position  was  indeed  intolerable.  They  stood,  as  it  were, 
in  a  chimney  conducting  the  hot  air  up  from  the  pit  and 
from  around  the  vessels  to  the  top  of  the  cupola  building. 
I  have  often  known  men  to  be  overcome  with  the  heat 
here,  faintings,  severe  hemorrhage  at  the  nose,  etc. 

When,  as  at  Harrisburg,  Figure  171,  they  sought  to 
remedy  this  by  setting  the  cupolas  farther  back  from  the 
vessels,  inordinately  long  runners  leading  from  cupola  to 
vessel  resulted,  in  which  much  cast-iron  solidified,  and 
much  runner  scrap  resulted,  which  had  to  be  remelted. 
Further,  the  additional  height  to  which  it  was  necessary 
to  raise  the  cupolas  in  order  to  give  the  runners  sufficient 
fall,  the  additional  cost  of  the  cupola  building,  which  had 
to  sustain  a  heavy  load  aloft,  and  the  additional  distance 
through  which  1,000  tons  of  material  had  to  be  hoisted 
daily,  were  no  trifle. 

Hence  many  builders  of  plants  have  abandoned  the  plan 
of  placing  the  cupolas  so  that  the  molten  cast-iron  can 
run  from  iron-ladles  standing  hard  by  them  through 
runners  directly  to  the  vessels,  and  instead  have  placed 
the  cupolas  in  a  position  convenient  for  receiving  pig- 
iron  and  coke,  and  for  discharging  their  debris  ;  and  they 
have  provided  traveling  iron-ladles,  carried  by  a  locomotive 
from  the  cupolas  to  the  vessels.  Here,  then,  it  is  found 


THE    BETHLEHEM     STEEL    PLANT. 


373 


319 


expedient  to  separate  the  operations  of  one  of  onr  four 
groups  from  those  of  the  others. 

There  are  three  common  ways  of   carrying  the  iron- 
ladle  from  the  cupolas  to  the  vessels, 


\ 

i 

1 

no 

M       BH 

L 

J 

.. 

,  

—  •-        / 

J 

/ 

Fig.  TU.     PLAN     OF  KKTHLKIIKM  FOI-K-VKSSKI.  PLANT. 
C  CASTING-CRANES,     c  INGOT-CRANES.     Co  CONVERTER,     n   HOISTS. 


CAST-IRON.     It  TRACK  FOB  CAST-IKON. 
SritoEL  CfvoLAs.    w  SCALES. 


O   OVENS  FOB  BOTTOMS. 


I  CUPOLA  FOR 
P  CASTING-PIT.     S 


1st.  It  may  run  on  a  track  on  the  general  level,  (Figures 
164,  209,)  be  raised  to  the  level  of  the  vessels  by  a  hoist 
(or  on  the  jib  of  a  crane  as  at  Rhymney  and  Eston)  stand- 
ing between  or  beside  them,  and  there  be  tipped  by  gearing 
attached  to  its  trunnions. 

2d.  It  may  run  on  an  elevated  track  at  about  the  level 
of  the  vessels'  trunnions  (figures  165,  168,  169)  ;  from  this 
track  it  pours  the  metal  into  the  vessel,  being  tipped  by 
gearing  attached  to  its  trunnions.  If  the  vessels  stand 
side  by  side  this  track  may  run  either  before  or  behind 
them  ;  if  opposite  each  other,  as  in  the  British  plan,  the 
track  should  ran  between  them,  as  at  West  Cumberland. 

3d.  It  may  be  carried  by  a  crane  to  tlie  vessel's  mouth, 
and,  while  suspended  aloft  by  its  own  trunnions,  be 
tipped  so  as  to  empty  its  molten  iron  into  the  vessel  by 
lifting  its  bottom  with  a  chain  (Figure  167). 

In  the  first  and  third  of  these  arrangements  the  cupolas 
need  only  be  raised  so  high  that  their  debris  can  be 
easily  removed  from  beneath  them ;  in  the  second  the 


cupola-bottoms  should  be  some  7  foci  above  the  vessel 
floor,  while  in  the  old  arrangement,  in  which  the  cast- 
iron  ran  through  gutters  to  the  vessels,  the  cupola- 
bottoms  stood  some  17  feet  above  \\\<-  vessel-floor. 

Of  these  three  plans  the  third  (carrying  the  ladle  by  a 
crane)  is  decidedly  the  cheapest  as  regards  cost  of 
installation,  but  is  much  less  convenient  than  the  others. 
In  pouring  from  the  ladle  into  the  vessel  four  men  and 
boys  are  required,  one  man  tipping  the  ladle,  a  second 
racking  it  in  towards  the  mast  of  the  crane  to  compen- 
sate for  the  horizontal  travel  of  its  lip  as  it  tips,  a  stage- 
boy  regulating  the  height  of  the  ladle,  and  another  the 
position  of  the  vessel.  With  the  second  arrangement 
I  (a  ladle  running  on  an  elevated  track)  only  two  men  are 
I  needed,  the  locomotive  engineer  and  a  man  to  tip 
the  ladle.  The  first  (a  ladle  running  on  a  surface  track) 
needs  but  slightly  more  labour  than  the  second,  to  wit,  a 
stage-boy  to  work  the  hoist  whicli  raises  the  ladle  to  the 
vessel's  mouth.  I  think  that  few  good  judges  would 
recommend  the  third  arrangement  for  works  designed  for 
large  output. 

As  between  the  first  and  second  plans,  the  first  may 
effect  a  slight  saving  in  first  cost,  the  cost  of  a  single 
hoist  being  less  than  that  of  elevating  the  track,  and  the 
lower  position  of  the  cupolas  effecting  a  slight  saving. 
As  regards  lifting  the  metal  both  the  first  and  third 
arrangements  are  at  a  slight  disadvantage,  for  their  two 
lifts,  first  from  the  general  level  to  the  cupola-charging 
platform,  and  second  from  the  general  level  to 
the  vessel,  are  collectively  rather  more,  say  four  to  six 
feet  more,  than  the  single  lift  of  the  second  plan,  allow- 
ing for  the  necessarily  higher  position  of  the  cupolas  in 
the  second  arrangement  than  in  the  others. 

But  the  chief  objection  to  the  first  arrangement  is  that 
the  surface  track  occupies  space  which  is,  if  not  more 
needed  for  other  purposes,  at  least  more  likely  to  be  en- 
cumbered or  obstructed  than  that  occupied  by  the 
elevated  track  of  the  second  arrangement.  This  may  be 
a  rather  serious  thing.  For  every  heat  four  trips  must  be 
made,  carrying  the  iron-ladle  to  the  vessels  and  back,  and 
spiegel-ladle  back  and  forth.  If  we  are  blowing  a  heat 
every  eight  minutes,  this  implies  a  trip  along  these  tracks 
every  two  minutes  on  an  average.  Moreover,  if  successive 
heats  are  to  be  made  in  vessels  served  by  the  same  track 
and  hoist,  the  vessel  which  is  preparing  to  blow  must 
receive  its  cast-iron  some  little  time  before  the  blow  in  its 
neighbor  ceases,  in  order  that  the  track  and  hoist  may  be 
free  to  bring  the  spiegel-ladle  to  the  blowing  vessel  the 
instant  that  its  blow  finishes.  In  the  Bethlehem  works, 
with  their  very  talented  management  and  with  their  four 
vessels,  this  arrangement  indeed  works  smoothly  ;  but 
with  a  two,  and,  perhaps,  even  with  a  three-vessel  plant, 
one  might  anticipate  considerable  delay,  owing  to  ob- 
structions to  the  track,  or  to  interference  between  the 
movements  of  the  spiegel  and  the  iron-ladle. 

The  length  of  time  during  which  the  vessel  is  delayed 
in  receiving  the  charge  of  molten  iron  is  practically  the 
same  for  all  these  plans,  as  the  numbers  in  Table  188 
indicate.  If  anything,  the  crane-method  here  gives  the 
best  results  when  we  consider  that  it  takes  longer  per  ton 
to  pour  a  small  than  a  large  weight  of  metal.  And,  lest 
it  be  thought  that,  tliough  the  crane-method  pours  the 
metal  rapidly,  it  wastes  time  by  swinging  the 


320 


THE    METALLURGY     OF    STEEL. 


clowly  from  the  cupola  to  the  vessel,  I  will  add  that  in 
oi:e  case  I  saw  the  stream  of  molten  iron  begin  running 
into  the  vessel  45  seconds  after  beginning  to  raise  th'-> 
ladle  which  held  it  from  the  scales  below  the  cupola. 

TABLB  188.— TIMK  OCCUPIED  IN  POURING  MOLTEN  CAST-IKON  INTO  VESSELS  BY 
DIFFERENT  METHODS. 


Mode  of  Transporting 
the  Caet-iron. 

By  Runners. 

By  Surface 
Track. 

By  Crane. 

Weight  of  Charge,  Tons  .  .  . 
Number  of  Observations.  .  . 
(Max  
Time  Occupied.  1  Min  
(Avge  
Seconds  per  Ton,  Avge  

10 
3 

21  5" 

1'  40" 
V  5.V 

ii'  y 

6 
1 

9» 
V 

V  38" 
13" 

2' 
V  15" 
1'  42" 
13" 

5 
5 
1'  5" 
55" 

57" 
11" 

4 

2 
50" 
45" 
47" 
12" 

i'  20" 
13" 

If  direct  metal,  I.e.  molten  cast-iron  brought  direct  from 
the  blast-furnace,  be  used,  it  is  necessary  to  combine  the 
direct-metal  arrangement  with  one  for  cupola-melted  cast- 
iron.  For  not  only  is  it  important  to  remelt  in  cupolas 
during  the  week  the  cast-iron  made  by  the  blast-furnaces  on 
Sunday,  when  the  steel  works  are  closed,  but  to  be  able 
to  substitute  cupola-metal  for  direct-metal  in  case  the 
supply  of  the  latter  should  fail,  or  in  case  its  composition 
should  suddenly  become  unsuited  to  the  Bessemer  process, 
through  some  temporary  derangement  of  the  blast-furnace 
or  otherwise.  For  simplicity  it  is  desirable  that  direct- 
metal  and  cupola-metal  should  be  carried  to  the  vessels 
through  the  same  channels,  be  weighed  on  the  same 
scales,  etc. 

§  374.  WEIGHING  THE  MOLTEN  CAST-IRON  FOR  THE 
VESSEL  CHARGE. — The  iron-ladle  usually  stands  on  scales, 
and  an  exact  charge  is  weighed  into  it,  the  stream  of 
molten  metal  being  interrupted  at  the  right  moment  by 
"  Botting  up8 "  the  cupola.  But  it  may  in  some  cases  be 
more  convenient  to  tap  a  larger  quantity  into  this  ladle, 
and  then  weigh  out  from  the  ladle  an  exact  vessel- charge. 
When  the  cast-iron  is  conveyed  by  a  crane,  the  weighing 
may  be  effected  by  a  hydraulic  weighing  machine  on  the 
trolley  'running  on  the  crane-jib.  This  machine  is  a 
hydraulic  cylinder  with  a  pressure  gauge,  and  the  ladle 
is  simply  suspended  from  its  plunger. 

This  last  plan  admits  of  many  modifications.  For 
instance,  the  weighing  cylinder  may  also  be  a  lifting 
cylinder  for  raising  or  lowering  the  ladle  ;  when  a  weight 
is  to  be  taken  the  admission  and  escape  of  water  are 
checked,  when  the  pressure-gauge  will  indicate  the  weight 
of  cast-iron  plus  tare,  I.e.  ladle,  plunger  and  suspending 
pieces.  Or  the  pressure-gauge  may  be  attached  to  the 
main  lifting-cylinder  of  the  crane  itself.  In  any  case  the 
gauge  should  be  so  set  that  it  points  to  zero  when  the 
water  or  other  fluid  is  supporting  only  the  weight  of  the 
tare. 

§  375.  ARRANGEMENT  OF  VESSELS,  PIT  AND  CONVEKT- 
ING-HOUSE  CRANES. — Here  we  have  quite  a  different 
problem,  to  arrange  matters  so  the  several  operations 
shall  not  interfere  with  each  other,  shall  not  hold  each 
other  back.  At  the  same  time  the  manoauvres  and  super- 
vision imist  be  easy,  and  the  cost  of  installation  must 
be  within  bounds.  In  approaching  such  a  problem 
we  must,  of  course,  have  some  starting  point,  and 
probably  as  good  a  one  as  any  is  to  assume  a 
given  weight  of  vessel-charge  and  given  boilor  and  blow- 


6  To  "  bot  up  "  is  to  stop  the  tap-hope  of  a  cupola  or  other  melting  furnace,  e.g. 
with  a  ball  of  clay  on  the  end  of  a  pole  or  "  bot-sticll," 


ing  engine  power,  so  that  a  heat  (of,  say,  ten  tons)  can  be 
blown  in  given  time  (say  eight  minutes)  ;  then  we  must 
seek  to  arrange  matters  so  that  we  shall  be  able  to  blow  a 
heat  every  eight  minutes,  one  vessel  turning  up  to  begin 
blowing  its  heat  the  moment  that  the  preceding  heat  is 
finished  in  another,  and  that  the  vessel  in  which  it  is 
blowing  turns  down.  In  at  least  one  American  three-vessel 
plant  the  blowing  engine  often  runs  continuously  for 
several  hours,  blowing  being  absolutely  continuous. 

After  the  metal  is  blown  it  is  recarburized,  is  poured 
into  the  casting- ladle,  is  teemed  thence  into  the  moulds,  is 
removed  to  other  departments.  Now,  in  the  mill  which 
we  are  designing,  as  soon  as  a  heat  is  blown  in  one  vessel 
and  before  it  is  recarburized  a  second  is  to  begin  blowing 
in  another  vessel ;  and  the  first  vessel  (or  a  third  in  case 
there  are  three)  must  be  ready  so  that  a  third  heat  may 
begin  blowing  as  soon  as  the  second  is  blown,  In  like 
manner  the  casting-ladle  must  deliver  its  steel,  undergo  its 
repairs  and  be  back  ready  to  receive  the  second  heat  as 
soon  as  the  second  heat  is  ready  to  be  poured  into  it.  So, 
too,  a  second  set  of  moulds  must  be  ready  to  receive  the 
second  heat,  as  soon  as  the  casting-ladle  has  received  this 
second  heat  and  swung  around  to  where  the  moulds  stand, 
and  so  on. 

I  need  not  here  combat  the  belief  of  many  European 
metal  1  urgists  that  such  extremely  rapid  work  is  prejudicial 
to  the  quality  of  the  product.  This  depends  chiefly  on 
the  proportion  of  phosphorus  and  sulphur  in  the  metal, 
which  is  of  course  wholly  independent  of  the  rapidity 
of  working,  and  further  on  the  temperature  of  blowing 
and  of  casting,  on  care  in  casting,  etc.  Now  the  rapid 
working  which  has  led  to  such  enormous  outputs  from 
American  mills  is  not  due  to  rapid  blowing,  but  to  avoid- 
ing delays  between  blows  ;  and  it  is  hard  to  see  how  tins 
is  to  injure  the  metal,  unless  by  inducing  slovenly  casting. 
Needless  to  say,  the  arrangements  for  teeming  must  be  so 
ample,  especially  when  high  quality  is  sought,  that  this 
important  operation  may  be  performed  carefully.  I 
think,  however,  that  even  in  some  of  our  quickest  working 
mills,  the  ingots  are  as  well  cast,  as  free  from  blowholes 
and  as  sound  as  those  made  in  the  most  leisurely  European 
practice. 

As  regards  uniformity  of  composition,  our  rapid  work 
leaves  nothing  to  be  desired.  (Of.  §  365.)  On  the  other 
hand,  rapid  working  not  only  lessens  the  interest  and 
general  charges  per  unit  of  product,  but,  by  preventing 
the  vessels  from  cooling  between  heats,  enables  us  to  use 
less  coke  in  the  cupolas,  and  cast-iron  which  has  less 
silicon  and  is  hence  cheaper,  than  in  case  of  slower  work- 
ing. 

§376.  NUMBER  OF  VESSELS,  ETC.,  NEEDKD — DISCUS- 
SION.— From  this  point  to  §378  follows  a  quasi  mathemat- 
ical discussion  of  the  number  of  vessels,  cranes,  etc., 
needed  to  permit  continuous  blowing. 

The  several  operations  which  have  to  keep  time  with  the 
blowing  are,  the  work  in  and  on  the  vessel  between 
blows  ;  the  work  done  by  and  on  the  casting-ladle ;  and 
the  work  in  stripping  and  removing  the  ingots  and  re- 
placing the  moulds,  or  the  pit-work.  But  for  the  pit- 
work  enough  time  must  be  allowed  not  only  for  this  work 
of  the  ingot-cranes,  but  also  to  permit  the  ingots  to  solidify 
and  become  firm  enough  to  bear  handling. 


TIME    KEQUIRED    IN     BLOWING    AND    CASTING.      §  376. 


321 


Thus  the  lengths  of  time  which  we  now  have  to  con 
sider  and  to  adjust  are  : 

1.  The  length  of  the  blow,  blowing-time B.  T. 

8.  Time  for  the  vessel-work,  ve«s»l-timc V.  T. 

3.  Time  for  the  casting-ladie  work,  ladle-time L.  T. 

4.  Time  to  teem,  cool  and  strip  the  ing  ts  of  a  heat,  and  to  replace  the  moulds 

for  a  new  heat,  mould-time M.  'I'. 

5.  Time  for  the  manoeuvres  of  the  inijot-cranes,  ingot-crane-time C.  T. 

With  this  discussion  in  view  I  have  made  more  thai 
500  observations  of  the  time  occupied  by  the  several  opera- 
tions connected  witli  the  production  of  ingots  by  thi: 
process. 

Some  results  condensed  from  these  will  now  be  presented 

1.  BT  consists  of  the  time  actually  occupied  in  blowing, 
plus  the  half  minute  occupied  in  turning  the  vessel  uj 
and  down.  The  time  occupied  by  the  blow  propel 
depends  on  the  proportion  of  carbon  and  silicon  in  the 
metal,  the  weight  of  the  charge,  the  number  and  size  oi 
the  tuyere-holes  and  the  pressure  of  the  blast ;  and  thi 
last  in  turn  on  the  capacity  of  the  blowing  engine.  A; 
the  engine-power  and  the  aggregate  area  of  the  tuyere- 
holes  are  usually  roughly  proportioned  to  the  weight  of 
the  charge,  the  chief  factor  in  determining  the  length  of 
the  blow  is  usually  the  proportion  of  silicon  in  the  cast- 
iron. 

Actually,  Forsyth  has  made  seven  10-ton  heats  in  an 
hour  and  73  in  twelve  hours  at  the  Union  works,  or  at  the 
rate  of  8.6  and  9.86  minutes  per  heat  respectively. 

At  Homestead  61  five-ton  heats  have  been  made  in  eight 
hours,  or  at  the  rate  of  7.87  minutes  per  heat":  and  at 
Scranton  78  heats  of  6.6  tons  each  have  been  blown  in  a 
single  twelve-hour  shift.  As  lately  as  1883  Forsyth  put 
the  limit  of  the  possible  production  of  the  South  Chicago 
pit  at  one  heat  per  twelve  minutes. 

Of  course  the  output  in  certain  single  hours  is  likely  to 
be  much  greater  than  the  average  of  the  day's  work.  It 
is  not  sufficient  that  the  casting  appliances  can  on  an 
average  receive  and  take  care  of  the  average  of  the  vessel's 
output ;  they  should  be  designed  to  receive  it  as  it  is 
delivered,  even  during  the  hours  when  its  delivery  is 
most  rapid.  Considering  the  advances  made  since  1883, 
we  discount  the  future  but  little  in  taking  BT  as  eight 
minutes,  i.  e.,  in  arranging  our  plant  so  that  it  can  receive 
and  handle  a  heat  every  eight  minutes. 

The  little  Swedish  vessels,  indeed,  go  far  beyond  the 
limit  of  eight  minutes  per  heat,  and,  by  using  a  very  large 
tuyere-area  per  ton  of  charge,  often  blow  a  heat  in  five 
minutes  ;  but  it  seems  doubtful  whether  a  proportionally 
large  tuyere-area  would  be  desirable  for  our  great  ten  ton 
vessels. 

2.  VT,  the  time  occupied  by  the  vessel' s  work  between 
heats,  consists  in  the  time  occupied  in  recarburizing,  in 
pouring  the  steel  into  the  casting  ladle,  in  emptying  slag, 
in  examining,  and,  if  need  be,  replacing  tuyeres  and 
performing  like  minor  repair?,  and  in  introducing  the  new 
charge  of  cast-iron  into  the  vessel.  If  we  except  time 
occupied  in  extraordinary  repairs,  such  as  changing  bot- 
toms, patching  the  lining,  etc.,  VT  is  usually  short 
eviough.  If  there  is  any  delay  here,  it  is  through  charg- 
ing large  quantities  of  cold  scrap  steel  by  hand  ; m  this 
may  be  avoided  by  charging  the  scrap  steel  through  a 
chute  during  the  blow. 


a  Eng.  and  Mining  Jl.,  XLIII.,  p.  253, 1887. 

.  v*  E.  ij.,  to  lower  tlie  temperature  of  the  blow.    This  may,  however,  be  done  by 
Vlowiug  steam  iutothe  vessel  ukm;;  with  the  blast, 


From  many  observations  I  believe  that  it  is  not  neces- 
sary that  the  different  parts  of  VT  should  occupy  more 
time  than  is  indicated  in  the  first  of  the  following  sets  of 
numbers  ;  I  have  actually  known  them  to  occupv  only 
the  intervals  given  in  the  second  column. 


TABLE  IWI.  —  DETAILS  or  VT. 


Kecarbnrizing 

Pouring  into  casting  ladle 

Kmptyiut;  glfly  and  turning  back  inti)  rrcriviiiL;  p"sitinn  . 
Receiving  cast-iron  and  examining  tuyeres 


Time 

probably 
needed. 


45" 


.Minimum 

observed 

time. 


ir," 

40" 
W 


Total. 


if  Si" 


2'  5r" 


I  have  never  known  the  whole  of  VT  to  take  so  little 
time  as  this,  simply  because  there  is  usually  no  reason  for 
haste,  as  VT  is  readily  made  so  much  shorter  than  BT. 
There  is  usually  more  or  less  waiting,  except  when  chang- 
ing bottoms  :  then  indeed  matters  are  hurried.  In  one 
case,  watch  in  hand,  I  noted  that  14'  30"  elapsed  between 
the  time  of  pouring  the  steel  of  one  heat  into  the  casting- 
ladle  and  that  of  running  in  the  charge  of  cast-iron  for 
the  next  charge,  and  during  this  time  a  bottom  was 
changed.  Adding  25"  for  recarburizing,  45"  for  pouring 
into  the  casting-ladle  and  1'  50"  for  receiving  the  cast-iron 
for  the  following  charge,  VT  would  in  this  case  be  17'  30". 
This  was  at  the  Homestead  works,  where  the  facilities 
for  changing  bottoms  are  not  remarkably  good.  At  the 
Union  works  VT,  including  changing  bottoms,  has  been 
as  short  as  17',  and  63  heats  have  been  blown  in  12  hours, 
usirgbut  one  vessel  and  changing  3  bottoms  ! 

3.  LT  usually  consists  of  the  time  occupied  by  a  single 
casting-crane  in  receiving  the  molten  steel  from  the  vessel, 
in  swinging  to  the  moulds,  in  teeming,  in  changing  or 
repairing  ladles  and  setting  stoppers,  and  in  swinging 
back  to  the  vessel  to  receive  a  new  charge  of  steel.  In 
plants  like  Forsyth's,  however,  the  time  occupied  in  pour- 
ing from  the  vessel  to  the  ladle  is  not  part  of  LT,  for  here 
the  casting-ladle  is  not  put  upon  the  casting-crane  until 
it  has  received  the  charge  of  molten  steel. 

The  details  of  LT  should  be  about  as  follows  in  rapid 
»vork: 

TABLE  190.— DETAILS  or  TIME  OCCUPIED  BT  THE  OPERATIONS  OF  THE  CASTING-CRANE,  FOB, 

10- TON  HEATS,  L  T. 


Vessel  ponrs  di 
rectly  to  casting- 
crane. 

Vessel  does  not 
pour  directly  to 
casting-crane. 

Minimum  time  ob- 
served. 

Receiving  the  molten  steel  

45" 

40" 

Swinging  to  the  moulds  
Teeming  10  tons  in  H  ingots.  ..  . 
Changing  or  repairing  ladles.  .  . 
Swinging  back  to  the  vessel  

28" 
5'  30" 
V    0" 
13" 

30" 
V  SO" 
V   0" 
13" 

25" 
5'  15" 
50" 
11" 

Total 

7'  56" 

V  13" 

",'  11" 

As  LT  consists  chiefly  of  the  teeming  proper,  its  length 
should  increase  almost  proportionally  with  the  weight  of 

he  charge.  For  given  total  weight  it  will  increase 
markedly  with  the  number  of  ingots  per  charge  ;  for  a  given 
weight  of  steel  is  more  rapidly  teemed  into  a  few  large 
than  into  many  small  ingots,  as  the  last  part  of  the  steel 

poured  into  each  mould  must  be  added  cautiously,  in  order 

,hat  the  ingot  may  have  exactly  the  desired  weight,  and 
is  time  is  lost  in  passing  from  mould  to  mould.  But  if 
Jie  ingots  are  cast  in  groups,  as  in  bottom-  and  otherforms 

f  multiple  casting,  LT  increases  relatively  little  with  the 
number  of  ingots.  The  teeming  is  slower  and  hence  LT 


322 


THE    METALLURGY    OF    STEEL. 


is  longer  in  case  of  very  low-carbon  steel  than  in  that  of 
rail-steel. 

4.  MT,  or  the  interval  from  the  time  when  we  begin  teem- 
ing into  a  set  of  moulds  to  the  time  when  we  can  again 
teem  into  a  set  standing  in  the  same  place  in  the  casting 
pit,  consists  (1)  of  the  time  needed  for  teeming  the  whole 
heat :  plus  (2)  the  time  during  which  the  last-teemed  ingot 
must  stand  in  its  mould  before  we  can  strip  it  without 
danger  of  its  bleeding,  or  the  time  needed  for  the  ingot  to 
contract  and  for  the  mould  to  expand  so  much  that  they 
separate  readily :  plus  (3)  the  time  needed  for  stripping 
the  last  teemed  ingot,  plus  the  time  needed  for  lifting  the 
last  four  ingots  from  the  pit  and  placing  them  on  cars  (for 
it  is  more  convenient  to  strip  at  least  four  ingots  consecu- 
tively and  then  to  lift  them  than  to  strip  and  lift  one  at  a 
time)  :  plus  (4)  the  time  needed  for  replacing  the  last  four 
moulds,  for  it  is  hardly  practicable  to  begin  teeming  into 
a  set  of  moulds  till  the  whole  set  is  in  place.  We  here 
assume  that  there  are  ingot-cranes  enough  to  care  for 
these  moulds  and  their  ingots. 

The  details  of  MT  should  be  about  as  follows  in  rapid 
work: 

TABLE  191.— DETAILS  OF  TIKE  OCCUPIED  IN  TEEMING  AND  REPLACING  MOULDS,  MT,  FOR 

10-TON  HEATS  OF  RAIL-STEEL. 


Time  probably 
needed. 

Minimum  time  ob- 
served. 

Teeming  10  tons  in  8  ingots  

y  30" 

&  15" 

W  20" 

9'  49" 

27" 

23" 

1'  50" 

1'  40" 

V  40" 

V  30" 

Total 

W  47" 

\y  37" 

Of  these  the  only  one  as  to  which  I  feel  in  doubt  is  the 
most  important,  to  wit,  the  time  the  ingot  must  remain  in 
the  mould  before  stripping.  I  have  known  ingots  stripped 
successfully  9'  49"  after  teeming,  but  I  have  seen  bleed- 
ing occur  when  a  rail-ingot,  cast  at  normal  temperature, 
was  stripped  9'  50"  after  teeming.  On  the  other  hand  it  is 
stated  that  at  Darlington  (Britain)  half  the  11-inch  ingots 
of  a  rail-steel  heat  are  stripped,  removed  and  placed  in 
the  soaking-pit  by  the  time  that  the  last  ingot  is  teeming, 
and  that,  in  case  of  wire-steel,  each  ingot  stays  in  its 
mould  but  8  minutes.  How  this  early  stripping  is  made 
possible  I  know  not,  but  it  seems  to  imply  some  such 
expedient  as  the  use  of  very  cold  and  thick-walled  moulds 
which,  as  pointed  out  in  §  225,  p.  151,  is  objectionable. 
Perhaps  in  addition  the  moulds  may  taper  more  strongly 
than  ours.  As  MT  consists  chiefly  of  the  time  occupied 
by  the  ingots  in  solidifying,  and  as  thin  ingots  solidify 
much  more  quickly  than  thick  ones,  so  its  length  depends 
chiefly  on  the  thickness  of  the  ingots,  and  to  a  smaller 
extent  on  their  individual  weight.  Further,  as  the  teem- 
ing time  forms  a  considerable  part  of  it,  MT  must  increase 
with  the  weight  and  the  number  of  ingots  per  charge.  So, 
too,  MT  seems  to  be  somewhat  longer  with  low  than  with 
high-carbon  steel,  as  the  former  must  be  teemed  slowly 
on  account  of  its  tendency  to  rise,  and  at  a  much  higher 
temperature  than  is  necessary  for  the  latter  ;  and  this  does 
not  seem  to  be  fully  offset  by  the  counter  consideration 
that  the  former  solidifies  at  a  higher  temperature  than  the 
latter,  and  hence  quicker.  The  explanation  appears  to  be 
that,  with  low-carbon  steel,  the  difference  between  the  tem- 
perature of  fluidity  sufficient  for  teeming  and  that  of 


Time  Probably 
Needed.     " 

Minimum 
Time  ubsi-rved. 

y  30" 

y  o" 

3'  30" 

3'  20" 

y  10" 

3'  0" 

Or  at  the  rate  of  about  \y±  minutes  per  ingot. 

W  10" 

9'  20" 

solidity  sufficient  for  stripping  and  handling,  is  greater 
than  with  high-carbon  steel. 

5.  CT  consists  of  the  time  occupied  by  a  single  ingot- 
crane  in  lifting  the  moulds  from  the  ingots,  and  placing 
them  either  on  cars  or  in  a  cooling-space  within  the  con- 
verting-room ;  in  lifting  the  ingots  and  placing  them  on 
cars  for  removal,  and  in  placing  the  moulds  for  another 
heat. 

TABLE  192.— DETAILS  OF  TIME  OCCUPIED  BY  THE  OPERATIONS  OF  THE  INGOT-CRANES,  CT. 


CT  clearly  depends  almost  wholly  on  the  number  of  in- 
gots per  charge,  and  only  through  this  on  the  weight  of 
the  charge,  save  that  heavy  ingots  cannot  be  raised  and 
swung  quite  so  quickly  as  light  ones. 

Table  198  condenses  part  of  the  foregoing. 

TABLE  193.— TIME  NEEDED  FOB  THE  DETAILS  OPERATIONS  IN  A  IO-TON  BESSEMER  CONVERT- 
ING House,  CASTING  8  INGOTS  PER  HEAT;   CONDENSED. 


Probable  time  in 
rapid  work. 

Minimum 
time  observed. 

Time  dwends 
chiefij  an 

Holley 
and 
like 
plants. 

Forsyth 
and 
like 
plants. 

30" 
V  30" 

19" 

(  %  silicon  in 
|     cast-iron. 

(  Weight    of 
1     charge   aiirf 
\     number    ot 
(     ingots. 
iThickness 
<     and  No.  of 
(   ingots. 
No.  of  ingotf*. 

25" 
45" 
25" 
V  50" 

15" 
40" 
22" 
V  40" 
25" 
y  15" 
50" 
11" 
9'  49" 
3'    0" 
3'  20" 
3'   0" 

3' 

2'  57" 
17' 

17'  11" 

IS'  37" 
9'  20" 

Receiving  cast-iron  and  examining  tuyeres  

28" 
5'  30" 
V    0" 
13" 
ID'  20" 
3>  30" 
3'  30" 
3'  10" 

SO" 
5'  30" 
1'    0" 
13" 

Stripping  8  ingots  and  setting  their  moulds  on  cars. 

&    0" 
3'  25" 

iy  o" 

7'  56" 

iv  47" 

10MO" 

VT  or  cycle  of  vessel  1  Without  changing  bottoms 

7'  13" 

If,  as  we  have  assumed,  blowing  is  to  be  continuous, 
and  if  we  let 

x  =  the  number  of  casting-cranes, 

y  =  the  number  of  sets  of  moulds  for  which  there  is 

space  in  the  casting  pit,  and 

z  =  the  number  of  ingot-cranes,  then  we  mnst  have 
(l)....x>£; 
(2).— y>-g;  and 
(3)..._z>|l 

As  we  shall  shortly  see,  expressions  (2)  and  (3)  require 
modification,  and  become 

(4)  _._y  >•£+!,  and 
(5)....  z>  1.5^  +  1. 

Further,  there  must  be  enough  casting-  and  ingot-cranes, 
x  and  z,  to  reach  the  y  sets  of  moulds. 

§  377.  APPLICATION  OF  THE  FOREGOING  DISCUSSION. — 1. 
Number  of  Vessels.  For  rapid  work  it  is  clearly  desirable 
that  there  should  be  at  least  two  vessels,  so  that  one  may 
blow  while  the  other  receives  and  discharges  metal  and 
undergoes  current  repairs.  If  we  take  BT  as  8'  and  VT  as  3' 
25",  then  clearly  with  two  vessels  we  can  make  a  heat 


OUTPUT    OP    AMERICAN    BESSEMER     WORKS.      g  377. 


323 


every  eight  minutes,  while  with  one  vessel  we  can  only 
make  a  heat  every  11'  25",  and  practically  the  difference 
would  be  greater  than  this. 

But,  while  with  two  vessels  blowing  may  be  continuous 
as  long  as  only  minor  repairs  are  needed,  since  VT  is  so 
much  shorter  than  BT,  yet  when  we  have  to  change  bot- 
toms blowing  must  be  interrupted,  since  in  this  case  VT 
is  likely  to  be  at  least  as  long  as  18'.  Assuming  VT  at 
even  19'  the  course  of  operations  is  as  follows  :  As  soon  as 
vessel  1,  whose  bottom  is  worn  out,  finishes  its  heat,  the 
work  of  changing  bottoms  begins  ;  even  before  the  steel 
is  poured  into  the  ladle  the  bottom  is  partly  iinkeyed. 
Now  while  the  bottom  is  changing,  vessel  2  blows  a  heat 
taking,  say,  8' ;  discharges  and  receives  metal  during,  say, 
8'  25"  or  VT  ;  and  blows  a  second  heat,  taking  8'  more,  or 
altogether  19'  25"  from  the  time  when  vessel  1  ceased 
blowing.  In  these  19'  the  bottom  of  vessel  1  has  been 
changed,  it  has  received  a  new  charge  of  cast-iron,  and 
is  ready  to  blow  as  soon  as  the  second  heat  of  vessel  2 
ends.  Thus  the  total  interruption  due  to  changing  bot- 
toms is  only  3'  25". 

If  now  a  bottom  last  25  heats,  then  on  an  average  there 
will  be  this  interruption  of  3'  25"  every  25  heats,  so  that 
the  blowing,  instead  of  being  absolutely  continuous,  will 
be  continuous  for  25  heats,  or,  say,  25  x  8  =  200',  and 
will  then  be  interrupted  for  3'  25",  so  that  the  interrup- 
tions on  this  account  will  amount  to  1.6$  of  the  total  time. 

But  occasionally,  especially  towards  the  end  of  the 
week,  the  lining  of  the  vessel  at  points  other  than  the  bot- 
tom needs  repairs,  so  that  it  may  be  necessary  to  blow 
three  or  even  four  consecutive  heats  in  one  vessel  while 
the  other  is  undergoing  repairs,  which  would  bring  the 
delay  up  to  10'  or  even  to  14'  out  of  every  200'.  Again, 
it  may  occasionally  happen  that  while  the  bottom  of 
one  vessel  is  changing  that  of  the  other  may  give  out, 
though  this  should  be  extremely  rare  in  well  conducted 
mills.  Taking  all  these  factors  into  consideration,  it  does 
not  seem  probable  that  the  interruptions  due  to  changing 
bottoms  and  repairing  linings  of  vessels  should  amount  to 
more  than  5%  of  the  total  time. 

Now  by  having  three  vessels  instead  of  two,  one  may 
always  be  ready  when  the  bottom  of  another  is  to  be 
changed,  so  that,  but  for  the  inevitable  occasional  delay, 
blowing  may  be  absolutely  continuous.  This  naturally 
leads  us  to  study 

The  relative  advantages  of  two-  and  of  three-vessel 
plants. 

We  find  that  the  conclusion  which  we  have  just  reached, 
that  only  about  5%  greater  output  should  be  expected 
from  a  three  than  from  a  two-vessel  plant,  is  born  out  by 
the  results  reached  in  practice,  both  as  regards  tonnage 
and  the  number  of  heats  made  in  given  time  :  witness  the 
latest  "record-breaking"  results  in  table  194. 

It  is  true  that  two  out  of  the  three  three-vessel  mills, 
South  Chicago  and  Edgar  Thomson,  are  at  a  disadvantage 
in  using  direct-metal,  while  the  Union,  Homestead  and 
Scranton  mills  use  cupola-metal.  Owing  to  unavoidable 
irregularities  in  the  conditions  in  the  blast-furnace,  the 
composition  of  direct-metal  is  less  perfectly  under  control 
than  that  of  cupola-metal.  Mills  using  direct  metal, 
therefore,  are  liable  to  have  occasional  heats  unduly  high 
in  silicon,  and  hence  unduly  long  in  blowing.  But 
the  third  three-vessel  plant,  Harrisburg,  labors  under  no 


such  disadvantage  ;  its  management,  too,  is  able  and  en 

ergetic. 

TABLE  l'.)4.-MAXixrx  OUTPUT  op  AMERICAN  BESSEMER  WORKS. 


Tons. 

Number  of  Heats. 

I* 
& 

a 

12 

^ 
it 
!s  'i 
si 
CO 

11 

Shifts  in  the 
month 
here  (,-iven. 

1*    * 

b. 
fc"    — 

£J 

££ 
8  1 

£.0 

f? 

*8 

.d 

sl 

y 

SE 
#§ 

Sja 

SE 

ij 

t* 
£| 

>.-5 

*s 

i  U 

X 

l's 

• 

~  1 

I!1 

5,486 

28,145 

73 

78 

2,858 

7f>o 

.    (  On  rail-steel,  1887 

'?'  1  Low-carbon  steel, 
lead.     |                          ]HW) 

4T7 
372 

891 
G19 

4,477 

111,  .',72 
13,291 

91.5 
69 

170 
116 

809 

3,636 
3,436 

8 
8 

16 
16 

71 
71 

Three-vessel 
Mills. 

789 
544 

701 

1,384 
1,089 
1,393 

7,557 
5,110 
6,402 

31,120 
20,947 
27,487 

71 
75 
60 

133 
141 
119 

719 

678 

.-,51  ; 

3,014 
2,929 
2,441 

12 
12 
12 

11,  \ 
11 
11 

Not 
given. 

48 
50 

Most  of  the  results  in  Table  194  were  given  me  in  May,  1889,  by  the  management  of  the 
several  mill*  as  their  best  record  up  to  that  time. 

Tin-  Homestead  shifts  are  of  eight  hours,  instead  of  twelve  hours  as  at  the  other  works.  To 
arrive  at  the  maximum  output  per  twelve  hours  at  Homestead  I  have  added  one-half  to  the 
maximum  output  per  eight-hour  shift,  so  as  to  get  data  as  nearly  comparable  with  the  others 
HS  practicable.  Needless  to  say  this  is  giving  Homestead  a  slight  advantage,  for  one  may 
keep  up  a  higher  speed  for  eight  than  for  twelve  hours. 

With  this  exception  the  numbers  given  represent,  actual  results  without  qualification  of 
.•in  v  kind.  Thus  Union  and  Edgar  Thomson  have  actually  made  2,858  and  3,014  heats  respec- 
tively in  one  calendar  month. 


Certainly  there  is  nothing  in  our  present  experience 
pointing  to  a  very  marked  difference  between  the  capacity 
of  a  two-  and  that  of  a  three-vessel  plant.-  But  the  three- 
vessel  plant  has  a  real  advantage  in  that,  thanks  to  our 
being  able  to  lay  one  vessel  off  for  repairs  without  inter- 
fering with  the  output  of  the  mill,  the  vessel-linings  may 
be  repaired  more  leisurely  and  at  more  convenient  times, 
e.  g.,  during  the  week  instead  of  on  Sunday,  by  daylight 
instead  of  hurriedly  at  night ;  and  in  that  bottoms  maybe 
changed  more  leisurely ;  needless  to  say  work  is  usually  not 
only  better  but  cheaper  when  leisurely  than  when  hurried. 
Finally,  the  superintendent's  energy,  spared  from  the  fre- 
quent Imrried planning  of  howto  make  vessel  one  last  till 
the  bottom  of  vessel  two  is  changed,  how  to  make  the  nose- 
lining  last  through  the  week,  etc.,  is  available  for  other 
matters.  In  a  word,  the  three-vessel  plant  works  a  little 
more  easily  and  hence  a  little  more  cheaply. 

On  the  other  hand,  the  three-vessel  plant  is  necessarily 
a  more  expensive  one.  First  we  have  to  provide  the 
third  vessel,  with  its  rotating  mechanism,  supports,  hood, 
etc.  In  a  mill  like  Harrisburg,  Figure  171,  or  Edgar 
Thomson,  Figure  177,  we  have  further  to  provide  a 
longer  building  and  a  second  casting- crane.  In  a  mill  on 
Forsyth's  plan,  like  South  Chicago,  Figure  168,  we  can 
have  three  vessels  without  a  second  casting-crane,  and  prob- 
ably without  materially  increasing  the  size  of  the  build- 
ing ;  but  we  at  least  have  to  have  an  additional  receiving 
crane. 

With  either  the  Edgar  Thomson  or  Forsyth's  plan  the 
number  and  size  of  cupolas,  the  engine  and  boiler  capa- 
city, the  number  and  size  of  ingot-cranes,  and  the  general 
strength  of  the  apparatus  should  be  the  same  for  a  two-  as 
for  a  three  vessel  plant,  for,  as  we  have  seen,  the  output 
is  practically  the  same,  the  quantity  of  cast-iron  to  be 
hoisted,  melted  and  blown,  the  quantity  of  air  needed  for 
blowing,  the  number  and  weight  of  ingots  and  moulds  to 
be  raised  and  lowered  are  all  practically  the  same  in  one 
case  as  in  the  other.  None  can  deny  that  during  the 
hours  when  there  is  no  changing  of  bottoms,  the  two- 
vessel  plant  blows  as  many  and  as  heavy  heats  as  the 
three-vessel  plant :  and  that  the  blowing,  hoisting  and 


324 


THE    METALLURGY    OF    STEEL. 


manipulating  machinery  must  be  designed  for  these  hour: 
of  maximum  output,  not  for  the  average  of  these  with  th< 
stock  hours.  I  have  been  surprised  at  the  deliberat< 
statements  of  eminent  engineers,  that  the  three -vesse 
plant  must  be  made  more  substantial  on  account  of  it: 
greater  output. 

Whether  the  greater  ease  of  working  pays  for  the 
extra  cost  of  the  three-vessel  plant,  is  a  question  on  whicl 
opinions  are  divided.  If  we  assume  that  the  extra  cost 
of  installation  is  $>5,000,h  a  charge  of  20%  per  annum  for 
interest  and  amortization  would  amount  to  $5,000,  or 
$0.025  per  ton  of  ingots  on  an  annual  output  of  200,000 
tons,  or  of  $17  per  diem  for  a  year  of  300  working 
days. 

2.  The  Size  of  Vessels. — There  is  nothing  in  the  experi- 
ence with  ten-ton  vessels  to  lead  as  to  doubt  the  practica- 
bility of  using  larger  ones.    Indeed,  the  new  vessel  shown 
in  Figures  198,  204  and  205  aims  to  hold  from  twelve  to 
fifteen  tons.     If  larger  charges  are  to  be  blown,  it  will  be 
necessary  either  to  increase  the  size  of  ingots,  so  as  to 
have  fewer  to  cast  per  heat,  or  to  provide  some  additional 
means  of  handling  them,  such  as  multiple  casting,  the 
use  of  a  second  or  even  a  third  casting-pit,   etc.     (See 
§  379,  and  the  last  part  of  §  378.) 

3.  NUMBER  OF  CASTING-CRANES  NEEDED. — We  saw  in 
Table  190  that  if,  as  in  most  plants,  LT  includes  the  time 
during  which  the  steel  is  pouring  from  the  vessel  into 
the  casting-ladle,  it  amounts  to  7'  56"  or  dangerously  neai 
BT,  which   is  8' :   if,  however,  the  casting-ladle  is  not 
placed  on  the  casting-crane  till  after  receiving  the  steel, 
LT  is  considerably  shorter,  to  wit  7'  13".     Here  LT  is  47" 
shorter  than  BT,  so  that  a  single  casting-crane  will  per- 
form its  functions  quickly  enough  to  receive  and  distri- 
bute the  steel  as  fast  as  it  is  blown.     A  single  casting- 
crane  then  satisfies  the  formula  y>-^-,  which  becomes 
!>71|-n8,  or  1>0.902.     This  inference  is  in  accord  with 
the  results  of  practice,  for  the  work  at  the  Union  mill, 
with  a  single  casting-crane  which  does  not  receive  the 
molten  steel  till  after  this  has  been  poured  into  the  ladle, 
is  practically  as  rapid  as  that  at  Harrisburg    and  Edgar 
Thomson    where  there   are   two  casting-cranes,    and  as 
that  at  Bethlehem  where  there  are  three. 

In  short,  a  single  casting-crane,  if  it  has  to  hold  the 
casting- ladle  while  the  steel  is  pouring  into  it,  has  so  little 
margin  of  time  that  it  is  liable  to  hold  the  work  back  at 
least  occasionally  :  but  if  it  be  free  to  attend  to  its  other 
duties  during  the  45"  in  which  the  steel  is  pouring  from 
vessel  to  ladle,  it  can  handle  the  steel  as  fast  as  the  vessels 
can  produce  it.  If,  however,  the  number  of  ingots  to  be 
cast  per  minute  were  materially  raised  beyond  its  present 
maximum  number,  whether  by  shortening  the  blow  or  by 
increasing  the  number  of  ingots  per  heat,  a  second  casting- 
crane  as  in  the  Harrisburg  type  would  be  needed,  iinless 
some  form  of  multiple  teeming  were  adopted.  This  is 
true  of  botli  two-  and  three-vessel  plants,  and  of  Forsyth 
as  well  as  of  other  types. 

4.  Number  of  Sets  of  Moulds  for  which  Space  must 


h  The  charge  of  $25,000  is  meant  to  cover  simply  those  items  which  are  neces- 
sitated by  the  addition  of  a  third  vessel  to  a  two-vessel  Forsyth  or  similar  plant ;  to 
wit,  the  third  vessel  with  its  rotating  gear,  hood,  receiving-crane,  additional  plat- 
forms, foundations,  pit  for  receiving  crane,  etc.;  but  it  does  not  cover  any  charge 
for  additional  engine  or  boiler-power,  casting  or  ingot-cranes,  cupolas,  hoists,  etc., 
•which,  from  this  point  of  view,  remain  the  same  as  for  a  two-vessel  plant. 


be  provided  in  the  Casting  Pit.  —  According  to  (2)  y 
must  be  greater  than  -f£:  according  to  Tables  192  and  193 
MT=19'  47"  and  BT=8':  hence  >'  ory=3. 


In  other  words,  if  (Table  193)  it  takes  5'  30"  to  teem  the 
steel  of  one  heat  ;  if  we  must  allow  the  last  ingot  of 
the  heat  10'  20"  to  cool  before  stripping  it  ;  and  if  to 
strip  it,  to  remove  the  ingots,  and  to  set  a  fresh  lot 
of  moulds  in  place  takes  3'  57",  we  cannot  begin  to 
teem  again  in  the  place  occupied  by  this  set  of  moulds 
till  5'  30"  +  10'  20"  +  3'  57"  =  19'  47"  after  the  time  when 
we  began  teeming  the  previous  heat  in  this  place.  That 
is  to  say,  this  casting-  space  can  receive  a  heat  of  steel 
only  once  in  19'  47"  :  and  in  order  that  there  may  be  a 
casting-space  ready  to  receive  a  heat  of  steel  every  8', 
there  must  be  space  for  at  least  19f|  -=-8  —  2.5  sets  of 
moulds  in  the  casting-pit,  or,  as  we  cannot  have  fractions, 
3  sets.  But  in  case  of  rapid  working  it  is  far  better  to 
have  a  spare  set  of  moulds  in  the  pit,  or  altogether  four 
sets,  so  that 

-«  4-1. 


This  is  desirable,  both  that  the  pit-men,  whose  labor  in 
hot  weather  is  extremely  trying,  may  have  an  occasional 
breathing  spell  ;  and  that,  no  matter  what  happens,  there 
may  always  be  moulds  enough  to  take  the  steel.  There 
is  not  enough  margin  between  the  temperature  of  the 
molten  steel  as  it  leaves  the  vessel  and  the  melting-point 
of  the  metal,  to  allow  us  to  hold  it  long  in  the  ladle  ; 
moreover,  the  casting-crane  is  in  constant  requisition.  It 
would,  indeed,  be  trying  to  have  a  heat  of  steel  blown 
and  in  the  ladle,  ready  for  teeming,  and  then  to  be  forced 
to  convert  i  t  into  scrap  for  want  of  moulds. 

A  set  of  eight  14|"  ingot-moulds  occupies  at  least  14 
running  feet  ;  for  four  sets  we  need  56  running  feet,  and 
it  is  better  to  allow  60  feet.  This  should  be  measured  on 
the  arc  of  a  circle  about  four  feet  less  in  diameter  than 
the  rim  of  the  casting-pit,  for  the  moulds  come  together 
only  on  the  edges  nearer  the  centre  of  the  pit,  gaping  at 
the  outer  edges.  In  a  40-foot  pit  an  allowance  of  60  feet 
for  the  inner  circle  of  the  moulds  calls  for  an  arc  of  191°. 

5.  Number  of  Ingot-cranes  Needed.  —  As  we  have  seen 
in  Tables  192  and  193  that  BT  and  CT  are  8'  and  10'  10" 
respectively,  to  satisfy  the  formula  z>-ff,  we  need 


more  than  (10  +  |$)  *  8  =  !-27»  «•  «.,  we  need  two  ingot 
cranes  ;  that  is,  as  it  takes  10'  10"  to  strip  and  lift  the 
ingots  of  a  single  heat  and  to  replace  their  moulds  for  a 
subsequent  heat,  so  in  order  that  an  ingot-crane  may  be 
ready  to  handle  a  set  of  ingots  and  moulds  every  8',  there 
must  be  two  ingot-cranes,  supposing  that  each  works  con- 
tinuously. But  this  cannot  be  the  case,  for  each  neces- 
sarily stands  idle  a  considerable  part  of  the  time,  e.  g., 
from  the  time  when  the  moulds  in  its  neighborhood  are 
n  place  and  ready  for  receiving  steel,  till  they  have  been 
filled  with  steel,  and  till  the  steel  ingots  within  them  have 
so  far  solidified  that  they  can  be  stripped  safely.  It  is 
;herefore  found  necessary  in  practice  to  have  three  ingot- 
cranes  for  a  ten-ton  plant.  In  addition,  the  crane  which 
s  used  for  removing  the  casting-ladle  from  the  casting- 
crane,  and  for  replacing  it  with  another,  and  (in  case  it  be 
unnecessary  to  change  ladles)  for  inverting  the  ladle  to 
jmpty  the  slag,  though  properly  speaking  a  ladle-shift 
ng  or,  as  it  is  called,  "dump"  crane,  is  often  clnssed 
with  the  ingot-cranes.  Indeed,  it  is  usually  exactly  like 


THE    CAPACITY    OF    A    CASTING    PIT.      §  878. 


325 


them.  Thus  we  actually  need  four  ingot  and  dump  cranes 
for  rapid  working  with  a  10-ton  plant.  I  think  that  the 
empirical  formula 

(5)  ..... 


gives  a  sufficiently  close  approximation  for  practical  pur- 
poses. In  case  of  a  six-ton  plant  this  formula  would 
require  three  ingot-cranes. 

In  point  of  fact  the  American  plants  noted  for  their 
quick  working  have  at  least  as  many  ingot  cranes  as  this 
fur  in  ula  calls  for,  Union,  S.  Chicago,  Harrisburg  and 
Homestead  having  four  each,  Scranton  (a  six-ton  plant) 
having  three,  and  Edgar  Thomson  five. 

As  the  large  number  of  ingot-cranes  needed  is  chiefly 
due  to  their  having  to  stand  idle  so  much  of  the  time,  so 
it  is  clear  that  the  number  of  ingot-cranes  needed  will  not 
increase  proportionally  to  the  number  of  ingots  cast  from 
each  heat. 

The  method  I  here  use  is  less  suited  to  the  case  of 
ingot-cranes  than  to  the  other  cases  to  which  it  is  ap- 
plied. 

§  378.  THE  CAPACITY  OF  A  CASTING-PIT  is  limited,  1st, 
by  the  rate  at  which  the  casting-  crane  or  cranes  can  teem  ; 
2d,  by  the  room  available  for  moulds  within  the  pit  ;  3d, 
by  the  number  of  ingots  and  moulds  which  the  ingot- 
cranes  can  handle. 

We  have  seen  that  a  single  casting-crane  can  teem  con- 
tinuously at  the  rate  of  one  1.25-ton  ingot  per  minute.  I 
should  think  that  it  could  teem  19-inch  3  ton  ingots  at 
the  rate  of  one  every  two  minutes,  and  7-inch  750-pound 
ingots  at  the  rate  of  two  per  minute.  A  second  casting- 
crane  would  cast  as  much  more. 

If  we  measure  the  space  available  for  moulds  along  the 
arc  of  a  circle  four  feet  less  in  diameter  than  the  pit,  the 
250°  of  a  40-foot  Forsyth  pit  available  for  moulds  would 
give  78  running  feet.  If  a  second  row  of  moulds  were 


placed  within  the  first,  70  running  feet  more  would  be 
available,  or  altogether  148  feet.  In  a  48- foot  pit  these 
numbers  become  90  and  183  feet  respectively.  For  a  10- 
(on  heat  of  14-inch  ingots  we  have  taken  MT,  or  the  period 
between  beginning  to  teem  into  a  set  of  moulds  and  again 
beginning  to  teem  into  a  second  set  standing  in  the  same 
place,  as  about  20  minutes  ;  if  we  take  MT  provisionally 
as  30  minutes  for  19-inch  and  15  minutes  for  7-inch 
ingots,  and  if  there  be  a  single  row  of  moulds  in  case  of 
19-  and  of  14-inch  ingots  and  a  double  row  in  case  of 
7-inch  ingots,  and  if  we  assume  that  our  ingot-cranes  can 
do  their  share  of  the  work,  then  it  follows  that,  as  far  as 
mould-space  is  concerned,  we  could  cast  in  a  40-foot  pit 
1.16  19-inch,  or  2.3  14-inch,  or  9.9  7-inch  ingots  per 
minute  ;  and  that  in  a  48-foot  pit  we  could  teem  1.4  19- 
inch,  or  2.9  14-inch,  or  12.2  7-inch  ingots  per  minute. 

Next,  as  regards  the  ingot-crane  capacity.  It  is  hardly 
practicable  to  have  more  than  three  cranes  devoted  solely 
to  the  care  of  ingots  and  moulds  at  a  40-foot  pit,  or  more 
than  four  at  a  48-foot  pit,  as  explained  in  §  380  B.  For 
each  ingot  three  separate  operations  are  needed,  and  to 
perform  these  we  have  seen  that  about  1.25  minutes  are 
needed  for  each  1.25-ton  ingot.  Let  us  assume  that  two 
minutes  would  be  needed  for  each  3-ton  ingot  and  one 
minute  for  each  750-pound  ingot.  When  casting  1.25- ton 
14-inch  ingots  the  ingot-cranes  may  have  to  stand  idle 
half  the  time  ;  but  in  casting  smaller,  say  750  pound, 
ingots,  they  would  work  much  more  nearly  continuously, 
and  I  think  that  we  may  assume  that  each  crane  would 
stand  idle  only  one-quarter  of  the  time.  Under  these  as- 
sumptions three  ingot-cranes  could  handle  3-ton  ingots  at 
the  rate  of  one  in  1.3  minutes  ;  1.25-ton  ingots  at  the  rate 
of  1.2  ingots  per  minute ;  and  750-pound  ingots  at  the 
rate  of  2.25  per  minute.  With  a  fourth  crane  these  rates 
would  be  increased  by  one-third. 

Some  of  these  inferences  are  summed  up  in  the  follow- 
ing table  : 


TABLE  195.- ESTIMATED  CAPACITY  or  A  SIHOLK  PIT  PER  24  HOURS. 


1 

fc 

1... 
2 

40-foot  pit  with  three  cranes  for  handling  ingots  and  moulds. 

48-foot  pit  with  four  cranes  for  handling  ingots  and  moulds. 

Casting  3-ton  19-inch 
ingots. 

Casting  1.25-ton  14- 
inch  ingots 

Casting   750-pound   7- 
inch  ingots:    2  rows 
of  moulds. 

Casting  3-ton  19-inch 
ingots. 

Casting  1.25-ton  14- 
incn  ingots. 

Casting 
7-inch 
rows  of 

750  pound 
ngots  :  2 

moulds. 

for  Twen 
Tons. 

y-four  hoi 
Ingots. 

Ingots. 

Tons. 

Ingots. 

Tons. 

Ingots. 

Tone. 

Ingots. 

Tons. 

Ingots. 

Tons. 

I.—  AB  limited  by  the  capacity  of  a  single  cast-  j 

720 

2,100 

720 

2,160 

1,440 

1,800 

1,440 

1,800 

II.—  As  limited  by  the  arailable  mould-space.  .  .  -J 
III.—  As  limited  by  the  capacity  of  the  ingot-  J 

(... 
4... 

5... 
g 

1,663 

5,000 

2,880 

2,048 

6,143 

3,370 

4,212 

4,147 

5,200 

14,000 

4,750 

17,568 

5.800 

7... 
ft 

1,080 

3,240 

1,440 

4,320 

1,728 

2,160 

2,304 

2,900 

] 

1 

3,240 

1,100 

These  numbers  indicate  that  the  mould-holding  capacity 
of  even  a  40-foot  pit  is  far  beyond  the  present  blowing- 
capacity  of  two  or  three  10-ton  vessels;  but,  bcfur.;  the 
tonnage  indicated  in  lines  4  to  6  was  reached,  grave  incon- 
veniences from  the  excessive  heat- radiation  from  so  enor- 
mous a  quantity  of  metal  compactly  stored  in  a  single  pit 
at  one  time,  would  arise. 

It  is  quite  otherwise,  however,  with  the  casting-  and 
ingot-crane  capacity.  The  former  of  these,  even  in  case 
of  1.25-ton  ingots,  is  barely  equal  to  the  actual  rate  at 
which  a  pair  of  vessels  has  turned  out  steel  for  a  consider- 
able period.  On  any  considerable  increase  in  the  tonnage 


or  in  the  number  of  ingots,  the  capacity  of  a  single 
casting-crane  would  be  exceeded.  As  regards  the  ingot- 
cranes,  the  case  is  not  so  bad,  for  with  a  48  foot  pit  four 
ingot-cranes  could,  according  to  this  estimate,  take  care  of 
more  1.25-ton  ingot  than  two  or  three  vessels  are  likely  to 
turn  out.  But  should  the  number  of  ingots  be  greatly  in- 
creased, e.  g.,  by  diminishing  their  size,  additional  ingot- 
crane  capacity  would  be  needed. 

In  short,  further  increase  in  blowing-capacity  is  likely 
to  necessitate,  first  an  increase  in  the  teeming-capacity, 
and  only  later  in  the  ingot-handling  capacity. 

The  teeming- capacity  may  be  increased  by  multiple- 


326 


THE    METALLURGY    OF    STEEL. 


teeming,  e.  g.,  by  teeming  through  a  funnel  which  delivers 
into  several  moulds,  and  by  other  devices  which  will  be 
considered  later  ;  or  by  the  use  of  a  second,  or  eventually 
a  third  casting  crane.  The  casting-cranes  may  all  stand 
in  the  same  pit ;  but  more  casting  room  can  be  had  and  a 
greater  number  of  ingot-cranes  can  be  used  if  we  have  a 
separate  pit  for  each  casting-crane.  Pits  may  be  arranged 
as  in  Figure  175,  which  may  be  considered  as  the  logical 
development  of  Forsyth's  plan. 

The  use  of  a  second  casting-crane  has  an  advantage  over 
multiple-teeming,  in  that  it  enables  us  to  use  more  ingot- 
cranes.  For  very  small  castings  multiple- teeming  seems 
to  be  a  necessity,  unless  proportionally  small  charges 
are  blown  in  little  vessels,  as  a  large  heat  would  chill 
before  it  could  be  teemed  separately  into  a  great  number 
of  small  castings. 

To  increase  the  capacity  of  the  ingot-cranes,  we  must 
cut  down  the  number  of  motions  per  ingot  which  they 
have  to  execute.  Usually  they  have  to  perform  three 
distinct  manoauvres,  placing  the  mould,  stripping,  and 
removing  the  ingot.  The  number  of  motions  may  be 
reduced  by  placing  several  moulds  on  a  single  plate, 
which  with  ingots  and  moulds  is  lifted  from  the  pit  by 
a  single  motion  of  the  crane  ;  or  by  lifting  ingot  and 
mould  together  from  the  pit;  or  by  placing  the  several 
moulds  of  a  group  of  ingots  in  a  common  frame,  so  that 
they  are  lifted  from  the  pit  by  a  single  motion  of  the 
crane,  the  ingots  remaining  behind.  In  the  first  two  cases 
no  real  saving  of  labor  is  effected,  if  the  ingots  and  moulds 
are  simply  carried  off  to  be  stripped  elsewhere  in  the  way 
in  which  they  are  usually  stripped  in  the  pit.  This 
simply  changes  the  venue ;  but  by  Laureau's  or  Jones.' 
mode  of  stripping,  a  saving  may  be  effected. 

§  379.  KLEINBESSEMEBEI,  SMALL  versus  LARGK  BES- 
SEMER PLANTS. — The  question  as  to  the  most  desirable 
weight  of  charge  naturally  divides  itself  into  two  quite 
distinct  parts.  1st.  Do  we  with  large  or  with  small 
charges  habitually  get  the  better  product  (or  the  more 
readily  make  a  product  of  given  excellence)  from  given 
materials  ?  2d.  Is  it  cheaper  to  blow  large  or  small 
charges  ?  We  have  two  distinct  questions,  one  of  quality, 
the  other  of  cost. 

The  question  of  quality  can  be  considered  better  in 
treating  of  the  chemistry  of  the  Bessemer  process.  I  may 
here  say,  however,  that  after  pretty  extensive  enquiries 
and  observations,  I  find  neither  good  reason  to  expect 
better  product  nor  convincing  evidence  that  better  product 
is  made  in  case  of  small  than  in  that  of  large  charges. 
Nor  is  it  clear  to  me  that  soft  ingot-iron  is  more  readily 
or  more  regularly  made  in  small  than  in  large  vessels. 

As  regards  the  question  of  cost,  much  confusion  has 
been  brought  into  what  should  be  a  very  simple  discus- 
sion, by  comparing  small  works  which  run  continuously 
with  larger  works  which  run  intermittently.  Nobody  will 
deny  that  the  more  nearly  continuous  the  work  the 
cheaper  it  will  be,  for  most  obvious  reasons.  We  have  in 
the  first  place  the  factors  common  to  all  industries  :  our 
workmen  and  machines  work  a  greater  proportion  of  the 
time,  charges  for  amortization  and  interest,  for  adminis- 
tration and  general  expenses  are  less  per  unit  of  product. 
But  beyond  these,  we  have  in  metalliirgial  operations  a 
very  important  factor :  the  loss  of  heat  from  furnaces, 


vessels  and  what  not  is  less  in  continuous  than  in  inter- 
rupted working. 

Now,  some  advocates  of  small  charges  have  assumed 
that  large  charges  cannot  be  blown  continuously,  which 
is  untrue ;  for  in  our  large  American  works  with  10-ton 
vessels  the  blowing  is  habitually  continuous,  one  vessel 
turning  up  to  blow  a  charge  the  moment  that  the  blowing 
of  the  preceding  charge  ends,  so  that  the  bio  wing- engine 
often  runs  for  hours  without  stopping.  Thus  Ehren- 
werth's  calculation  that  the  little  Bessemer  plant 
at  Avesta  is  more  economical  than  the  larger  ones  is  most 
misleading,  for  he  compares  a  four-ton  plant  making  only 
fifteen  heats  daily  with  an  880-pound  plant  making 
fifty  heats  daily,  while  our  ten-ton  plants  make  twice  this 
number  of  heats.  Now  it  is  not  the  greater  size  of  the 
four-ton  plant,  but  the  very  small  number  of  charges 
which  it  makes  daily,  that  puts  it  at  a  disadvantage. 
Whatever  merit  there  was  in  the  Avesta  work  was  in  its 
continuousness,  not  in  the  lightness  of  its  charges. 

This  does  not  really  merit  discussion,  but  if  proof  is 
needed,  it  is  at  hand  in  the  fact  that  the  Avesta  small 
charges  were  kept  up  for  more  than  five  years  without  an 
imitator,  and  th;it  even  here  it  was  found  best  to  increase 
the  charges  to  3,300  pounds. 

In  this  country  the  little  Clapp-Grriffiths  vessels  at  first 
had  a  capacity  of  two  tons  ;  the  later  ones  have  three  tons 
capacitj'.  Indeed  the  American  Clnpp-Grifnths  practice 
can  hardly  come  under  the  term  "  Kleinbessemerei," 
which  was  applied  to  the  half-ton  Avesta  practice  in 
distinction  to  the  Austrian  four-ton  work,  termed  "Gross- 
bessemerei." 

What,  then,  is  the  most  advantageous  weight  of 
charge  ?  Usually  that  which  with  continuous  blowing, 
or  with  an  interval  of  not  over  two  minutes  between 
blows,  will  yield  the  output  which  is  aimed  at  in  the 
establishment  under  consideration,  supposing  this 
establishment  to  run  say  ten  months  out  of  the  year.7 
This,  however,  is  only  true  within  limits.  I  doubt 
whether  it  would  be  wise  under  most  conditions  to  make 
the  weight  of  the  charge  less  than  two  tons,  even  when  a 
very  small  output  is  aimed  at. 

What  the  expected  output  is  to  be  must  depend  on  many 
conditions,  the  kind  of  steel  aimed  at,  whether  for  rails 
or  steel  pens,  the  supply  of  cast-iron,  the  expected  de- 
mand, etc.  If  a  mill  is  to  be  built  to  supply  steel  for  fish- 
hooks alone,  a  pair  of  twelve-ton  vessels  would  be  absurd  ; 
no  less  absurd  would  the  Avesta  toy-vessels  be  for  rail- 
making.  I  take  it  that  the  claim  that  steel  can  be  made 
cheaper  in  little  than  in  large  mills  does  not  deserve  dis- 
cussion. Other  things  being  equal,  if  the  demand  for 
steel  will  keep  a  ten-ton  plant  fully  occupied,  that  steel 
can  be  made  cheaper  in  a  ten-ton  plant  than  in  a  one-ton 
or  in  a  half-ton  plant. 

Many  factors  tend  to  concentrate  industries  into  colos- 
sal establishments,  ruled  by  giants  of  administration. 
Among  these  we  have  the  increased  facility  of  transpor- 
tation, and  the  growth  of  scientific  and  technical 
knowledge  applicable  to  industries  to  such  an  enormous 


y  I  say  ten  rather  than  twelve  months,  because  in  case  of  many  large  manufact- 
uring industries  it  is  thought  more  profitable,  if  a  given  quantity  of  output  is  to  be 
made  in  a  certain  year,  to  make  that  output  in  ten  months,  even  if  the  mill  be  thereby 
slightly  pressed,  than  to  spread  the  work  over  the  whole  year.  It  is,  moreover, 
better  that  the  capacity  of  the  establishment  should  be  rather  larger  than  the  ex- 
pected output,  so  that  an  unexpected  demand  can  be  taken  advantage  of. 


KLEINBESSERMERIE  :     LARGE    VS.     SMALL    PLANTS.      §  379. 


327 


volume  and  to  such  value  that  trained  specialists, 
reservoirs  of  this  knowledge,  can  be  advantageously 
employed.  Their  salaries  clearly  form  a  smaller  charge 
against  a  large  than  against  a  small  output.  The  cost  of 
engines,  of  plant,  of  administration,*  clearly  does  not  in- 
crease proportionally  to  the  size  of  the  establishment. 
Hence  it  occurs  that,  in  many  industries,  enterprises  large 
enough  to  employ  the  best  administrative  talent  to  their 
fullest  capacity — but  not  larger,  and  not  too  large  for  their 
market — can  be  operated  at  less  cost  than  smaller  ones. 

These  considerations  seem  to  apply  with  especial  force 
to  the  manufacture  of  steel  ingots  ;  for  the  proportion  of 
the  total  heat  generated  which  is  lost  in  case  of  large  con- 


But  it  is  quite  in  accordance  with  these  views  that  small 
works  should  sometimes  be  profitable.  Local  conditions,  a 
small  local  demand  for  steel  in  a  region  which  offers  the  raw 
materials,  but  is  remote  from  other  markets  ;  the  manu- 
facture of  a  special  or  even  secret  kind  of  steel,  suited  to 
certain  small  demands;  the  need  of  unusual  knowledge 
and  skill  or  extraordinary  care  ;  in  short,  the  conditions 
which  permit  little  industries  to  flourish  all  over  the 
world  without  being  overwhelmed  by  the  great  producers, 
may  permit  small  Bessemer  works  to  live  and  even 
thrive.  But  as  the  increased  facility  of  transportation 
and  indeed  the  whole  march  of  civilization  favors  the  con- 
centration of  industries  into  large  establishments,  ruled 


For  Repair  of  ladles  /"Jill  For  Repair  of 


TWO   3-TON    VESSEL    PLA'NT. 

Gorton;  Strobfl  &  taitresut. 


165. 


verters,  large  furnaces  for  heating  and  melting,  is  less 
than  in  case  of  small  ones ;  the  loss  in  scrap  and  by 
oxidation  is  less,  the  consumption  of  refractory  materials 
and  moulds  is  less  per  unit  of  product  in  case  of  large 
charges  than  in  that  of  small  ones." 


a  In  certain  industries  (e.  g.,  in  making  sewing  machines)  the  cost  of  adminis- 
tration, advertisement,  and  collection  is  said  to  be  far  greater  than  that  of  manu- 
facture proper. 

b  Classing  as  small  all  workshops  with  five  workmen  or  less,  and  as  large  all  with 
more  than  five  workmen,  Dr.  H.  Albrecht  finds  that  in  Germany,  according  to  the 
trades  census  of  1882,  99$  of  the  mining,  smelting,  and  salt-making  establishments 
are  large,  while  the  proportion  is  much  less  in  other  industries,  running  from  76$ 
in  chemical  manufacture  to  10%  in  clothing  and  repairing.  ("  Tlje  Ration,"  N,  Y., 
XLVI1I,  P,  480,  1889,  from  "  Jahrbucli  fur  Geeetzgebung.") 


by  giants  of  administration,  so  the  times  seem  to  favor 
larger  rather  than  smaller  steel  mills. 

Again,  while  it  is  beyond  question  that  well  designed 
large  works  can  turn  out  large  ingots  of  usual  sizes  more 
cheaply  than  small  works,  most  of  them  have  not  been 
equipped  for  turning  out  ingots,  billets  or  slabs  of  a  wide 
variety  of  sizes,  shapes  and  compositions. 

It  may  be  much  cheaper  to  make  slabs  for  nail-plates, 
for  instance,  by  making  ingots  in  little  vessels,  and  roll- 
ing those  ingots  down  while  they  still  preserve  their  ini- 
tial heat,  than  to  buy  even  cheaper  but  cold  ingots  from  a 
large  mill,  pay  freight  and  brokerage,  and  then  heat  these 
cold  ingots  at  great  outlay  for  fuel,  labor,  and  repairs  to 


328 


THE    METALLURGY    OF    STEEL. 


heating  furnaces.  A  pound  of  hot  ingots  is  worth  more 
in  such  cases  than  a  pound  of  cold  ones.  This  has  been 
especially  true  in  the  past  somewhat  crude  condition  of 
our  Bessemer  industry,  crude  in  the  sense  that  it  has  been 
chiefly  planned  for  turning  out  an  enormous  quantity 
of  ingots  of  uniform  size,  to  be  rolled  into  one  kind  of 
product,  rails.  In  this  way  the  little  Bessemer  works 
have  had  a  real  reason  for  existence.  As  the  manufac- 
ture of  billets  or  slabs  of  a  certain  size  and  composition 
in  small  mills  assumes  serious  proportions,  t!ie  large 
mills  equip  themselves  for  making  these  very  products, 
and  roll  their  ingots,  with  their  initial  heat,  into  these 
very  forms,  and  this  special  reason  for  the  existence  of 
the  little  works  evaporates. 

The  same  thing  may  happen  in  the  case  of  little  ingots. 
Our  great  mills  with  their  one  or  two  circular  casting  pits 
can  make  a  thousand  tons  of  large  ingots  daily  ;  but  they 
are  not  prepared  to  turn  their  product  into  little  ingots. 
Let  some  little  Bessemer  works  develop  a  valuable  trade 
in  little  ingots,  and  the  great  works  will  establish  some 
special  form  of  pit  or  of  multiple  casting,  swoop  down 
and  carry  off  the  prey. 

While  the  great  works  may  drive  the  little  ones  from 
some  positions  readily,  in  others  to  which  they  are 
specially  fitted  the  little  mills  may  hold  their  own  long,  or 
even  permanently. 

This,  however,  belongs  rather  to  political  economy  than 
to  metallurgy.  All  that  I  can  do  is  to  point  out,  and  in- 
deed to  insist,  that  the  forces  which  make  for  concentra- 
tion elsewhere  are  and  will  remain  at  work  in  case  of  the 
Bessemer  process,  in  which  they  are  reinforced  by  the 
special  conditions  of  the  process  itself. 

Figure  165  shows  a  good  arrangement  for  a  small  Besse- 
mer plant.  Two  cupolas  deliver  the  molten  cast  iron  to 
a  ladle  which  runs  on  an  elevated  track,  and  which  in 
turn  delivers  it  to  the  vessels.  A  common  casting-ladle 
casts  the  steel  into  moulds  standing  along  the  rim  of  a 
semi-circular  casting-pit.  From  this  pit  the  ingots  are 
drawn  by  a  crane,  which  deposits  them  on  end  in  a  heat- 
ing-furnace or  soaking-pit,  whence  they  are  drawn  later 
and  deposited  on  the  feed-rollers  of  the  blooming-mill. 

The  refractory  materials  are  prepared  behind  the  ves 
sels,  in  a  space  served  by  a  15  foot  crane.     Near  here 
stands  a  small  engine  which  drives  the  fan  blowers  for  the 
cupola   furnaces,    and    the    crushing    and    pulverizing 
machinery  for  the  refractory  materials. 

§  380.  THE  GENERAL  DISPOSITION  OF  THE  VESSELS, 
PIT,  AND  INGOT-CRANES.* — In  the  early  Bessemer  plants, 
Figure  166,  the  vessel-trunnions  were  but  three  or  four  feet 
above  the  general  level.  This  necessitated  a  very  deep  cast- 
ing pit,  so  that  the  vessels  might  empty  their  slag  through 
their  noses  on  being  inverted,  that  their  bottoms  might 
be  removed  and  replaced  from  beneath,  and  that  the 
casting-crane  might  raise  the  casting-ladle  above  the  tops 
of  the  moulds  standing  in  the  casting-pit  without  having 
a  very  long  lift,  which  would  have  increased  its  cost  ma,- 
terially,  especially  as  the  British  cranes  are  not  sup- 
ported at  the  top.  "In  this  confined,  unventilated  and 
comparatively  inaccessible,"  indeed,  infernal  abyss, 


hemmed  in  by  red-hot  ingots  and  moulds,  bespattered  by 
the  vessel's  white-hot  spittings  as  it  turned  up  or  down, 
scorched  by  the  slag  which  it  dropped  between  heats, 
and  threatened  by  the  floods  of  molten  steel  which  now 
and  again  broke  through  its  nether  parts,  the  salaman- 
drine  pit-men  intolerably  reeked  and  wrought. 

The  vessels  were  placed  opposite  each  other. 

In  the  early  American  or  Holleyb  plants  the  vessels  were 
raised,  as  shown  in  Figure  163,  to  nine  feet  above  the 
general  level,  while  in  still  later  plants,  e.  g.,  S.  Chicago, 
their  height  has  been  further  increased  to  15',  and  they 
have  almost  uniformly  been  placed  side  by  side.  This  en- 
ibled  Holley  to  use  a  shallow  pit,  only  30"  deep,  though 
in  later  mills  the  pit  is  36"  deep.  At  the  same  time  its 


a  For  admirable  descriptions  of  Bessemer  plants  see  Macar,  Revue  Universelle 
2d  Ser.,  XII.,  p.  143,  1882,  from  which  I  have  borrowed  several  illustrations  ;  also, 
Cireiner,  Idem,  XI.  ;  Daelen,  Zeit.  Vereins,  Deutsch,  lug.,  XXIX.,  pp.  554,  1016, 
A.  1).  1885.  Other  illustrations  are  borrowed  from  Trasenter,  "  L'Industrie 
rurgique  aux  Etats-Unis,"  Rev.  Univ.,  3d  Ser.,  XVII.,  p.  231, 1885, 


Fig.  166.    STANDARD  BRITISH  BESSEMER  PLANT.    HOLLEY. 

C  casting-crane,    c  ingot  cranes.    Co  Converter.    G  rack  for  rotating  vessel.    N  ingot  moulds. 
T  hoods. 

diameter  has  been  increased  to  40'  and  even  to  48'.  In 
some  late  British  plants  the  vessels  are  supported  aloft 
in  Holley' s  style0. 


b  On  Jan.  36th,  1869  (U.  S.  Patent  86,303),  Ilolley  patented  supporting  one  side  of 
the  vessel  on  a  beam,  so  that  a  car  could  be  run  beneath  it  (for  removing  bottoms, 
etc.),  a  hollow  column  for  supporting  this  beam,  and  at  the  same  time  carrying  the 
blast  to  the  vessel-trunnion,  and  what  appears  equivalent  to  raising  the  trunnion- 
level  high  above  the  general  level.  I  do  not  find  that  he  patented  placing  the 
vessels  side  by  side  :  Indeed,  he  stated  in  1871,  that  Bessemer  did  this  in  his  early 
practice,  but  not  in  such  a  way  as  to  realize  the  advantages  of  the  Holley  plant. 
(Lecture  at  the  Stevens  Inst.  of  Technology,  1872,  p.  34  :  Journ.  Franklin  Inst., 
XCrV.,  pp.  252,  391, 1872). 

c  In  the  model  of  a  (British)  Bessemer  plant  exhibited  at  the  Paris  Exhibition  of 
1880,  by  J.  Ojers,  the  vessels,  pit,  and  cranes  are  arranged  much  as  in  Figure  169, 
save  that  tl  e  receiving-crane  delivers  direct  to  the  casting-crane  without  Forsyth's 
transfer-track,  and  that  the  cast-iron  is  brought  to  the  vessels  by  a  hoist  which 
stands  between  them,  as  at  H  in  Figure  164, 


DIMENSIONS    OF    BESSEMER    PLANTS. 


380. 


329 


A.  Raising  the  vessels  and  shallowing  the  pit  has  had 
the  following  advantages : 

1.  The  pit  is  much  cooler. 

2.  The  pit-level  is  so  nearly  that  of  the  ground  outside 
the  works  (indeed,  in  many  works  the  pit-bottom  is  level 
with  the  ground  outside,  the  general  working- level  of  the 
converting-mill  being  raised  some  three  feet  above  this), 
that  the  vessel-slag  and  the  casting  ladle  slag,  which  may 
amount  to  some  150  tons  daily,  are  readily  removed  by 
cars  running  on  a  track  level  with  the  pit-bottom,  instead 
of  being  shoveled  up  as  from  the  old  deep  pit  a  tremen- 


The  short  lift  means  not  only  diminishing  the  outlay  for 
power  by  half,  but  lessening  by  about  one-third  that  for 
labor,  since  the  pit-men  who  guide  the  rising  and  falling 
ingots  and  moulds  must  stand  in  the  unbearable  heat 
about  half  longer  for  an.  eleven-  than  for  a  five- foot  lift. 
Indeed  I  should  put  the  saving  in  labor  even  higher  than 
this :  for  with  the  shallow  American  pit  the  tops  of  theingots 
and  moulds  are  at  such  a  level  that  crane  dogs  and  hooks 
can  be  attached  to  them  conveniently  by  the  men  standing 
on  the  general  level,  and  these  same  men  swing  the  crane, 
after  it  has  lifted  the  ingot  or  mould,  around  to  the  cars 


TABLE  196.— BESSEMER  PLANT. 


Number. 

Pit. 

Vessels. 

Tuyeres. 

Blast-pressure,  Ibs.  per 
square  inch 

Cnbic  con- 
tents of 
vessels. 

Diameter. 

A 

13. 

& 

1 

M 

m 

Xumber. 

x 
I 

11 

,8 

® 

111 

$»3 

S 

Diameter. 

Concentric  or  not 

Sides  straight  or 
contracted. 

8 

o* 
S3 

& 

B 
4> 

Og 

"1 
Is 

Size  holes. 

Grosa  area  of  tuy- 
ere-square inches. 

Sq.  in  tuyere-hole 
area  per  2240  Ibs. 
of  charge. 

Cubic  feet. 

Cubic  feet  per  ton 
cap'y. 

TJ.  S.  Clapp-Grifflths   

1 
2 
3 
4 
5 

6 

7 
8 

9 

10 
11 

13 
13 

14 

15 

16 
17 
18 
19 
30 
21 
23 

40> 

y 

cir. 
cir. 

cir. 

2 
2 

«{ 

2 

•\ 

3 

2 
2 

2 

2 
3 

2 
2 

2 

4 

2 
1 
2 
2 
2 
2 
2 

2 

2 

3 
2 

10 

7- 

lOc 
10.  7b 

IOC 

9.2i 
10 

7 

4 

5. 

7b 
7^b 

7«g-9h 
6a 

8.95d 

Sen 

9 
6c 

3?b 

10 
10 
2 
3.5b 

bll. 

4 
3 

8 
8 

iy 

6c 

8 
8 
2  4 

<     10-e      I 
I    IW3"    f 

6' 
lOe       1 
7'  lOV'f  1 

con. 

con. 

15 

12 
(14 

1+4 
13 

15 

14 
12 

12 

12 

12 
12 
12 

10 

7 

X" 
X" 

% 

X" 
X" 

X" 
X" 

19.8 
15.9 

j-  34.7k 
30.6 
29.4 

19.1 
16.5 

1.98 

30 

21  ©25 

650 

65 

W 

y 

exc. 

str. 

3.47 
3.06 
3.26 

2.72 
4.12 

596 

55.5 

4' 

y 

I 

10± 
8 

con. 

con. 

580 

62.3 

48> 

sc.  ann. 

F 

20 

exc. 
exc. 

exc. 

exc. 
exc. 
exc. 

str. 

str. 

str. 
str. 

40p.  14'  6"  q 

y  6" 

cir. 
sc. 

ID'S" 

7'  6" 

13 
19 

13 
17 

19 

17 

16 

8 

12 
12 

12 
19 

12 

12 

12 
10 

X" 
X" 

%" 

X" 

'A" 

X" 

X" 
X" 

30.6 
25.2 

17.2 
35.7 

25.2 

22.5 

21.2 
15.7 

4.87 
3.36 

1.91 
5.95 

3.15 

3.00 

2.35 
2.61 

277 

36.9 

34' 

4' 

1C± 

y 

V 

20 

str. 

995 

32.7 

18®  25 

exc. 

exc. 
con. 

str. 

str. 
str. 

y 

1(X 

303 

41.7 

14'  6" 

20 

y 

ann. 

str 

7" 

con. 
exc. 

str. 
con. 

15 

7 

7 
12 

%" 
w 

11.6 
31.2 

1.18 
3.12 

BRITAIN  —  Rhymney  

23 
24 

35 
26 

27 

9 

19 

12 
12 

17®  18 
18®  25 

588 
201 

53.4 
60.3 

42'  11" 

V  11" 

sc.  ann. 

1       1(X      1 
f  7'  ll"f  ( 

con. 
con. 

str. 
str. 

X" 

25.1 

2.28 

Sheffield 

28 
29 

28' 

y 

West  Cumberland. 

Eston  

SO 

2 

2 
2 

2 
4 

9f 

8'  4" 

con. 
con. 

con. 

21 

626 

78.2 

"     New 

31 

r. 

20' 

Darlington  

iff 

33 



6M1" 

exc. 

15 
16 

13 
13 

1 
17 

w 

*59 
.59 
.59 
.13 

.47m 

15. 
23. 
29. 
25.3 
32. 
13.5 
1.2 

20.2 

1.87 
2.87 
12 
10 
8.5 
6.1 
3. 

3.3 

SWEDEN—  I,angshyttan  

34 

35 

10®  11 

»ai7 

10®  17 
9@11.5 
14.8 
17. 
11.  5®  10.  8 

Nykroppa  

% 

2  4 

v  10" 

4'  10" 

Bangbro  

87 

2.7 
2  2 

V  10" 

exc. 

Vestanf  ors  

38 

G 

15.2 

Avesta  

W 

39 

3'  4" 

y7"@5Mi" 

con. 

str. 

Sandviken       

40 

r< 

2 

3 

2 

2 
2 

3to 
6 

\  

Domnarfvet       

41 

2? 

6 

42 

cir. 
cir. 

cir. 

cir. 
cir. 

5 

8 
6 
6 
8 

43 

Seraing  "old  pit"  .. 
"       "  new  pit1'  o 
Oberhansen  

44 
45 
4« 

9/2" 

9/2" 

34' 

y  9" 

261 

43.4 

dous  lift  of  nine  feet,  and  then  being  shoveled  again  into 
cars. 

3.  The  vessel-bottoms  may  be  removed  and  replaced 
from  the  general  level,  and  are  thus  readily  brought  by 
cars  running  on  the  general  level  to  and  from  the  repair- 
shop. 

4.  That  we  lift  the,  say,  1,000  tons  of  ingots  and  2,000 
tons  of  moulds  handled  daily  only  five  feet  in  transferring 
them  from  the  pit  to  cars  on  the  general  level,  instead  of 
eleven  feet.    A  like  saving  is  effected  in  lowering  the 
moulds  into  place  in  the  pit ;  and  each  time  we  raise  or 
lower  an  ingot  or  a  mould  we  have  to  lift  the  rising  parts 
of  an  ingot-crane. 


on  which  they  deposit  its  burden:  while  they  cannot 
readily  reach  down  low  enough,  in  case  of  the  deep  nine- 
foot  pit,  to  attach  the  dogs,  etc.,  to  the  ingots  and  moulds 
whose  tops  must  be  far  beneath  them. 

5.  The  space  on  the  general  level  occupied  in  the  old 
British  mills  by  the  vessels  and  by  the  mechanism  for 
rotating  them,  and  by  the  runners  through  which  the 
molten  cast-iron  is  brought  to  them,  as  well  as  that  which 
is  occupied  part  of  the  time  in  examining  and  replacing 
the  tuyeres  between  heats,  is,  in  American  mills,  used 
advantageously  for  other  purposes :  for  the  vessel-trun- 
nions and  the  working  platform  at  their  level  is  supported 
on  cast-iron  columns,  leaving  the  space  beneath  free. 


330 


THE    METALLURGY    OP    STEEL. 


6.  Raising  the  vessels  enables  us  to  raise  the  level  of 
the  casting-crane,  which  must  be  able  to  descend  low 
enough  to  receive  the  steel  from  the  vessel.  Raising  the 
casting-crane  enables  us  to  support  its  top  with  tie  bars 
level  with  the  roof -trusses,  and  thus  quite  out  of  the  way. 
Moreover,  the  cylinder  of  the  casting  crane  is  brought  to 
a  more  accessible  level. 

Indeed,  in  late  works  the  vessels  stand  so  high  that  the 
top  of  the  cylinder  of  the  casting-crane  is  at  the  general 


platforms,  on  which  many  tons  of  cast-iron,  etc.,  may  be 
piled,  cannot  be  suspended  aloft  for  nothing.  Yet  it  is 
doubtful  whether  this  really  costs  much  in  the  end, 
because  for  given  surface  of  land  we  have  more  available 
working  space,  and  the  area  which  it  is  necessary  to  give 
our  converting-mill  is  thereby  lessened. 

Raising  the  level  of  the  vessels  does  not  necessitate  rais- 
ing that  of  the  cupolas  materially.  For  the  level  at  which 
the  cupolas  must  stand  in  order  to  deliver  their  iron  by 


TABLE  196.— BESSEMER  I>LANT.— Concluded. 


Number. 

Vessel-cylinder. 

Iron-cnpolaa. 

Blowing  engines. 

Cranes. 

Water  pressure. 
Ibs.  per  sq.  in. 

3 

i 

CO 

1 

X 

3 

y 

M 

jSf 

'3 
• 

Steam  cylin- 
ders. 

Air  cylinders. 

Casting-cranes. 

Ingot-cranes. 

Other  cranes. 

Diamter. 

Stroke. 

Number. 

Diameter. 

O 

I 

-  Number. 

s 

a 

1 

Number. 

3 

S 
1 

1 
Iq 

^ 

Radius. 

1 
2 

3 
4 
5 

6 

7 

9 

11 

12 

18 

5 

V 

8* 

1<K 
10* 
8f± 

8* 
8' 

8* 
y± 

20-± 
15*6" 
IS*  11" 

ay6"± 

24' 

4 

2 
1 

4 
4 
tt 

20* 

22'  I 
22'  f 

21' 

20'± 

20'  I 
30*  f 

Is 
1 

\y 

\yy 

300 

300 

300 

400 
300 

300 

350 

450 

450 

500 
400 

14*" 
20" 

11'  3" 
V  6" 

42" 
54" 

V± 
V 

42" 

y 
y 

4'  5") 
4'5"( 

60" 

2 

a 

•{ 

1 

54" 
66" 

40"  ± 
4'  5" 

60" 

y 
y 

4'5±  i 
4'  5"  f 

60" 

1 
1 

2 

1 

6" 

6* 
6* 

y 

IV 

ii' 

y 

y 
y 

V  3" 

Uf 

1V±\ 

w 

2 
2 

18" 
16" 

y 

7'  6" 

4 
3 

a 

3 

4 

| 

7' 

2V 

16" 

1' 

IV 

iff  \ 

36" 

25" 
51" 
40" 
54± 

50" 

36" 
60" 
32" 

80" 
42" 
20" 

48" 

V 

{•  70" 

4'  6'' 
60" 

60" 

60" 
66" 
54" 

36" 

y 

30" 
72" 

2 

1 
2 

2 
2 
2 

48" 

60" 
54" 
50" 

60" 

48" 
54" 
48" 

46" 

y 

70" 

V  6" 
60" 

60" 

60") 
66"  f 
54" 

36" 

1 
2 

3 
1 
1 

& 

iy&'± 

4 
4 

y 

H 

1 
1 
1 

1 

7 

9' 

y 

9 

ly  | 

IV  [ 
22'  j 

c 

4 

41 

8 
4 

4 
2 
\ 

V± 
IV 
8'  6" 

y 

V 

& 
V 

U.  8.  Clapp-Grimths  

14 

15 
16 

18 
19 
20 

22 

wy\ 
iy 

24' 
W± 

21" 

iff 

3 

n 

y 

ay 

3 

2 
2 

2 
1 

2 

54" 

48" 

60" 

54" 
54" 

54" 
50" 

y 

30" 
72" 

5< 

y 

y 
y 

1 
1 

1 

1 

3 

21 

26 

97 

21" 

IV 

5 
f 

V 

29' 

y 

IV 

2 
2 

y 

w  -J 

2 
1 

11'  10" 
ft 

20'  3" 
13V 

45" 
40" 

40" 
40" 

y 
y 

y 
y 

Sheffield  

98 

1' 

yv> 

37' 

V 

J 

2 
2 

V 

er 

20-  I 

vtr  j 

West  Cumberland  

OT 

i 

Eston   

so 

"      New  

31 

x> 

a 
a 

3 
10 

3 

3 

3 

ax 

fW 

2 

as 

SWEDEN—  Bangbro  

S7 

2 

2 

46" 
39" 

46" 
89" 

1 

1 
1 
2 

iv± 

(M 

41 

•19 

4 

Bochumacid  "old  pit"  

43 

44 

:'< 

R 

&&' 

V  11" 
Va" 

45 

r... 
1 

IV 

Oberhausen  

46 

a  Changed  from  4  tons  in  1886. 

b  Actual. 

c  Nominal. 

d  Average  of  1  month. 

e  Outside  diameter. 

f  Inside  diameter. 

f  Formerly. 
Now. 
i  Average. 
3  Usual, 
k  Total. 


1  The  total  number  of  tuyere-holes  for  Avesta,  90  ;  Lang- 
shyttan,  148;  Nykroppa,  91;  Bangbro,  84;  Vestanfors,  49; 
Sandviken,  117. 

m  .47  Upper  diameter. 
.94  Lower  diameter. 

n  I  am  informed  that  the  usual  charge  la  7>4  tons. 

o"  American  pit." 

p  Casting-pit. 

q  Receiving-pit. 

r  No  pit. 

s  Receiving-crane. 


cir.  Circular. 

sc.  Semi-circular. 

ann.  Annular. 

In  several  of  the  works  there  are  four  vessels,  but  where 
these  are  grouped  in  pairs,  each  pair  having  a  separate  pit, 
etc.,  I  have  regarded  each  pit  with  its  pair  of  vessels  as  a 
separate  unit,  and  thus  have  given  the  number  of  vessels  as 
two,  etc.  In  number  15,  however,  I  have  given  it  as  four,  for 
here  all  the  vessels  work  together,  and  there  is  much  less 
separation  of  the  work  than  in  other  4-vessel  mills. 


level,  and  the  little  pit  in  which  this  cylinder  stands,  being 
the  higher,  is  the  more  readily  drained. 

7.  Finally,  by  raising  the  vessels  a  little  higher  than 
would  otherwise  be  necessary,  we  can  in  the  basic  Bes- 
semer process  easily  remove  the  vessel-shell  without 
disturbing  its  trunnion-ring,  and  carry  it  off  on  the 
general  level  to  a  repair-shop  in  an  adjoining  building, 
replacing  it  rapidly  with  another. 

It  is  true  that  these  ponderous  vessels  and  their  strong 


means  of  traveling  ladles  into  vessels  whose  trunnion-axes 
are  even  as  much  as  fifteen  feet  above  the  general,  is  but 
a  few  feet  higher  than  that  at  which  they  would  at  any 
rate  have  to  stand  in  order  to  dump  easily. 

B.  Placing  the  vessels  side  by  side  instead  of  opposite, 
has  the  following  advantages  : 

1.  For  given  diameter  of  casting-pit  a  much  longer  arc 
of  its  rim  is  available  for  placing  ingot-moulds,  to  wit, 
about  160°  instead  of  about  125°;  or,  for  given  space  avail- 


BESSEMER    PLANT:     POSITION     OP    THE    VESSELS.       §380-1. 


881. 


able  for  placing  moulds,  the  diameter  of  the  casting-pit 
may  be  less  than  when  the  vessels  stand  opposite  each 
other.  A  considerable  arc  is  occupied  part  of  the  time  by 
the  repairing  and  shifting  of  ladles,  and  is  hence  unavail- 
able for  moulds.  We  have  already  seen  that  we  must 
provide  space  along  the  rim  of  the  casting-pit  for  many 
moulds.  A  further  reason  why  a  long  arc  of  this  rim 
should  be  available  for  moulds  is  this :  we  need  three 
ingot-cranes  for  plants  of  even  moderate  large  output, 
and  four  in  case  the  output  is  to  be  great,  or  in  case  many 
ingots  are  to  be  cast  per  heat.  It  is  important  that  these 
cranes  should  have  fairly  long  jibs,  so  that  each  may 
command  two  railway  tracks,  one  for  moulds,  the  other 
for  ingots,  and  beyond  these  tracks  a  considerable  space 
on  the  floor  of  the  converting-mill  for  storing  moulds, 
which  are  thus  in  readiness  in  case  at  any  time  it  be  in- 
convenient or  inexpedient  to  bring  others  in  by  rail. 

The  areas  which  the  several  cranes  command  must 
not  overlap,  lest  their  jibs  collide.  In  a  Pennsylvania 
mill,  in  which  the  areas  of  two  of  these  cranes  overlapped, 
annoying  and  well-nigh  fatal  accidents  occurred  :  e.  g.,  the 
lower  side  of  one  jib  in  descending  struck  on  the  other  jib, 
which  was  rising,  and  unshipping  fell  on  the  floor  of  the 
mill.  Now  it  is  impossible  to  place  four  long-jibbed 
cranes  so  that  they  all  draw  from  the  casting- pit,  and  that 
their  areas  do  not  overlap,  without  giving  the  casting-pit 
large  diameter.  This  is  readily  verified  by  experimenting 
with  a  pair  of  dividers,  pencil  and  paper,  or  indeed,  by  an 
inspection  of  the  plans  of  Bessemer  works,  Figures  169, 
171  and  177.  A  pit  to  be  served  by  four  cranes  with  20- 
foot  jibs  can  hardly  be  less  than  32  feet  in  diameter,  and  is 
better  if  40  feet  in  diameter,  even  if  it  be  a  complete 
circle,  and  if  the  cranes  have  access  to  the  whole  of  its 
rim. 

Now  the  cost  of  the  casting-crane  rises  rapidly  as  the 
diameter  of  the  pit  and  the  consequent  length  of  its  own 
jib  increases,  rising  perhaps  with  the  square  if  not  with 
a  higher  power  of  the  jib-length" ;  moreover,  if  its  jib  be 
very  long,  the  casting-crane  becomes  extremely  heavy  and 
unwieldly,  so  that  much  time  is  lost  in  manipulating  it. 
Hence  it  is  desirable  to  keep  the  diameter  of  the  casting- 
crane,  and  hence  that  of  the  casting-pit  within  bounds, 
and  yet  to  have  a  long  arc  of  the  rim  available  for  moulds 
and  commanded  by  the  ingot-cranes ;  and  these  two 
requisites  can  only  be  satisfied  simultaneously  by  having 
an  arc  of  many  degrees  available  for  moulds. 

2.  The  vessels  are  much  more  easily  charged  with 
molten  cast-iron.  A  single  runner  split  at  its  lower  end 
(Figures  171-173)  readily  carries  the  metal  from  a  common 
point  to  either  vessel ;  or,  in  case  the  cast-iron  is  brought 
in  a  traveling  ladle  drawn  by  a  locomotive,  a  single 
straight  track  serves  both  vessels  if  they  stand  beside  each 
other  (Figures  165,  169),  while  if  they  stand  opposite 
some  more  complex  arrangement  of  tracks  is  needed. 

On  the  other  hand,  placing  the  vessels  side  by  side  has 
the  disadvantage  that  in  turning  up  and  down  they 
bespatter  the  casting  space. 

It  must  be  distinctly  understood  that  the  fact  that  the 
vessels  in  the  old  British  pit  stand  opposite  instead  of 
side  by  side  does  not  limit  the  output  directly,  but  only 
indirectly.  Of  course  it  takes  no  longer  to  blow  a  heat, 
to  recarburize,  to  charee,  or  to  change  bottoms  in  case  of 
a  vessel  which  turns  its  belly  than  in  case  of  one  which 


turns  its  side  towards  its  mute  :  the  difference  is  chiefly 
in  the  amount  of  space  available  for  ingot-cranes  and  for 
casting. 


C.  Costing-crane  and  crane  for 

cast -Iron, 
c.    Ingot-cranes. 
Co.  Converters. 

D.  Sticker-press. 
H.  Hoist. 

I.    Cupolas  for  cast-Iron. 
S.    Cupolas  for  spiegeleisen. 
W.  Scales. 


Fig.  167.    HOMESTEAD  BESSEMER  PLANT.    TBASENTER. 

Thus,  on  the  one  hand,  about  sixty  heats  are  now  made 
in  the  Holley  pit  at  Seraing  per  twenty-four  hours,  while 
in  the  adjoining  British  pit  only  about  thirty-six  heats  are 
made.  At  Homestead  (Figure  167),  on  the  other  hand, 
the  vessels  indeed  stand  opposite  each  other  in  old  British 
style,  but  here  the  casting-space  has  been  enlarged,  the 
pit  shallowed,  and  the  number  of  ingot- cranes  raised  to 
four:  and  here  as  many  heats  have  been  made  in  eight 
hours  as  in  the  Seraing  Holley  pit  in  twenty -four.  The 
charges  are  of  about  six  tons  in  both  cases. 

Indeed  Homestead  has,  I  believe,  made  more  heats  in 
eight  hours  than  any  other  works  in  the  world.  But  this 
is  a  little  deceptive,  for  only  three  ingots  are  made  in 
each  Homestead  heat  against  eight  in  each  Union  heat,  so 
that  Union  has  for  twelve  hours  cast  more  than  twice  as 
many  ingots  per  hour  as  Homestead  in  her  best  eight- 
hours'  work. 

§  381  FORSYTH'S  PLAN,Q  Figures  168  and  169,  adopted  at 
South  Chicago,  Union  and  Wheeling,  goes  a  distinct  step 
beyond  Holley's  in  still  further  removing  the  vessels  from 
the  casting  space — a  second  instance  of  the  advantage  of 
separating  the  operations  of  one  group  from  those  of 
another — and  in  giving  still  more  degrees  of  the  rim  of  the 
casting  pit  for  purposes  of  teeming,  to  wit,  about  250°, 
while  the  old  Holley  and  British  types  give  about  160° 
and  125°  respectively.  Forsy  th  thus  increases  the  casting- 
space  by  more  than  50%. 

The  vessels  stand  apart  from  the  casting-pit,  and  pour 
their  steel  into  a  casting-ladle  standing  on  a  special  re- 
ceiving-crane, (Re.  Figure  168),  which  may  have  a  short 
jib.  This  crane  delivers  the  ladle  to  a  short  transfer 
track  Tr  leading  to  the  casting-pit,  a  hydraulic  cylinder 
on  the  receiving-crane  pushing  it  upon  this  transfer 
track,  from  which  it  is  drawn  upon  the  jib  of  the  casting- 
crane,  C,  by  the  usual  radial  hydraulic  cylinder  of  the  latter. 


IV. S.  patent  276,384,  April  34th,  1883  :    Trans.  Am.  lust.  Min.  Eng.,  XII,  p.  354, 
1864. 


332 


THE     METALLURGY     OF     STEEL. 


J 

h 


Fig.  168.    PLAN  SOUTH  CHICAGO  BESSEMER  WOBKB.    THREB  10-rou  VESSEL   FOBSTTH  PLANT. 


p  n  • 

"         CUPOLAS'. 

0 


IRON.  CUPOLAS..  to 


TWO  TEN-TON  VESSEL     FORSYTH  PLANT, 
WITH  SPACE  FOR  ADDITIONAL  VESSELS. 


Bt.  Bottom-track. 

c.  Ingot  cranes. 

c'.  Ladla-cleaning  crane. 

C.  Casting-crane. 

Co.  Converter. 

I.  Irou-cupolas. 

It.  Track  for  cast-iron  Uillo. 


L.  Track  for  light  ladle  repairs. 

Lt.  Ladle  track  to  ripair-alioii. 

P.  Casting-pit. 

Re.  Receiving-crane. 

S.  Spiegel  cupolas. 

St.  Stage. 

T".  Stand  for  light  ladle  repairs. 


Fig.  109. 


VARIOUS    ARRANGEMENTS     OF     WORKS.       §  382. 


3:5; 


After  teeming,  the  casting-crane  delivers  its  empty  ladle 
to  the  repair  track  T8,  and  is  then  ready  to  receive  a 
full  ladle  from  the  vessel  which  is  blowing.  Thus  the 
casting-crane  is  free  to  attend  to  its  other  duties  during 
the  time  when  the  steel  is  pouring  from  the  vessel  to  the 
casting-ladle,  a  further  advantage  of  this  type.  The  ladle  on 
the  repair-track,  inverted  by  the  crane  C3,  empties  its  slag 
into  a  pan  beneath  it  which  is  later  removed  by  this  same 
crane  ;  receives  a  new  stopper  ;  undergoes  temporary  re- 
pairs, and  is  then  swung  by  crane  C3  to  the  transfer-track 
T,  and,  if  need  be,  is  taken  to  the  further  transfer-track. 
Slagged  ladles  are  taken  by  a  locomotive  to  the  repair- 
shop,  whence  fresh  ones  are  returned  direct  to  crane  C3. 
In  this  same  repair-shop  the  bottoms  also  are  repaired. 
We  have  here  still  another  instance  of  the  separation  of 
one  group  of  operations  from  the  rest. 


Fig.  170.     PLAN  or  NORTH-EASTERN  STEEL  WORKS 


A  Cupolas.    B  Repair-shop.    C  Turn-table  for  vessels  and  ladle-cars.    D  Converters.    E 
Receiving-cranes.    F  Casting-crane.    G  Ingot-cranes. 

§  382.  OTHER  PLANS.— Intermediate  between  Forsyth's 
and  the  normal  Holley  type  is  that  at  the  North  Eastern 
Steel  Works  (Fig.  170)  and  at  Rhymrjey,  in  which  the  cast- 
ing-ladle stands  on  a  receiving-crane  while  it  receives  the 
molten  steel,  and  is  then  "transferred  to  the  casting-crane, 
by  bringing  the  jib-ends  of  both  cranes  together.  But 
this  does  not  permit  us  to  remove  the  vessels  as  far  from 
the  pit  as  seems  desirable,  while  Forgyth's  transfer-track 
has  a  certain  further  advantage  "  in  that  it  admits  of  ad- 
justment, both  vertically  and  horizontally,  to  suit  vari- 
ations in  the  position  of  the  crane-jibs  due  to  wear  of  top- 
supports,  elasticity  of  materials,"  etc. 

In  the  North  Eastern  plan  the  receiving-crane  may  be 
so  arranged  that  it  holds  a  receiving-ladle  from  which  the 
molten  steel  is  repoured  into  the  casting-ladle,  to  insure 
better  mixing.  It  is,  however,  doubtful  whether  this  is 
needed,  for  the  heterogeneousness  formerly  attributed  to 
imperfect  mixing  may  be  wholly  due  to  segregation. 

At  Eston  the  cast-iron-ladle  is  or  was  raised  to  the 
vessels  by  means  of  the  steel-casting  crane ;  but  this  is 
very  unwise,  because,  as  we  have  seen,  the  casting-crane 
is  fully  occupied  by  its  duty  of  casting  the  steel. 

At  Khymney  a  receiving-crane  stands,  or  stood,  between 
the  vessels  and  the  casting-pit.  It  raises  the  molten  cast- 
iron  and  pours  it  into  the  vessel ;  then  at  the  end  of  the 
blow  it  raises  the  molten  spiegel  and  pours  this  too  into 
the  vessel,  then  swings  around  and  receives  the  steel  in  a 
ladle  on  its  other  end,  and  finally  delivers  this  ladle  to 
the  casting-crane  proper. 

When  matters  are  running  perfectly  smoothly  these  three 
operations  of  the  receiving- crane  need  not  interfere  with 
each  other,  for,  as  we  have  seen,  there  is  usually  plenty 
of  time  during  the  blowing  of  one  heat  to  charge  in  the 
idle  vessel  the  cast-iron  for  the  following  heat,  and  this 
would  naturally  be  done  long  before  the  vessel  now  blow- 
ing was  ready  to  receive  its  spiegeleisen.  But,  owing  to 


delays,  we  often  cannot  linish  charging  the  idle  vessel  till 
just  as  the  blow  is  ending  in  the  other;  and  then  the 
Rhymney  arrangement  would  certainly  cause  delay. 

Of  the  many  other  ways  of  grouping  the  vessels,  some 
of  them  intermediate  between  the  British  and  Holley' s 
type,  only  the  following  seem  to  deserve  especial  consid- 
eration. 

The  converging-axed  plan  (Figures  174  and  176)  has 
the  advantage  in  case  of  three-vessel  plants  that  a  single 
casting-crane  can  receive  steel  from  any  of  the  vessels; 
while  if  the  trunnion-axes  are  in  a  straight  line,  as  at 
Harrisburg  and  Edgar  Thomson  (Figures  171,  177),  a  single 
casting-crane  can  hardly  be  arranged  to  serve  all  three 
vessels.  This,  however,  is  a  doubtful  advantage,  for  the 
three  converging-axed  vessels  occupy  so  many  degrees  of 
the  rim  of  the  casting  pit,  that  we  can  only  get  sufficient 
length  of  rim  for  the  work  of  the  ingot-cranes  in  the 
casting  space,  by  having  a  very  wide  pit,  and  hence  a 
costly  and  unwieldy  casting-crane.  For  a  three-vessel 
plant  the  Edgar  Thomson  and  the  Forsy  th  plan  seem  much 
better  fitted  than  the  converging-axed  type. 

When  we  come  to  two-vessel  plants  the  converging- 
axed  type  lacks  even  the  questionable  advantage  which  it 
has  in  case  of  three  vessels,  for  two  vessels  with  their  axes 
in  line  are  readily  served  by  a  single  casting-crane  (Figure 
173). 

Further,  whether  there  be  two  or  three  vessels,  if  their 
axes  converge  they  bespatter  not  only  the  casting  space, 
but  what  is  really  serious,  the  casting-crane,  on  which  the 
man  who  is  to  rack  the  ladle  as  it  receives  the  steel  from 
the  vessel  should  now  be  standing.  Here  Rothman's 
telescopic  screen  for  the  plunger  of  the  casting-crane  is 
especially  needed  (X  Figure  163). 

The  Bochum  plan,  Figure  176,  exaggerates  some  of 
these  difficulties,  and  combines  them  with  some  of  those 
of  the  British  type  ;  but  it  escapes  part  of  their  conse- 
quences by  placing  the  vessels  far  from  the  casting-pit, 
thus  going  a  step  beyond  Forsyth's  plan.  Here  the  con- 
verging-axed plan  enables  a  single  receiving- crane  to  serve 
three  vessels  :  but  the  vessels  are  less  conveniently  placed 
for  receiving  cast-iron  than  when  their  axes  are  in  line. 

The  Harrisburg  Plan  (Figure  171). — We  have  just 
seen  the  advantages  which  this  plan  has  over  the  con- 
verging-axed plan  for  three-vessel  plants.  It  was  the 
natural  outcome  of  an  attempt  to  apply  the  Holley  type 
to  a  three-vessel  plant,  for  here  a  single  casting-crane 
could  not  serve  all  three  vessels,  unless  it  had  so  long  a 
jib  as  to  be  most  unwieldy  as  well  as  expensive. 

Compared  with  Forsyth's  plan  it  has  one  disadvantage 
of  the  two-vessel  Holley  plant,  the  heat  and  spatterings 
of  the  vessels  interfere  with  the  casting ;  but  in  other 
respects  it  is  as  well  if  not  better  off  than  Forsyth's,  for 
it  offers  a  greater  length  of  pit-rim  for  casting,  and  the 
length  of  the  ladle-cycle  (LT,  §  876,  3),  may  be  longer 
without  holding  the  vessels  back.  In  order  that  a  ladle 
may  always  be  ready  to  receive  the  blown  steel  it  is  only 
necessary  that  the  length  of  the  ladle  cycle,  LT,  should  be 
less  than  twice  as  great  as  the  blowing  time,  BT.  Indeed, 
as  we  have  already  seen,  in  case  the  number  of  ingots  to 
be  cast  per  minute  were  to  be  materially  increased,  For- 
syth's plan  would  require  a  second  casting-crane.  It  will 
be  noted  that,  whichever  pair  of  vessels  is  in  actual  use, 
whether  the  two  outside  vessels  or  either  outside  and  the 


331 


THE    METALLURGY    OF    STEEL. 


middle  vessel,  two  casting-cranes  will  always  be  available 
for  serving  them. 

The  diver  g  ing-axed  arrangement,  Figure  172,  has  the 
advantage  already  pointed  out  that  the  vessels  do  not 
bespatter  the  casting-space.  Indeed,  they  blow  so  wide 


is  to  be  used,  this  modification  is  very  desirable,  as  ex- 
plained in  §  395. 

But  if  the  vessels  stand  back  from  the  pit,  as  in  Forsy  th'  s 
and  in  the  North  Eastern  plan,  the  Joliet  modification  is  not 
necessary.  It  is,  however,  a  wholly  unobjectionable  modi- 


of  it  in  turning  up  and  down  that  the  pulpit  or  stage  (St)  fication  ;  it  necessitates  some  change  in  the  shape  of  the 
from  which  the  rotation  of  the  vessels  and  the  rise  of  the  vessel,  making  its  nose  "concentric"  instead  of  eccentric, 


cranes  is  governed,  can  be  placed  immediately  opposite 


Fig.  171.    HAKRISBUHG  BESSEMER  WORKS,  NEW  PIT.    TRASENTER. 


Note  to  figures  171,  172  and  173, 

Bt.  Track  for  vessel-bottoms. 

C.   Casting-cranes. 

c.    Ingot-cranes. 

Co.  Converters. 

F.   Ladle  for  cast-iron. 

U    Hoists. 

I.    Iron-cupolas. 

It.  Track  for  cast-iron. 

K.   Ladle  for  spiepeleisen. 

O.  Ovens  for  bottoms. 

P.    Casting  pit. 

B.  Runners  from  cupolas  to 

vessels. 

S.    Spiegel-cupolas. 
St.  Stage  or  pulpit. 


Fig.  172.    BESSEMEB  PLANT,  AXES  DIVERGING. 

the  centre  of  the  casting-pit  and  thus  close  to  the  work 
directed,  without  being  bespattered.  It  has  a  further 
advantage  in  that  the  horizontal  travel  of  the  vessel' s  nose 
in  pouring  the  steel  into  the  casting-ladle  may  be  wholly 
compensated  for  by  swinging  the  ladle-crane,  without 
radial  motion  of  the  ladle,  so  that  the  hydraulic  cylinder 
usually  employed  to  move  the  ladle  radially,  and  the  man 
who  controls  it,  are  not  needed.  The  diverging-axed  plan 
seems  hardly  applicable  to  three-vessel  plants. 

In  the  Joliet  modification  of  the  H  >lley  type,  Figure 
173,  the  vessels  turn  down  away  from  instead  of  towards 
the  pit  to  receive  the  charge  of  cast-iron.  If  the  casting- 
ladle  is  to  stand  on  the  casting-crane  while  receiving  the 
steel  from  the  vessel,  and  if  at  the  same  time  "direct  metal" 


but  this  change,  as  we  shall  see,  seems  in  itself  desirable. 


MOULDS 


Fig.  17S.    PLAN  OF  JOLIET  PLANT.    TRASENTER. 

§  383.  OTHEK  FORMS  OF  CASTING  PIT. — Up  to  this  point 
we  have  considered  the  casting-pit  chiefly  in  connection 
with  the  arrangement  of  the  vessels  ;  but  there  are  certain 
forms  of  casting-pit  whose  value  depends  relatively  little 
on  the  disposition  of  the  vessels.  Let  us  now  glance  at 
them,  and  at 

I.  The  Suppression  of  the  Casting-pit. — In  several 
European  works  the  casting-pit  has  been  wholly  sup- 
pressed, the  ingots  being  cast  either  on  the  level,  or  on 
cars  running  on  the  level.  It  is  often  said  by  superficial 
observers  that  the  pit  is  a  useless  nuisance.  A  nuisance 
it  may  be,  but  a  most  useful  one.  First,  it  gives  ready 
access  to  the  tops  of  the  moulds,  for  teeming,  for  stopping 
them  with  sand  or  water,  and  for  attaching  crane-hooks 
to  the  ears  of  the  moulds,  and  crane-dogs  to  the  ingots 
themselves.  Secondly,  it  restricts  the  area  flooded  by 
"messes,"  i.  e.,  by  molten  steel  spilt  from  the  ladle,  from 
ill-fitting  or  cracked  moulds,  from  bleeding  ingots  and 
what  not.  These  cannot  be  ignored  in  providing  for  ex- 
treme celerity. 

If  there  be  no  pit,  an  elevated  platform,  A,  must  be  pro- 
vided to  give  access  to  the  mould-tops  in  teeming,  etc," 
unless  only  short  ingots  are  to  be  cast.  (See  Figure  174.) 


a  Holley  wrote  in  January,  1881,  "  Placing  the  moulds  on  the  general  level  for 
casting,  appeared  to  be  very  unsatisfactory.  The  moulds  for  5  to  6  rail  ingots  are 
above  6  ft.  high,  so  that  there  must  a  working  platform  about  4  ft.  high  around 
them.  This  platform  is  a  series  of  planks  laid  on  a  temporary  staging  ;  it  is  nar- 
row, insecure  and  inconvenient.  The  bursting  of  a  mould  endangers  the  lives  of 
all  the  men  about  it.  The  steel  cast  when  I  was  at  the  works  was  very  rising.  I 
saw  it  boil  out  of  a  mould,  and  drive  all  the  men  off  the  platform,  twice  in  one 
afternoon."  It  is  only  fair  to  say  that  the  platform  need  not  be  narrow  and  inse- 


BESSEMER    PLANT  :     POSITION,     ETC.,     OF    CASTING    PIT. 


383. 


33.1 


If  the  ingot-moulds  stand  on  the  ground  during  teem- 
ing, I  see  no  important  advantage  in  suppressing  tne  pit. 
If  they  stand  on  cars,  we  can  remove  them  readily  to  a 
convenient  place  for  stripping,  and  we  may  thus  make 
use  of  some  economical  stripping- device,  such  as  Lau- 
reau's  or  Jones',  which  we  will  consider  later.  But  in 
either  case  we  are  likely  to  have  much  trouble  with  foul- 
ing the  running-gear  of  the  cars  on  which  the  moulds 
stand  ;  and  the  fouling  of  a  single  wheel  or  of  the  track 
would  detain  a  whole  train  of  cars,  and  temporarily  par- 


A.  Cuttag  platform. 

C.   CasttnK-crane. 

c.    Infill -crane. 

Co.  Converters. 

H.  Hoist. 

I.     Cupolas  for  cast-Iron. 


L.   Ladle  undergoing  repairs. 

Mt.  Track  for  moulds. 

S.    Cupolas  for  spk'gelelsc'n. 

St.  Stage  or  pulpit. 

Tc.  Travcllug-cniiie. 


Fig.  nit.    PHOENIX  BKSSEMKK  PLANT.    MACAB. 

alyze  the  establishment.  Opinions  are  divided  as  to  the 
detention  which  would  be  thus  caused  in  actual  rapid 
work.  It  is  stated  that  this  system  has  been  used  in  some 
European  works  without  serious  trouble.  But  in  these 
works  the  output  is  relatively  small,  and  it  seems  to 
me  that  leaky  nozzles  and  moulds  are  still  common 
enough  to  form  a  serious  menace,  when  such  extreme 
rapidity  of  working  as  is  common  in  this  country  is 
sought,  and  where  every  delay  of  even  a  few  seconds  is 
to  be  guarded  against. 

2.  Removing  the  casting-place  from,  the  converting- 
house.  In  this  case  the  casting-ladle  is  carried  by  rail 
from  the  converting-house.  If,  as  usual,  the  vessel  pours 
the  steel  directly  into  the  casting-ladle,  this  must  stand 
on  a  crane  while  receiving  the  steel,  in  order  that  its 
position  may  shift  and  follow  the  motion  of  the  vessel's 
nose. 

It  is  asserted  that  in  practice  no  serious  trouble  has 
arisen  from  fouling  the  running-gear,  either  by  the  burst- 
ing of  the  ladle  or  by  spilling  steel  over  its  edge  ;  and  cer- 
tainly the  danger  seems  to  be  relatively  slight,  for  the 
ladle  need  not  be  put  on  the  car  till  after  receiving  the 


steel,  and  may  be  removed  from  it  before  teeming,  so  that 
no  pouring  need  occur  in  direct  connection  with  the  track 
and  cars.  The  danger  is  certainly  far  less  than  when  the 
six  or  eight  ingots  of  a  heat  are  teemed  while  standing  on 

urs  ;  for  here  an  ill-fitting  mould  would  not  be  detected 
till  it  had  begun  to  leak  over  cars  and  track,  and  the 
leakage  from  the  nozzle  in  passing  from  mould  to  mould, 
very  often  a  considerable  matter,  as  well  as  the  boiling 
over  of  imperfectly  stopped  ingots,  would  have  to  be 

ared  for  most  jealously.  Indeed  it  is  clearly  less  danger- 
ous to  the  running-gear  to  teem  from  a  ladle  which  stands 
on  a  car,  than  to  teem  into  moulds  ou  cars. 

This  plan  may  be  regarded  as  carrying  Forsyth's  a  step 
farther.  The  casting- place  is  certainly  freer  from  the  heat 
and  spattering  of  the  vessels,  andtheworkof  the  pit-men  is 
thereby  facilitated ;  but  in  Forsyth' s  arrangement  the  dis- 
tance between  vessels  and  pit  is  already  so  considerable, 
and  the  quantity  of  heat  radiated  from  vessels  to  pit 
seemed  to  me  even  in  midsummer  so  slight,  that  I  doubt 
whether  any  considerable  additional  outlay,  for  the  sake 
of  separating  them  still  farther,  would  be  expedient. 


Fig.  175.    8-piT  FORBYTH  PLANT. 

C  Casting-cranes,     c  Ingot-cranes.     Co  Converters.     EC  Rcceiving-cnnei.     The  black 
circles  are  the  casting-pits. 

3.  Auxiliary  Pits.  Taking  a  hint  from  the  Oberhausen 
plant,  one  or  even  two  auxiliary  pits  might  be  arranged 
as  in  Figure  175,  if  it  should  be  desirable  to  cast  a  very 
great  number  of  small  ingots  from  each  of  many  heats 
following  each  other  quickly.     The  casting-ladles  would 
preferably  stand  on  receiving  cranes  while  receiving  the 
steel    from  the  vessels,  and   pass   thence  to  whichever 
casting-pit  was  ready. 

4.  Straight  Pits  instead  of  circular  ones  have  been 
used  (Figures  176  and  176  a).    Their  advantage  is  that  the 
casting  place  may  be  as  long  as  you  please,  so  that  teem- 
ing and  stripping  may  be  more  leisurely  and  hence  cheaper 
than  in  case  of  a  circular  pit  or  pits,  the  length  of  whose 
casting-space  is  limited  by  the  necessity  of  keeping  the 
length  of  the  crane-jib  within  bounds. 

The  cost  of  installation  for  straight  pits  may  be  some- 
what less  than  that  for  circular  pits  with  their  costly 
casting-cranes.  But  the  straight  pit  suffers  under  one 
very  great  disadvantage.  There  is  no  means  by  whicli  the 
casting-ladle  can  be  moved  from  point  to  point,  and,  as  is 
necessary  in  teeming  very  soft  steel,  endlessly  backwards 
and  forwards,  with  anything  like  the  ease  with  which  it 
is  swung  while  resting  on  the  jib  of  a  hydraulic  crane. 
Locomotive  ladle-cars  and  simple  ladle-cars  moved  by 
stationary  engines  have  been  proposed,  but  it  seems 
simpler  to  have  a  plain  ladle-car  drawn  by  a  locomotive. 
At  Hoerde  the  ladle-car  has  a  steam-engine  for  locomo- 
tion, a  casting-crane  moved  by  hydraulic  pressure,  gen- 
erated by  a  pump  on  the  car  itself ;  a  system  of  wheels 
and  chains  for  rotating  the  casting-crane,  and  arrange- 
ments for  tipping  the  ladle  in  case  of  accident.  One 
naturally  shrinks  from  the  use  of  so  complex  a  machine 
for  this  purpose,  where  the  first  requisite  is  absolute  cer- 


330 


THE    METALLURGY    OF    STEKL. 


tainty.  In  tliis  particular  case  the  casting-ladle  stands 
on  its  traveling  car  while  receiving  the  steel  from  the 
vessel. 

In  another  case  (Peine),  the  casting-car  carries  a  ten-ton 
hydraulic  casting-crane,  witli  pumps  ;  two  steam-engines, 
one  for  locomotion,  the  other  to  drive  these  pumps;  a 
twelve-horse  boiler,  and  the  levers  needed  for  operating 
these  machines. 


!  between  t!ie  radial  and  parallel  arrangement  of  the  casting- 
pit  would  probably  be  chi.'fly  governed  by  the  extent  and 
shape  of  the  available  ground. 

It  seems  on  the  whole  wiser  to  adhere  to  circular 
pits,  having,  if  necessary,  two  or  even  three  pits,  as  in 
Figure  175:  for,  as  we  have  seen  in  §  378,  in  case  we  are  to 
cast  ingots  even  of  small  size  and  hence  numerous, 
whose  moulds  need  not  be  in  place  till  immediately  be- 


a.    Casting-car. 
c.    Ingot-crane. 
C.  Receiving-crane, 
Co.  Converters. 
St.  Stage. 


Fig.  ne. 

BociruMEB.  VEREIN  BESSEMER  PLANT,  WITH  RADIAL  CASTING-PIT. 


___  .._i — _ — $_  -__  ~$—  — $ — 4- — 


/r- I -\ /-I 4 X 

--•     r  i       • 


Fig.  niia.    PEINE  BESSEMER  PLANT.    MACAB. 
c  Ingot-crane.    Co  Converter.    L  Casting-ladle. 


A  straight  pit  may  be  either  parallel  with  the  vessel- 
axes,  in  case  these  stand  in  line,  as  in  Figure  176  a,  or 
it  may,  as  in  Figure  176,  be  radial  to  the  orbit  of  a  receiv- 
ing crane  on  which  the  casting-ladle  rests  while  receiving 
the  steel  from  the  vessel.  In  the  former  plan  the  ladle 
may  rest  either  on  a  receiving-crane  or  on  the  casting-car 
while  receiving  the  steel.  The  usual  advantages  of  the 
receiving-crane,  removing  the  casting  space  from  the  ves- 
sels and  leaving  the  casting-car  or  casting-crane  at  liberty 
for  its  other  duties  while  the  steel  is  pouring  from  the 
vessel  into  the  casting-ladle,  may  apply  here.  The  choice 


fore  teeming,  we  are  likely  to  need  increase  of  casting- 
crane  capacity  and  after  that  of  ingot-crane  capacity, 
much  sooner  than  of  mould- space.  Now,  in  a  radial 
straight  pit,  as  in  Figure  176,  we  can  use  but  one  cast- 
ing-ladle ;  in  a  pit  like  that  in  Figure  176«,  but  two,  so 
that  these  are  equivalent  in  casting-ladle  capacity  to  a 
one-  and  to  a  two-casting-crane  plant  respectively.  In  or- 
der that  more  ladles  should  be  used,  some  mode  of 
switching  the  empty  ladles  back  past  the  full  ones  to  the 
vessels  would  be  needed,  as  for  instance,  by  uniting  the 
two  pits  of  Figure  176  by  a  Y,  or  by  uniting  them  as  in- 


ARRANGEMENT     OF     CASTING    PITS    AND     TRACKS. 


385. 


3o~ 
o  1 


dicated  in  dotted  lines  so  that  they  formed  one  continu- 
ous pit.  In  such  a  pit  any  desired  number  of  ladles 
could  work  simultaneously. 

But  the  numbers  in  §  378  show  us  that  in  a  pair  of 
Forsyth  pits  we  can  have  all  the  casting-crane,  ingot- 
crane  and  mould  capacity  that  is  likely  to  be  needed 
for  two  or  three  vessels,  while  preserving  the  advantage 
of  moving  the  casting-ladle  by  hydraulic  cranes. 

In  harmony  with  these  views  is  the  experience  of  Mr. 
John  Fritz. w  Having  seen  certain  advantages  of  the 
straight  pit  at  some  German  works,  he  fitted  up  two 
straight  pits  for  his  two  new  vessels  at  Bethlehem,  with 
every  convenience,  determined  to  give  the  system  a  fair 
trial.  But  he  was  unable  to  teem  and  remove  even  the 
relatively  small  normal  output  of  those  days. 

The  single  hydraulic  casting-crane  in  the  circular  pit 
connected  with  his  old  pair  of  vessels  did  more  work 
than  the  two  straight  pits  and  their  casting-cars.  He 
therefore  returned  to  the  use  of  the  circular  pit,  putting 
in  two  casting-cranes  each  with  its  own  pit  to  serve  his 
new  pair  of  vessels,  to  provide  for  rapid  working. w  So, 
too,  many  if  not  most  European  metallurgists  seem  to 
have  come  to  the  conclusion  that,  even  for  their  relatively 
small  output,  the  straight  German  pits  are  less  convenient 
than  circular  ones. 

We  cannot  conveniently  use  the  circular  pit  and  the 
hydraulic  casting-crane  when  the  casting  work  is  to  be 
like  that  of  a  common  foundry,  i.  e.,  when  we  are  to  teem 
a  great  number  not  of  ingots  but  of  small  sand-castings, 
whose  moulds  occupy  a  great  extent  of  floor-room  for 
given  weight  of  casting,  require  long  preparation,  cannot 
be  swung  about  rapidly,  but  should,  during  teeming, 
stand  in  the  place  in  which  they  are  prepared. 

Here  the  straight  pit  offers  weighty  advantages.  But  it 
is  not  probable  that  a  large  part  of  the  enormous  output 
of  many  large  and  rapidly  working  plants  will  be  used 
for  this  kind  of  work :  ingots  are  their  normal  product. 

Multiple-casting  and  other  means  of  casting  many 
small  pieces  from  a  single  heat  will  be  considered  in 
connection  writh  the  open-hearth  process. 

5.  Annular  casting-pits  have  been  tried  at  several 
works.  They  indeed  give  a  little  more  floor-room,  the 
"Island,"  on  thegeneral  level,  Figures  167,  172  ;  butifc  is 
not  clear  that  this  room,  lying  as  it  does  in  the  centre  of 
the  pit,  is  much  more  useful  for  being  at  the  general  level 
instead  of  at  the  pit-level.  The  jib  of  the  casting-crane 
sweeps  across  it  so  often  that  it  is  in  either  case  little 
more  than  waste  ground.  Moreover,  messes  are  certainly 
removed  more  easily  from  the  open  circular  than  from  the 
relatively  confined  annular  pit. 

If  an  annular  pit  be  used,  the  casting-ladle  cannot  be 
lowered  so  far  as  is  possible  in  a  plain  circular  pit,  and 
hence  the  height  at  which  the  vessels  must  stand  in  or- 
der that  they  may  pour  the  steel  into  the  casting-ladle 
is  greater.  But  in  the  best  works  lately  built  the  vessels, 
even  in  case  of  a  plain  circular  pit,  stand  quite  as  high 
as  would  be  necessary  were  the  pit  annular. 

§  384.  MINOR  ARRANGEMENTS. — The  ingot-cranes  (cf. 
§  380,  B)  are  usually  placed  as  close  to  the  pit  as  is  pos- 
sible without  having  their  orbits  intersect. 

PLACE  FOR  REPAIRING  LADLES  AND  BOTTOMS. — In  the 


wHolley,  Engineering,  XXXII.,  p.  428,   1881. 


earlier  works,  which  aimed  at  what  now  appears  to  be 
a  small  output,  ladles  and  bottoms  were  relined  on 
the  floor  of  the  con  verting- room,  and  spaces  along  its 
walls  were  reserved  for  this  purpose.  The  moulds,  too, 
were  allowed  to  cool  on  the  floor  of  the  converting-room. 
Thus  a  space  to  the  left  of  the  lower  ingot-crane  in 
Figure  173  might  be  reserved  for  repairing  ladles,  and  the 
spaces  indicated  for  moulds  and  bottoms. 

But  to  provide  for  the  enormous  product  of  our  later 
mills,  ten  times  as  great  as  that  of  sixteen  years  ago,  a 
correspondingly  great  number  of  bottoms  and  ladles 
must  be  kept  on  hand,  and  must  be  simultaneously  under 
repairs.  The  floor-space  which  this  requires  is  so  great 
that  it  is  found  far  better  to  make  these  repairs  in  a  sepa- 
rate building,  as  in  Figure  168,  or  at  least  in  a  separate 
room,  as  at  L,  Figure  177,  with  ample  floor-space.  This 
enables  us  to  keep  a  large  number  of  both  bottoms  and 
ladles  on  hand,  and  to  dry  the  bottoms  slowly,  a  point  of 
considerable  importance. 

So,  too,  in  many  of  the  works  lately  built,  the  moulds 
are  removed  from  the  converting-room  immediately  after 
stripping  ;  they  cool  and  are  examined  in  the  open  air. 

These  are  very  important  steps.  The  attempt  to  repair 
ladles  and  bottoms  littered  up  the  converting-room  and 
cramped  the  operations  of  the  pit-men;  while  the  hot  moulds 
not  only  did  this,  but,  radiating  great  volumes  of  heat, 
raised  the  temperature  of  the  converting-room,  which  even 
without  them  is  tryingly  hot  in  summer.  But  beyond  this, 
it  is  necessary  to  throw  a  stream  of  water  on  the  moulds, 
so  that  they  may  cool  quickly  and  be  ready  for  use.  The 
steam  into  which  they  convert  this  water  not  only  ob- 
scures the  view  and  thus  interferes  with  operations,  but 
converts  the  converting-room  into  a  Turkish  bath.  As  the 
perspiration  will  not  evaporate  in  the  atmosphere  thus 
saturated  with  moisture,  we  cut  off  the  human  body's 
chief  means  of  keeping  its  temperature  below  that  of  the 
air  and  of  the  hot  objects  which  surround  it.  We  merci- 
lessly enhance  the  sufferings  and  reduce  the  working 
power  of  these  suffering  and  expensive  men. 

§  385.  GENERAL  ARRANGEMENT  OF  TRACKS,  ETC. — This 
must  of  course  be  regulated  by  the  shape  and  size  of  the 
ground  available  ;  I  cnn  therefore  only  point  out  what 
tracks  are  needed,  and  certain  desirable  positions  for 
them.  All  the  tracks,  except  that  which  brings  the  pig- 
iron  and  fuel  to  the  works,  may  be  of  narrow  gauge. 

1.  The  Pig-iron  and  Cupola-fuel  may  be  brought  by  an 
elevated  broad-gauge  tiack,  running  if  possible  over  a 
series  of  bins  standing  behind  the  cupola  room,  each  re- 
ceiving iron  of  a  certain  grade.    The  bottoms  of   these 
bins  should  be  on  a  level  with  the  bottom  of  the  hoists 
which  raise  the  pig-iron  and  fuel  to  the  cupola  charging 
platfoims,   and  within  reasonable  wheeling  distance  of 
them.     Between  the  bins  and  the  hoists  stand  scales  for 
weighing  iron  and  fuel. 

2.  Iron-Hoists. — Convenient  positions  for  the  hoists  for 
pig-iron  are  shown  at  H  in  Figure  173  for  the  Holley  type  of 
plant,  and  in  Figures  171  and  177.     It  is  well  to  have  two 
hoists,  not  alone  on  account  of  the  enormous  quantity  of 
material  to  be  lifted,  which  may  reach  1,500  tons  in  twenty- 
four  hours,  but  also  lest  the  whole  establishment  be  para- 
lyzed by  the  temporary  disablement  of  one  hoist.    Though 
a"  general  discussion  of  the  merits  of  different  kinds  of 


333 


THE    METALLURGY     OF     STEEL. 


hoists  is  far  beyond  the  limits  of  this  work,  I  may  point 
out  that  overwinding  cannot  occur  in  hydraulic  elevators ; 
that  hydraulic  pressure  to  drive  them  is  always  available  in 
Bessemer  works;  and  that  there  is  always  a  number  of 
men  at  hand  skilled  in  the  maintenance  of  hydraulic 
apparatus,  and  accustomed  to  guard  it  from  freezing.  In 
a  word,  hydraulic  elevators  are  readily  applicable  here, 
and  here  their  disadvantages  are  minimized. 

As  the  cupola-charging  platforms  in  the  older  works 
were  very  high,  sometimes  more  than  forty  feet  above  the 
general  level,  it  was  found  best  to  make  the  length  of 
hydraulic  lifting-cylinder  but  half  the  travel  of  the  hoist- 
cage.  This  was  therefore  lifted  by  a  chain  running  over  a 
sheave  fastened  to  the  end  of  the  piston-rod  of  the 
hydraulic  cylinder  ;  it  is  the  common  pulley-arrangement 
reversed. 

3.  Track  for  Cupola- Debris. — A  track  which  may  be 
of  narrow  gauge  should  run  on  the  general  level,  and  near 
the  rear  of  the  cupolas,  for  removing  their  debris. 

4.  Track  for  Molten  Cast-iron. — If  direct-metal  is  used, 
it  may    be  brought  from   the    blast-furnace  in   a  ladle 
drawn  by  a  locomotive,  and  by  it  carried  up  an  incline, 
raising  it  to  the  level  of  the  vessels.    At  South  Chicago 
this  incline  has  an  average  rise  of  2$.     It  is  stated  that  at 
Ebbw  Vale  direct  metal  was  brought  successfully  a  distance 
of  six  miles  to  the  vessels. 

At  the  head  of  this  incline  may  be  a  siding,  on  which 
the  locomotive  places  its  full  ladle  or  ladles,  returning  to 
the  blast-furnace  with  one  or  more  empty  ones. 

Prom  this  siding  a  special  locomotive,  which  runs  only 
on  this  elevated  track,  carries  the  molten  iron  to  the 
vessels.  The  track  may  run  either  behind  the  vessels,  as 
in  Figures  1G3,  173  and  177,  or  in  front  of  them,  as  in 
Figures  168  and  169,  in  case  Forsyth's  or  a  similar  arrange- 
ment be  adopted.  In  the  former  case  the  vessels  must 
be  concentric,  in  the  latter  they  may  be  either  eccentric  or 
concentric.  Or,  finally,  the  track  may  run  between  the 
vessels,  as  in  Figure  164. 

In  all  direct-metal  plants  the  cupolas  should  be  so  placed 
as  to  deliver  their  molten  iron  into  ladles  running  on  this 
same  track.  This  arrangement  works  so  admirably  that 
it  is  well,  even  if  cupola-metal  only  is  to  be  used,  to  bring 
the  molten  cast-iron  from  the  cupolas  to  the  vessels  by 
means  of  a  locomotive.  This  incidentally  allows  us  to 
remove  the  cupolas  from  the  immediate  neighborhood  of 
the  vessels,  as  shown  in  Figures  165  and  169,  and  as  ex- 
plained in  §  373.  This  has  been  done  in  several  of  the  best 
works  lately  built. 

5.  The  Tracks  at  and  near  the  general  level  have  four 
chief  functions  ;  A,  to  remove  the  debris  of  the  vessels  ; 
B,  to  carry  moulds  in  and  out  of  the  converting  room  ;  C, 
to  carry  ingots  away  for  further  treatment ;  and  D,  to 
carry  ladles  and  bottoms  back  and  forth  between   the 
repair-shop  and  the  converting-room.     There  are  so  many 
ingots  and  moulds  to  be  carried  in  and  out,  and  it  is  so 
important  to  remove  them  quickly  from  the  convertJng- 
room,  that  there  should  be  a  track  devoted  solely  to  ingots, 
and  another  solely  for  moulds.    Each  track  should  be  com- 
manded by  all  of  the  ingot-cranes.     Indeed  it  is  better  to 
provide  two  tracks  for  moulds,  so  that  the  removal  of  hot 
moulds  may  not  interfere  with  bringing  in  cool  ones. 
Admirable  examples  of  track-arrangement  are  afforded 
by  Figures  168  and  177,      In  the  latter  we  have  three 


parallel  sets  of  tracks,  a  Y  giving  in  addition  a  short 
branch.  In  the  former  works,  by  laying  the  ingot-tracks 
at  right  angles  with  the  mould-tracks,  the  total  number 
of  tracks  that  can  convenient!}'  be  laid  is  greatly  increased. 
This  facilitates  handling,  for  cars  standing  on  any  one  of 
the  eight  branches  do  not  prevent  bringing  other  cars  to 
any  of  the  other  branches  ;  while  even  with  the  three 
parallel  tracks  of  the  Edgar  Thomson  mill  some  planning 
and  switching  may  occasionally  be  needed,  e.  g.,  to  bring 
cars  to  the  end  of  a  given  track,  at  a  time  when  its  middle 
is  occupied  by  other  cars  which  are  receiving  ingots  or 
moulds,  etc. 


Fig.  177.    CROSS  SECTION  AND  PLAN  OF  NEW  EDGAR  THOMSON  CONVERTING  MILL. 

TRASENCKR. 

At  South  Chicago  we  have  practically  three  sets  of 
ingot-  and  five  of  mould-tracks.  The  latter  have,  in  the 
yard  adjoining  the  converting-room,  many  sidings  on 
which  the  mould-cars  can  stand  while  their  moulds  cool 
and  are  inspected. 

If  the  ingot-cranes,  which  lift  the  ingots  from  the  cast- 
ing-pit, deliver  them  directly  to  other  cranes  which  place 
them  in  soaking-pits,  ingot-car-tracks  are  of  course  un- 
necessary. 

If,  as  at  Edgar  Thomson,  the  ladles  are  repaired  in 
a  room  adjoining  the  converting-room,  no  track  is  needed 
for  removing  them,  and  they  may  be  swung  by  a  pair  of 
cranes  into  this  repair-room.  But  if,  as  at  South  Chicago, 
the  ladles  are  repaired  in  a  separate  building,  a  track 
must  be  provided,  as  at  Lt,  in  Figure  168.  The  bottoms 
at  S.  Chicago  are  removed  by  the  tracks  Bt  shown  in 
the  same  figure,  running  back  from  beneath  the  vessels. 
At  Harrisburg  (Figure  171)  and  many  other  works  they 


POSITION    OF    THE    HEATING    FURNACES.      §  386. 


S3!) 


are  removed  on  a  track  Bt,  running  beneath  the  vessels, 
but  parallel  with  their  trunnion  axes  (Figure  163).  It  is 
evidently  desirable  tlmt  this  bottom-track  should  run 
immediately  beneath  the  vessels,  &o  that  the  transfer  of 
bottoms  from  car  to  vessel  and  back  may  be  as  direct  and 
rapid  as  possible.  The  turn-table  arrangement  in 
Figure  177  enables  us  to  side-track  a  bottom  close  by  its 
vessel,  leaving  the  main  bottom-track  free  for  bringing 
bottoms  to  or  from  other  vessels,  for  removing  slag,  etc. 

6.  The  Vessel-  and  Pit-debris  is  best  removed  by  a  track 
running  at  the  level  of  the  bottom  of  the  pit.  The  cars 
may  run  directly  beneath  the  vessels,  which,  after  pouring 
the  steel  into  the  casting-ladle,  are  inverted  and  empty 
their  slag  directly  into  them.  At  South  Chicago  these 
cars  run  on  the  track  which  brings  the  bottoms  to  and 
from  the  vessels,  a  very  good  arrangement.  At  most 
works  the  vessel  slag  track  runs  parallel  with  the  trun- 
nion-axes of  the  vessels. 

§  386.  THE  POSITION  OP  THE  HEATING-FURNACES, 
SOAKING-PITS,  ETC. — These  usually  stand  close  to  the 
(blooming)  rolls  in  which  the  ingots  are  to  be  reduced,  and 
in  a  building  apart  from  the  converting-house.  At 
Bethlehem  the  roll-trains,  heating-furnaces  and  convert- 
ing department  are  all  contained  in  the  nave  of  a  single 
imposing  building.  There  is  a  certain  gain  in  facility  of 
supervision  and  of  communication  between  the  superin- 
tendents of  the  different  departments,  so  that  they  co- 
operate more  readilj'.  But  it  is  doubtful  whether  this 
gain  is  equivalent  to  its  cost.  For  the  temperatuie  in  this 
stately  hall  must,  other  things  being  equal,  be  consider- 
ably higher  than  when  each  department  stands  in  a 
separate  building  of  its  own,  with  abundant  space  for 
fresh  (if  not  cool)  air  to  blow  in  on  all  sides  during 
summer. 

The  saving  of  time  in  carrying  ingots  from  the  casting- 
pit  to  furnaces  in  the  same  rather  than  in  another  building 
is  inconsiderable,  for  once  they  are  loaded  on  a  car  and 
once  the  locomotive  has  started,  a  few  hundred  feet  more 
or  less  counts  for  little.  I  noted  the  following  intervals 
in  transporting  ingots  from  the  casting-pit  to  soaking-pits 
in  another  building  at  an  American  mill : 


Four  ingots  were  placed  on  the  car  at  the  casling-pit  at 

They  had  been  carried  to  out-door  scales  and  had  been  weighed  at. 

They  arrived  at  the  soaking-pitn  HI  another  building  at 

The  first  ingot  was  in  the  t-oaking-pit  at 

The  last  was  in  the  soaking-pit  at 


Minutes.    Seconds. 


0 
27 
30 
55 
15 


This  is  quicker  work  than  I  have  happened  to  notice  in 
mills  in  which  the  heating-furnaces  and  casting-pit  are 
in  the  same  room. 

Here  the  length  of  time  during  which  the  locomotive 
and  ingot-cars  were  detained  because  the  soaking-pits 
were  in  another  building  instead  of  being  in  the  convert- 
ing-house, was  less  than  one  minute. 

Another  plan  is  to  place  soaking-pits  so  near  the  cast- 
ing-pit that  ingots  drawn  from  the  latter  by  one  crane  may 
be  deposited  by  a  second  directly  in  the  soaking-pits,  or 
may  even  be  deposited  in  the  soaking-pits  by  the  very 
crane  which  lifts  them  from  the  casting-pit,  as  indicated  in 
Figure  16f>.  This  expedient  certainly  saves  the  whole 
expense  of  the  transportation  by  locomotive.  In  a  very 
large  establishment  it  might  wholly  dispense  with  one 
locomotive  by  day  and  another  by  night.  The  number  of 
motions  of  the  ingot-cranes  would,  however,  be  the  same 
as  when  the  ingots  are  carried  to  the  soaking-pits  or  other 


heating-furnaces  in  a  separate  building;  for  it  does  not 
take  appreciably  longer  to  place  an  ingot  on  or  to  remove 
it  from  a  car  than  to  set  it  on  or  pick  it  from  the  ground. 
From  these  soaking-pits*  other  cranes  transfer  the  ingots 
directly  to  the  feed-rollers  of  the  blooming  rolls.  This 
appears  to  be  an  admirable  arrangement  in  case  of  small 
output.  Where  a  large  output  is  sought  we  must  weigh 
against  the  advantage  just  considered  the  higher  temper- 
ature which  must  prevail  both  in  the  converting  and  in 
the  rolling  department,  owing  to  their  proximity  to  each 
other.  This  is  a  serious  thing  in  case  of  large  output, 
owing  to  the  enormous  quantity  of  hot  metal  at  hand  at 
once,  and  to  the  frequency  with  which  masses  of  metal 
are  brought  out  into  the  air,  radiating  heat  in  all  directions. 
§  387.  THE  SEVERAL  LEVELS. — To  recapitulate  these  we 
have : 

1,  The  cupola-charging  level ; 

2,  The  cupola-tapping  level ; 

3,  The  vessel-trunnion  level  ; 

4,  The  general  level  of  the  converting-house  ; 

5,  The  pit-level ;  and 

6,  The  level  of  the  subterranean  passages  in  which  the 
hydraulic  and  other  pipes  lie. 

Of  these  we  have  seen  that  2  and  3  are  identical  in  some 
of  the  best  works  lately  built,  while  4  and  5  are  identical 
in  some  works,  but  to  doubtful  advantage. 

§  388.  THE  BESSEMER  CONVERTER  OR  VESSEL"  is  essen- 
tially a  chamber  lined  with  refractory  material,  and 
suited  to  carrying  out  the  Bessemer  process.  In  this 
view  the  many  vessels  which  are  now  offered  to  the  pub- 
lic are  all  Bessemer  converters  ;  there  may  be  a  Clapp- 
Griffiths  Bessemer  converter,  a  Robert  Bessemer  con- 
verter, which  we  may  call  simply  a  "  Robert  converter," 
remembering  that  this  is  merely  an  abbreviation,  and 
that  it  is  essentially  a  Bessemer  converter  still. 

§389.  BESSEMER' s  EARLY  VESSELS. —Figure  178  shows 
the  apparatus  in  which  Bessemer' s  earliest  experiments 
were  carried  out,  a  40-pound  clay  crucible,  heated  in  a 
common  crucible-furnace,  and  provided  with  a  tap-hole 
for  removing  the  molten  metal  and  a  central  clay  pipe 
through  which  the  blast  was  introduced.  In  this  ten  or 
twelve  pounds  of  cast-iron  were  melted  and  then  blown. 

Next  a  rotating  converter  (Figure  179)  was  designed  by 
Bessemer,  but  not  built,  spherical,  to  reduce  the  loss  of 
heat  by  radiation  to  a  minimum,  and  with  a  clay  tuyere 
inserted  and  withdrawn,  much  as  in  Figure  178. 

Next  came  the  vessel  shown  in  Figure  180,cand  used  for 
Bessemer's  public  experiments  at  St.  Pancras  in  1856.  Its 
resemblance  to  Figure  188  is  striking,  while  its  general 
arrangement  is  much  like  that  of  Figure  216. 


a  By  soaking-pits  I  mean  those  with  auxiliary  gas-firing.  There  seems  little 
sense  in  constructing  furnaces  so  that  we  cannot  use  auxiliary  gas  if  we  wish. 
There  is  no  reason  for  tieing  our  hands  in  this  matter,  except  that  we  thereby  cut 
down  the  cost  of  installation  slightly. 

b  As  far  as  my  observation  goes,  metallurgical  writers  almost  invariably  use  the 
word  "  converter,"  while  in  the  steel  works  the  word  "  vessel  "  is  almost  always 
used.  Vessel  has,  of  course,  a  generic  sense,  but  it  has  acquired  a  distinct  specific 
meaning — the  Bessemer  converter.  It  seems  to  me  high  time  that  this  unobjection- 
able word  should  be  recognized.  Indeed,  as  the  briefer  name,  and  as  the  one  in 
actual  use,  it  seems  on  the  whole  preferable  to  converter. 

*  "  This  fixed  converter  has  turned  out  to  be  the  father  of  a  very  numerous 
family,  all  having  a  strong  likeness  to  their  ancient  progenitor,  and  inheriting  but 
too  many  of  his  defects  and  shortcomings.  And  it  therefore  affords  anything  but 
an  example  of  the  survival  of  the  fittest." — Bessemer,  Journal  Iron  and  Steel 
Institute,  1886,  II.,  p.  640. 


340 


THE    METALLURGY     OF     STEEL. 


Next  came  the  first  rotating  vessel,  Figures  181, 182.  Its 
trunnions  were  concentric  with  the  pouring  lip,  so  that  it 
poured  readily  into  moulds  set  beneath  it.  In  designing  it 
Bessemer  aimed  chiefly  to  make  the  metal  circulate,  so 
that  all  parts  would  be  acted  on  alike  by  the  blast. 


years,  when  the  form  shown  in  Figure  204  was  introduced. 

Later  still — in  1862 — we  have  the  rotating  vessels, 
Figures  185,  186,  with  side  tuyeres,  which  were  readily 
brought  above  the  level  of  the  molten  metal. 

Of  these  all  but  that  in  Figure  204  are  of  Bessemer' s 


fig.  178. 

Bessemer's  original  ap- 
paratus. 


Fly.  179. 
Vessel  first  patented,  1855. 


Fig.  ISO. 
St.  Pancras,  1853. 


Fig.  181.  Fig.  1SS. 

First  rotating  vessel,  185G. 


Fig.  183. 

Early  vessel  with  inter- 
nal tuyere,  1861. 


Fig.  18U. 
About  1856.    Rotating  vessel,  with  emerging  tuyeres. 


Fig.  185.  Fig.  186. 

Rotating  side-blowing  vessel. 

BESSEMBR'S  EABLT  CONVERTERS.    FROM  BESSEMER. 


Fig.  1ST. 
1858  (»). 


Note  to  figure  188. 
A.  Blast-box, 
a.    Tuyeres. 

C.    Free  space  above  bath 
t.    Tap-hole, 
n.  Nose. 
K.  Charglng-hole. 


Fig.  188.    OLD  FIXED  SWEDISH  CONVERTER,  WITH  SIDE  TUYERES.    KERL. 

Soon  followed  the  rotating  vessel  shown  in  Figure  184, 
which  also  was  pivoted  concentrically  with  its  pouring 
lip,  and  liad  in  addition  the  advantage  that,  when  turned 
for  receiving  molcen  cast-iron  or  for  discharging  molten 
steel,  its  tuyere  was  above  the  level  of  the  metal. 

Later — in  1858  —we  have  the  vessel  of  Figure  187.  This 
form  was  used  with  but  little  alteration  till  within  a  few 


Fig.  180.    PART  PLAN  OF  OLD  FIXED  SWEDISH  CONVERTER 

WITH  BIDE  TUYERES. 

design.  The  rotating  vessel  lies  with  its  major  axis  hori- 
zontal when  receiving  or  discharging  metal ;  before  the 
blowing  operation,  or  "blow"  or  "heat"  begins,  the 
blast  is  let  on  and  the  vessel  then  turned  so  that  its  axis 
is  vertical,  submerging  the  tuyeres  ;  the  vessel  is  then 
said  to  be  "  turned  up."  At  the  end  of  the  operation  it 
is  "  turned  down,"  i.e.,  its  axis  is  again  made  horizontal, 


CLASSIFICATION-    OF    BESSEMER    CONVERTER?.      §  390. 


841 


BACK 


SHOULDER 


Fig.  SOI. 


CLLLY 


Fig.  191. 


and  the  tuyeres  emerge 
from  below  the  metal.  So, 
ABREAST  too,  should  a  tuyere  fail  or 
should  the  charge  break 
through  the  lower  part,  of 
the  vessel  we  at  once  "  turn 
down." 

Fig.  201  shows  the  names 
applied  to  certain  parts  of  the  vessel.  In  concentric  vessels 
the  side  on  which  the  charge  of  cast-iron  is  received  is 
termed  the  "iron-side,"  that  where  the  steel  is  discharged 
the  "  steel- side. "p 

§  390.  VKSSKLS  CLASSIFIED.  The  most  important 
classification  of  vessels  is  into  the  fixed  and  the  rotating, 
and  into  the  side-  and  the  bottom-blowing.  They  are  also 
divided  into  those  with  straight  and  those  with  contracted 
shells ;  and  into  "  eccentric  "  and  "  concentric,"  or  "  sym- 
metrical," i.e.,  into  those  in  which  the  vessel  is  retort- 
shaped,  as  in  Figs.  197  and  202,  and  those  in  which  the  nose 
is  almost  concentric  with  the  major  axis  (Figs.  192,  195). 

§  391.  FIXED  vs.  ROTATING  VESSELS.— Fixed  vessels 
(e.  g.,  Figures  188-9  and  216)  have  four  chief  defects. 

p  This  strange  monster,  "truly  unique  among  organic  forms,"  breathes  through 
his  nether  parts,  feeds,  spits,  roars  and  flames  through  his  nose,  which,  like  his 
breast,  strangely  enough  grows  above  his  back,  while  his  shoulder  lies  beneath  bis 
middle. 

Fig.  195. 


Xston,  15-ton,  about  1880. 

Fig.  196. 


Bethlehem,  8-ton,  1881. 
Fig.  197. 


Edgar  Thomson,  10-ton,  1889. 
Fig.  198. 


Union,  10- ton,  about  1881. 
Tig.  199. 


S.  Chicago,  10-ton,  1882. 


Cambria,  old,  9-ton, 


Cambria,  new,  12  to  15  tons,  1888. 


Avesta,  880-pound. 


843 


THE    METALLURGY    OF    STEEL. 


1st.  They  hardly  permit  bottom-blowing,  hence  they 
involve  greater  loss  of  iron  in  conversion.  If  the  tuyeres 
were  introduced  through  the  bottom  of  a  h'xed  vessel,  the 
failure  of  a  single  tuyere  would  let  the  whole  charge 
escape  and  might  greatly  injure  the  vessel.  Should  part 
of  the  charge  be  tapped  out,  it  would  be  scrap.  If  a 
tuyere  in  a  rotating  vessel  fails,  the  vessel  is  simply  turned 
so  as  to  bring  the  tuyeres  above  the  level  of  the  metal, 
when  the  faulty  one  can  be  repaired.  The  failure  of  a 
tuyere  during  the  blow  is  no  uncommon  thing.  It  causes 
but  a  brief  delay. 

8d.  Even  in  side-blowing  the  failure  of  a  tuyere  is  a 
serious  thing  in  case  of  fixed  vessels,  because  it  is  then 
necessary  to  remove  the  charge  from  the  vessel  at  once, 
converting  it  into  scrap. 

3d.  At  the  end  of  the  blow  the  charge  has  to  be  tapped 
out  instead  of  being  poured  out  of  the  vessel's  nose. 
Formerly  serious  accidents  were  liable  to  arise  through 
inability  to  open  the  tap-hole  in  case  of  a  cold  charge  ;  but 
now  that  the  proportion  of  silicon  in  the  charge  is  more 
closely  attended  to,  and  that  heats  follow  eacli  other 
rapidly,  this  is  of  little  moment.  But,  so  far  as  my  ob- 
servation goesj  the  proportion  of  carbon  in  the  steel  is  less 
closely  under  control  in  case  of  fixed  than  in  that  of  rota- 
ting vessels,  because  the  length  of  time  taken  to  tap 
varies  more  than  that  needed  for  turning  a  rotating  vessel 
down  at  the  end  of  the  blow,  and  for  other  reasons  ex- 
plained in  considering  side-blowing. 

4th.  It  is  impossible  to  recarburize  within  the  vessel. 
This  is  relatively  unimportant  in  case  very  soft  steel  is  to 
be  made,  since  in  this  case  the  metal  may  be  recarburized 
advantageously  in  the  ladle,  but  in  case  of  rail-steel  it  is 
a  serious  thing. 

Several  minor  objections,  supposed  greater  difficulty  in 
charging  and  in  repairing,  etc.,  are,  I  think,  of  little 
weight.  The  only  serious  difficulties,  I  believe,  are  the 
less  complete  control  over  the  proportion  of  carbon  in  the 
steel;  that  the  apparatus  does  not  work  as  smoothly,  as 
surely  and  as  quickly  as  the  rotating  vessel ;  and  that  the 
loss  of  iron  is  heavier. 

It  must  be  admitted  that  the  work  done  in  the  little 
fixed  Clapp-Griffiths' vessels,  as  improved  by  Witherow,  is 
extremely  creditable.  The  difficulties  which  hung  aboat 
the  old  Swedish  fixed  vessels,  leading  to  their  abandon- 
ment, and  which  caused  even  so  broad-minded  a  man  as 
Hoi  ley0  to  believe  them  beneath  notice,  have  certainly 
been  overcome  to  a  most  surprising  degree.  That  46  heats 
should  be  made  in  a  pair  of  fixed  vessels  in  eight  hours, 
speaks  volumes  for  the  energy  of  the  superintendent,  and 
something  for  the  possibilities  of  a  vessel  long  despised 
and  rejected. 

The  fixed  vessel  is  certainly  very  much  cheaper  than 
the  rotating  one,  and,  where  it  is  absolutely  imper- 
ative that  the  cost  of  installation  should  be  as  low  as 
possible,  even  at  the  cost  of  additional  loss  of  iron  in  con- 
version and  of  some  slight  irregularity  in  the  proportion 
of  carbon  in  the  product,  it  may  be  used  with  advantage. 


c  "As  recarburization  cannot  be  performed  in  such  a  vessel,"  i.  e.  a  fixed  one, 
"  and  as  it  is  otherwise  impracticable  for  a  maximum  production,  we  may  properly 
omit  its  consideration  "  (Holley  "  Bessemer  Machinery,"  p.  8).  Now  a  pair  of  fixed 
vessels  has  turned  out  in  eight  hours  twice  as  many  heats  as  Holley  then  thought 
the  normal  product  of  a  pair  of  rotating  ones  for  twenty-four  hours.  Still,  Holley 
was  right. 


But  under  all  common  conditions  the  rotating  vessel  is  to 
be  preferred. 

§  392.  SIDE-  vs.  BOTTOM-BLOWING. — The  tuyeres  have 
sometimes  been  placed  at  the  sides  instead  of  in  the  bot- 
tom, 1st,  in  low  side-blowing  (as  in  the  old  Swedish 
vessels,  Figure  188),  in  which  they  were  close  to  the  bot- 
tom, to  permit  the  use  of  a  fixed  and  therefore  cheap 
vessel:  2d,  in  Jiigh  side-blowing  (as  in  the  Durfee  vessel11  and 
later  in  many  others  in  which  the  tuyeres  are  raised  far 
above  the  bottom),  to  lessen  the  blast-pressure  needed  to 
keep  the  metal  from  running  into  the  tuyeres,  and  thus  the 
power  needed  to  drive  the  blowing-engines,  and  the  cost 
of  installation  of  these  engines  and  of  their  boilers.  To 
accomplish  this  object  the  tuyeres  must  be  near  the  top 
of  the  bath  of  metal,  or  at  least  raised  an  appreciable  dis- 
tance above  the  bottom.  The  same  object  could  be 
attained  with  bottom-blowing  by  making  the  bath  of 
metal  very  shallow  :  but  this  would  necessitate  using  ex- 
tremely wide  and  hence  expensive  vessels. 

The  system  has  three  chief  disadvantages. 

1st.  The  action  of  the  blast  is  not  uniform  through  the 
whole  of  the  bath,  as  in  bottom-blowing,  but  is  strongest 
in  the  outer  ring  of  metal  above  the  tuyeres,  the  air 
bubbling  up  somewhat  as  sketched  in  Figure  186.  Actu- 
ally the  whole  bath  is  in  active  motion,  and  in  tapping  its 
different  parts  mix.  But  it  is  quite  possible,  if  not  indeed 
probable,  that,  at  the  moment  of  tapping,  the  metal  im- 
mediately above  the  tuyeres  contains  considerably  less 
carbon  than  the  central  part  of  the  lower  layer  of 
metal  does ;  and  that  this  heterogeneousness  is  not 
fully  removed  in  tapping  into  the  ladle  and  thence 
into  the  moulds,  so  that  the  ingots  are  less  homogeneous 
than  in  case  of  bottom-blowing.  Lacking  direct  evidence 
on  this  point,  I  cannot  tell  how  much  weight  should  be 
attached  to  this  objection. 

2d.  The  metal  immediately  around  the  points  where 
the  blast  enters  becomes  highly  oxygenated.  In  case  of 
bottom-blowing  the  metal  is  so  thoroughly  mixed  up,  and 
the  path  of  the  blast  through  the  metal  is  so  long,  that 
this  iron-oxide  yields  up  its  oxygen  in  great  measure  to 
the  carbon,  silicon,  etc.,  of  the  bath.  At  the  end  of  the 
blow,  when  there  is  but  a  trifling  quantity  of  these  ele- 
ments present,  the  iron-oxide  is  not  so  fully  reduced,  and 
much  of  it  escapes  along  with  the  blast  from  the  upper 
surface  of  the  metal,  in  the  form  of  a  dense,  brownish  red 
smoke,  and  the  metal  is  now  over-blown. 

In  case  of  side-blowing,  however,  the  mixing  is  so  much 
less  perfect  that  the  iron-oxide  produced  by  the  blast 
comes  in  contact  much  less  rapidly  with  carbon,  silicon, 
etc.,  and  is  therefore  less  rapidly  deoxidized.  This  is  es- 
pecially true  towards  the  end  of  the  blow,  when  the  small 
proportion  of  carbon  and  silicon  in  the  limited  quantity  of 
metal,  with  which  a  given  lot  of  iron-oxide  comes  in  con- 
tact, does  not  suffice  for  its  deoxidation,  and  we  get  local 
over-blowing  in  the  region  immediately  above  the  tuyeres 
before  the  rest  of  the  bath  is  thoroughly  decarburized. 
But  the  blast  must  be  kept  up  till  the  middle  as  well  as 
the  outer  part  of  the  charge  is  decarburized.  Now,  all  ad- 
mit that  side-blown  charges  give  off  very  much  more  red 


d  In  1863-4  Z.  S.  and  W.  F.  Durfee  designed  and  built  at  Wyandotte,  Michigan, 
a  side-blowing  fixed  vessel,  with  the  tuyeres  near  the  upper  surface  of  the  metal,  so 
that  light  blast-pressure  might  be  used,  and  with  a  movable  bottom.  Trans.  Am. 
Inst.  Min.,  Eng.  XIII.,  p.  771, 1885.  Let  us  call  this  high  side-blowing. 


SIDE      VERSUS     BOTTOM    BLOWING. 


392. 


843 


smoke  than  bottom-blown  ones  at  the  beginning  of  the 
blow",  and  to  my  eye  they  do  towards  the  end  of  the  blow 
also. 

It  is,  therefore,  natural  that  the  loss  should  be  heavier 
in  side — and  especially  in  high  side— than  in  bottom-blow- 
ing. From  the  data  at  hand  I  think  that  it  is  about  4^ 
greater. 

In  order  that  the  action  of  the  blast  might  be  less  local- 
ized, the  tuyeres  in  the  old  Swedish  fixed  side-blown  vessels, 
Figures  188,  189,  were  placed  not  radially  but  in  a  po- 
sition intermediate  between  that  of  a  radius  and  that  of  a 
tangent,0  so  as  to  give  the  metal  a  horizontal  rotation.  In 
the  Robert  vessel,  Figures  217,  218,  the  same  thing  is 
done,  while  to  induce  a  vertical  as  well  as  a  horizontal 
rotation,  the  tuyeres  are  placed  on  one  side  only. 

The  third  disadvantage  of  side-blowing  is  that,  as  the 
bottom,  and  the  sides  near  and  below  the  tuyeres,  wear 
away,  the  weight  of  charge  remaining  constant,  the  depth 
of  metal  above  the  tuyeres  diminishes,  so  that  blowing 
becomes  more  and  more  localized.  Now,  even  those  who 
prefer  to  localize  the  blowing  must  admit  that  it  is  im- 
portant that  the  conditions  of  blowing  should  be  as  nearly 
constant  as  possible,  in  order  that  the  desired  degree  of 
decarburization  may  be  hit  accurately  ;  or,  if  we  seek  to 
remove  all  the  carbon,  that  we  may  arrest  the  operation 
as  soon  as  possible  after  decarburization  is  complete,  and 
so  overblow  and  oxidize  iron  as  little  as  possible.  Clearly, 
the  more  constant  the  conditions  of  blowing,  the  more 
accurately  can  we  hit  the  point  of  complete  decarburiza- 
tion. In  bottom-blowing  the  depth  of  metal  above  the 
tuyeres  changes  but  very  slightly,  the  corrosion  being 
chiefly  on  the  bottom  proper,  and  the  side  of  the  vessel 
slagging  away  but  slowly. 

I  have  no  direct  evidence  as  to  how  serious  this  effect 
is,  for,  though  I  have  found  that  the  composition  of  the 
steel  varies  more  from  heat  to  heat  with  side-  than  with 
bottom-blowing,  yet  the  side-blown  vessels  concerning 
which  I  have  data  are  also  fixed,  while  the  bottom -blown 


a  "We  have  volumes  pouring  out  at  the  very  commencement,  of  brown  iron-oxide 
smoke.  The  whole  things  looks  as  the  Bessemer  converter  does  when  it  is  turned 
over,  with  air  blowing  across  the  top  of  the  metal." — R.  W.  Hunt,  Trans.  Am 
Inst.  Min.  Eng.,  XIII.,  p.  767-8,  1885.  When  a  bottom-blown  vessel  is  thus  inclined 
so  that  some  of  the  tuyeres  emerge,  or  at  least  so  that  they  are  brought  near  the 
surface  of  the  metal,  enormous  volumes  of  red  smoke  pour  out ;  we  thus  raise 
the  temperature  by  burningiron,  and  probably  also  by  burning  a  large  proportion  of 
the  carbon  to  carbonic  acid  instead  of  to  carbonic  oxide. 

In  the  Clapp-Grifflths  side-blown  vessel  a  thick  gray  smoke  appears  the  moment 
that  the  charge  of  cast-iron  begins  to  run  into  the  vessel.  In  about  30",  or  proba- 
bly at  the  instant  that  the  level  of  the  molten  metal  reaches  the  tuyeres,  the  smoke 
changes  suddenly  from  gray  to  dense  brownish  red,  and  remains  of  this  hue  for  about 
one  to  one  and  a  half  minutes,  when  the  flame  gradually  assumes  the  same  appear- 
ance as  in  bottom-blown  charges.  Towards  the  end  of  the  blow,  the  reddish  smoke 
again  appears,  and  becomes  very  dense  as  the  flame  shortens.  The  blast  is  now 
partly  shut  off,  and  the  metal  is  tapped  almost  immediately,  the  brownish  red 
smoke  continuing  for  about  20  seconds  after  the  steel  begins  to  run  out  of  the  tap- 
hole,  when  it  ceases  suddenly,  probably  just  as  the  surface  of  the  metal  sinks  below 
the  tuyeres.  In  four  observations  I  found  that  the  red  smoke  continued  from  12" 
to  23"  after  the  steel  began  running,  or  an  average  of  17". 

In  the  few  charges  which  I  have  seen  blown  in  the  Robert  vessel,  in  which  the 
blast  enters  still  nearer  the  top  of  the  bath,  there  was  a  great  deal  of  smoke 
throughout  the  blow,  which  lasted  twenty  minutes.  Though  the  smoke  smelt  very 
strongly  of  iron-oxide,  it  was  less  strongly  red  than  that  from  the  Clapp-Grifliths 
vessel.  This  difference,  I  think,  is  reasonably  ascribed  to  a  difference  in  the  com- 
position of  the  irons  blown,  that  treated  in  the  Robert  vessel  being  highly  silicious, 
and  containing  \%  of  manganese, — a  very  "  hot "  iron. 

The  loss  in  this  case  is  kept  down  by  interrupting  the  blow  very  early,  i.  e.,  by 
"  blowing  young :"  but  I  learn  that  in  epite  of  this  it  amounts  to  15$.  The  difficulty 
in  getting  trustworthy  information  about  the  loss  is  too  well  known  to  need  com- 
ment here. 

c  It  is  generally  stated  that  the  tuyeres  were  tangential ;  but  I  believe  that  this 
Is  inaccurate. 


ones  rotate,  and  how  much  to  assign  to  the  side-blowing 
and  how  much  to  the  fact  of  being  fixed,  I  know  not. 

In  the  Robert  vessel  this  wearing  away  of  the  bottom 
may  be  compensated  for  by  tipping  the  converter  more. 

On  the  other  hand,  side-blowing,  or  at  least  high  side- 
blowing,  has  two  decided  advantages.  If  the  tuyeres  be 
close  to  the  bottom,  as  in  the  old  Swedish  vessels,  side- 
blowing  merely  enables  us  to  use  a  cheaper  because  fixed 
vessel. 

High  side-blowing,  however,  not  only  lessens  the  blast- 
pressure  needed,  but  greatly  prolongs  the  life  of  the 
tuyeres.  In  good  American  bottom-blowing  practice  the 
average  life  of  the  bottoms  is  usually  about  18  or  20  heats, 
though  under  favorable  conditions  the  average  life  rises 
to  28  heats,  while  single  bottoms  sometimes  last  more 
than  50  heats  ;  but  I  am  informed  that  the  average  life 
of  the  bottom  in  some  Clapp-Grimths  (side-blown)  vessels 
is  as  high  as  120  heats,  and  that  a  single  bottom  has  lasted 
225  heats.d  The  average  life  in  the  Robert  side-blown 
vessel  is  said  to  be  250  heats. 

This  may  be  partly  because  the  blast,  moving  relatively 
slowly  through  the  tuyere  because  under  lower  pressure, 
corrades  or  abrades  the  edges  of  the  tuyere-holes  less  as 
it  issues  from  them,  but  chiefly  because,  in  spite  of  its  lower 
pressure,  it  holds  the  molten  metal  away  from  the 
tuyere-holes  more  fully  than  when  there  is  a  greater  deptli 
of  metal  above  them  (Cf.  §  404). 

The  heavier  loss  of  iron  in  high  side-  than  in  bottom- 
blowing  naturally  leads  to  a  higher  temperature,  the 
excess  of  iron  burnt  giving  out  a  great  deal  of  heat ;  and 
we  perhaps  have  a  larger  proportion  of  the  carbon  burnt 
to  carbonic  acid  instead  of  carbonic  oxide  than  in  bottom- 
blowing,  as  the  blast  passes  through  a  thinner  layer  of 
fuel. 

Neglecting  for  the  moment  the  minor  disadvantages  of 
side-blowing,  that  the  composition  is  likely  to  vary  more 
from  heat  to  heat,  and  also  more  in  the  different  parts  of 
the  metal  from  a  single  heat,  we  have  to  weigh  against 
the  greater  loss  of  iron  which  it  entails  its  advantages  in 
saving  blast-power  and  prolonging  the  life  of  the  bottom 
and  tuyeres. 

If  we  assume  that  the  loss  is  four  per  cent,  greater 
in  side  than  in  bottom-blowing,  side-blowing  uses  121 
pounds  more  of  cast-iron  than  bottom-blowing  does, 
per  ton  of  ingots.  If  we  further  assume  that  the  saving 
in  blast-power  in  side-blowing  is  equivalent  to  saving 
half  the  total  quantity  of  fuel  burned  under  the  boilers 
in  bottom-blowing,  and  further  if  we  assume  that  side- 
blown  vessels  need  no  repairs  whatever  to  their  refractory 
material,  then  side-blowing  saves  about  150  pounds  of 
coal,  92  pounds  of  refractory  materials  (sand,  clay, 
quartz),  and  0.1  of  a  tuyere,  per  ton  of  ingots.  But 
manifestly,  even  if  we  add  a  slight  saving  in  the  labor 
needed  to  make  up  the  refractory  materials,  no  calcula- 
tion is  needed  to  show  that  the  value  of  this  saving  is 
much  less  than  that  of  the  121  pounds  of  cast-iron  with 
which  side-blowing  is  charged.  The  data  which  I  have 


d  Oliver  Brothers  and  Phillips,  private  communication,  June  7, 1889.  In  another 
American  work  the  bottoms  of  the  Clapp-Grifliths  vessels  last  only  30  heats,  their 
maximum  life  being  52  heats. 

In  1886  I  was  informed  that  the  life  of  the  bottoms  of  some  Clapp-Griffitlis 
vessels  had  averaged  55  heats  for  one  week,  and  that  for  many  weeks  it  had  averaged 
48  heats. 


344 


THE    METALLURGY     OF    STEEL. 


indicate  that  the  case  is  really  less  favorable  to  the  side- 
blown  vessels  than  I  have  here  assumed. 

Beyond  this,  the  life  of  the  shell-linings  is  usually 
shorter  in  side  than  in  bottom  blown  vessels.  (Cf.  §  403.) 
Doubtless,  this  is  because  the  iron-oxide  is  formed  locally 
along  the  sides  of  side- blown  vessels,  and  the  lining  around 
and  above  the  tuyeres  is  thus  exposed  to  more  iron-oxide 
and  to  a  locally  more  basic  slag  than  in  bottom-blown 
vessels,  especially  if  the  tuyeres  of  the  latter  be  concen- 
trated near  the  middle  of  the  bottom.  In  this  case  the 
iron-oxide,  formed  in  excess  in  front  of  the  ends  of  the 
tuyeres,  is  well  reduced  by  the  carbon  and  silicon  of  the 
metal  before  it  reaches  the  shell-lining. 

§  393.  INTERNAL  BLOWING. — Whether  the  tuyeres  be 
in  the  side  or  the  bottom,  it  is  in  their  neighborhood  that 
the  lining  wears  out  the  soonest,  the  iron-oxide  formed  in 
abundance  by  the  entering  blast  rapidly  corroding  the  sili- 
cious  lining  of  the  vessel.  To  remedy  this,  and  also  to 
have  a  ready  means  of  stopping  and  starting  the  blow  at 
any  instant  without  the  costly  expedient  of  the  rotating 
vessel,  Bessemer  early  designed  a  vessel  with  an  internal 
tuyere,  Figure  183.  Indeed,  as  Figure  179  shows  us,  the 
internal  tuyere  may  be  considered  as  older  than  that 
built  into  the  lining,  whether  at  side  or  bottom.  As  a 
simple  clay  tube  was  liable  to  crack,  and  as  the  slightest 
crack  would  be  fatal,  Bessemer  used  the  built-up  tuyere 
of  Figure  183,  an  iron  tube  coated  with  silicious  refractory 
material,  much  as  ladle-stoppers  now  are.  But  it  has  been 
found,  both  by  Bessemer  and  in  later  experiments  in  this 
country,  impossible  to  maintain  this  internal  tuyere,  part- 
ly because  of  the  difference  in  expansion  between  the  in- 
tensely-heated immersed  part  and  the  rest  of  the  tuyere.* 

§  394.  STRAIGHT  vs.  CONTRACTED  SHELLS.— In  the  ear- 
lier vessels,  Figure  187,  the  shell  was  contracted  towards 
the  bottom.  The  reason  for  this  appears  to  be  that,  as 
the  bottom  is  the  place  that  wears  out  soonest  and  must 
most  often  be  repaired,  so  it  was  desired  to  make  it  small 
in  order  that  but  little  might  have  to  be  repaired  and 
replaced.  Contracting  the  shell  at  both  ends,  in  that  it  is 
a  step  towards  the  spherical  form,  which  has  the  mini- 
mum of  heat-radiating  surface,  tended  to  preserve  the 
heat  generated  within  the  vessel.  Finally,  the  lining 
thus  arched  held  firmly  in  place,  tended  less  to  fall  out, 
e.  g.y  when  the  bottom  of  the  vessel  was  removed  for  re- 
pairs. 

But  experience  has  shown  that  all  this  is  false  economy. 
Here,  as  in  the  case  of  the  Siemens'  furnace,  it  has  been 
found  best  to  sacrifice  to  other  considerations  part  of  that 
extreme  compactness,  which  was  at  first  sought  in  order  to 
reduce  the  heat- radiating  surface  to  a  minimum.  The 
fuel-economy  thus  gained  was  paid  for  too  heavily  in  in- 
creased cost  of  repairs.  A  ring  of  stout  angle-iron  (Fig- 
ures 202-204)  at  the  bottom  of  a  straight-sided  vessel 
effectively  prevents  the  well-sintered,  tightly  rammed, 
monolithic  shell-lining  from  falling  out  when  the  bottom 
is  removed.  While  contracting  the  lower  part  of  the 
shell  certainly  made  the  bottom  smaller,  so  that  there  was 
a  smaller  piece  to  repair,  it  really  increased  the  cost  of  re- 


g  F.  W.  Gordon,  U.  S.  patent  361,634,  April  19, 1887,  describes  a  movable  tuyere, 
with  elaborate  and  ingenious  devices  for  moving  and  protecting  it.  It  was  inserted 
through  the  side  of  a  stationary  vessel,  a  little  above  the  surface  of  the  molten 
metal  into  which  it  dipped.  Serious  if  not  fatal  technical  difficulties  arose  in  ex- 
periments made  with  it. 


pairs,  in  two  ways.  First,  it  gave  a  greater  depth  of  metal 
above  the  tuyeres,  and  this  has  been  found  by  experience 
to  shorten  the  life  of  the  bottom,  apparently  because  for 
given  blast-pressure  the  metal,  rich  in  nascent  iron-oxide, 
•  is  less  fully  kept  away  from  the  ends  of  the  tuyeres  by  the 
blast.  Next,  because  the  shell-lining  itself  was  liable  to 
be  eaten  away  near  the  bottom,  and  this  is  far  more  diffi- 
cult to  repair  than  the  bottom  itself.  The  vessels  lately 
built  have  perfectly  straight  sides  within  and  without. 
They  are  cheaper  to  build  and  to  maintain,  for  the 
straight  side  within  is  so  far  from  the  tuyeres  that  it  cor- 
rodes very  little.  With  weekly  repairs  the  linings  of  such 
vessels  last  a  year  easily. 

§  395.  EXCENTRIC  vs.  CONCENTRIC  NOSES. — When  a  ves- 
sel with  the  old  excentric  nose  was  turned  down  (Figure 201), 
a  very  large  charge  of  molten  metal  could  lie  in  its  belly, 
without  running  into  the  tuyeres  or  out  of  the  nose.  The 
excentric  nose  was  further  thought  to  hinder  slopping,  i.  e., 
to  lessen  or  to  guard  against  the  tendency  of  the  boiling 
metal  to  be  carried  out  of  the  vessel  through  the  nose. 
Finally,  as  works  were  then  arranged,  it  discharged  the 
molten  steel  and  the  gaseous  products  of  combustion  con- 
veniently, and  received  the  molten  cast-iron  without 
excessive  inconvenience."1  In  designing  the  excentric  nose, 
however,  care  had  to  be  taken  that  the  whole  bottom  of 
the  vessel  should  be  visible  through  it,  so  that  the  condition 
of  this,  the  most  perishable  part  of  the  lining,  might  be 
readily  learned  between  blows. 

This  was  all  very  well  as  long  as  the  cast-iron  was  melt- 
ed in  reverberatory  or  cupola  furnaces,  for  these  could 
be  placed  at  such  a  height  that  the  metal,  ran  from  them 
through  long  runners  to  the  vessel  turned  down  towards 
the  pit,  like  the  right-hand  vessel  in  Figure  173  and  the 
middle  one  of  Figure  177. 

But  even  in  this  case,  the  greater  height  which  we  had 
to  give  the  cupolas,  and  the  greater  length  which  the  run- 
ners needed,  in  order  to  carry  the  cast-iron  not  merely  to 
the  vessels  but  past  their  whole  length,  was  an  inconveni- 
ence, even  if  it  was  not  realized. 

When,  however,  molten  metal  was  brought  direst  from 
the  blast-furnace,  it  was  found  too  serious  an  inconveni- 
ence to  raise  it  so  high  that  it  would  run  past  the  length 
of  the  vessels  into  their  noses  ;  and,  in  case  the  metal 
had  for  any  reason  become  cool  during  its  passage  from 
the  blast-furnace  to  the  converting-mill,  an  excessive  quan- 
tity of  it  would  freeze  in  the  long  runners. 

Two  expedients  suggested  themselves.  The  cast-iron- 
ladle  could  be  brought  to  a  hoist  H,  standing  between  the 
line  of  the  trunnion-axes  and  the  pit,  as  in  Figures  164  and 
209,  and  here  raised  so  as  to  pour  through  a  short  runner 
into  the  vessel ;  or  the  nose  of  the  vessel  could  be  made 
concentric  or  symmetrical,  so  that  it  could  receive  molten 
cast-iron  when  turned  down  away  from  the  pit,  and  at 
the  end  of  the  blow  receive  spiegeleisen  and  discharge 
steel  when  turned  down  towards  the  pit,  as  in  Figures  173 
and  177. 

We  have  already  seen  that  the  surface  track  of  the 
Bethlehem  plan  occupies  space  which  might  be  utilized 
for  other  purposes,  and  which  is  likely  to  be  encumbered, 
and  is  hence  not  very  well  suited  for  the  extremely 
frequent  trips  of  the  iron-  and  the  spiegel-ladle. 


d  Holley  indeed  said  of  it  "  We  can  hardly  sec  how  the  shape  can  be  improved,  or 
how  any  other  would  be  admissible."    (Lecture  at  Stevens'  Inst.,  1872,  p.  9.) 


EXCENTRIC    VS.     CONCENTRIC    NOSES.       §  395. 


34. "5 


Thus  the  concentric  vessel  seemed  to  offer  a  very  simple 
solution.  It  allowed  the  >piegel-and  cast-iron-cupolas  to 
remain  in  their  old  places  behind  the  vessels,  the  spiegel- 
eisen  running  though  the  old  bifurcated  runner  into  the 
vessel  as  this  lay  turned  down  towards  the  pit  at  the  end 
of  the  blow  ;  the  cast-iron  running  into  ladles  standing 
on  a  track  which  ran  behind  the  vessels,  and  to  which  the 
direct-metal  was  brought  over  an  incline  by  a  locomotive, 
a  special  locomotive  always  standing  on  the  track,  ready 
to  move  both  the  direct  and  the  cupola-metal  ladles  to 
and  from  the  vessels.  (See  Figures  163,  173,  177.) 

But  the  concentric-nosed  vessel  must  be  made  much 
larger  than  the  excentric  one,  in  order  that,  when 
turned  down,  it  may  hold  a  charge  of  given  weight  with- 
out allowing  it  to  run  either  out  of  the  nose  or  into 
the  tuyeres,  and  hence  is  a  much  more  expensive 
vessel.  The  old  excentric  vessels  had  from  about 
33  to  about  42,  the  new  concentric  ones  have  from 
about  50  to  about  80  cubic  feet  capacity  per  ton  of 
charge  (Table  190).  The  little  Avesta  vessel  had  about 
15  cubic  feet  capacity  per  ton  of  charge.  Now  this 
increased  volume  turns  out  to  be  a  great,  if  unexpected, 
blessing,  for  very  much  less  slopping  occurs  with  it.  The 
vessel  is  so  roomy,  and  the  height  from  the  upper  suiface 
of  the  metal  to  the  nose  is  so  great,  that  the  metal  which 
is  carried  up  by  the  blast  from  the  surface  of  the  foaming 
bath  falls  back  again  before  reaching  the  nose;  indeed, 
even  some  of  that  which  issues  from  the  nose  may  fall 
back,  for  the  name  passes  vertically  from  the  nose  to  the 
hood.  This  has  diminished  the  loss  of  iron  greatly; 
indeed,  many  metallurgists  think  that,  even  for  given 
volume,  the  concentric  vessels  slops  less  than  the  excen- 
tric one ;  but  why  this  should  be,  no  one  can  explain. 
With  our  large  vessels  the  loss,  including  that  in  remelt- 
ing  the  cast-iron  in  cupolas,  is  sometimes  repoted  as  below 
8%  for  a  month  at  a  time  ;  and,  when  direct-metal  is  used, 
the  loss  during  a  whole  year  has  been  reported  as  only 
1.5%. 

Still  a  third  expedient  is  to  remove  the  vessels  so  far 
from  the  casting-pit  that  the  cast-iron  can  be  brought  by 
an  overhead  elevated  track  running  between  them  and  the 
pit,  as  in  Forsyth's  plan  (Figures  168,  169).  In  this  way 
direct-  and  cupola-metal  are  brought  to  the  vessel  easily, 
while  it  is  turned  down  towards  the  pit.  But  even  in  this 
case  the  concentric  vessel  is  often  used  to  diminish  slop- 
ping. Perhaps  it  is  well  that  this  plan  was  not  worked 
out  till  after  after  the  advantages  of  the  concentric  vessel 
had  been  found  out. 

A  further  advantage  of  the  concentric  vessel  is  that  its 
lining  wears  ont  much  less  rapidly  than  that  of  the  excen- 
tric vessel,  as  explained  in  §  403. 

One  inconvenience  of  the  excentric  vessel,  which  has 
lost  some  precious  lives,  is  that  the  hood,  or  chimney  K 
(Figure  209),  must  stand  above  the  rear  of  the  vessel. 
Now,  this  is  just  above  where  the  vessel-men  must  stand 
while  examining  the  tuyeres  between  heats,  and  here  they 
are  threatened  with  the  masses  of  steel  sloppings  which 
hang  over  their  heads  on  the  walls  of  the  hood,  giving  to 
the  eye  little  indication  as  to  how  firmly  they  hang,  or 
when  they  may  fall.  It  has,  indeed,  been  found  desirable 
to  provide  swinging  platforms  or  awnings  to  shield  the 
vessel-men  from  these  falling  masses.  The  hood,  in  case 


of  concentric  vessels,  stands  directly  over  the  trunnion 
axis,  and  the  vessel-men  work  in  comparative  safety  when 
examining  bottoms. 

The  concentric  vessel  has  been  widely  adopted  by 
American  engineers,  but  it  seems  to  have  met  with 
relatively  little  favor  in  Europe. 

§  396.  SIZE  OF  VESSKL-NOSK. — A  small  nose  yields  a 
higher  working  temperature  within  the  vessel  for  two 
reasons.  First  the  radiation  of  heat  from  within  the  vessel 
is  less  ;  second,  by  checking  the  escape  of  the  products  of 
combustion,  it  leads  to  higher  pressure  within  the  vessel, 
and  thus  not  only  lessens  the  absorption  of  heat  due  to 
the  expansion  of  the  blast  as  it  emerges  from  the  tuyeres, 
but  also  lessens  the  degree  to  which  dissociation  occurs. 
At  Eston  a  four-foot  nose  was  contracted  to  two  feet,  and 
the  temperature  of  the  blow  is  said  to  have  increased 
plainly.  Similar  results  were  obtained  at  West  Cumber- 
land by  reducing  a  large  nose.6 

In  case  of  concentric  vessels  a  small  nose  has  a  further 
advantage,  in  increasing  the  quantity  of  molten  metal 
which  the  vessel  can  hold  when  "turned  down." 

It  is  thought  by  some  that,  with  the  broad  flame  which 
the  wide  nose  affords,  the  point  of  complete  decarburiza- 
tion  can  be  hit  more  accurately  than  if  the  nose  and  flame 
be  narrow.  Others,  however,  think  that,  if  the  blowing 
be  more  accurate  in  case  of  wide  noses,  it  is  because  the 
temperature  of  the  blow  is  somewhat  lower  than  if  the 
nose  be  narrow ;  the  cooler  the  heat  the  more  accurately 
may  the  point  of  complete  decarburization  be  hit. 

§  397.  DETAILS  OP  THE  CONSTRUCTION  OF  BESSEMF.R 
CONVERTERS. — To  fix  our  ideas  I  shall  describe  two  large 
vessels  (Figures  202  to  206)  lately  built,  and  designed  by 
distinguished  engineers. 

The  vessel  consists,  first,  of  the  iron  body,  and,  second, 
of  the  lining ;  the  preparation  of  the  latter  will  be  de- 
scribed in  §  402. 

As  the  region  around  the  tuyeres  (i.  e.,  in  bottom-blown 
vessels,  the  bottom)  wears  out  very  much  sooner  the  rest 
of  the  lining,  so  the  bottom  is  almost  universally  remov- 
able. The  necessity  of  this  is  seen  from  the  fact  that, 
while  a  bottom  lasts  on  an  average  from  twenty  to  thirty 
heats,  or  in  rapid  running  only  about  seven  hours  in- 
cluding the  intervals  between  heats,  the  rest  of  the  lining 
lasts  a  year  easily  in  the  best  American  and  European 
practice. 

The  iron-work  then  consists  of  the  body  and  of  a  re- 
movable bottom.  The  former  consists  of  the  trunnion- 
ring  A,  i.  e.,  that  part  to  which  the  trunnions  are  attached, 
and  which  carries  the  whole  weight  of  vessel,  lining  and 
charge ;  and  the  shell  proper  B  C.  The  shell  may  be 
made  as  in  Figure  202  in  a  single  riveted  piece,  or  as  in 
Figure  204  it  may  be  in  two  pieces,  a  cylinder  B  and  a 
coneC,  bolted  together. 

The  trunnions  themselves,  D,  are  very  heavy  castings, 
preferably  of  steel.  An  excellent  form  is  shown  in  Figure 
204.  One  of  them  must  be  hollow,  and  conducts  the  blast 
through  the  goose-neck  E  to  the  tuyere  box  F.  In  Figure 
202  the  blast  passes  to  the  goose-neck  through  a  space 
cored  in  the  trunnion-ring.  In  Figures  204  to  206  the 
goose-neck  is  carefully  shrunk  directly  upon  the  trunnion 
itself.  Instead  of  coring  a  single  large  hole  in  the  un- 

Pr*.  Rept.,7880,  II.,  p.  12 ;  1881,  I.,  P-  58. 


340 


THE    METALLURGY    OF    STEEL. 


The  bliell  itself  is  of  heavy  wrought-  or  ingot- 
iron  plates.  In  Figure  202  the  middle  of  the 
shell  is  of  two  plates,  I"  and  f "  thick  respective- 
ly, the  upper  part  being  of  a  single  1"  plate. 
In  Figure  204  the  middle  of  the  shell  is  made 
of  two  plates,  each  1"  thick.  In  another  vessel 
lately  built,  with  a  capacity  of  ten  tons,  the 
middle  of  the  shell  is  1"  thick  for  three  feet  of 
its  length,  and  only  \"  thick  beyond  this, 
and  is  strengthened  with  wrought-iron  bands, 
1" x 12". 

The  method  of  attaching  the  shell  proper  to 
the  trunnion-ring  is  important.  Formerly  the 
trunnion-ring  was  part  of  the  shell  proper,  but 
in  later  vessels  it  is  a  distinct  piece,  separated 
from  the  shell  itself  by  an  air-space,  which  in 
great  measure  prevents  the  heat  and  expansion 
of  the  shell  from  heating  the  trunnions  and 
shifting  their  position. 

As  the  shell  grows  much  hotter  than  the 
trunnion-ring,  so  these  two  parts  should  be  so 
attached  that,  while  the  shell  is  held  firmly, 
each  is  free  to  expand  and  contract  indepen- 
dently. This  is  effected  in  the  vessel  shown  in 
Figure  202  by  hanging  the  shell,  by  means  of 
stout  cast-iron  brackets,  upon  the  upper  edge 
of  the  trunnion-ring.  This,  of  course,  only 
holds  the  vessel  as  long  as  it  is  upright.  When 
it  is  inverted  it  hangs  from  the  trunnion-ring, 
resting  on  the  keys  I,  which  in  Figure  202  are 
at  the  lower  end  of  the  bolts  J.  The  whole 
weight  of  the  vessel  is  now  borne  by  these  bolts, 


Fig.  iOl.    10-Ton  CONVERTER  WITH  REMOVABLE  SHELL,  NORTH  CHICAGO  STEEL  Co. 


der  side  of  the  trunnion  to  admit 
the  blast  to  the  goose-neck,  the 
blast  may  be  taken  off  through 
a  number  of  radial  slots,  as  in 
Figure  206,  and  gathered  by  a 
heart-shaped  box,  with  wings  G 
designed  to  prevent  the  different 
bodies  of  blast  from  interfering 
v  ith  each  other.  This  trunnion 
is  cast  solid,  and  then  bored  out ; 
it  is  an  expensive  one,  but  it 
should  be  very  strong  for  its 
weight,  and  relatively  free  from 
internal  stress. 

To  the  other  trunnion  the 
shrouded  cast  -  iron,  or  better 
cast-steel,  pinion  (Figure  209), 
which  rotates  the  vessel,  is 
keyed. 

The  trunnion- ring  A  was  for- 
merly a  very  heavy  iron  casting, 
stoutly  ribbed,  and  bolted  firmly 
to  the  trunnions.     In  some  ves- 
sels lately  built,  however,  as  in 
Figures  204  and  205,  it  is  of  heavy 
wrought-  or  ingot-iron  plate,  say  £ 
H  or  2  inches  thick,  with  flanges  «• 
at  either  end.  v- 


L. 


Tnmnion-ring. 

Main  shell. 

Upper  part  of  shell. 

Trunnions. 
K.     Goose-neck. 
P.     Tuyere-box. 

G.    Wings fordivertingaircurrente. 
I.,I.  Keys. 

J.     Key-bolts  attaching  vessel  to 
trunnion-ring. 

Brackets  lor  removing  shell. 


False  plate. 

Tuyeres. 

Keys  bo  (ting  lid  of  tuyere-box. 

Key-bolt  holding  bottom. 

Key-link  holding  bottom. 


I 
Fig.  y>U.    12  TO  15-Tos  CONVERTER— VERTICAL  SECTION. 


HOLLETS    S  HELL-SHI  PTIWJ    DEVICE. 


847 


J.  At  the  same  tim^a  series  of  stout  radial  set  screws 
supports  the  vessel  when  it  is  inclined.  Here  the  shell  is 
clearly  free  to  expand  and  contract  longitudinally,  simply 
sliding  past  the  points  of  the  set-screws.  And,  since 
these  set-screws  need  not  s°'e  to  &&-  202  to  206  i«ei"iw. 

_  A.  Trunnion-ring. 

bind  the  shell  tightly  when  "  M;;°boilJ'or 
it    is    cold,    a   considerable  £. 

*  i  •    i  •  F.    i  uyere-Do: 

amount  of  radial  expansion  o.  vanes  to  K 

1  I.    I'Keysfasi 

may  also  occur,  the  set- 
screws  simply  denting  the 
shell  slightly.  Indeed,  there 
might  be  a  little  play  between 
shell  and  set- screws  when 
the  vessel  is  cold.  This  is 
especially  true  of  eccentric 
vessels,  for  the  set-screws  on 
their  rear  sides  are  never 
called  on  to  support  much 
weight. 

In  the  vessel 
shown  in  Figures  — 
204  and  205,  two 
sets  of  cast-iron 
brackets,  one  above  and  one 
below,  bolted  together  by  the 
bolts,  J,  attach  the  shell  to 
the  trunnion-ring.  But  here 
we  have  no  means  of  com- 
pensating for  the  difference 
in  expansion  between  the 
shell  and  the  trunnion-ring, 
and  in  many  cases  this  mode 
of  hanging  has  given  much 
trouble.  Either  the  bolts, 
J,  or  the  brackets,  K,  break. 
Indeed,  in  many  vessels  these 
brackets  have  purposely 
been  of  wrought- iron  or 
steel,  so  that  they  might 
bend  rather  than  break,  and 
there  they  stand  all  bent 
out  of  shape. 

Holley' s  Shell-  shifting  De- 
vice.— The  cast-iron  brack- 
ets, LL,  Figure  202,  are  to 
enable  us  to  remove  the  ves- 
sel-shell by  Holley' s  method, 
shown  in  Figure  207,  so  that 
we  may  carry  it  to  the  re- 
pair-shop, and  immediately 
replace  it  with  a  newly-lined 
shell,  whose  lining  may  be 
preheated.*  In  the  basic 
Bessemer  process  the  appar- 
ently unavoidably  rapid  de- 
struction of  the  shell  lining 
must  greatly  lessen  the  out- 
put, unless  we  are  prepared 
to  replace  the  worn-  out  lin- 
ing rapidly.  This  is  nearly  as  essential  to  large  output  in 
the  basic  process  as  quick  changing  of  bottoms  is  in  the 
acid  process. 


T.    Kcy-ltolta    for    fastening 

bottom  to  shell. 
C\U.  Links  for  fastening  bottom 


bbttom  to  sh<-ii.        "  repair-shop,    e. 


»  See  Holley,  Trans.  Am.  Soc.  Mech.  Eng.,  I.,  10th  paper,  1880. 


The  vessel  is  inverted,  and  a  heavy  car  standing  on  the 
bottom-jack  J  (Q  in  Figure  163)  is  raised  so  as  to  sustain 
the  shell  through  these  brackets,  L.  The  keys  I  (Figure 
202),  are  then  drawn,  thus  releasing  the  shell  from  the 

I,.   Brackets    for  supporting   fmnnirm   Tinrr      A          T1)!*}    V»/-»f 
shell  when  removed  by    "UliniOn-ring,    A.        1U6 

N.  Lid0oftyuyepnM;o*.         torn-jack  is  lowered  till  the 

O.  Tuyere-plate. 

Kate.  shell  is  wholly  tree  from  the 

^JSJSST*  "d  to  trunnion-ring,  when  car  and 

S.     Joint  between  shell  and     in  *     i  ,  i 

bottom.  shell  are  carried  away  to  the 

ff.,   by    the 
track  Bt,  Figure  168. 

The  extra  cost  for  instal- 
lation for  this  admirable  ar- 
rangement   is    not    severe. 
The  hydraulic  jacks  beneath 
the  vessels  must  be  strong 
enough  to  lift  not  merely 
the  bottom,   but   the   shell 
and  lining:  and  a 
few  strong  cars  are 
needed.  The  strong 
bottom  -  jacks  are 
useful  for  another 
purpose :  they  enable  us  to 
squeeze  the   joint    between 
the  linings  of  shell  and  bot- 
tom just  so  much  the  tighter, 
and  thus  to  guard  the  better 
against  leakage. 

The  plan  is  obviously  in- 
comparably better  than  that 
ii—  of  carrying  away  for  repairs 
not  only  the  shell,  to  whose 
lining  alone  repairs  are  need- 
ed, but  also  the  exceedingly 
heavy  trunnion  -  ring  and 
trunnions,  by  means  of  an 
over  -  head  traveling  -  crane. 
First,  the  cost  of  such  a 
crane,  strong  enough  to  lift 
the  shell  and  trunnions,  and 
installed  at  such  a  height,  is 
great.  Next,  its  motions  are 
relatively  slow  and  clumsy, 
while  nothing  could  be  sim- 
pler than  the  plain  up  and 
down  stroke  of  the  hydraulic 
bottom-jack.  Then  vessel 
and  trunnions  must  be  coax- 
ed into  place  while  swinging 
from  chains,  steadied,  guid- 
ed, and  lowered  little  by 
little  ;  the  bottom  car,  how- 
ever, brings  the  shell  exactly 
under  its  place  in  the  trun- 
nion-ring, and  a  single  stroke 
HOST'S  VBSSBL-  of  the  bottom-jack  sets  it  in 
DBTIOB.  place,  to  be  merely  keyed 
on.  Again,  removing  the 

whole  vessel  implies  duplicating  or  triplicating  the  costly 
trunnion-ring,  trunnions  and  pinion.  Finally,  breaking 
and  making  the  blast-pipe  connections  with  the  trunnions 
must  waste  some  time. 


84P 


THE    METALLURGY    OP    STEEL. 


Justice11  very  slightly  lessens  the  difficulties  just  men- 
tioned by  splitting  the  trunnion  ring,  so  that  when  the 
vessel  is  turned  horizontally,  it,  together  with  the  then 
lower  half  of  the  trunnion-ring,  may  be  lowered  upon  a 
car  standing  beneath,  and  carried  off  for  repairs.  But 
then  the  vessel  cannot  be  relined  conveniently  while  thus 
lying  on  its  side. 

The  Trunnion-axis  may  pass  through  the  centre  of 
gravity  of  the  iron-work  and  lining  of  the  vessel,  bottom 
included  ;  but  it  is  probably  better  that  it  should  pass 
rather  below  this  point,  so  that  the  vessel  may  be  slightly 
top-heavy  when  empty,  for  the  following  reason.  We 
need  the  greatest  rapidity  of  motion  when  turning  the 
vessel  down  after  the  blow,  for,  until  we  have  swung  it 
somewhere  about  30°,  all  the  tuyeres  are  still  submerged, 
and  all  the  blast  is  still  passing  through  the  molten 
metal  and  burning  iron.  But  at  this  time,  as  all  the 
metal  is  at  the  bottom  of  the  vessel,  we  have  not  only  to 
overcome  the  inertia  of  the  vessel  and  bath,  but  to  lift  the 
bath  itself.  And  now,  when  we  most  need  quick  motion, 
the  top-heaviness  of  our  vessel  itself  comes  to  our  assist- 
ance, and  helps  us  turn  down.  Many  vessels  have  a 
massive  hook  on  their  breasts,  to  which  heavy  weights  can 
De  attached  during  the  last  part  of  the  week,  when  the 
corrosion  of  the  lining  of  the  breast  has  lowered  the 
vessel's  centre  of  gravity. 

§  398.  THE  BOTTOM.— In  the  bottom  itself  we  have, 
besides  the  tuyeres  and  the  refractory  matrix  which  we 
will  consider  in  §  404,  the  tuyere-box,  F,  (Figures  202-4), 
which  receives  the  blast  from  the  goose-neck  and  dis- 
tributes it  to  the  butt-ends  of  the  tuyeres. 

The  lid,  N,  which  covers  it,  must  be  large,  quickly 
removable,  and  very  tightly  fitting  ;  large,  that  the  ends 
of  all  the  tuyeres  may  be  easily  accessible  for  examination 
and  removal ;  quickly  removable,  that  no  time  need  be 
lost  in  examining  the  tuyeres  between  heats  ;  and  tightly 
fitting  lest  the  blast  be  wasted.  The  importance  of  having 
it  fit  tightly  is  clear  when  we  remember  the  length  of 
the  joint  between  lid  and  tuyere  box,  about  17  running 
feet  in  the  case  before  us.  These  requirements  are  fully 
met  by  fastening  the  lid  with  many  keys,  R,  and  by 
facing  it  and  the  edge  of  the  tuyere-box  accurately,  or 
even  cutting  in  them  a  tongue  and  groove,  as  in  Figure 
202.  In  some  cases  the  joint  has  been  part  of  the  surface 
of  a  sphere  of  long  radius. 

Though  no  gasket  of  any  kind  is  provided,  this  joint 
leaves  nothing  to  be  desired.  Though  many  bottoms  are 
provided  for  each  vessel,  so  that  each  may  be  long  and 
carefully  dried,  one  lid  only  is  needed.  Of  course  there 
should  be  a  second  lid  in  reserve,  lest  an  injury  to  that  in 
use  paralyze  the  establishment. 

A  light  crane,  P,  Figure  209,  serves  for  handling  the 
bottom-lid  for  inspection  between  heats,  the  vessel  then 
standing  turned  down,  as  shown  in  dotted  lines. 

The  tuyere-plate,  O,  has  round  openings  which  receive 
the  butts  of  the  tuyeres,  and  which  are  grooved  (Figure 
204)  so  as  to  make  a  tight  joint  with  the  luting  with  which 
the  tuyere-butts  are  coated  before  they  are  inserted.  The 
tuyeres  are  held  in  place,  during  the  ramming  of  the 
bottom-lining,  by  dogs,  clamps  or  screws  of  various 
designs,  the  important  point  being  that  they  shall  be 
quickly  removable.  In  case  of  acid  (silicious)  linings,  the 


h  Wedding,  der  Basische  Bessemer  oder  Thomas-Process,  p.  80, 1884. 


tuyeres  are  bound  so  firmly  by  the  lining  rammed  around 
them  that  these  dogs  are  not  needed  after  the  bottom  is 
rammed.  In  some  cases,  as  in  Figure  193,  a  sort  of  staple 
projects  from  the  tuyere-plate  on  either  side  of  each 
tuyere  ;  a  stick  of  wood  or  an  iron  rod  is  held  by  these 
staples  across  and  tightly  against  the  butt-end  of  each 
tuyere,  during  the  ramming  of  the  bottom-lining,  and  is 
then  knocked  out,  leaving  the  tuyere-end  free  for  ex- 
amination. 

By  means  of  the  false  plate,  P,  an  air-space  which  com- 
municates with  the  outer  air  is  left  between  tuyere-box 
and  bottom  lining,  for  two  purposes.  First,  if  the  joint 
between  the  tuyere-plate  and  one  of  the  tuyeres  be 
imperfect,  the  blast  which  works  through  simply  escapes 
into  the  outer  air,  instead  of  cutting  between  the  neces- 
sarily rather  loose  bottom-lining  and  the  tuyere  a  ragged 
channel,  and  thus  quickly  destroying  the  bottom.  2nd, 
should  a  tuyere  wear  too  short  during  a  heat,  the  molten 
metal,  instead  of  cutting  through  and  filling  up  the 
tuyere-box,  goes  spitting  out  through  this  air-space  into  the 
outer  air.  The  pyrotechnic  effect  of  the  escape  of  the  first 
little  portion  of  metal  in  this  way  is  so  striking,  that  the 
stage-boy  in  charge  sees  it  at  once  and  turns  the  vessel 
down  before  any  harm  is  done.  The  lid  or  bottom-plate, 
N,  is  removed,  the  short  tuyere  knocked  out,  its  hole 
rammed  full  of  "ball-stuff"  (plastic  clay  -balls),  and  the 
blowing  is  resumed  with  but  a  few  minutes  delay. 

The  sharp  swift  sparks,  due  to  this  escape  of  metal 
between  bottom  and  tuyere-box,  are  readily  distinguished 
from  the  slow  droppings  of  white-hot  metal  due  to  leak- 
age through  the  joints,  between  the  lining  of  the  shell  and 
that  of  the  bottom,  Figures  202-204.  Such  a  leak  can 
usually  be  stopped  by  raising  it  about  the  surface  of  the 
metal  by  rotating  the  vessel,  chilling  it  if  need  be  from 
without  with  the  hose. 

The  bottom  must  be  so  attached  to  the  shell  of  the  vessel 
that  it  can  be  quickly  and  easily  removed  and  re-attached. 
To  that  end  it  is  almost  always  keyed 
on.  Figures  202  and  209  show  key-bolts, 
T,  riveted  to  the  shell,  which  pass  through 
eyes  on  brackets  on  the  bottom.  While 
it  is  not  likely  that  the  shell  can  warp 
so  much  that  these  bolts  would  not  enter 
their  eyes  readily,  yet  it  may  be  well  to 
avoid  this  danger  wholly  by  using  simple 
key-links,  such  as  U  in  Figure  205.  But 
others  again  object  to  these  links  on  the  Fia'  m'  n°LLKT'8  Ex- 

C  J  TEKNALLY        RAMMED 

ground  that  when  the  bottom  is  removed 

and  the  vessel  is  turned  over,  they  faU 

off,  or  at  least  require  attention.      An-  %£$»£££ 

other  good  form  of  link  (W.  B.  Jones'  design)  is  shown 

in  Figure  208. 


BOTTOM-JOINT. 

iJjJL  tffuS 

to 


8hell> 


TABLE  197—  TOTAL  AREA  OP  TUYERE-HOLES  IN  SQUARE  INCHES  PER  TON 
OF  CAPACITY  OF  VESSEL. 

American,  present  .......................................  from  1.16  to    5.95 

M      6.1    to  12. 
n      0.8    to    1.83 
11      3.18  to    3.44 

3.73 
.  ............          2.1    to    1.6 


Swedish,  1885 

German,  1871 

British,     it 

Obonchoff 

England  and  Belgium,  1877 


§  399.  THE  SIZE  OF  THE  TUYEKE-OPENTNGS  still  varies 
greatly.  I  condense  Table  197  from  the  detailed  data  in 
Tables  196  and  198.  It  is  at  first  very  surprising  that,  as 
happens  in  some  works,  all  the  blast  delivered  by  two 
54-inch  blast-pistons  running  at  full  speed  should  be 
squeezed  through  a  lot  of  f-inch  holes,  whose  collective 


THE    BOTATING    MECHANISM.     |  400. 


840 


area  is  less  than  tliat  of  a  four-inch  pipe.  One  would 
suppose  that  the  consumption  of  power  which  this 
implies  must  be  very  considerable  ;  yet  it  is  hard  to 
conceive  any  other  arrangement  by  which  we  can  have 
rapid  and  uniform  blowing,  without  excessive  loss  of  iron 
or  excessive  destruction  of  the  bottoms.  But  as  the  total 
consumption  of  fuel  under  the  con  verting- works'  boilers 
is  onl}'  300  pounds  and  in  some  works  only  200  pounds  of 
coal  per  ton  of  ingots,  and  as  a  considerable  part  of  this 
is  chargeable  to  blowing  the  cupolas  and  to  the  movements 
of  the  cranes,  hoists,  etc.,  we  can  hardly  charge  more 
than  14  cents  per  ton  of  ingots  for  blowing-power,  where 
fuel  is  of  moderate  price.  Indeed,  in  some  mills  the  fuel 
for  generating  the  blast  probably  does  not  cost  more  than 
five  cents  per  ton  of  ingots.  An  I  this,  too,  without  com- 
pound engines  and  with  but  moderate  expansion. 

TABLE  198.— SIZE  OF  TITTERS-HOLES.    (SEE  ALSO  TABLE  197.) 


Authority. 

Name  of 
Works. 

Capacity 
of  the 
Converter 
in  Tons. 

Number  of 
Openings 

in  the 
Tuyeres. 

Diameter 
of  the 
Openings 
in  Inches 

Total  Area 
of  the 
Openings 
in  Sq. 
InchfB. 

Area  of  the 
Openings  in 
Sq.  Inches 
per  Ton. 

Konigshutte... 

3 

49 

J4 

2.40 

0.80 

Neillierg  

3 

49 

L£ 

4.27 

1.43 

1.  Drown  .  . 

/wickati 

3 
2 

42 

42 

A 

5.12 
3.68 

1  71 
1.83 

Heft  

Crewe  

5 

144 

% 

u.n 

3  18 

Dowlait*.     . 

S 

I'lO 

yt/ 

17.22 

3.44 

Zeltwe" 

5 

58 

2 

11  02 

2  20 

n 

5 

84 

i% 

14.70 

2.94 

Obouchofl  

5 

189 

n 

18.  63 

3.73 

.    !„„,„,,      1  i  England  &  liel- 
3.  Jordan...^  <,,„,„  abont  1877 
d    TT  ll          j  Brown,     Bay  ley 

5  to  7 

77 

12 

10.5 

2.1  to  1.5 

Jiiey...-j  iam]  j)ixon    18rv( 

8 

195 

A 

15 

1.87 

S.  Holley...  | 

Another  British 
Mill,  1881  

8 

208 

M 

23 

2.87 

1.  Drown,  Trans.  Am.  Innl.  MID.  Eng.,  I.,  p.  88,  1871. 

3.  Jordan,  Jeans,  Steel,  p.  370,  from  Albirn  da  (Joure  de  Mctallursjie,  18T7. 


§  400.  The  ROTATING  MKCIIANISM  (Figure  20'J), 
almost  always  consists  of  a  heavily  shrouded  pinion, 
preferably  of  steel,  keyed  to  one  of  the  trunnions  (B) 
of  the  vessel,  and  driven  by  a  rack,  which  is  keyed  to 
the  end  of  the  piston-rod  of  a  powerful  hydraulic 
cylinder  (D).  Eccentric  vessels  should  be  able  to  turn 
through  an  arc  of  270°  ;  concentric  vessels — at  least 
those  which  receive  the  charge  when  turned  down 
away  from  the  pit. — should  turn  rather  farther, 
say  300°. 

At  first  placed  horizontally,  so  as  to  be  accessible, 
the  hydraulic  cylinders  were  next  set  vertically  to 
save  floor-room,  and  beneath  the  trunnions  to  secure 
easy  foundations.  In  this  position  it  was  found 
hard  to  give  the  cylinder  sufficient  length,  without 
carrying  it  to  a  depth  inconvenient  to  drain.  Of 
course,  the  longer  its  stroke  the  larger  could  be  the 
radius  of  the  pinion,  and  the  lighter  therefore  the 
stress  on  the  rack.  Accordingly  the  cylinder  was  next 
placed  above  the  trunnion — standing  vertically.  Here  it 
could  have  whatever  length  was  needed. 

The  position  finally  adopted,  however,  is  that  shown  in 
Figure  209.  The  cylinder  lies  horizontally  beneath  the 
platform  at  the  trunnion-level.  It  is  thus  wholly  out  of 
the  way,  while  the  platform  prevents  rubbish  from  falling 
between  the  teeth  of  the  rack.  It  is  better,  however,  to 
protect  the  rack  and  pinion  further  with  sheet-iron  cases, 
for  even  a  small  lump  of  metal  lodged  between  the  rack's 
teeth  might  lead  to  a  serious  or,  indeed,  a  fatal  accident"1.  I 


have  known  a  vessel  to  be  overturned,  emptying  its  whole 
charge  into  the  pit.  from  such  an  accident. 

The  ports  of  the  hydraulic  cylinder,  shown  beneath  in 
Figure  209,  should  be  above  the  cylinder,  so  that  the 
breakage  of  a  pipe  may  not  allow  the  water  to  leak  out  of 
either  end  of  the  cylinder.  To  make  this  clear,  suppose 
that  the  vessel-bottom  has  been  removed  so  that  the  ves- 
sel is  top-^eavy  ;  that  the  piston  has  been  moved  to  the 
right-hand  end  of  the  cylinder,  so  that  the  vessel's  nose  is 
turned  down  to  the  left  ;  that  the  pipe  leading  the  water 
to  the  left-hand  end  of  the  cylinder  has  burst  or  broken, 
and  that  the  water  has  run  out.  Now  the  stage-bo}', 
ignorant  of  what  has  happened,  turns  the  vessel  over  to 
the  right  by  admitting  water  to  the  right-hand  end  of  the 
cylinder.  The  moment  that  the  center  of  gravity  of  the 


rotating 


A.  Ladle  for  cast-Iron. 

B.  Trunnion. 

D.  Cylinder      for 

vessel. 
J.   Runner 
K.  Hood  or  chimney. 
M.  Foundation  of  hydraulic 

lift  for  cast-lion  laitlr. 
N.  Foundation    of    column 

supporting  vessel. 
P.  Hand-cram'  for  ranov.nc 

lid  of  tuyere-box. 


d  Some  have  recommended  placing  the  rack  and  cylinder  horizontally,  but  so  that 
the  rack  would  be  above,  instead  of  below  the  pinion,  in  order  that  lumps  of  metal 
and  splashings  might  not  lodge  between  iU  teeth.  Here,  however,  rack  and  cylinder 
would  be  badly  in  the  way,  and  enclosing  tliem  iu  sheet- irou  cases  protects  them  fully. 


Kg.  t09.    BETHLEHEM  VESSEL,  WITH  ROTATING  MECHANISM.    HOLLET. 

vessel  passes  to  the  right  of  the  trunnion  axes,  the  top- 
heavy  vessel  turns  down  with  a  rush,  as  there  is  no  water 
in  the  left-hand  end  of  the  cylindefto  oppose  its  motion, 
and  drives  the  piston  through  the  end  of  the  cylinder  or 
breaks  the  rack.  This  has  happened  repeatedly. 

The  disadvantage  of  the  rack-and-pinion  arrangement 
is  that,  however  long  the  cylinder  and  rack,  the  vessel  can 
only  turn  a  certain  number  of  degrees  in  one  direction,  be 
that  number  270°,  or  360°,  or  720°.  Now,  it  may  happen 
that,  when  the  vessel  is  inverted,  it  would  be  a  little  more 
convenient  to  turn  it  90°  farther  away  from  the  pit  to 
receive  a  charge  of  iron  on  the  rear  side,  than  to  turn  it 
back  270°  to  reach  this  same  position.  Practically,  this 
disadvantage  is  of  little  moment ;  but  to  avoid  it  the  ves- 


350 


THE    METALLURGY    OF    STEEL. 


sel  is  sometimes  rotated  by  a  worm  and  worm-wheel,  in 
which  case  it  can,  of  course,  turn  indefinitely  in  either 
direction.  The  worm  is  probably  best  driven  by  two  or 
three  hydraulic  engines.  While  no  serious  objection  can 
be  made  to  such  a  design,  probably  the  great  majority  of 
engineers  prefer  the  simpler  and  wholly  satisfactory  rack 
and  pinion. 


a.  Wing-piston. 

b.  Trunnion. 

c.  Fixed     abutment 

cylinder. 


fig.  tlO. 


Durfee*  would  rotate  the  vessel  by  means  of  a  wing- 
piston,  a,  (Figure  210),  keyed  directly  to  the  vessel  trunnion 
b,  and  turning  nearly  360°  in  a  cylinder  concentric  with  the 
trunnion.  In  this  cylinder  is  a  fixed  abutment  c,  which 
takes  the  place  of  both  heads  of  a  common  cylinder. 
Water  admitted  on  either  side  of  this  abutment  drives 
the  wing-piston  in  the  desired  direction.  The  attachment 
is  certainly  more  direct  than  in  the  rack-and-pinion 
arrangement,  and  there  should  be  a  saving  in  power  as 
well  as  in  cost  of  installation. 

§  401.  THE  JOINT  BETWEEN  THE  LINING  OF  THE  SHELL 
AND  THAT  OF  THE  BOTTOM. — In  early  practice,  as  soon  as 
the  bottom  was  worn  out  the  stumps  of  the  old  tuyeres 
were  knocked  out,  new  tuyeres  inserted,  and  the  space 
between  them  filled  by  pouring  "slurry"  (a  semi-fluid 
mixture  of  fire-clay,  quartz  or  ganister, and  water),  through 
the  vessel's  nose,  and  allowing  it  to  set  around  them.  Of 
course  blowing  was  interrupted  during  the  long  time 
needed  for  drying  this  bottom,  which,  moreover, was  most 
untrustworthy,  flaky,  inadherent  and  full  of  drying 
cracks.  Another  way  was  to  allow  the  vessel  to  cool,  and 
then  make  up  the  bottom  from  within  by  ramming  "ball- 
stuff"  (a  stiff,  slightly  plastic  mixture  of  clay  and 
quartz)  around  the  tuyeres  ;  or  better  by  placing  a  pre- 
viously baked  bottom  within  the  vessel,  and  then  ram- 
ming ball-stuff  into  the  joint  from  within  the  vessel.  But 
here,  too,  great  delay  arose,  since  for  twelve  or  even 
twenty-four  hours  after  blowing,  the  vessel  was  still  too 
hot  to  enter.  Cooling  was  sometimes  hastened  by  re- 
moving the  vessel's  nose,  but  then  this  had  to  be  replaced, 
and  the  joint  thus  made  had  to  be  rammed  :  or  by  pour- 
ing water  into  the  vessel,  a  practice  which  injured  the 
lining  greatly. * 


e  Trans.     American  Institute  of  Mining  Engineers,  XII.,  p.  271,  1884. 

x  Even  as  lately  as  1879  bottom-joints  were  made  in  some  British  works  by  pour- 
ing slurry  through  the  vessel-nose,  so  that  it  ran  between  the  shell-lining  and  a 
previously  baked  bottom.  Setting  a  bottom  in  this  way  took  five  hours,  and  the 
bottom  itself,  soaked  and  weakened  by  the  slurry,  lasted  but  seven  heats  (Holley, 
Priv.  Kept.,  1880,  No.  2,  p.  30). 


It  is  strange  that  Holley  and  Pearse's  simple  expedient, 
of  ramming  the  joint  between  a  previously  baked  bottom 
and  the  vessel  lining  from  without,  was  not  earlier  thought 
of."  This,  as  improved  by  Holley, b  Figure  211,  lasted  till 
lately,  and  is  in  use  in  some  mills  even  now.  The  iron- 
work of  the  bottom  was  so  shaped  that,  between  the 
brackets  by  which  it  was  keyed  to  the  shell,  lumps  of 


Fly.  Sll.    IIOLLEY'S  EXTBKNALLT  RAMMED  BOTTOM-JOINT— OLD  STYLE. 

ball-stuff  could  be  inserted  and  rammed.  The  bottom 
was  first  keyed  on  while  the  vessel  stood  upright.  The 
vessel  was  then  turned  on  its  side,  and  the  balls  were 
rammed  in  as  shown  in  Figure  211.  The  vessel  was  then 
turned  up  again,  and  a  few  pailf uls  of  slurry  were  poured 
through  its  nose  to  fill  any  cracks  in  the  ball-stuff  joint. 

In  later  practice,  in  the  few  cases  in  which  this  form  of 
bottom  is  used,  the  vessel  is  held  upright  until  a  single 
row  of  clay  balls  has  been  rammed  between  the  upper 
edge  of  the  bottom  and  the  shell-lining,  and  is  then  turned 
on  its  side  for  ramming  the  rest  of  the  joint.  This  is 
done  lest  the  bottom  break  apart  by  its  own  weight  when 
the  vessel  is  turned  on  its  side. 

A  later  form  of  the  joint  is  shown  in  Figure  208.  This 
joint  is  rammed  from  the  pit  level  while  the  vessel 
stands  upright.  There  is  evidently  less  danger  of  tearing 
the  shell-lining  of  the  vessel  in  breaking  this  flat  joint, 
than  in  pulling  out  the  conical,  tightly  wedged  bottom  of 
Figure  211.  I  am  informed  that  this  form  of  joint  is  very 
frequently  used  in  Europe. 

The  dish-bottom,  Figures  202-204,  is  the  form  now  gen- 
erally used  here.  Its  upper  service  is  level.  Thejoii.tia 
made  by  spreading  on  the  upper  side  of  the  bottom  a  ring 
or  "noodle"  of  ball-stuff,  covering  this  with  a  little 
graphite,  and  squeezing  the  bottom  tightly  against  the 
shell-lining  by  means  of  the  bottom-jack.  The  graphite 
preserves  a  good  parting,  so  that  the  bottom,  when  worn 
out,  may  be  removed  without  tearing  away  the  lining  of 
the  shell,  instead  leaving  it  so  smooth  that  a  sound 
joint  is  easily  made  with  the  next  bottom.  The  powerful 
bottom-jacks  in  some  recently  built  works  exert  a  press- 
ure of  about  2,000  pounds  per  foot  on  the  joint,  which 
thus  made  never  leaks.  In  some  works  which  have 
neither  bottom-jacks  nor  hydraulic  bottom-car,  the  vessel 
is  inverted,  a  ring  of  ball-stuff  set  on  the  edge  of  the 
shell-lining,  the  bottom  placed  on  this  by  means  of  a 
crane,  and  merely  keyed  tightly.  Even  this  uncom- 
pressed joint  serves  admirably. 

As  stated  in  §  376,  2,  the  total  time  between  blows  of  a 


a  U.  S.  Patent  86,304,  Jan.  26,  1869,  A.  L.  Holley  and  J.  B.  Pearse. 
b  U.  S.  Patent  106,162,  Aug.  9,  1870,  A.  L.  Holley. 


THE    VESSEL-LININGS.     §  402. 


351 


single  vessel,  including  changing  bottoms,  has  been  as 
short  as  17  minutes  at  the  Union  (Illinois)  works. 

§  402.  THE  VESSEL-LININGS  are  usually  monolithic,  a 
mass  of  clay  and  quartz  rammed  solidly  together  and 
thoroughly  dried  :  some  vessels,  however,  are  lined  with 
blocks  of  stone,  which  give  good  results,  but  so  far  as  my 
observation  goes  do  not  last  so  long  as  the  monolithic 
lining.  In  either  case  the  vessel  stands  inverted  and 
without  its  bottom  during  re-lining. 

The  monolithic  lining  is  usually  made  of  a  mixture  of 


was  rammed  around  an  iron  core  set  within  the  vessel,  by 
a  gang  of  eight  or  ten  men,  who  marched  slowly  in  the 
annulus  between  core  and  shell,  ramming  the  mixture 
with  butt-rammers  like  those  in  Figure  211,  a  few  shovel- 
fuls of  the  mixture  being  added  at  intervals. 

In  what  is  perhaps  the  most  successful  present  prac- 
tice (columns  17, 18  and  20,  Table  199),  the  mixture,  whose 
materials  (quartz,  sand  and  clay)  are  finely  ground  to- 
gether, has  so  much  water  that  it  balls  readily,  and 
is  indeed  a  stiff,  decidedly  plastic  mass  or  "  ball-stuff." 


TABLE  199.— VESSEL  -LININGS  AND  BOTTOMS  (C'F.  TABLE  196). 


1872 

1 

1872 
2 

1871 
3 

1872 
4 

1872 
5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

6 
2  2 

•& 

6 

r* 

9 

1  25 

7H 

10 

1.45 

4 

ft 

9 

ef 

V 

20« 

18± 
W&W 

1-oS 

L1L 

}l|fe 

9@18 

y  so"  @  iy 

1     ~    :') 

m 

&%3 

iy 

66 

"l7" 
17 

,g.  Ground  : 
^  ganiwter.  : 

21  @  «'  45" 

*a  ao 

a"x 

.asg 

sss 

5 
3,400 

11'  10"-  ^  45" 

w 

B 
2 

13/  28"—  14'  55" 

sl>a 

ssl 

fi 

12 

COMPOSITION  op  VESSEL-LINING  :;Y  WEIGHT— 
Quartz,  #  
Fire-sand,  %  

53$ 
40 

e41}-f41J 

7H  g 
M» 

Loam-sand,  %  
Fat  clay,  %  

6} 

168 

28* 

Heats 

3,750 

18 

"& 

18@(25 
35.7 
dish. 

20 
S& 

& 

30.6 
i 

A 

dish. 

W 
lf.5 

I 

n* 

(lisli. 

Hollcy. 

COMPOSITION  OP  BOTTOM—  Fire  sand,  %  

37.5 

13)4 

*$     ( 

1 

i 

W 

3 

5 

« 

i 

• 

w? 

33 

U*> 

60 
'46 

40 
SOh 

Ion  i 

50 
1SH 

6fi§h 
3:lJ 

62«g 

Pi 

\M1 

40 

40 

O     V 

8®  10 

84 

24 

DURATION  OP  BOTTOM— 

14 

11.45 

25  @  30 

12®  16 
2H.35' 

13 
2h.36' 

19 

6h.  sy 

23 

8h.  23' 

24± 
4h.  47' 
38®  40 
7h.  34" 

16 
3h.  46'-8h.  32' 

•jii  ft  at; 

4  to  8 

usual,  j  'ptmc  collectively.  .. 

25 

22 

Maximum,  \  ftme  Coiie^hreiy.'.:  \ 

TABLE  199.— VESSEL  LININGS  AND  BOTTOMS.—  Concluded. 


16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

27 

Bangbro. 
H 

Avesta. 
29 

10 

6@7 

9.2 

10.73 

5.5 

7X 

7 

7 

11 

3.5 

2q 

2.7 

0.39 

1  25 

1  8 

1  4 

1.5 

1.6 

1.75 

2.0 

1.02 

1  4 

6' 

10 

10± 

& 

& 

10' 

4'  10" 

3M" 

1294 

13  7 

12i£ 

ISW 

13  @  14 

W  30'' 

16 

10®  11 

11'  30"—  13' 

10®  17 

13 

IV—  W  30" 

9'    13'.  5 

COMPOSITION  OF  VESSEL-LINING  BY  WEIGHT  — 

83  n 

grf 

88 

5  vol. 

16 

17 

S-g 

-i  «  o. 

a! 

=  §->- 

23 

17 

17 

53 

*il 

1  vol. 

12 

6 

2 

1  5@2 

4000@8800 

200@300 

20 

21  @25 

20 

20 

25 

17®  18 

](!(./   17 

\/n 

if 

&£ 

t/tf 

U  &A 

ajf 

4i 

M 

% 

.59 

.13 

159 

198 

29  4 

347 

252 

252 

19^1 

25^1 

22 

1.2 

Hoi    e 

dish. 

dish. 

Hol. 

i 

dish,  i. 

dish. 

dish. 

26 

8" 

12 

26 

12 

17 

20 

50 

25o 

55 

47 

17 

43 

41 

23 

50 

21 

27 

Calcined  olav,  %  

16m 

24  a—  14  b 

24 

48®  % 

48 

24  a  48 

24 

48 

12 

26 

10 

DURATION  OP  BOTTOM  — 

TTannl    j  HeatS  

14 

20.56 

11  ± 

22.  23 

20± 

15  @  17H 

20 

28 

15 

30®  120 

150 

7 

Janal,  ^  Time  conectively  .  .  .  . 
Maximum,  -j  "f^f  coiiecavely  '  ;  1  1 

'"25"' 

3h.  38 

2n.  56" 

H  h.  53" 

3h.  24' 
25 

5h.  14' 

6h.  IV 

52 

3  h. 

52  @  225 

a  TJnually. 

b  Occasionly. 

c  With  ball-staff,  pin-rammed  in  the  joints. 

e  Fine  Canister. 

f  Coarse  ganister. 

g  Chickius  rock,  fine. 


h  Canister. 

i  Like  Figure  212. 

j  Like  Fignre  213. 

1  Like  Figure  214. 

m  Coke-dnst. 

n  All  materials  ground  fine. 


0  Coarse. 

p  In  blocks. 

q  Clapp-Griffiths. 

Hol.  Holley  conical  bottom,  like  Figure  211. 

1  to  5,  F.arly  American. 
6.  British,  1875. 


7.  American,  1875. 
8  to  26,  Present  American. 
27.  U.  S.  Clapp-Grifflths. 
28-9.  Swedish,  about  1885. 


from  50  to  66  %  of  coarsely  crushed  quartz,  in  pieces  whose 
largest  dimension  is  not  over  two  inches,  and  from  17  to 
25  %  of  finely  pulverized  fat  fire-clay,  the  remainder  con- 
sisting of  some  finely  ground  silicious  material,  such  as 
old  fire  bricks,  fire-sand  or  loam  sand. 

No  more  fat  clay  is  used  than  is  needed  for  binding 
the  mass.  As  this  would  not  be  enough  to  fill  the  inter- 
stices between  the  large  lumps  of  crushed  quartz,  some 
finely  ground  silicious  substance  is  needed. 

Formerly  this  mixture,  only  very  slightly  moistened, 


This  is  spread  on  the  floor  in  a  thick  layer,  and  trodden 
under  foot,  but  not  under  bare  feet.  It  is  then  cut  up 
into  lumps,  which  a  man  standing  within  the  vessel 
throws  against  its  sides :  he  then  smooths  and  pats  them 
into  shape  with  a  wooden  mallet.  The  lining  thus  made 
is  dried  by  a  lire  within  the  vessel. 

A  ten-ton  vessel  has  been  lined  in  the  same  general  way 
in  seven  hours.  But  quick  and  hence  cheap  as  this  way 
of  lining  is,  it  is  so  effective  that  at  many  works  the  ves- 
sels are  relined  but  once  a  year,  during  which  each  may 


352 


THE    METALLURGY    OF    STEEL. 


make  14,000  heats,  or  some  140,000  tons,  so  that  the  cost  of 
reliuing  is  insignificant  when  reckoned  on  the  ton  of 
product. 

In  many  works,  however,  the  lining  must  be  patched 
every  week,  and  with  rapid  running  temporary  patching 
must  often  bs  applied  during  the  week. 

In  1872  linings  made  of  American  refractory  materials 
lasted  from  400  to  500  heats  :  the  best  British  materials 
gave  double  this  life,  or  about  one-fourteenth  the  life  of 
our  present  American  linings. 

The  linings  of  the  Alpine  Bessemer  vessels  last  200 
heats  of  30  minutes  each,  according  to  Ehrenwerth,  who 
estimated  that  the  Avesta  little-vessel  linings  would  last 
500  heats  of  10  minutes  each".  At  Eston  the  linings  are 


The  life  of  mica-schist  linings  has  been  as  long  as  five 
months,  in  which  3,400  heats,  or  34,000  tons  of  steel  were 
made  in  one  vessel.  I  am  informed  that,  at  another 
American  mill,  stone  blocks  have  lasted  a  year  ;  in  this 
case  they  .were  laid  dry,  and  ball-stuff  was  rammed  care- 
fully between  their  joints. 

In  other  cases  the  blocks  of  mica-schist  are  laid  in 
thin  mortar.  They  are  usually  about  one  to  two  inches 
thick,  and  are  laid  with  their  cleavage  horizontal :  but  at 
either  end  of  the  shell  a  ring  of  these  blocks  or  slabs  is 
laid  with  their  cleavage  vertical,  apparently  so  that  the 
ends  of  the  lining  may  be  thus  tightly  wedged  into 
place. 

Blocks  of  mill-stone  grit,  roughly  shaped  to  the  circle 


TABLE  300.— ULTIMATE  COMPOSITION  OP  REFRACTORY  MATERIALS  AND  MIXTURES  FOR  THE  BESSEMER  PROCESS. 


Number. 

Authority. 

Composition. 

SiO,. 

Al.,0,. 

Fe,0,. 

FeO. 

CaO. 

MgO. 

MnO. 

HjO. 

Na.,0. 

KjO. 

NaCl 

V  ^ 

is 

S3 

o« 

1 
1 
3 
4 

5 

6 

7 
8 

Maynard  

GANISTKR— 
British  

93.28 
94.79 
84.86 
83.75 

89.55 

93.5 
82.94  ®  97.31 
96.54 

1.36 
2.89 
8.15 
4.45 

4.85 

4.23 
1.61  ©10.48 
2.50 

3.23 
1.03 

0.03 
0.32 
0.78 
0.392 

0.60 

0.26 
0.10®  0.78 
0.09 

0.35 
0.12 
0.4H 
0.517 

0.11 

trace 
trace  fe.,VJ 
0.80 

1.71 

0.05 
0.15 

0.11 
0  35 

Holley  

3.2-j 
7.00 

2  93 

trace 

0  73 

Snelns  

Sheffield  

0  94 

0.85 

Dowlais  

0.80 
0.19  @  4.02 
.93 

.18®  .30 

trace  @.94 
0  '3 

g 

10 

Q0AKTZ— 

93.18 
95.5 

2.37 
1.5 

2  74 

81 

.70 

.48 

.03 

Porsyth  

2.75 

0.40 

11 
a 

MOULDING  SAND  

78.81 
79.75 

12.76 
18.30 

2.71 

'l!75' 

0.99 
0.55 

1.08 
0.68 

0.91 

.13 

0.11 

2.30 

Holley  

Sand  for  Ladle,  Sheffield  

4  5 

13 

1! 
15 

Holley   

87. 
88.2 
81.5 

8.5 
7.3 
13.7 

1 

3  Oa 

"           "          Sheffield  

1.15 

0.18 
0.75 

.87 
0.25 

2  12a 

Walker 

•'           "          American    1888 

8.67 

2  7 

10 

Holley  

Ball-stuff,  Seraing  

78. 

17. 

1.6 

3.5a 

17 

a 

a 

Holley  

Bottoms    Seraing  

67.5 
89.3 
85.5 

26.5 
3.8 

8.75 

1  00 

5  5a 

"        Sheffield..  . 

3.6 

0.67 

.36 

8.5 

2  85 

Forsyth 

"        Illinois.      . 

2.00 

20 

Holley  

97  8 

1.02 

.75 

0 

0 

5 

21 

For;*yth  

78.5 

13.5 

2.25 

5 

22 

u 

25 

H 
27 

Holley  .  .  . 

Tuyeres,  Seraing  

69. 
53  4 
64.9 
58.9 
67.7 

23.5 
37.5 
30.9 
39.3 
27.1 

2 

5 

Walker  

"       American  

5.36 
2.60 
trace 
4.05 

0.70 
0.40 
0.70 
0.30 

0.40 
0.25 
.36 

trace 

Snelus  

Tuyeres,  British  

95 

74 

it 

it           it 

85 

2S 

28 

Holley  .  . 

70. 
59.85 

24. 

1  2 

4  5a 

Walker 

a,  Water  and  volatile  matter. 
Maynard,  Private  Communications. 
Holley,  Private  Reports. 


9-10.  Lake  Superior  quartz  used  in  mixtures  for  vessel  linings,  etc. 
Snelus,  Jour.  Iron  and  St.  Inst..  18?5,  II.,  p.  516. 
Forsyth,  Trans.  Am.  Inst.  Mining  Eng.,  IV.,  p.  138,  1876. 


11,  Waterford  (N.  Y.)  moulding  sand. 

Stoppers  and  nozzles  are  those  of  the  steel-casting  ladle. 


said  to  last  1,000  heats.  Allowing  for  the  difference  in 
the  length  of  the  heats,  the  American  linings  appear  to 
last  about  "25  times  as  long  as  the  Alpine. 

In  some  American  works  monolithic  linings  are  made 
from  ground  ganister"  or  ground  millstone  grit,  both  of 
which  give  admirable  results.  The  latter  is  said  to  last 
from  12  to  18  months. 

Blocks  of  mica-schist  and  of  millstone-grit  are  also  used 
in  this  country  for  vessel-linings,  and  with  good  results. 


e  Das  Eisenhiittenwesen  Schwedens,  p.  109,  1885. 

b  The  name  "ganister,''  originally  applied  to  a  slightly  argillaceous  sandstone 
found  near  Sheffield,  is  now  applied  generically  to  like  silicious  rocks  containing  a 
little  clay,  and  indeed  sometimes  to  an  artificial  mixture  of  ground  quartz  and  fire- 
clay suitable  for  vessel-linings, 


of  the  vessel's  shell,  (10"  wide  measured  radially,  18"  long 
measured  circumferentially,  and  6"  thick  measured  paral- 
lel with  the  length  of  the  vessel),  are  also  used  with  fail- 
results,  lasting  about  six  to  eight  weeks,  or  say  1,200  to 
1,600  heats.  It  is  necessary  to  place  a  layer  of  one-inch 
boards  between  the  blocks  and  the  shell  of  the  vessel,  for 
if  the  blocks  are  laid  flush  with  the  shell  their  expansion 
bursts  the  iron-work.  After  a  campaign  neither  boards, 
charcoal  nor  ashes  can  be  found. 

Silicious  brick  linings  are  used  in  some  European  works. 

The  life  of  certain  vessel-linings,  the  proximate  compo- 
sition of  the  mixtures  used,  and  the  ultimate  composition 
of  some  of  the  components  of  these  mixtures  are  given  in 
Tables  199  and  200. 


WEAR    OF    THE    SHELL-LININGS    S  403. 


353 


§403.  WEAR  OF  THE  SHELL  Lisrffas.— Under  certain 
conditions  the  shell-lining  grows  thinner,  under  others  it 
grows  thicker  during  use.  In  the  former  case  it  must  be 
patched  from  time  to  time,  chiefly  on  Sundays,  but  oc- 
casionally also  during  the  latter  days  of  the  week.  Where 
accretions  form  they  must  be  cut  out,  or  sometimes  even 
blasted  out  with  dynamite,  so  excessively  hard  are  they. 
J.  II.  Cremer  found  in  one  of  these  kidney -shaped  accre- 
tions," 


Hanganous  Oxide, 
6* 


Silica, 
fill  t 


Alumina  and  Iron-oxide, 
25.5* 


Total, 
99.5*. 


The  lining  may  grow  thin  from  actual  wearing  away, 
or  from  corrosion  by  the  slag  and  metal.  But  while  the 
slag  may  corrode  at  a  given  temperature,  if  the  tempera- 
ture be  but  slightly  lower  the  same  slag  may  freeze 
against  the  sides  of  the  vessel  and  form  accretions. 
Where  the  slag  comes  most  in  contact  with  the  lining, 
there  will  it  tend  most  to  cut  the  vessel  if  it  be  sufficiently 
hot  and  hence  fluid,  and  sufficiently  basic  to  cut :  and 
here  will  it  tend  most  to  form  accretions  if  so  cool  as  to 
stick  instead  of  cutting.  Other  things  being  equal,  the 
hotter  parts  of  the  lining  will  tend  to  cut  more  than 
the  cooler  ones. 

Now  the  shape  of  the  vessel,  the  position  of  the  tuyeres, 
the  depth  of  metal,  and  other  factors  affect  the  di?tribu- 
tion  and  position  of  the  slag  so  much,  and  its  comp  >si- 
tion  is  so  much  affected  by  the  proportion  of  silicon  and 
manganese  in  the  cast-iron,  by  the  depth  of  metal,  the 
rapidity  of  blowing,  etc.,  and  indeed  changes  so  much 
during  the  blow,  that  a  complete  analysis  of  the  condi- 
tions would  be  extremely  difficult.  Suffice  it  to  point  out 
a  few  considerations. 

The  path  over  which  the  cast-iron  runs  into  the  vessel, 
and  that  over  which  the  steel  runs  out,  are  heated  very 
highly  by  the  passage  of  the  metal,  and  being  the  more 
highly  heated  tend  to  cut  the  more.  In  certain  c^ses  we 
actually  find  grooves,  which  appear  as  if  worn  by  the  p  iss- 
agc  of  the  metal,  and  sometimes  a  sort  of  pocket  as  at  A, 
Figure  196.  It  is  probable  that  the  metal  does  not  itself 
wear  these  grooves,  but  merely  heats  the  lining  here  so 
highly  that  it  is  readily  corroded  by  the  slag,  or  actually 
melted  out. 

This  cutting  is  naturally  more  severe  in  vessels  which 
receive  and  discharge  their  metal  on  the  same  side,  than 
in  those  which  receive  cast-iron  when  turned  away  from 
the  pit,  and  discharge  steel  while  turned  toward  the  pit, : 
and  it  is  especially  severe  in  excentric  vessels,  as  in  these 
the  blast  and  the  rush  of  metal  during  the  blow  impinge 
more  directly  on  this  spot,  which  has  been  so  highly  heated 
and  softened  by  the  entering  and  departing  aharge. 

Further,  when  the  vessel  is  turned  down  at  tlie  end  ol 
the  blow,  as  in  Figure  201,  the  pasty  slag  lies  as  a  placid 
layer  above  the  molten  metal,  and  has  a  good  opportunity 
to  attach  itself  to  the  vessel' s  sides.    As  the  vessel  is  turned 
down  still  farther  to  pour  the  steel  out,  the  fall  of  the  tide 
beneath  leaves  the  slag  adhering  to  the  vessel's  sides 
especially  towards  the  nose,  against  whose  sides  the  flow 
presses  the  slag  which  had  been  in  the  middle  of  the  sur- 
face of  that  fiery  pool,  and  which  floats  towards  and  ii 
part  out  of  the  nose  with  the  stream.     In  a  narrow  nose 
the  slag  engorges,  like  freshet-ice  in  a  narrowing  stream 
Hence  the  nose  blocking  so  troublesome  in  the  basic  pro- 


b  Private  communication,  A.  D.  1874. 


3ess,  and  hence  the  ridges  of  slag  at  C,  Figure  196,  which 
ometimes  form  even  in  silicious  vessels  along  the  sides,  at 
ind  beneath  the  level  of  the  surface  of  molten  metal  when 
he  vessel  is  turned  down.  Slag  so  infusible  as  to  be 
pasty  during  the  blow,  becomes  hard  and  solid  as  it  cools 
)etween  blows. 

Still  another  place  where  action  is  apt  to  be  serious 
appears  to  be  along  the  level  occupied  by  tlie  slag  during 
the  blow  itself,  say  at  D,  Figure  196. 

Finally,  there  is  often  a  strong  tendency  lo  form  accre- 
;ions  near  the  very  bottom  of  the  bath  of  metal,  just  above 
the  joint  between  the  bottom  and  the  shell  lining,  as  at  B, 
^igure  196.  What  the  caus.j  of  this  is  I  know  not ;  but 
;he  following  is  a  possible  explanation.  Just  at  the  end 
of  the  tuyeres  the  metal  is  highly  oxygenated  ;  as  we 
travel  farther  and  farther  from  this  point  the  proportion 
of  iron-oxide  decreases,  that  of  silica  increasing,  as  the 
silicon  is  oxidized  by  the  iron-oxide.  Now  it  may  be 
that,  at  a  certain  distance  from  the  tuyere-ends,  at 
ertain  stages  of  the  blow,  and  with  iron  of  certain  com- 
position, there  is  developed  within  the  bath  a  silicate  of 
xtremely  infusible  composition.  If  the  swirl  and  eddy 
be  such  as  to  pr6ject  this  mixture  in  its  infusible  yet 
slightly  pasty  state  against  the  lining,  there  it  sticks,  and, 
3eing  of  the  same  composition  as  the  iron-silicate  in  the 
surrounding  bath,  is  not  fluxed  or  cut  by  it. 

In  acid  vessels  the  accretions  or  skulls  may  be  removed 
by  making  the  slag  more  basic,  e.  g.,  by  addition  of  lime 
or  of  iron-ore,  or  by  intentional  over-blowing  ;  this  last  is 
surely  a  costly  way  of  introducing  iron-oxide,  but  we  get 
a  very  high  temperature,  while  if  iron-ore  be  thrown  in  it 
owers  the  temperature  of  ihe  vessel  rapidly.  So,  too,  it  is 
thought  that  when  direct  metal  is  used  the  vessels  skull 
less  than  in  treating  cupola-metal,  because  of  the  basic 
blast  furnace  slag,  a  little  of  which  is  apt  to  run  into  the 
vessel  along  with  the  cast-iron.  The  cupola-slag  on  the 
other  hand  is  silicious.  At  certain  works  hard  silicious 
kidneys  form,  when  the  cast-iron  is  unusually  rich  in  sili- 
con. In  others  irons  with  much  manganese  and  little 
silicon  cause  skulling,  while  those  relatively  free  from 
manganese  but  rather  rich  in  silicon  cut  the  lining  instead 
of  skulling. 

Again,  there  is  much  less  skulling  when  the  steel  is 
recarburized  in  the  vessel,  than  when,  as  in  making  very 
soft  steel,  it  is  recarburized  with  ferro-mangane;e  in  the 
casting-ladle;  for  in  the  former  case  the  oxide  of  man- 
ganese, formed  by  the  reaction  between  the  oxygenated 
blown  metal  and  the  spiegeleisen  or  ferro-mmganese, 
makes  the  slag  more  basic,  and  especially  more  fusible 
and  fluid. 

The  linings  of  side-blown  vessels  usually  endure  fewer 
heats  than  those  of  bottom-blown  vessels,  because, as  point- 
ed out  in  §  392,  the  former  are  much  more  exposed  to  iron- 
oxide,  or  at  least  to  locally  basic  slag,  than  the  latter. 
The  linings  of  British  Clapp-Grifliths  vessels  are  reported 
to  last  from  400  to  600  heats.*  The  American  Clapp-Grif- 
fiths vessel-practice  is  much  better  than  this  ;  at  one 
works  the  linings  usually  last  4,000  heats  ;b  at  another 
they  are  said  to  last  8,000  heats  usually,  and  one  lining 
has  lasted  8,800  heats." 
At  one  French  works  the  brick  lining  of  a  Robert  vessel 

a  J.  Hardisty,  Journ.  Iron  and  St.  Inst.,  1886,  II.,  pp.  657,  660. 
b  Information  from  the  management,  June  7tb,  1889. 


3.~4 


THE    METALLURGY    OF    STEEL. 


is  patched  after  about  every  fifteen  heats,  and  is  almost 
wholly  replaced  after  from  200  to  300  heats :  in  making 
soft  steel  the  repairs  are  still  heavier.  But,  as  the  blowing 
is  confined  to  one  side  of  the  vessel,  parts  of  the  lining, 
like  the  greater  part  of  that  of  common  vessels,  last  indefi- 
nitely. On  the  whole  the  repairs  to  the  linings  of  Robert 
vessels  seem  much  more  severe  than  those  of  common 
vessels.0 

§  404.  PREPARATION  OF  THE  BOTTOM-LININGS.— In  this 
country  the  holes  through  which  the  blast  is  admitted  are 
almost  if  not  quite  universally  contained  in  pi'eviously 
thoroughly  burned  fire-clay  tuyeres,  usually  bought  from 
makers  of  fire-bricks,  who  burn  them  in  kilns  much  as  in 
making  fire-bricks. 

The  spaces  between  these  tuyeres  may  either  be  wholly 
filled  with  "bottom-stuff,"  a  mixture  of  clay  and  silicious 
matter ;  or  they  may  be  partly  filled  with  tiles  standing  on 
end,  between  which  in  turn  bottom-stuff  is  rammed,  as  in 


Fig.  SIS. 
a.b.c.d.   Tiles  between 

tuyeres. 
e.     Tuyeres. 

TKASKNTER. 


Fig.  ISIS. 


Fig.  ilk. 


Figure  212;  or  they  may  be  almost  wholly  filled  with  bricks 
shaped  so  as  to  fit  around  the  tuyeres  closely,  as  in  Figures 
213  and  214,  a  very  little  bottom-stuff  being  rammed 
between  these  bricks  and  around  the  tuyeres,  to  fill  the 
slight  crevices  which  are  unavoidable. 

Tuyeres  may  be  wholly  dispensed  with,  the  bottom- 
stuff  being  rammed  around  pins  which  are  withdrawn 
later,  leaving  holes  for  the  entrance  of  the  blast ;  but  this 
system  can  be  considered  to  better  advantage  in  connec- 
tion with  the  basic  Bessemer  process. 

In  case  drying  has  to  be  wholly  dispensed  with,  as  may 
occur  owing  to  the  sudden  unexpected  failure  of  a  large 
number  of  bottoms  in  succession,  we  may  build  up  a 
bottom  wholly  of  bricks  laid  with  the  least  possible 
quantity  of  mortar,  and  attach  it  to  the  vessel  at  once. 
This,  however,  is  but  a  makeshift. 

Cone-shaped  bottoms,  like  that  in  Figure  211,  are  made 
up  by  ramming  within  a  conical  mould.  Dish-bottoms 
clearly  need  no  mould. 

The  bottom- stuff  usually  contains  much  more  clay  than 
the  vessel  linings,  from  20  to  40  and  even  50%.  At  some 


o  Information  from  the  management,  July  2!>th,  1889. 


mills  all  the  bottom-stuff  is  finely  ground  and  thoroughly 
mixed.  In  others  the  crushed  fire-brick  used  is  in  lumps, 
some  of  which  are  1£  inches  long.  These  coarse  lumps 
promote  drying,  und  also  bind  the  mass  together. 

Usually  a  few  shovelfuls  of  bottom-stuff  are  added  at  a 
time,  and  thoroughly  rammed  with  rammers  like  those 
shown  in  Figure  211,  sometimes  heated  red-hot,  that 
they  may  not  adhere  to  the  bottom-stuff,  and  that  they 
may  assist  in  drying  it.  It  is  barely  moist  enough  to  be 
balled  with  the  hand  ;  it  is  indeed  almost  dry.  This  is  so 
that  it  may  dry  the  more  thoroughly  and  more  quickly, 
and  that  the  escape  of  moisture  may  not  crack  it. 

The  bricks  and  tiles  inserted  between  the  tuyeres, 
Figures  212  to  214,  further  facilitate  drying,  at  the  same 
time  opposing  any  tendency  to  flake.  Further,  the  kiln- 
burning  which  they  receive  makes  them  harder  than  the 
simply  baked  bottom-stuff.  But  while  they  probably 
prolong  the  life  of  the  bottom,  they  increase  its  cost.  In 
one  American  works  these  bricks  are  made  of  bottom- 
stuff  rammed  in  a  mould,  and  baked  for  twenty-four 
hours. 

After  thorough  ramming  the  bottom  is  carefully  dried. 
Enough  bottoms  should  be  on  hand  to  allow  us  to  dry 
each  of  them  for  forty-eight  hours,  though  in  many  works 
the  bottoms  are  dried  but  twenty-four  hours  or  even  less. 
Works  which  are  to  run  rapidly  should  have  at  least 
twelve  bottoms.  One  American  works  has  twenty-six 
bottoms  on  hand.  The  South  Chicago  repair-shop  has 
twelve  bottom-drying  hoods. 

In  the  older  works  the  bottoms  were  placed  on  a  car 
which  was  then  run  into  a  brick  chamber  containing  a  fire- 
place, and  here  car,  bottom  and  all  were  baked,  to  the 
great  detriment  of  the  running-gear  of  the  car.  An 
excellent  arrangement  is  that  shown  in  Figure  215.  The 
bottom,  when  its  lining  is  worn  out,  is  removed  by  means 
of  the  bottom-car,  which  to  that  end  is  raised  by  the 
hydraulic  bottom-jack  (e.  g.,  Q,  Figure  163),  so  as  to 
press  against  the  bottom  while  this  is  still  attached  to  the 
vessel.  The  bottom-jack  presses  directly  against  the 
cast-iron  funnel  (Figure  215)  which  hangs  down  from  the 
car,  and  the  length  of  stroke  which  it  is  necessary  to  give 
the  bottom-jack  is  thus  shortened  by  the  length  of  the 
funnel. 

The  keys  holding  the  bottom  to  the  shell  of  the  vessel 
are  then  withdrawn,  and  car  and  bottom  lowered  and 
removed  to  the  repair-shop.  The  bottom  does  not  leave 
this  car  until  it  is  again  attached  to  the  vessel.  The  car 
is  run  over  a  pit  (see  Figure  168),  where  the  stumps  of  the 
tuyeres  are  knocked  out,  and  after  them  the  remaining 
bottom- stuff.  •  New  tuyeres  are  then  inserted,  wooden 
dummies,  however,  being  set  in  three  of  the  places  left 
for  tuyeres.  The  ends  of  the  tuyeres  are  then  covered,  so 
that  the  tuyere-holes  may  not  be  stopped  up  by  grains  of 
bottom-stuff  falling  into  them  and  lodging,  and  the  bot- 
tom is  carefully  rammed  as  above  described.  It  is  then 
placed  under  the  hood  shown  in  Figure  215,  which  has 
above  a  gas  blow-pipe,  with  air  and  gas  supply  regulated 
by  the  butterfly -valves  shown.  The  flame  from  this  hood 
passes  down  through  the  three  holes  left  by  the  removal 
of  the  wooden  dummies,  which  are  knocked  out  as  soon  as 
the  bottom  is  rammed  up,  and  through  the  cast-iron 
funnel  to  a  flue  leading  to  the  chimney.  We  can  thus 
heat  the  bottom  gradually  at  first,  while  it  is  still  steam- 


PREPARATION    OF    THE    BOTTOM-LININGS    8  404. 


8.05 


ing,  and  so  avoid  drying  it  so  fast  as  to  crack  it,  and 
later  thoroughly  bake  or  even  burn  it,  and  that  without 
first  burning  the  iron-work  of  the  car.  We  apply  the 
heat  just  where  it  is  wanted,  to  the  bottom-lining  itself, 
and  thus  with  good  efficiency. 

After  thorough  baking,  tuyeres  are  inserted  in  the 
holes  left  by  the  removal  of  the  dummies,  and  the  bot- 
tom, while  still  highly  heated,  is  brought  with  its  car  to 
beneath  the  vessel,  raised  again  by  the  bottom  jack,  and 
again  attached  to  the  vessel  for  blowing.  It  is  not  well  to 
.allow  the  bottom  to  cool,  as  its  contraction  during  cooling 
may  break  off  some  of  the  tuyeres.  In  some  cases  as 
many  as  five  or  six  tuyeres  have  been  thus  broken  in  a 
single  bottom. 

Certain  data  connected  with  the  composition  and  life  of 
bottoms  are  given  in  table  199. 

The  increase  in  the  life  of  bottoms  has  been  remarkable. 
In  1872  bottoms  lasted  but  from  four  to  eight  heats.  In  1875 
their  life  had  increased  in  at  least  one  mill  to  an  average  of 
eleven  heats,  taken  over  a  period  of  eight  months.  The 
bottoms  in  this  case  were 
made  with  bricks  of  baked 
bottom-stuff,  somewhat  as 
sketched  in  Figure  214.*- 
There  are  now  many  works 
in  which  the  average  life 
of  the  bottoms  is  more 
than  twenty-five  heats. 

Heavy  blast  -  pressure, 
short  and  cool  heats,  small 
tuyere-holes,  small  depth 
of  metal  above  the  surface 
of  the  tuyeres,  as  well  as 
proper  materials,  careful 
ramming,  and  above  all 
very  thorough  baking,  all 
lengthen  the  life  of  the 
bottom.  The  heavy  blast- 
pressure,  small  tuyere- 
holes  and  small  depth  of 
metal  probably  lengthen 
the  life  of  the  bottom  by 

lessening  the  intimacy  of  contact  of  the  tuyeres  (and  it  is 
they  that  cut  out  before  the  surrounding  bottom)  with 
the  bath  of  metal,  which  in  the  neighborhood  of  the 
tuyere-ends  is  highly  charged  with  iron-oxide,  a  powerful 
flux  for  the  silicious  tuyeres.  The  smaller  the  tuyere- 
holes  the  more  rapidly  will  the  blast  emerge  from  them, 
and  the  more  will  it  lift  the  metal  from  them. 

The  direct  effect  of  lieavy  blast-pressure  is  probably  to 
corrade  the  ends  of  the  tuyeres,  but  this  effect  is  out- 
weighed by  its  holding  the  metal  away  from  the  tuyere- 
ends.  I  have  already  pointed  out  in  §  392  that  the  life  of 
the  tuyeres,  and  hence  of  the  bottoms,  is  very  much  greater 
in  side-blown  vessels,  such  as  the  Clapp- Griffiths  and  the 
Robert,  in  which  the  blast  enters  near  the  upper  surface 
of  the  metal,  than  in  bottom-blown  vessels,  rising  even  to 
250  heats. 

While,  in  view  of  the  many  factors  which  influence  the 
life  of  the  bottom,  the  data  at  hand  do  not  indicate  de- 
cisively the  most  long-lived  type,  yet  they  corroborate  in 
a  rough  way  some  of  the  points  which  I  have  just  noted. 


f.  Forsytb,  Trans.  Am.  Inst.  Mining  Eng.,  IV.,  p.  132,  1876. 


We  find  in  case  of  the  bottom-blown  vessels  of  Table  199, 
that,  taking  the  average  of  the  average  life  of  each  class 
the  monolithic  bottoms,  rammed  around  tuyeres,  last 
17.5  heats,  bottoms  like  Figure  212  last  21.4  heats,  and 
those  like  Figure  213  last  2:5  limits,  which  indicates  in  a 
rough  way  that  the  burnt  fire-bricks  set  in  the  bottoms 
prolong  their  lives.  I  am  informed  that  in  Continental 
Europe,  where  the  space  between  the  tuyeres  is  almost 
completely  filled  by  burnt  bricks,  the  bottoms  usually 
last  25  heats  of  say  15  minutes.  So,  too,  bottoms  which 
are  dried  for  24  hours  or  less  last  on  such  a  general  average 
15  heats,  while  those  dried  48  hours  or  more  last  23  heats. 
In  the  Walrand  (Robert)  vessel,  instead  of  using  the 
common  fire-clay  tuyeres,  the  blast  was  formerly  admitted 
through  openings  in  the  sides  of  the  monolithic  silicious 
vessel-lining,  formed  by  ramming  basic  material  around 
little  wooden  plugs.8  The  strong  local  corrosive  action  of 
the  iron-oxide  of  the  metal  on  the  lining  was  thus  lessened. 
This  practice  has  since  been  abandoned. 
In  bottom-blowing,  after  a  bottom  has  been  in  use  for  a 

number  of  heats,  partly 
determined  by  experience, 
partly  by  inspection 
through  the  vessel's  nose 
between  heats,  the  length 
of  its  tuyeres  must  be  de- 
termined by  actual  meas- 
urement, e.  g.,  by  passing 
a  wire  with  a  hooked  end 
through  the  tuyere-holes 
from  behind,  while  the 
vessel  is  turned  down  be- 
tween heats.  Starting 
with  a  length  of  two  feet, 
the  bottom  is  used  in  some 
mills  till  the  shortest  tuy- 
eres are  only  4"  to  5"  long. 
As  2.5"  to  3"  of  the  length 
of  the  tuyere  lie  below  the 
false-plate  P,  this  means 
that  the  bottom  is  used 
till  its  lining  is  only  from 
2"  to  3"  thick  in  the  thinnest  parts. 

A  convenient  device  for  learning  when  the  bottom  is 
worn  thin  is  to  insert  in  the  bottom,  before  ramming  it,  a 
short  dummy  tuyere,  say  seven  inches  long,  which  projects 
only  some  five  inches  above  the  false-plate  P,  Figure  203. 
When  the  bottom  is  worn  down  to  the  end  of  this  dummy 
tuyere,  which  can  readily  be  learned  by  inspection  through 
the  vessel's  nose  between  heats,  the  bottom  may  be  re- 
moved, or  at  least  the  length  of  its  tuyeres  should  be 
examined  carefully  by  direct  measurement. 

In  earlier  practice  if  one  or  two  tuyeres  were  worn  too 
short  while  the  rest  of  the  bottom  was  still  in  condition  to 
blow  another  heat,  the  vessel  was  turned  down  on  its  side, 
the  bottom-plate  was  removed,  the  short  tuyeres  were  cut 
out,  and  the  holes  thus  left  were  rammed  full  of  ball  stuff. 
There  is  usually  time  between  heats  to  do  this  without 
delaying  matters,  for  a  tuyere  can  be  thus  ' '  blinded ' '  while 
the  cast-iron  for  the  succeeding  charge  is  running  into  the 
vessel. 
In  present  practice  it  is  found  better  to  cut  out  the  old 


Fig.  215.    GAS-BLOWPIPE  HOOD  ASB  CAB  FOB  DBTINQ  BOTTOMS. 


K  J.  Hardisty,  Journ.  Iron  and  Steel  Inst.,  1886,  II.,  p.  C60. 


THE    .MKl'AbURtrY     OF    STEEL. 


tuyere    and  insert   a    new    one.  preferably    of   smaller 
diameter  and  coated  with  wet  fire-clay. 

But  tuyeres  are  still  sometimes  "blinded,"  wholly  or 
in  part,  by  inserting  in  the  tuyere-holes  "  rat  tails"  of 
fire-clay,  which,  are  tlien  rammed  lightly  ;  or,  if  we  are 
greatly  hurried,  by  throwing  a  ball  of  wet  plastic  clay 
against  the  butt  of  the  tuyere,  and  covering  it  with  a 
thin  iron  plate,  which  the  blast-pressure  and  the  adhesion 
of  the  clay  hold  in  place. 

When  the  bottom  is  worn  out,  its  upper  surface  looks 
somewhat  as  sketched  in  Figure  202,  with  deep  gougings 
here  and  there  at  one  or  more  of  the  holes  of  some  of  the 
tuyeres. 

§  405.  SPECIAL  FORMS  OF  CONVERTERS. — Within  the 
last  few  years  several  forms  of  converters  have  been 
brought  forward,  which  are  said  by  certain  interested  per- 
sons and  by  some  others  to  produce  results  which  are  so 
different  from  those  attained  in  the  converters  previously 
used  as  to  constitute  new  processes,  e.  g.,  the  Clapp- 
Griffiths  and  the  Robert  "process."  Thus  the  "Direc- 
tory to  the  iron  and  steel  works  of  the  United  States" 
for  1887  divides  the  steel  works  of  the  country  into  Besse- 
mer, open-hearth,  crucible  and  Clapp-Griffiths,  implying 
that  the  difference  between  the  Bessemer  and  Clapp- 
Griffitlis  process  (?)  is  co-ordinate  with  that  between  the 
Bessemer  and  the  open-hearth  process.  So,  too,  most 
astonishing  accounts  of  the  Robert  process  (?)  have  ap 
peared  in  the  non-technical  papers. 

A  change  in  the  shape  of  the  vessel  or  in  the  manner 
of  introducing  the  blast  is  likely  to  induce  some  modifi- 
cation in  the  process  itself,  perhaps  trifling,  perhaps  im 
portant.  But  it  certainly  seems  that  those  pecuniarily 
interested  have  given  others,  and  probably  themselves,  a 
very  exaggerated  notion  of  the  importance  of  these  par- 
ticular modifications.  They  have,  in  some  cases  through 
inadvertence  or  hasty  judgment  I  believe,  put  themselves 
in  a  wholly  false  position,  by  claiming  to  obtain  startling 
results  by  means  which  appear  wholly  inadequate,  with- 
out offering  sufficient  evidence  that  these  results  have 
actually  been  reached.  From  this  position  they  might 
extricate  themselves  by  showing  that  the  means  are  really 
adequate,  or  by  properly  substantiating  their  claims. 

§406.  THE  CLAPP  GRIFFITHS  VESSEL,!  Figure  216,  is 
essentially  a  high  side-blown  stationary  vessel,  with  a 
spout  H  at  such  a  level  that  the  slag  runs  out  of  it  dur- 
ing the  boil.  This  slag-spout  is  the  only  real  novelty.1 
Its  effect  can  better  be  considered  under  the  chemistry  of 
the  Bessemer  process.  Thus  far  I  have  found  no  jot  of 
evidence  that  it  accomplishes  anything  valuable  ;  nor  is 
there  strong  reason  to  expect  that  it  should.  At  G  is 
shown  the  tap-hole  through  which  the  steel  is  removed  at 
the  end  of  the  blow.  The  blast  enters  the  wind-box  C 
through  the  goose-neck  K,  in  which  the  valves  L  en- 
able us  to  shut  off  the  blast  almost  or  quite  wholly. 

Arrangements  have  been  devised  for  preventing  the 
steel  from  backing  into  the  tuyeres  when  the  blast  is  shut 
off  at  the  end  of  the  blow.  The  simplest  way,  however, 


i  I  have  heard  it  said  that  this  ^lag-spout  is  DO  real  novelty,  as  it  was  used  on 
the  old  Swedish  vessels  (Figure  188);  they  certainly  had  such  a  spout,  but  I  am 
informed  that  it  was  not  used  for  removing  slag.  Indeed,  the  Swedish  steel- 
makers wisely  preferred  to  retain  the  slag,  so  as  to  keep  the  metal  hot  while  in 
the  casting-ladle.  (Consul  Goransson,  private  communication,  April  13th,  1888.) 

j  Trans.  Am.  Inst.  Min.  Engineers,  XIII.,  pp.  745,753;  XIV.,  pp.  139,  919; 
XV.,  p.  340.  Science,  VI.,  p.  342,  1885.  Stahl  und  Eisen,  VII.,  No.  5,  1887. 
Journ.  Iron  and  St.  lust.,  1886,  II.,  p.  654. 


is  not  to  shut  the  blast  off  entirely,  but  to  admit  just 
enough  of  it  into  the  wind-box  to  keep  the  metal  out  the 
tuyeres.  In  practice  this  is  found  wholly  effective. 

For  cleaning  the  tuyeres  a  readily  opened  door  is  pro- 
vided in  the  wind-box  opposite  each. 

The  bottom  section  of  the  vessel  is  removable,  the  joint 
as  shown  being  high  above  the  tuyeres.  As  already  pointed 
out,  the  life  of  the  bottom  is  excellent. 

Beneath  the  vessel  is  a  hydraulic  cylinder,  P,  fer 
removing  and  replacing  bottoms. 

There  was  but  one  Clapp  Griffiths  vessel  in  this  country 
in  1884  ;  there  were  13  in  August,  1886;  16  in  November, 

1887,  and  15  at  the  end  of  1888, 
one  having  been  removed  to 
Mexico. 

The  increase  in  the  number 
of  other  Bessemer  vessels  was 
13  between  September  1884 
and  August  1886  ;  16  between 
August  1886  and  November 
1887  ;  and  8  between  November 
1887  and  December  31st  1888. 

In  short,  between  August 
1886  and  January  1889  only 
three  Clapp-Griffiths  vessels 
were  built,  against  twenty-four 
other  Bessemer  converters. 
It  is  not  easy  to  make  a  fair 

Fiy.  316.    CLAW -(VniFFiTiis  BE^KMKR 

CONVERTER,  j.  v.  winiKiiow.       comparison  between  the    rate 

box       D. P  Hand-holes  "'for*'  examining     of      ind'CaSC      of      the       pl'OduC- 
tuyerers.     G.   lap-hole.     K.  Goose-neck 

rS5££J5£53Sr*2^SS:  tion  of  Clapp-Griffiths  and  of 
other  vessels,  because  the  great  mass  of  the  non- Clapp- 
Griffiths  Bessemer  steel  goes  into  rails,  while  none  of 
that  made  in  Clapp  Griffiths  vessels  does,  and  the  demand 
for  rails  bears  no  close  relation  to  that  for  the  ingot-iron 
made  in  the  Clapp-Griffiths  vessels.  The  best  approach 
to  fairness,  and  it  is  not  a  very  close  approach,  which  I  can 
make,  is  to  compare  the  increase  of  the  output  of  the 
Clapp-Griffitiis  vessels  with  that  of  Bessemer  steel  used  for 
purposes  other  than  rails.  This  class  includes  the  soft 
steel  made  in  common  Bessemer  vessels,  which  is  used  for 
the  same  purposes  as  that  made  in  Clapp-Griffiths  vessels  ; 
indeed,  the  two  are  probably  wholly  undistinguishable 
by  any  but  transcendental  tests. 

TABLE  SOI.— INCREASE  IN  THE  NUMBER  OP  THE  CLAPP-GRIFFITHS  VESSELS  IN  THE  UNITED 
STATES,  AND  OP  THEIR  OUTPUT. 


Date. 

Sept.  1884. 

Aug.  1886. 

Nov.  1887. 

Dec.  1888. 

1.  Vessels  existing.  ]g'tahPP-Grifflth6- 

1 
45 

13 

58 

16 

74 

15 

82 

Period. 

1884  to  1886. 

12 
13 

3 
16 

-1 
8 

2.  Vessels    built.  .  .  -j  other                

Year. 

1886. 

1887. 

1888. 

3   OutDut                  i  Clapp-Griffiths  

48,371 
473,907 

08,679 
587,115 

81,157 
931,105 

i.  uuipui  -j  other  than  rail  

2,541,493 

3,288,357 

2,812,500 

Year. 

1887. 

1888. 

4.  Percentage    of    in-    («,„_„  rriffiti,- 

rrpRSp    of     output    J  Clapp-Cil 

48.1 

18.3 

23.9 

58.6 

ceding  year. 

Thus  the  construction  of  Clapp-Griffiths  vessels  took  a 
sudden  start  between  1884  and  1886,  owing,  we  may  sur- 

ROBERT    OR    WALRAND    CONVERTER.      §  407. 


807 


raise,  to  the  remarkable  claims  made  for  the  so-called 
process  ;  but  it  seems  that  experience  has  not  verified 
these  claims  to  such  a  degree  as  to  induce  manufact- 
urers to  adopt  these  vessels  farther.  In  accord  with  this 
is  the  great  increase  in  the  output  of  the  Clapp-Griffiths 
vessels  in  1887,  following  the  completion  of  those  built  in 
1886.  In  1888,  however,  the  ratio  of  increase  in  the  out- 
put from  Clapp-Griffiths  vessels  is  much  less  than  that  of 
steel  for  purposes  other  than  rails  and  made  in  other  ves- 
sels (line  4,  Table  201). 

The  fifteen  Clapp-Griffiths  vessels  existing  in  1888  had 
a  nominal  capacity  of  43  tons  per  heat  collectively,  and 
should  be  able  to  turn  out  some  1,000  tons  per  24  hours, 
or  to  turn  out  the  total  output  reached  in  1888  in  some  80 
days  of  active  running.  The  other  Bessemer  converters 
existing  in  1888  had  a  nominal  capacity  of  somewhere 
about  500  tons  per  heat 
collectively, and  should, 
if  turning  out  as  many 
heats  per  24  hours  as 
the  Clapp-Griffiths  ves- 
sels, have  a  total  capac- 
ity of  about  11,500  tons 
per  24  hours.  At  this 
rate  they  would  turn 
out  the  total  output 
reached  in  1888  in  about 
175  days.  This  gives 
the  Clapp  Griffiths  ves- 
sels an  unfair  advan- 
tage, for  their  small 
heats  should  be  more 
rapidly  handled  in  the 
casting-pit.  But  even 
taken  in  this  way  it 
would  seem  that  the 
Clapp-Griffiths  vessels 
were  less  than  half  as 
fully  occupied  during 
1888  as  the  other  vessels, 
although  the  output  of 
rails  in  1888  was  much 
below  that  of  1887.  In 
other  words,  while  the 
capacity  per  heat  of  the 
Clapp-Griffiths  vessels 
is  about  one-tenth  of 
that  of  the  other  Besse- 
mer vessels,  the  actual  output  of  the  latter  in  1888  was 
more  than  twenty  times  that  of  the  Clapp- Griffiths 
vessels. 

The  Clapp-Griffiths  vessels  in  Britain  seem  to  be  doing 
well,  but  the  French  ones  have  not  been  successful : 
several  have  been  abandoned,  and  I  do  not  learn  of  one 
now  running. 

Nation's  Converter  seems  to  be  essentially  like  the 
Clapp-Griffiths,  except  that  it  lacks  the  slag-spout. 

§  407.  IN  THE  ROBERT  OK  WALRAND  VESSKL*  (Figures 


Fig.  217.    THE  KOBERT  CONVERTER 


*  U.  S.  Patents  395,633,  Jan.  1st,  1889 :  493,010,  March  19th,  1889  :  Harper's 
Weekly,  XXXIII.,  No.  1679,  p.  151,  Feb.  23d,  1889 :  Iron  Age,  XLIII.,  p.  656,  1*89  : 
Journ.  Iron  and  St.  Inst.,  1886,  II.,  p.  659.  We  are  informed  in  Harper's  Weekly 
that "  the  Bessemer  converter  must  be  relined  after  a  very  few  blasts  ;  the  Robert 
after  1,000  blasts; "  that  the  metal  is  heited  much  hotter  than  by  the  Bessemer 
process  and  is  therefore  more  fluid.  Actually  the  lining  of  the  Bessemer  converter 


217,  218)  the  blast  is  introduced  through  horizontal  tuyeres 
near  the  upper  surface  -of  the  metal,  and  placed  seini- 
tangentially,  so  as  to  give  the  bath  a  rotary  motion.  The 
vessel  itself  is  rotary  ;  it  is  tipped  so  that  during  the  first 
part  of  the  blow  the  tuyeres  almost  emerge  from  the  bath, 
and  as  the  blow  proceeds  the  level  of  the  tuyeres  is 
gradually  lowered. 

Rotary  motion  of  the  bath  is  sought,  in  order  that  the 
action  of  the  blast  may  be  less  strongly  localized.  This, 
of  course,  is  no  novelty,  having  been  adopted  in  the  old 
Swedish  vessels.  Great  stress  is  laid  on  the  highly  local- 
ized "stripping"  or  "atomizing"  action  of  the  blast,  on 
the  gyrations  of  the  bath,  and  on  regulating  them  so  that, 
while  they  may  expose  each  particle  of  the  metal  to  the 
blast  in  turn,  they  may  not  draw  down  into  the  bath  of 
metal  the  "  impurities  "  already  separated. 

As  far  as  I  can  make  it  out,  the  idea  is  that  in  bot- 
tom-blown vessels  "the  impurities"  eliminated  from  the 
cast-iron  become  mixed  up  with  the  iron,  while  in  the 
Robert  vessel  they  do  not.  First,  bottom-blowing  is  not 
essential  to  the  Bessemer  process :  the  earlier  successful 
vessels  were  blown  from  the  sides.  Rotary  motion  was 
induced  in  a  way  closely  similar  to  that  of  the  Robert 
"process"  by  setting  the  tuyeres  semi-taugentially.  High- 
side  blowing  was  adopted  long  ago  by  Durfee,  and  later 
by  Clapp  and  Griffiths.  Here,  then,  is  no  novelty.  It  is 
claimed,  apparently,  that  restricting  the  blowing  to  one 

side  of  the  vessel  leaves 
the  "impurities"  in  a 
quiescent  state  on  the 
leeward  side  of  the  ves- 
sel, while  if  the  blast 
enters  on  all  sides  this 
repose  is  lost.  What 
now  are  these  impurites 
eliminated  during  the 
process,  whose  return  is 
to  be  dreaded  ?  Gases, 
which  rush  out  of  the 
vessel's  nose ;  slag, 
which  cannot  be  made 
to  unite  with  the  iron 
by  any  possibility;  iron- 
oxide,the  purifying  sub- 
stance itself,  licked  up 
voraciously  by  the  slag, 
probably  wholly  remov- 
ed by  the  recarburizer.m 

Where  is  the  evidence  that  injurious  impurities,  remov- 
able by  such  purely  mechanical  means,  exist  in  Bessemer 
steel,  or  that  one-sided  blowing  furthers  their  removal  ? 
What  the  reason  to  expect  that  it  should  ?  Shall  in- 

lasts  many  thousand  blows,  and  the  difficulty  usually  is  to  keep  the  temperature 
down,  not  up. 

In  the  earliest  description  of  this  vessel  which  I  have  seen  (Hardisty,  Journ.  Iron 
and  St.  Inst.,  1886,  II.,  p.  659),  it  is  spoken  of  us  the  "  Walrand  "  converter.  It  is 
now  always  called  the  "Robert"  vessel  so  far  as  my  observation  goes:  and  M. 
Robert  informs  me  that  the  design  is  his  solely.  A  letter  of  inquiry  on  this  subject 
which  I  have  sent  M.  Walrand  remains  unanswered. 

m  During  casting,  when  metal  and  slag  become  cool  and  viscid,  there  is  indeed 
danger  of  their  becoming  mixed.  But  this  danger  is  not  lessened  by  keeping  them 
separate  during  the  blow  while  molten,  for  then  they  separate  automatically  and 
need  no  aid.  It  is  mixing  during  and  immediately  before  their  pouring,  and  not 
during  the  blow,  that  we  should  avoid. 

The  oxide  of  iron  is  the  purifying  substance  itself,  to  borrow  the  language  of  th« 


Fig.  118.    SECTION  OF  KOBEKT  CONVERTER. 


358 


THE    METALLURGY    OF    STEEL. 


ventors  next  patent  stirring  porridge  to  left  instead  of 
right ;  methods  of  making  wood  float  and  lead  sink? 

The  chief  advantage  claimed  for  the  Robert  over  the 
common  converter  is  that  it  yields  a  better  product  and  a 
higher  temperature,  so  that  it  can  be  used  advantageously 
for  making  small  steel  castings. 

The  present  evidence  that  its  product  is  superior  is  of 
the  usual  wholly  unsatisfactory  kind,  and  merits  neither 
presentation  nor  rebuttal. 

I  see  nothing  in  the  many  castings  which  I  have  seen, 
made  from  the  Robert  vessel,  which  indicates  that  an  ex- 
traordinarily high  temperature  is  reached  ;  some  of  them 
were  doubtless  cast  a  a  decidedly  high  temperature,  yet 
not  higher  than  can  be  readily  attained  in  common  vessels. 
I  am  sure  that  the  temperature  in  the  vessel  when  it  was 
turned  down  after  the  blows  which  I  have  seen  was  not 
higher,  and  I  think  that  it  was  decidedly  lower,  than  that 
of  the  common  vessel  at  the  end  of  a  normally  hot  blow  : 
and  so  said  an  eminent  metallurgist  who  was  with  me. 
Yet  the  conditions  at  hand  should  have  insured  an  un- 
usual temperature  even  in  a  common  vessel,  for  the  cast- 
iron  was  an  unusually  "hot"  one,  containing  2.4%  of 
silicon,  \%  of  manganese  and  3.75$  of  carbon ;  the  walls 
of  the  vessel  were  unusually  thick,  about  16"  I  was  in- 
formed ;  and  the  charge  was  recarburized  with  only  \%  of 
ferromanganese,  so  that  the  chilling  effect  of  a  large 
recarburizing  addition  was  avoided. 

Suppose,  however,  that  we  concede  that  an  unusually 
high  temperature  may  be  reached  thanks  to  these  pre- 
cautions, to  the  combustion  of  an  excessive  proportion  of 
the  iron  of  the  charge  (it  is  admitted  that  the  loss  is  15%, 
and,  judging  from  the  amount  of  smoke  and  from  the 
well-known  tendency  of  the  siderurgical  mind  to  persuade 
itself  that  the  loss  is  much  lower  than  it  actually  ia,  I 
should  put  the  loss  at  nearer  18%,  or  say  half  greater  than 
in  common  vessels),  and  perhaps  to  the  combustion  of  an 
unusually  large  proportion  of  the  carbon  to  carbonic  acid, 
due  to  introducing  the  blast  near  the  top  of  the  bath — 
admitting  all  this,  what  follows?  That  these  same  con- 
ditions can  be  reproduced  in  the  common  converter,  by 
inclining  it  so  as  to  bring  some  of  the  tuyeres  near  the  top 
of  the  bath,  as  has  long  been  habitually  done  in  case  of 
unduly  cold  heats. 

But  as  this  is  not  patentable,  while  the  mysterious  gyra- 
tions, moderation  and  regulation  of  currents,  and  atom- 
izing stripping  action  seem  to  be,  the  cynic  readily  sur- 
mises why  the  former  simpler  explanation  is  less  palatable 
to  the  promoters  of  the  Robert  process  than  the  latter, 
which,  foggy,  mysterious,  incomprehensible,  is  certainly 
of  the  kind  which,  rightly  or  wrongly,  we  involuntarily 
associate  with  charlatanry  and  imposture.  Therefore, 
while  I  believe  that  M.  Robert  is  quite  sincere  though 
clearly  mistaken  as  to  the  rationale  of  the  effects  of  his 
particular  modification  of  the  Bessemer  converter,  it 
seems  well  to  warn  the  public  that  wholly  disinterested 
experts  regard  the  extravagant  statements  of  the  pro- 


quack  It  is  by  oxide  of  iron  that  the  carbon,  silicon  and  manganese  are  removed. 
To  prevent  oxide  of  iron  from  impregnating  the  bath,  if  it  were  possible,  would  be 
to  arrest  the  process.  Now  it  is  only  the  last  traces  of  iron-oxide  that  can  remain 
mixed  up  with  the  molten  metal  during  the  blow.  The  great  bulk  of  it  either  oxi- 
dizi-s  carbon,  etc.,  or  separates  by  gravity  from  the  metal,  which  is  able  to 
dissolve  but  a  minute  portion  of  it.  As  this  minute  portion  must  be  and  is  mixed 
up  with  the  metal  in  the  Robert  vessel,  it  profits  nothing  to  attempt  to  keep  the 
rest  of  the  iron-oxide  from  the  metal.  Such  propositions  do  not  deserve  seiious 
consideration. 


moters  of  his  process  (?)  most  incredulously,  and  are  most 
skeptical  as  to  its  possessing  any  real  value. 

Laureates  Converter.  —  The  corrosion  of  the  lining  is,  of 
course,  much  more  rapid  at  the  tuyeres  than  elsewhere. 
In  these  high  side-blown  vessels  the  renewal  of  the  tuy- 
eres implies  renewing  a  considerable  mass  of  lining  below 
them.  To  obviate  this  the  tuyeres  in  Laureau's  high-side- 
blown  vessel  lie  in  a  separate  zone  or  ring  of  the  lining, 
quite  distinct  from  the  bottom  proper.  When  this  ring 
is  worn  out  a  new  one  is  inserted,  the  old  shell-lining  and 
the  old  bottom  remaining  in  use. 

Instead  of  introducing  tuyeres  all  around  the  circum- 
ference of  the  vessel,  he  groups  them  close  to  the  plane  of 
the  trunnions,  /.  e.,  just  beneath  the  trunnions  and  slightly 
to  right  and  left.  As  theiv  are  no  tuyeres  in  the  front  of 
the  vessel  (i.  e.,  the  part  nearest  the  pit),  we  do  not 
have  to  turn  the  vessel  through  so  many  degrees  to  bring 
the  tuyeres  above  the  surface  of  the  metal  as  in  Bessemer's 
rotating  side-blown  vessel,  Figures  185,  186e. 

§  408.  DAVY'S  PORTABLE  CON- 
VERTER, Figure  219,  is  a  half  ton 
bottom-blown  rotating  vessel,  whose 
trunnions  rest  in  fixed  supports 
during  blowing.  At  the  end  of  the 
blow  the  vessel  is  turned  down  by 
a  hand-  or  power-driven  worm,  gear- 
ing into  a  worm-wheel  on  one  of  the 
trunnions.  The  charge  is  then  re- 
carburized and  rabbled,  and  the  ves- 
sel, together  with  its  trunnions,  is 
carried  by  a  crane  to  the  casting 

-  - 

place,  leaving  the  standards  free  to 
receive  another  vessel* 

This  arrangement  aims  to  avoid  the  loss  of  heat  which 
occurs  when  the  steel  is  poured  into  a  relatively  cold 
ladle,  and  which  is  the  more  serious  the  lighter  the 
charge.  A  vessel  so  small  as  to  be  portable  is  not  suited 
to  the  production  of  ingots,  while,  if  castings  are  to  be 
made,  a  serious  difficulty  arises  :  —  in  dispensing  with  the 


Fig.  219.  DAVY'S  lo-cwr. 

PORTABLE  VUSSEL. 


Fig.  220.    CASTING-LADLE. 

a  Stopper-Rod,     b  Socket,     c  d  c  Hand-Screws,     f  Lever,      h  Guide,    i  Casting  riveted 
to  Ladle,    k  Sliding-Bar.    1  Trunnions. 

casting-ladle  we  have  thrown  away  the  only  certain  way  of 
keeping  the  infusible  slag  from  running  out  of  the  vessel 
into  the  moulds,  and  so  ruining  the  castings. 

§  409.  THE  LADLES. — Those  for  cast-iron  discharge  their 
metal  by  tipping.      They  are  made  of  boiler-plate,    and 


e  U.  8.  Patent,  358,559,  March  1st,  1887. 


THE    LADLES.      §  409. 


359 


suspended  from  trunnions.     An  arrangement  for  tipping 
is  shown  at  F  and  K  in  Figure  163. 

Figure  221  shows  a  ladle  for  carrying  molten  cast-iron 
from  the  blast-furnace  to  the  Bessemer  converters.  In 
tipping,  as  the  rack  into  which  the  trunnion-pinion  gears 
is  fixed,  the  trunnion,  and  with  it  the  ladle,  shifts 


Tllllof  Udl*£ir.  "iit  I-dl.  Tilwi. 

Fig.  SSI.    WEIMER'S  DIRECT-METAL  LADLE. 

towards  the  side  to  which  we  tip  it,  so  that  the  stream 
of  metal  the  more  readily  falls  clear  of  the  ladle-car  and 
the  tracks. 

The  Steel  ladles  discharge  the  steel  through  a  fire-clay 
nozzle  in  their  bottom,  as  shown  in  Figure  220,  and  also  at 
L  in  Figure  163.  If  we  attempted  to  cast  the  steel  over 
the  edge  of  the  ladle,  as  in  foundry  practice,  the  infusible 
slag  which  floats  above  the  steel  in  the  ladle,  and  which 
acts  as  a  blanket  to  keep  it  hot,  would  run  into  the  moulds. 
It  would,  moreover,  be  impossible  to  pour  rapidly,  much 
scrap  would  be  made,  and  the  fall  of  the  stream  of  molten 
metal  would  be  excessively  long,  cutting  the  mould- 
bottoms  (stools)  and  agitating  the  metal.  Still,  it  is 
necessary  to  provide  rotating  gear  as  shown  at  L  in  Figure 
163,  so  that  we  may  adjust  the  ladle  to  deliver  its  stream 
of  molten  steel  vertically  into  the  moulds,  thus  compensat- 
ing for  any  irregularity  in  the  shape  of  the  nozzle.  It 
might  be  thought  well  to  provide  the  ladle-trunnion  with  a 
whole  worm- wheel  instead  of  only  a  sector  of  one,  as  shown, 
so  that  in  case  the  steel  chilled  in  the  nozzle  of  the  ladle  it 
could  be  poured  out  over  the  upper  edge,  lest  it  freeze  into 
a  solid  unmanageable  mass.  In  this  case,  however,  it  is  less 
easy  to  invert  the  ladle  after  teeming,  so  as  to  pour  out 
the  slag. 

The  Nozzle  is  stopped  by  a  graphite  or  fire-clay  plug  or 
"stopper,"  keyed  to  the  end  of  an  iron  stopper-rod,  as 
shown  in  Figure  220.  This  rod  may  be  covered  with  a 
sleeve  of  annular  fire-clay  bricks,  or  it  may  be  coated  with 
a  plastic  mixture  of  fire-clay  and  sand  and  then  baked. 
Examples  of  the  proximate  composition  of  such  mixtures 
are  given  in  Table  202,  and  of  the  ultimate  composition  of 
fire-clay  nozzles  in  Table  200.  The  stopper-rod  coat- 
ings are  generally  richer  in  fire-clay  than  the  "  ball-stuff'' 
and  other  refractory  mixtures  used  in  the  Bessemer  process, 
and  are  applied  to  the  stopper-rod  in  a  very  soft  state. 
After  baking,  the  drying  cracks  are  plastered  over. 

It  is  important  that  the  stopper  should  fit  the  nozzle 
closely.  We  adjust  the  stopper-rod  in  one  direction  by 
turning  it  in  the  socket  6,  and  then  clamping  it  with  the 
hand-screw  c.  To  adjust  it  in  the  other  direction  Holley's 
ingenious  device  is  used1.  In  this  the  stopper-rod  is  a 
usual  raised  and  lowered  by  the  lever/,  but  the  guide  h, 
in  which  the  sliding-bar  #  plays,  instead  of  being  fastene' 


rigidly  to  the  shell  of  the  ladle,  rests  by  its  trunnions  s 
on  a  casting  ii  which  is  riveted  to  the  ladle.  By  means 
of  the  hand-screws  dd  the  sliding-bar,  and  through  it  the 

topper-rod,  can  be  rocked  about  the  trunnions  to  adjust 
the  stopper.  The  guide  h  is  then  clamped  by  <ld. 

The  stopper  thus  adjusted,  the  hand-screw  e  clamps  the 
sliding-bar  down  till  teeming  begins,  lest  the  molten 
metal  buoy  up  the  stopper-rod  and  allow  the  steel  to 

iscape  through  the  nozzle.  It  is  well  to  make  the  stopper- 
rod  straight,  as  shown,  lest  its  expansion  when  heated  by 
the  metal  uncenter  it,  as  may  happen  with  the  bent 
stopper-rod  shown  in  dotted  lines. 

The  Linings  of  ladles  for  carrying  direct-metal  from 
the  blast-furnace  to  the  vessels  should  be  thick  to  diminish 
the  loss  of  heat  during  the  transit,  and  especially  in  winter. 
They  are  usually  of  fire  brick. 

The  steel-ladles  should  have  as  light  a  lining  as  practi- 
cable, as  their  weight  must  be  supported  at  arm's  length  by 
the  casting-crane.  Formerly  lined  with  a  more  or  less 

layey  mixture,  and  even  now  in  some  European  works 
with  three  inches  of  fire-brick,  in  this  country  they  are 
almost  if  not  quite  always  lined  with  moulding  sand 
about  as  moist  as  in  common  foundry  moulding.  After 
lining,  the  ladle  must  be  thoroughly  dried,  and,  especially 
in  case  of  soft  steel,  well  heated.  This  was  formerly  done 
by  inverting  the  ladle  over  a  coke  fire,  or  by  a  coke  fire 
within  it,  blown  with  a  gentle  blast.  A  better  way  to 
dry  the  ladles  is  that  already  shown  in  Figure  215  for 
bottoms.  The  composition  and  life  of  some  ladle-linings 
is  given  in  Table  202. 

TABLE  203.— MIXTURES  or  REFRACTORY  MATERIALS  FOR  APPARATUS  FOR  THE 
BRSSEMBI:  PROCESS. 


Works. 

Weight  of  Charge,  tons. 

Kind  of  product. 

Proximate 
Composition. 

Life. 

Life 

Cupola 
Liuin.;. 

Fire-sand. 

Moulding-sand. 

K 

\ 

5" 

Loam-sand. 

Fill  Chiv. 

a 
B 

• 

as 
0-j 
*| 

I 

Period  covered. 

1 

ft 

V 

:i 
? 

8. 
U 

y 

ou 

American 

6@7 
8 
9.2 
5  5 
4 
7 

1^ 
7H 

6 
10 

6@7 
10 
7@B 

TX 

Rail-stee 
Soft-stee 
Rail-stce 

100    . 
100    . 

40®  50 

25 

10 

SW.  1C) 

1887 

**         < 
*         ( 

Seraing 
American  < 

American  d 
"         ( 

100    . 
100    . 

100 

* 

40 

1872 
1872 

1888 
1887 

32 
15 

i 

'i 

!» 

:il 
ire 

li 

-Y. 

h 

....  a 

...  6 

rick 
g 

D  
8  
j  Sides     50 
•    |  bottom  25 
2  35 

Rail-stee 

STOPPER-SLEEVES. 

"•^  "V" 

100 

"-2.5 

5 

3@4 

•"i 

H 

—  ~x* 

..  4 

3           

187° 

9.2 

7M 
10 
10 

7 

7@. 
9.2 
10 
10 
6®7 
8 
5.5 
4 

* 
Soft-etee 

ii 

....  4 

1  
2  5 

isr. 

1SS.S 

1SS7 
188h 
18* 
188? 

1888 

ISS- 

iss- 

i  st- 
un 

3. 

1.99 

3.25 

CDPOLA-LININOS.  .  . 

4 

2 
5 
4 
7.11 

8  

•• 

•;...  r> 

'*}' 

3 
3 

7M 
210 
600 

». 

K 
fit 
S 
I 

B 

(i- 

..  1 
i 

ui 

!;il 

1-s 

-K 

17    I 
-one 
uffi 

7 

d  Direct-metal  is  nsed,  t.  e.,  cast-iron  direct  from  the  blast-furnace,  while  slill  molten. 

Our  loam-sand  ladle-linings  are  so  trustworthy  that, 
visiting  one  American  mill  fourteen  years  after  it  started, 

j  U.  S.  Patent  86,303,  Jan.  20th,  1869.     A.  L.  Holley. 


360 


THE    METALLURGY    OF    STEEL. 


Fig.   lit.      CASPKRSSON'8  CONVERTER- 

LADLB.    AKERHAN. 

A.  Entrance  to  ladle.  B.  Nose  of  conver- 
ter. C.  Bar  (or  lifting  stopper.  D.  Ladle 
proper.  E.  Nozzle. 


I  found  all  the  original  ladles  still  in  use.  I  was  informed 
thnt,  during  all  this  time,  there  had  been  but  four  cases  ir 
which  a  ladle  had  burnt  through. 

§  410.  CASPERSSON'S  CONVERTER  LADLE™  aims  to 
diminish  the  loss  of  heat,  and  consequent  formation 
scrap  and  skulls,  which  occurs  when  small  charges  of  soft 
steel  are  poured  from  the  vessel  into  a  common  casting- 
ladle,  by  diminishing  the  size  of  the  ladle,  and  by  allow- 
ing any  given  particle  of  steel  to  remain  in  it  but  a  few 
minutes.  The  ladle  DDD,  Figure  222,  is  luted  and  firmly 

keyed  to  the  month  of  the  ves- 
sel, after  the  latter  has  been 
turned  down  at  the  end  of  the 
blow.  No  recarbtirizer  is  used 
at  Westanfors  where  the  con- 
verter-ladle is  in  use.  If  the 
charge  were  to  be  recarburized, 
it  would  have  to  be  mixed  be- 
fore attaching  the  converter- 
ladle  by  rabbling,  by  turning 
the  vessel  up  for  a  few  seconds, 
or  otherwise. 

After  attaching  the  ladle  five 
minutes  are  allowed  for  the 
luting  to  dry,  and  then  the  vessel  is  turned  a  little 
lower  so  as  to  let  a  little  steel  run  into  the  ladle.  This  is 
purposely  made  very  small  so  as  to  abstract  as  little  heat 
as  possible  from  the  metal.  Indeed,  most  of  the  metal  is 
held  back  at  first  in  the  extremely  hot  and  thick-walled 
converter,  and  only  runs  gradually  into  the  ladle,  passing 
rapidly  through  it  into  the  moulds. 

On  raising  the  stopper  by  means  of  the  stopper  rod,  C, 
the  metal  runs  through  the  nozzle  of  the  ladle  into 
moulds  standing  on  a  turn-table,  which  brings  them  in 
succession  beneath  the  ladle. 

Before  teeming  begins  the  tuyere-box  must  be  opened, 
e.g.,  by  removing  the  lid  N,  Figure  204,  so  that  air  may 
enter  the  vessel  to  take  the  place  of  the  steel  that  runs 
out;  but  for  this  the  air  would  bubble  in  through  the 
ladle,  interfere  witli  teeming,  and  cool  the  metal. 

The  small  size  of  the  ladle,  and  the  short  stay  of  the 
steel  in  it,  give  us  a  higher  casting- temperature  for  given 
temperature  of  blow,  an  important  thing  especially  when 
small  ingots  of  soft  steel  (ingot-iron)  are  to  be  cast.  As  the 
steel  is  hotter  there  is  less  danger  of  it  _,  freezing  in  the  noz- 
zle, and  thus  causing  scrap  by  preventing  the  stopper  from 
shutting  off  the  stream  as  we  pass  from  mould  to  mould  ; 
this  is  especially  important  in  case  of  very  soft  steel,  in 
casting  which  we  have,  in  common  practice,  to  pass  back 
and  forth  repeatedly  to  fill  the  mould  with  the  foaming 


m  Akerman,  Jour.  Iron  and  St.  Inst.,  1880,  II.,  p.  599  ;  1881,  I.  p.  36  ;  Hardisty, 
Idem,  1886,  II.,  p.  662. 


metal.  Freezing  in  the  nozzle  also  roughens  the  ingots, 
by  making  the  metal  squirt  against  the  side  of  the  moulds, 
into  which  it  cuts,  and  against  which  it  freezes  in  lumps 
which  may  not  later  unite  completely  with  the  rest  of  the 
ingot. 

Moreover,  we  can  safely  pour  the  hotter  steel  more 
slowly  without  incurring  risk  of  its  chilling,  and  the 
small  depth  of  metal  in  the  ladle  causes  the  steel  to  rush 
less  rapidly  through  the  nozzle.  The  thinner  and  slower- 
falling  stream  cuts  the  bottoms  of  the  moulds  less ;  causes 
less  foaming,  both  because  of  the  slower  arrival  of  the 
metal  and  because  less  air  is  dragged  down  ;  and  thus  en- 
ables us  to  fill  the  mould  at  a  single  pouring,  instead  of 
going  back  and  forth  from  mould  to  mould.  Thus  more 
solid  ingots  are  obtained,  and  we  avoid  the  surfaces  of 
imperfect  union  which  often  occur  when  an  ingot  is  filled 
by  several  separate  additions  instead  of  at  one  pouring. 

In  Sweden  the  use  of  this  device  seems  to  have  reduced 
the  proportion  of  scrap  materially.  Akerman  reports 
the  results  condensed  in  Table  203. 


TABLE  803.— EFFECT  OF  CASPEUSSON'S  COSVEUTER-LAULB  is  REDUCING  THE  PROPORTION  of 
CASTING-SCRAP,  ETC.    AKERMAN. 


Works. 


Westanfors 

Westanfore 
Bjorneborg 

Nykroppa. . 


Kind  of 
Steel  Made. 


(Ingot  iron,  / 
225  t-:ini?ol-V 
steel,  78;:— .\ 


t  Ingot-iron.. 

)  I  n<,'Ol-*teel . 
Kt  of  ingot- 
iron,  15*  of 
ingot-steel. 


Period. 


1S78 
20     / 

W,-rk.x  > 

1880    ) 


Per  100  of  Cast-iron  (Direct-metal) 
treated,  there  resulted 


Clean 

ingot*. 


Scrap 


Without  the  With  the 

converter-ladle,    converter-ladle 


The  *  of 
ingots  in- 
creased 
by 


84.48 


83 

86®  87 

88.74 


U.  W 


3.4 


88.11 

88  b 

87. 25 ± 
89. 5± 

89.58 


On  using  the 
converter-ladle. 


The*  of 
scrap 

decreas- 
ed by 


3.G3a 


4.25a 
3±a 


O.SJa 


a  Per  100  of  cast-iron  blown. 

b  This  number  is  given  as  80  in  the  original,  but  apparently  incorrectly.     I  believe  that  88 
la  the  right  number. 


If (i  ins  worth"  would  accomplish  results  like  those  at- 
tained by  the  converter-ladle,  by  pouring  the  steel  from 
the  vessel  into  a  deep,  stopperless  runner,  which  dis- 

harges  into  the  moulds,  preferably  through  an  inter- 
mediate stopperless  funnel  which  has  several  nozzles,  one 
over  each  mould.  The  runner  and  the  moulds  are  carried 
by  vertical  hydraulic  plungers,  so  that  as  the  vessel  turns 
down  lower  and  lower  in  pouring,  they  may  sink  and 
follow  its  travel.  The  flow  of  metal  is  thus  regulated 
wholly  by  turning  the  vessel  down  faster  or  slower,  and 
by  changing  the  inclination  of  the  runner,  which  to  that 

nd  is  mounted  on  trunnions.  It  may  have  a  dam  for 
liolding  the  slag  back,  but  in  spite  of  this  one  anticipates 
that  the  last  part  of  the  metal  will  be  accompanied  by 
slag. 


n  U.  8.  Patent  284,005,  Aug.  38th,  1883. 


MANGANESE-STEEL.       §  413. 


361 


APPENDIX     I. 

SPECIAL  STEELS. 


MANGANESE  STEEL."— Since  §86,  p.  48,  was  writ- 
ten, Hadfield's  extremely  important  papers  on  manganese- 
steel  have  very  greatly  increased  our  knowledge  of  this 
remarkable  substance,  discovered  by  him  ;  yet  much  re- 
mains to  be  learnt. 

Briefly,  manganese-steel  of  the  best  composition,  with 
say  14$  of  manganese  and  not  more  than  \%  of  carbon,  is 
very  fluid  ;  solidifies  rapidly  and  with  great  contraction  ; 
does  not  form  blow-holes,  but  pipes  deeply  ;  does  not 
seem  subject  to  segregation ;  is  forgeable,  but  welds 
poorly  if  at  all.  Naturally  brittle,  only  moderately 


but  is  rapidly  made  brittle  by  cold-work,  ductility  being 
restored  by  reheating  and  quenching  ;  does  not  recalesce 
during  cooling;  its  density  (sp.  gr.  7  63  for  manganese 
13-75),  modulus  of  elasticity  and  (apparently)  its  rate  of 
corrosion  are  about  the  s;uue  ;is  those  of  common  iron  ;  its 
electric  resistance  is  enormous,  thirty  times  that  of  copper 
and  eight  times  that  of  wrought-iron,  but  thrice  as  con- 
stant with  varying  temperature  as  that  of  iron  ;  it  can  be 
magnetized  very  considerably  temporarily,  but  only  with 
most  extreme  difficulty,  and  hardly  at  all  permanently. 
Now  to  examine  some  of  these  points  in  more  detail. 


TABI.K  206.— MANOASKSI-STEEI.,  FOKOKII.— Hodflold. 


NOMBEBS. 

Competition. 

Physical  properties. 

c. 

Si. 

Mil. 

P. 

8. 

ID  the  "natural  state." 

Air-toughened. 

Oil-toughened. 

Water-toughened. 

Tensile  strength, 
Ibs.  per  sq.  in. 

Elongation  %  in 
8  inches. 

Contrnclion  of 
area*. 

Tensile  strength, 
IbB.  per  sq.  in. 

Elongation  :  in 
S  inches. 

Tensile  strength, 
Ibs.  per  sq.  in. 

Elongation  %  in 
8  inches. 

Tensile  strength, 
Ibs.  per  sq.  in. 

Elongation  f  in 
8  Inches. 

Contraction  of 
area  %. 

1... 

•20 
•40 
•40 

•52 
•47 

•03 
•15 
•09 
•37 
•44 

•83 
2-80 
8-89 
6-95 
7-22 
7-50 
7  90 
9-15 
9-20 
9-37 
10-11 
10-60 

•09* 

.« 

*or>± 
u 

73,920 
125,440 
85.120 
56,000 
60,480 
87,860 

31 
6 
1 
2 
2 
4 

46 

7 

47,040 
00,480 

62,720 

2 
5 

8 

42,560 
56,000 

67,200 
94,080 

85.120 
91,840 
94,080 

2 
8 

7 
17 

15 
20 
19 

51,520 
56,000 

87,860 

89.600 
(        108,040  a 

\       112,000  a 

|        118,720  a 

1        141,120 
\        148,860 
/        145,600 
120,960 

186,640 
(        148,860 
\        143,860 
|         147,840 
186.640 
\        143,860 
145,600 
150,080 
154,560 
156,800 
141,120 
136.640 
118,720 
123,200 
132,160 

2 
2 

15 

17 
22  a 
25  a 
29o 

45 
46 
50 
27 

87 
45 
45 
49 
48 
50 
51 
446 
46    1 
40    f 
87 
81 
10 
5 
4 

8T 

2 

S  

4..  . 

B 

6... 

9 

7                  

•50 

i-oo 

•28 
•42 

8 

9... 

89,600 
73.920 
85,120 
76,160 

6 
5 
5 
4 

10 

85,120 
87.360 
91,840 

1C 
14 
17 

10 

•61 
•95 

•85 

•80 
•21 
•28 

11 

12 

13 

14 

•72 

•37 

10-88 

" 

*i 

15  

16... 

87,360 

4 

8 

17     . 

IS 

•85 

•87 

12  ".'9 

" 

** 

19 

20 

no 

•16 

12-60 
12-70 
12-81 

M 

« 

87,360 
105,280 
87,860 

2 
6 
5 

82,880 
107,520 

11 
20 

112,000 
129,920 

28 

82 

21... 

22... 

•92 

•42 

23 

24 

•85 

•*3 

13-75 

'• 

*• 

25 

26 

27 

•85 

•28 

13-75 

* 

** 

28 

29 

•85 
1-15 
1-15 
1-10 
1-24 
1-54 
1-83 
1-60 
1-90 
2-10 

•28 
•84 
•84 
•82 
•16 
•16 
•26 
•26 
•32 
•46 

14-01 
14-27 
14-27 
14-4.S 
15-06 
18-40 
18-55 
19MO 
19-98 
21-69 

" 

• 

80,640 

2 

107,520 

14 

123,200 

27 

3D 

81 

32 

87,860 
109,760 
114,240 
96820 
116,480 

1 

2 

1 
1 

1 

109,760 
105,280 
87,360 

5 
2 
1 

33 

84 

35 

36 

91,840 

1 

87 

51,520 
73,920 

0 
11 

88 

80,640 

9 

76,160 

12 

*'  Natural  state"  means  that  the  metal  was  simply  cooled  slowly  after  forging  ceased. 

*'  Air-toughened"  means  that,  after  cooling,  it  was  reheated  to  a  yellow  heat  and  allowed  to  cool  slowly  in  the  air. 

"  Oil-toughened"  and  "  water-toughened"  mean  that,  after  forging,  it  cooled  blowly,  was  then  heated  to  a  yellow  heat,  and  quenched  in  cold  oil  or  water. 

The  fractures  of  bars  with  from  :J  to  9%  of  manganese  were  always  coarae  and  granular  :  those  of  bars  with  more  than  %  of  manganese  which  had  been  water- toughened  were  silky  ana  fibrous. 

The  contraction  of  area  of  the  water-toughened  pieces  is  usually  from  30  to  40£. 

O  Lowest,  highest  and  average  results  of  twelve  tests. 

b  This  piece  is  still  unbroken.     Had  field,  Journ.  Iron  and  Steel  Inst.,  1888,  II.  ;  Excerpt  Proc.  Inst.  Civ.  Eng.,  XCIII.,  III.,  1888,  p.  40  et  seq. 


strong,  and  with  very  low  elastic  limit,  it  is  made  extreme- 
ly tough  and  very  strong  and  (under  impact)  stiff  by 
quenching  from  whiteness,  which  neither  cracks  small 
bars  of  it,  changes  its  fracture  (which  before  forging  is 
strongly  crystalline),  nor  greatly  raises  its  elastic  limit ; 
this,-  however,  is  greatly  raised  by  cold-stretching,  only  to 
fall  on  reheating.  Test-bars  stretch  nearly  uniformly,  like 
brass,  instead  of  necking  like  iron.  It  is  so  hard  that  it 
can  barely  be  machined,  but  is  slightly  softened  by  sud- 
den cooling  from  very  dull  redness  (V)  ;b  is  not  brittle  at 
blueness,  nor  (apparently)  made  brittle  by  blue-work, 


a  Journ.  Iron  and  Steel  Inst.,  1888.  II.  ;  Proc.  Inst.  Civ.  Eng.  XCIII.,  III.,  1888. 
U.  S.  Patents  303,150-1 :  British  Patents  200  of  1883,  and  8,263  and  16,049  of  1884. 

b  It  has  been  stated  that  manganese-steel  is  greatly  softened  by  water-quench- 
ing. This,  however,  is  an  eiror.  Mr.  Hadfleld  informs  me  that  water-quenching 
makes  It  more  pliable,  but  changes  its  hardness  as  measured  by  indentation,  etc., 
very  little. 


While,  as  already  pointed  out,  the  effect  of  small  pro- 
portions of  manganese  on  the  strength  and  ductility  of 
steel  is  probably  slight,  that  of  higher  proportions  is 
astonishing.  Beginning  at  some  point  now  unknown,  but 
probably  at  about  2  '5$,  further  increase  of  manganese 
diminishes  both  strength  and  ductility,  while  conferring 
remarkable  hardness.  This  effect  reaches  a  maximum 
when  the  manganese  has  risen  to  somewhere  between  4 
and  6$.  With  further  increase  the  strength  and  tough- 
ness both  increase  while  the  hardness  diminishes  slightly, 
the  maximum  of  both  strength  and  toughness  being 
reached  with  somewhere  about  14$  of  manganese,  the 
hardness  still  remaining  so  high  that  the  metal  can  hardly 
be  machined. 

As  the  manganese  rises  above  I5f0  the  ductility  falls  off 


362 


THE    METALLURGY    OF     STEEL. 


abruptly,  the  tensile  strength  remaining  nearly  constant 
till  the  manganese  passes  20$,  when  it  in  turn  falls  off 
quickly.  The  effect  of  these  high  proportions  of  man- 
ganese is  obscured  by  that  of  the  accompanying  carbon, 
which  rises  unavoidably  with  the  manganese. 

Steel  containing  from  4  to  6.5%  of  manganese,  even  if 
it  has  only  0'37$  of  carbon,  can  be  powdered  under  j 
a  hand-hammer,  yet  it  is  extremely  ductile  when  hot. 
With  11%  of  manganese  the  metal  after  heat- treatment 
has  an  elongation  of  22%  and  a  tensile  strength  of  about 
110,000  pounds  per  square  inch,  while  with  about  14%  of 
manganese  we  have  51%  of  elongation  in  8  inches  and  a 
tensile  strength  of  145,  COO  pounds  per  square  inch.  This 
combination  of  strength  and  elongation  is  far  greater  than 
any  other  which  I  have  met,  better  even  than  that  of 
nickel-steel,  with  the  exception  of  one  reported  instance 
of  25$  nickel-steel :  and  I  do  not  know  how  trustworthy 
is  the  authority  which  gives  this  case. 

Manganese-steel  wire  is  reported  with  a  tensile  strength 
of  246,000  pounds  per  square  inch.  This,  while  good,  is  by 
no  means  remarkable,  as  wire  with  344, 960  pounds  tensile 
strengthhas  already  been  described.  (Foot  note  to  page  33.)  [ 


the  strongest  and  toughest  group  of  manganese-steels. 
Beyond  these  limits  the  influence  of  heat- treatment  on 
tensile  strength  is  not  very  clearly  traceable  in  Hadfield'  s 
results,  but  its  influence  on  ductility  persists  till  the  man- 
ganese reaches  about  18%. 

Within  these  limits  reheating  manganese-steel  forgings 
to  whiteness  svith  slow  cooling  usually  increases  strength 
and  ductility  wonderfully,  while,  if  quenching  be  sub- 
stituted for  slow  cooling,  the  increase  of  strength  and 
ductility  is  simply  marvelous,  tensile  strength  being 
sometimes  nearly  doubled,  and  elongation  jumping  from 
2  to  44^  in  one  case. 


TABLE  207.— PKOPEETIES  OFM  »M;  .NKSE  STKKI.  AS  AFFECTED  itv  RAPIDITY  OF  COOLING. 

IViisih-  .strength,  pounds         Klongation, 
per  square  inch.  %  in  8". 

58  32-8 

57  to  C8  89-8  to  50 


Quenched  in  water  at  202"  P 
72°  F 


sulphuric  acid . 


507 


These  effects  may  be  traced  in  Table  206,  in  which  we 
note  that,  within  the  above  limits  of  composition,  oil- 
quenching  gives  better  results  than  air-cooling,  and  water- 
quenching  gives  better  still :  while  Table  207  indicates 
that  cold  water  is  a  better  quenching-medium  than  hot, 
and  that  sulphuric  acid,  represented  as  a  still  better  con- 
ductor, is  better  yet. 


SCALE  OF  TONS  PEB  80.  INCH 
0  c.  S  S  8  8  8 

Fig.  226 

TESTED  AS  FORGED 

SCALE  OF  TONS  PER  8Q.  INCH 
0  C*  S  g  8  £  £ 

Fig.  227                                                                             Fig.  228 

HEATED  AND  OOOLED  IN  AIR                                                                 WATER  TOUGHENED 

C      -&X 
Si.    -.13* 

Mn.-  12.65*  E, 

, 
jjjgBB 

EXT 

ENSION 

Si.   -',f3# 

o  -xi% 
SI.  -JM 

Mn.-12^5^ 

Si 

/ 

f 

X 

r 



ERMAN^ 

NTJ2. 
^.-  * 

TMJS 

ENSION_ 

_ 

5 

z 

/ 

fc 

PERM* 

—  .         — 

^g2 

4ENT  SET           __ 
—               p 
^XTENS10N_ 

—      — 


1 

/ 

>F  TONS  PER  SQ. 

;  S  t 

^ 

'  4 
& 

/ 

/ 

#/ 
w/ 

/ 

/ 

/Bre; 

kingL 

Eh 

oad37 
ngatio 

Tons 
n  8.0 

aer  sq. 

Inch 

/ 

/Bre 

iking  I 
Elo 

oad  45  Tons 
rigatlon  26%  c 

persq 
n8' 

inch 

I 

3 
I 

'/Bre 

aking  Load  5( 
Elongatior 

Tons 
38^o 

persq 
n8' 

inch 

/ 

/ 

1 

0 

/ 

.005        .010        .015 


.035       .0         .005        .010        .015 
EXTENSIONS  IN  INCHES 


.025        .030    .    .035        .0         .005        .010        .015        .020        .025        .030 
EXTENSIONS  IN  INCHES 


MANGANESE-STEEL  UNDER  TENSILE-STRESS  (HADFIELD). 


Manganese-steel  is  benefited  by  forging,  and  some  varie- 
ties of  it  are  improved  wonderfully  by  heat-treatment. 

Forging  destroys  the  very  marked  crystallization  of  un- 
forged  manganese-steel  castings,  and  according  to  Hadfield 
increases  their  strength  and  ductility :  but  he  gives  us  no 
quantitative  data  on  this  point,  as  his  transverse  tests  of 
the  cast  metal  and  the  tensile  tests  of  the  forged  are  not 
readily  comparable.  Indeed,  the  "natural  state,"  i.  e. 
unquenched  forgings  of  Table  206  seem  surprisingly  brit- 
tle. Even  when  containing  as  much  as  21  '69$  of  manga- 
nese and  2'1%  of  carbon,  manganese-steel  can  be  forged. 
But  the  engineers  of  Chatillon  et  Commentry,  where  man- 
ganese-steel was  tried  for  making  armor-plates,  report  that 
even  when  hot  it  is  so  extremely  hard  that  the  difficulty 
of  forging  it  is  prohibitory.  If  manganese-steel  ingots 
are  heated  too  strongly,  they  burst  in  forging. 

Heat- Treatment. — Both  castings  and  forgings  are 
strengthened  and  toughened  by  heating  to  a  yellow  or, 
better,  to  a  white  heat,  especially  if  then  suddenly  cooled. 
The  higher  the  temperature  (probably  provided  this  is  not 
above  bright  whiteness),  and  the  more  sudden  the  cooling, 
the  more  is  the  metal  benefited. 

The  effect  of  heat-treatment  on  the  tensile  strength  and 
ductility  of  forgings  is  very  marked  in  case  of  steel  con- 
taining from  about  12  to  about  15%  of  manganese,  i.  e. 


Indeed,  it  seems  quite  necessary  to  quench  manganese- 
steel  rapidly  in  order  to  give  it  any  considerable  value. 
Fortunately,  pieces  of  moderate  size  do  not  crack  on 
quenching:  but  in  attempting  to  quench  large  pieces  such 
as  armor-plates,  in  which  the  quencliing-stresses  would 
naturally  be  much  greater  than  in  small  ones,  Chatillon 
et  Commentry  found  great  liability  to  crack. 

The  improvement  caused  by  quenching  is  partly  lost  on 
subsequent  heating  followed  by  slow  cooling,  such  for 
instance  as  usually  occurs  after  forging  has  ceased.  Hence 
it  is  usually  loosely  stated  that  the  improvement  caused 
by  quenching  is  removed  by  subsequent  fogging :  but  Mr. 
Hadfield  informs  me  that  his  experience  indicates  that  it 
is  riot  the  forging  as  such  that  injures  the  metal,  but  the" 
slow  cooling  which  habitually  follows  forging  (Cf.  §  54 
A,  p.  34).  The  injury  due  to  slow  cooling  may,  however, 
be  removed  by  again  quenching  from  whiteness.  Still,  the 
matter  is  obscure :  for  in  this  view  it  is  hard  to  explain 
why  manganese-steel  forgings  are  improved  by  heating  to 
whiteness  and  cooling  slowly. 

Heating  and  quenching,  however,  instead  of  increasing 
seems  rather  to  lower  the  elastic  limit,  already  unfortun- 
ately low,  and  it  is  possible  that  it  may  thus  injure  rather 
than  benefit  the  metal  for  many  important  purposes  (Cf. 
Figures  226-8). 


MANGANESE-STEEL.       §  413. 


36a 


Under  stress  manganese-steel  acts  very  differently  from 
wrought-iron  and  carbon-steel.  As  Figure  '228  shows, 
manganese-steel  with  125,000  pounds  (56  tons)  tensile 
strength  may  begin  taking  serious  permanent  set  under 
stress  of  about  35,000  pounds  per  square  inch,  so  that  in 
this  respect  it  is  little  better  than  common  soft  steel  with 
say  60,000  pounds  tensile  strength. 

Moreover,  the  enormous  elongations  reported  may  be 
found  later  to  have  given  a  greatly  exaggerated  notion  of 
the  metal's  ductility.  A  test-bar  of  iron  or  carbon-steel 
undergoes  a  certain  amount  of  elongation  over  its  whole 
length,  but  much  of  its  elongation  occurs  just  at  and  near 


it  may  be  better,  for  others  worse,  that  the  elongation 
should  be  distributed  as  in  manganese-steel  rather  than 
concentrated  as  in  carbon-steel.  But,  while  we  may  dis- 
pute whether  the  toughness  of  manganese-steel  of  25#  of 
elongation  is  on  the  whole  greater  or  better  rather  than 
less  or  worse  than  that  of  carbon-steel  of  like  elongation, 
the  important  point  is  that  it  is  a  different  toughness, 
which  does  not  necessarily  tit  the  metal  for  the  purposes 
to  which  carbon-steel  of  25$  elongation  is  properly  put. 

Thus,  Stromeyer  found  that  manganese-steel,  whose 
elongation  under  tensile  stress  led  him  to  expect  that  it 
could  be  bent  back  and  forth  many  more  times  before 


TABLE  208.— MANGANESE-  AND  SILICO  MANGANESE  STEKL  SHOWN  AT  PARIS  BY  HOLTZER.    (Cf.  8  86,  p.  48.) 


Number.  1 

if 

•ss 
^ 

Tensile  strength,  pounds  per  square  inch. 

Elastic  limit,  pounds  per  square  inch. 

Elongation,  %  in  7-9". 

Contraction  of  area,  ;f  . 

Natural  state 
(torged). 

Oil  hardened  and 
tempered. 

Oil-hardened  and 
annealed. 

Natural  state 
(torged). 

Oil-hardened  and 
tempeml. 

Oil-hardened  and 
annealed. 

Natural 
state. 

Oil-hard- 
ened and 
tempered. 

Oil-hard- 
ened and 

;miif.-i].'il. 

Natural 
•tate, 

Oil  hard- 
ened and 
tempered. 

Oil-hard- 
ened and 

:mn<  :tlr<l. 

1.. 

•20  @-30 

[        88,488 

42,668 

22 

42 

146,210 

109,230 

12-5 

45 

\  .:: 

112,075 

91,026 

18 

38 

2.. 



j         87,612 

49,210 

14 

149,197 

110,227 

11-8 

46 

"46"' 

131,  184 

98,706 

10 

s 

(         97,710 

46,866 

20-8 

42 

164,175 

119,756 

8'5 

36-5 

j  

161,571 

129,285 

18 

40 

4.. 

j         107,882 

57,083 

16 

85-5 

163,277 

188,409 

10 

41 

141,232 

122,600 

11-8 

43-5 

6.. 

\         102  546 

57,033 

19 

51 

176,651 

146,211) 

7-5 

81 

154,175 

138,409 

8-5 

45 

6.. 

10  db 

I          98,706 

55,042 

28'5 

49-2 

176,868 

155,882 

8 

81 

j  

148,201 

121,605 

11-5 

40 

7.. 

12®  14 

1          119,681 

58,882 

29 

26 

122,316 

61,869 

i  

28 

28-5 

1  

137.107 

52,908 

41-5 

86-5 

8.. 

f          51,202 

88,970 

86 

73 

87,828 

63,575 

15 

76 

68,553 

52,197 

24-5 

72-5 

9.. 

(          96,572 

47,219 

14 

21 

189,098 

19,200 

10-5 

42'2 

"'46' 

128,289 

100,555 

11-2 

10.. 

(        91,026 

44,517 

21-5 

42-S 

159,580 

118,760 

13 

88-5 

138,409 

104,538 

10-5 

46 

U.. 

2± 

92,021 

47,504 

23 

50'5 

161,571 

139,098 

10 

88-5 

146,210 

121,605 

12  5 

46 

The  "  natural  state  "  pieces  are  simply  cooled  slowly  after  forging. 

The  oil-hardened  and  tempered  pieces  are  quenched  in  oil  from  ahont  W,  a  low  yellow,  and  slightly  reheated. 
The  oil-hardened  and  annealed  pieces  are  similarly  quenched,  then  reheated  to  very  dull  redness,  say  V,  and  cooled  slowly. 

It  is  possible  that  the  labels  of  tempered  and  annealed  pieces  have  been  misplaced  in  the  show-case  in  certain  Instances.    In  Number  8  I  have  transposed  them,  feeling  confident  that  they  haye 
been  thus  misplaced. 

The  compositions  given  are  only  rough  guesses  made  at  my  request  by  M.  Brustlein. 


the  point  of  rupture,  where  the  metal  "necks."  It  is 
owing  to  this  that  the  percentage  of  elongation  of  short  iron 
test -bars  is  so  much  greater  than  that  of  long  ones.  Man- 
ganese-steel, however,  like  brass,  stretches  more  nearly 
uniformly  over  its  entire  length,  without  much  necking.  Its 
elongation  would  exceed  that  of  equally  strong  carbon-steel 
much  less  if  measured  over  a  length  of  £th  inch  than  if, 
as  now,  measured  over  8  inches.  Now,  elongation  is  in- 
deed an  index  of  toughness  and  ductility :  but  the  relative 
toughness  of  different  metals  under  given  conditions  can 
be  safely  inferred  from  their  elongations  only  when  those 
elongations  occur  in  like  manner.  For  certain  conditions 


rupture  than  wrought-iron  and  carbon-steel,  was  actually 
rather  brittle  when  tested  in  this  way,  enduring  only  7 
bendings  when  in  its  natural  state  and  from  10  to  18  after 
quenching  from  redness,  while  wrought-iron  and  carbon- 
steel  endured  in  four  cases  20,  26,  12-5  and  21  bends. 

Again,  the  results  in  Table  209  show  that,  while  the 
shock-resisting  power  of  manganese-steel  of  12 '55$  of  man- 
ganese is  much  greater  than  that  of  the  best  carbon  axle- 
steel  with  which  it  was  compared,  yet  in  spite  of  its  enor- 
mous elongation  under  static  tensile  stress,  its  ultimate 
deflection  on  rupture  tinder  transverse  shock  is  less  than 
half  as  great  as  that  of  the  carbon-steel. 


304 


THE    METALLURGY    OP    STEEL. 


As  the  elastic  limit  and  modulus  of  elasticity  of  man- 
ganese-steel are  low,  while  its  permanent  set  seem  to 
increase  at  normal  rate  under  increasing  load,  its  stiff- 
ness under  shock  is  a  little  puzzling.  We  have  here 
another  instance  of  the  discrepancies  between  ductility 
under  static  stress  and  under  shock. 


TABLE  209.  —  EFFECT  OF  TRANSVERSE  SHOCK  ON  MANOANESI-  AND  CAEBON-STEEL  (HADKIELD). 

Energy  de- 
veloped in 

foot  tons. 

Sum  of  permanent  deflections,  Inches. 

Special  carbon-stet-1  axle. 

Manpanese-steel  axle. 

At  the    5th  blow 

79-883 
208-581 

848-591 
49T-988 

•24'95.'i 
66-188 
(  105-248 
1  broke. 

8-501 
19-403 

j.  80-212 

j  39-491 
'I  broke. 

"      10th    "     

"      15th    "     

"      20th    "        

Bars  4J"  in  diameter  and  4'  6" 
and  reversed  after  each  blow. 

ong,  on  bearings  8  feet  apart,  were  struck  by  a  20'75-cwt.  ram, 

Cold-worMng  influences  manganese-steel  greatly.  Thus 
in  drawing  wire  it  is  found  necessary  to  anneal  the  metal 
by  quenching  from  whiteness  after  every  two  draughts. 
As  in  case  of  iron  and  carbon-steel,  the  stretching  which 
occurs  in  tensile  testing  raises  the  elastic  limit  so  that 
when  again  tested  it  equals  the  maximum  stress  previously 
applied  (Of.  §  270,  p.  213),  e.  g.  while  the  first  application 
of  a  stress  of  50,000  pounds  per  square  inch  gives  a  strong 
permanent  set,  no  farther  set  arises  on  repetition  of  this 
same  stress.  But,  unlike  that  of  iron  and  of  carbon-steel, 
the  elastic  limit  of  manganese-steel  in  the  f riw  cases  which 
have  been  described  declines  instead  of  rising  during  rest 
after  stretching,  so  that  in  one  case  the  elastic  limit  which 
had  been  raised  to  56,000  pounds  per  square  inch  by  a 
stress  of  that  amount,  fell  in  about  two  months  to  about 
40,000  pounds,  distinct  permanent  set  arising  with  this 
stress. 

As  regards  friction  the  statements  are  not  easily  recon- 
ciled. On  the  one  hand  Mr.  C.  W.  Hubbard  is  quoted  as  be- 
lieving that  manganese- steel  has  the  very  essence  of  "anti- 
friction": on  the  other  brake-blocks  are  said  to  "bite" 
manganese-steel  wheels  much  better  than  cast-iron  ones. 
This  certainly  seems  like  blowing  hot  and  cold.  The 
presence  of  grease  in  one  case  and  its  absence  in  the  other 
may,  however,  cause  the  discrepancy. 

Oompressitie  S'rength. — Under  a  load  of  224,000  pounds 
per  square  inch,  blocks  one  inch  long  and  0 '79-inch  in  di- 
ameter, of  steel  (A)  with  10  and  (B)  with  15  to  20$  of 
manganese,  shortened  (A)  by  25$  and  (B)  by  from  10  to  13$ 
respectively.  The  compressive  strength  thus  is  lower 
than  one  would  anticipate  from  the  hardness  proper. 

Structure. — The  fracture  of  manganese-steel  ingots  is 
strongly  crystalline,  and  is  not  changed  even  by  strongly 
reheating  and  quenching,  though  this  treatment  strength- 
ens and  toughens  the  metal.  The  crystalline  structure  is 
broken  up  by  forging.  The  brittle  group  with  3  to  7'5$ 
of  manganese,  if  cast  in  a  4-inch  square  mould,  has  strongly 
marked  brittle  needles  about  1 -5  inches  long,  normal  to 
to  the  cooling  surface,  at  the  outside.  In  the  centre  is  a 
heterogeneous  mass  of  crystals. 

With  8  to  12$  of  manganese  the  fracture  resembles  that 
of  "scalded"  carbon-steel,  and  is  completely  covered  with 
bundles  of  little,  hard,  and  very  tough  needles  normal  to 
the  cooling  surface. 

With  more  than  12$  of  manganese  the  acicular  struct- 
ure gradually  gives  way  to  a  coarsely  crystalline  structure 
like  that  of  coarse  cast-iron. 


According  to  Hadfield,  the  fracture  of  manganese-steel 
with  less  than  1 3$  of  manganese  has  a  peculiar  burnished 
or  polished  appearance,  especially  if  metal  be  very  hot 
when  cast. 

The  ingot  from  which  Holtzer's  manganese-steel,  Num- 
ber 6,  Table  2u8,  appears  to  have  been  made  has  a  most 
remarkable  fracture,  made  up  almost  wholly  of  fine  fibres 
like  very  fine  cambric  needles,  normal  to  the  cooling  sur- 
face, and  highly  splendent.  Seen  through  the  glass  show- 
case the  central  non-acicular  part  looked  fine  hackly. 
Around  the  outside  is  a  sub-acicular  fringe  about  0'12" 
deep. 

Pieces  of  the  manganese-steel  of  numbers  8  and  9  of 
Table  208  have,  after  melting  in  crucibles  and  rolling 
into  bars,  been  ''converted,"  i.  e.  carburized,  by  the 
cementation  process.  Their  fracture  is  very  remarkable. 
There  are  long-bladed  faces  in  it,  recalling  in  a  most 
striking  way  the  prism-faces  of  crystals  of  hornblende  in 
crystalline  rocks. 

Segregation. — Hadfield  detected  no  serious  segregation 
in  16-inch  square  ingots  containing  14$  of  manganese : 
but  it  is  not  clear  from  his  statements  whether  his  borings 
were  so  taken  that  they  would  have  detected  segregation 
had  it  occurred. 

Carbon-condition. — Manganese-steel,  which  by  combus- 
tion showed  111$  of  carbon,  gave  Stead  0'90$  of  carbon 
by  Eggertz'  coloration  test :  as  in  case  of  carbon-steel, 
the  coloration  test  showed  less  carbon  in  quenched  than 
in  slowly-cooled  metal.  This  indicates  that  the  carbon  is 
in  combination  :  whether  its  condition  of  combination  re- 
sembles that  of  carbon  in  carbon-steel  remains  to  be  shown. 

Magnetization. — Exposed  to  a  gentle  magnetizing  force, 
wrought-iron  is  about  8,00;)  times  as  susceptible  of  mag 
netization  as  manganese-steel,  but  as  the  magnetizing 
force  increases  this  difference  diminishes  greatly.  A  mag- 
netizing force  of  10,000  C.  G.  S.  units  produced  in  man- 
ganese-steel an  intensity  of  magnetism  of  nearly  400  C.  G. 
S.  units,  which  is  as  high  as  the  intensity  commonly 
found  in  permanent  magnets.  This,  however,  was  a  tour 
de  force  ;  for  practical  purposes  manganese-steel  may  be 
regarded  as  wholly  unmagnetizable  (Ewing). 

Preparation. — Manganese-steel  is  made  by  mixing 
molten  iron,  decarburized  by  the  open-hearth  or  Bessemer 
process,  with  ferromanganese  in  a  ladle.  It  is  less  desir- 
able to  mix  them  in  crucibles,  because  these  are  cut  by  the 
manganiferous  slag.  The  steel  usually  contains  about  0'5$ 
less  manganese  than  the  ferromanganese  added  would 
imply  were  there  no  loss.  It  gives  off  a  strong  sulphurous 
smell  while  molten,  confirming  the  observations  recorded 
in  §81,  p.  43.  But,  as  the  composition  of  ferromanganese 
(Table  20,  p.  43)  had  already  shown,  even  a  large  pro- 
portion of  manganese  may  not  bring  the  proportion  of 
sulphur  below  say  0-06$ :  this  is  shown  by  the  analyses 
in  Table  206. 

Uses. — Manganese-steel  is  as  yet  used  only  tentatively. 
Among  the  objects  for  which  it  seems  specially  fitted  are 
car-wheels,  on  account  of  its  combined  hardness  and 
toughness  ;  resistance-coils  on  account  of  its  elecirical  re- 
sistance ;  and  the  bed-plates  of  dynamos  o  3  account  of  it ; 
low  magnetic  susceptibility.  At  first  sight  it  seem-; 
admirably  fitted  for  armor-plate:  but,  owing  to  its 
relatively  low  crushing  strength,  it  may  prove  to  have 
much  less  power  of  resisting  penetration  by  projectiles 


SILICON    STEEL.       g  414. 


365 


than  its  hardness  as  measured  by  its  resistance  to  abrasion 
would  lead  us  to  expect.  At  present  its  use  is  greatly 
hampered  by  the  extreme  difficulty  of  machining  and  ap- 
parently also  of  forging  it.  These  and  its  liability  to 
crack  in  quenching  led  Com  men  try  et  Chatillon  to  wholly 
abandon  the  serious  attempts  which  they  made  to  use 
manganese-steel  for  armor-plates.  Moreover,  its  ex- 
tremely low  elastic  limit  is  a  serious  defect.  Indeed,  ductile 
as  it  is,  one  is  not  sure  that  its  combination  of  elastic  limit 
and  useful  toughness  for  most  purposes  is  as  good  as  that 
of  carbon-steel.  Still,  its  combination  of  ductility  with 
tensile  strength  is  so  great  that  it  should  give  it  some 
important  uses,  while  its  simply  marvelous  combination  of 
ductility  with  cf rtain  kinds  of  hardness,  unapproached 
so  far  as  I  know  in  any  matt  rial  whatsoever,  unless  it  be 
nickel-steel,  may  well  give  it  great  value  for  the  many 
purposes  for  which  this  combination  seems  important 

The  thoroughness  with  which  its  discoverer"  has  ex- 
amined it,  and  especially  the  modesty  with  which  he  has 
described  it  and  the  candor  and  impartiality  with  which  he 
has  laid  stress  on  its  shortcomings,  command  admiration. 
§413  A.  EFFECT  OF  SMALL  QUANTITIES  OF  MANGANESE.— 
An  important  French  manufacturer  is  now  intentionally 
introducing  about  \%  of  manganese  into  thin  armor-plates, 
believing  that  the  resistance  to  penetration  is  thereby  in- 
creased, without  incurring  brittleness  under  shock.  So, 
too,  St.  Chamond  shows  steel  with  (V9o$  of  manganese  and 
u'Sfl^  of  carbon,  yet  with  142,000  pounds  tensile  strength 
per  square  inch  and  '%  of  elongation.  Again,  two  armor- 
plates  lately  made  by  an  eminent  British  maker  have  over 

1  '25$  of  manganese.     Their  composition  follows  : 

p. 


No. 
1... 


r. 

0-91 
0-98 


0-28 
11-04 


Mn. 
1"2G 
1-87 


1  is  a  plate  which  a  Krupp  shell  failed  to  pierce  :  2  is 
the  face  of  a  compound  plate.  These  facts  harmonize 
with  the  conjecture  expressed  on  page  48  that  the  effects 
of  moderate  quantities  of  manganese  in  causing  brittleness 
have  been  grossly  exaggerated. 

414.  SII.ICON-STKKL. — The  ferro-silicons  and  silico- 
spiegels  (/.  e.  ferro-silicons  rich  in  manganese)  whose 
composition  is  given  in  Table  210,  are  shown  at  the  Paris 
Exhibition.  The  tendency  of  manganese  to  raise  and  of 
silicon  to  lower  the  saturation-point  for  carbon  is  readily 
traced  in  this  table  (Cf.  §§  18,  19,  pp.  t-',  9). 

TAIILE  210.— FKKKO-SILICON  (Cf.  p.  86). 


•=.-•  Number. 

Composition. 

Makers. 

C. 

1-40 

Si. 

Mn. 

P. 

8. 

As. 
tr. 

Cu. 

Fc. 

12-05 
12- 

12-25 
12- 

2-10 
3@4 

19  '25 

i  rw2<  > 

•04 

•01 

•01 

84-39 

Gjers,  Mills  it  Co. 
81.  Louis. 

Gji-rs,  Mill.-*  Cu. 
!*t.  l>ouis. 
Firminr. 

1.. 

•' 

1  39 

•05 

Silico-spiegel. 

S. 
tr. 

As. 
tr. 

Cu. 
•01 

Fe. 

67-05 

a 

i'<i 

n-oo 

18-09 

•oss 

tr 

Kino  gray,  very  bubbly,   half 
voids. 
Very  course  open  gray,  bub- 
bly. 

14.. 

8-5 

10-30 

18-00 

•OS 

Ferro-silicon  with  about  10$  of  silicon  and  at  most  2-5$ 
of  manganese  is  made  on  a  considerable  scale,  and  sells 

a  M.  H.  A.  Brustlein  informs  me  that  he  discovered  the  properties  of  these  man- 
ganese-steels in  1879.  but  was  deterred  from  making  them  by  the  difficulty  in  ma- 
chining them,  which  he  thought  would  effectually  prevent  their  use.  But,  as  he 
kept  his  discovery  to  himself,  it  is  to  Hadfield's  wholly  independent  discovery  that 
we  owe  our  knowledge  and  thanks. 


in  I-'ngland  for  less  than  $20  per  ton.1'  Some  of  it  has  but 
little  phosphorus,  but  some  with  l-5  to  1-7$  of  phos- 
phorus is  also  m-de,  for  foundry  work.  According  to 
Gaulier  four  establishments  only  are  now  making  ferro- 
silicon. b 

In  order  to  make  ferro-silicon  in  the  blast-furnace,  the 
slag  should  be  acid,  and  often  contains  10  or  12$  of 
alumina;  the  burden  must  be  very  light,  and  the  blast 
very  hot.  Two  or  even  three  tons  of  coke  per  day  may 
be  needed  per  ton  of  ferro-silicon  produced. 

Alumim,  acting  perhaps  as  an  acid,  is  thought  to  facili- 
tate the  reduction  of  silicon.  Pourcel  added  sulphate  of 
baryta  to  the  blast-furnace  charge,  believing  that  baryta 
was  a  less  powerful  base  and  would  thus  hold  the  silica 
less  firmly  than  lime,  and  because  the  presence  of  baryta 
gave  a  more  fluid  slag.  In  England  ferro-silicon  is  also 
made  in  the  blast-furnace  by  charging  iron-silicates  with 
but  little  lime  and  much  alumina.1" 

For  making  silico-spiegel  in  the  blast-furnace  we  need 
similar  conditions,  save  that  the  burden  must  be  rich  in 
oxide  of  manganese.  Gautier  gives  the  following  as  an 
example  of  the  charge: 


420 
460 
190 


Coke 2,500  I  Combined  silica 

Ferric  oxide 940  I  Carbonate  of  lime 

Manganese  oxide 570  I  Sulphate  of  baryta 

Free  silica 360  1 

Table  210  A.  gives  the  calculated  and  the  actual  slag  of 
another  blast-furnace,  making  silico-spiegel  of  about  17$ 
of  silicon  and  18$  of  manganese,  closely  like  number  13 
of  Table  210. 

TABLE   210A.— CALCULATED  SLAG,  ACTTTAL  SLAG,  ETC.,  MADK  TOGETHER  WITH  RICH  SILHTO 
SPIEGEL  IN  THK  KLAST-FURNACE. 


1. 

Calculated  Slag. 

2. 
Probable  Slag. 

8. 

Actual  Slag. 

4. 
Fume. 

Silica  

50  0 

39 

83'9 

38-6 

Lime  

41-5 

50-0 

27'9 

Alumina  

8-5 

13-2 

2-0 

6'5 

Ferrous  oxide  

0 

tr. 

1 .  Calculated  on  the  assumption  that  all  the  silica  of  the  charge  enters  the  slag. 

2.  Calculated  on  the  assumption  that  enough  of  the  silica  of  the  charge  is  reduced  to  give  tho 
metal  produced  17£  of  silicon,  and  that  the  rest  enters  the  slag. 

3.  The  sing  actually  made. 

4.  The  fume  found  in  the  flues  of  the  blast-furnace.    It  is  thought  that  the  fact  that  the  ratio  of 
silica  to  lime  in  the  fume  is  much  higher  than  that  in  the  "  actual  slag  "  explains  why  Hie  latter 
contains  go  much  less  silica  than  the  "  probable  slag."    The  relatively  hi^ti  proportion  of  oxide  of 
manganese  in  the  fume  recalls  Jordan's  statement  (§77,  p.  42)  that  10#  of  the  manganese  chanred 
in  a  certain  blast-furnace  could  not  be  accounted  for  by  the  contents  or  the  metal,  the  slag  ami  tin- 
dust. 


The  slag  actually  made  has  in  this  case  nearly  the  same 
composition  as  that  which  accompanies  common  Bessemer 
cast-iron,  nearly  all  of  the  excess  of  silica  charged  being 
either  reduced  to  silicon,  or  carried  away  in  the  fume. 

Firminy's  statement  that  their  blast-furnace,  which 
turns  out  from  110  to  120  tons  of  common  cast-iron  daily, 
may  not  produce  more  than  from  10  to  15  tons  of  silico- 
spiegel,  which  sometimes  contains  over  20$  of  silicon,  is 
instructive.  Here,  as  in  making  ferro-silicon,  two  or  even 
three  tons  of  coke  may  be  needed  per  ton  of  product. 

Ferro-silicon  is  used  in  the  iron-foundry  for  softening 
cast-iron,  and  for  enabling  the  founder  to  use  a  larger 
proportion  of  scrap.  It  is  also  used  as  a  final  addition  in 
making  ingots  and  other  steel  castings,  to  prevent  thj 
formation  of  blow-holes.  Silico-spiegel  is  used  for  this 
latter  purpose  and  at  the  same  time  for  giving  forgeable- 
ness.  The  choice  between  these  two  alloys  depends  chiefly 
on  the  relation  between  the  composition  of  the  bath  to 
which  the  addition  is  to  be  made  and  that  which  the 


b  Gautier,  bes  Alliages  Ferro-metalliques,  pp.  91-96     Excerpt  Bull.  Soc.  Indust. 
Minerale,  2nd.  Ser.,  III.,  1889. 


366 


THE    METALLURGY    OF    STEEL. 


product  shoiild  have,  ferro-silicon  alone  being  used  if  the 
bath  is  already  rich  enough  in  manganese.  It  is  in  gen- 
eral cheaper  to  add  silico-spiegel  than  to  add  ferro-silicon 
and  ferro-manganese  separately. 

In  the  manufacture  of  silicon-steel  itself  little  progress 
is  apparent.  Holtzer  indeed  exhibits  the  silicon-  and 
silico-manganese  steels  whose  properties  are  given  in 
Table  211,  but  I  cannot  find  that  they  are  more  than 
curiosities. 

The  electrical  resistance  of  silicon-steel  is  reported  as 
six  or  seven  times  that  of  iron,8  and  thus  almost  as  great 
as  that  of  manganese-steel. 

A  paper  on  silicon  steel  is  expected  from  Hadfield. 

Gautier"  reports  that  two  types  of  silicon  steel,  one 
with  about  \%,  the  other  with  from  1 -5  to  1  'Q%  of  silicon, 
are  used  successfully  by  Hadfield  in  dressing  steel  castings. 
These  steels  are  made  by  melting  selected  scrap-iron  with 
ferro-silicon  in  crucibles.  With  caution  they  can  be 
forged  very  well.  The  tools  are  water-quenched.  Though 
containing  only  about  0'50$  of  carbon  they  are  hard 
enough  for  general  use  in  the  machine-shop  :  hence  Gau 
tier  conjectures  that  the  silicon  present  intensifies  their 
hardness,  at  least  when  quenched.  I  have,  however,  known 
tool-j  made  from  common  rail- steel,  containing  say  0-40$ 
of  carbon,  to  give  tolerable  results  in  the  machine-shop. 


point  for  carbon.    Number  17,  with  only  16$  of  chromium, 
has  actually  9i%  of  carbon. 

TABLE  212.— FEBEO-CIIROME.    (Cf.  Table  81,  p.  76.) 


C. 

9i. 

Mn. 

P. 

8. 

Cr. 

1 
i 

8 
4 
5 
6 

7 
8 
9 
111 
11 

u 
tl 

14 
IB 

16 
11 

18 
It 

2ll 
21 
22 
23 
24 

as 

M 

27 

lioucau  (St.  Chamond)     . 

11-1 
8-50 
8-75 
9-10 
9-38 
9-55 
10-05 
11-80 
3-80 
7-30 
7-50 
5-00 
S-IXI 
9-00 

•40 
0-40 
0-32 
0-56 
0-45 
0-60 
0-40 
0-38 
4-50 
2-10 
S-20 

s-oo 
s-oo 

4 

0-40 
0-40 
0-35 
0-50 
0-45 
0-42 
0-38 
2-50 
0-40 

•06 
•08 

tr. 
•01 

•02 

65- 
44-80 
51-10 
55-50 
57-96 
60-35 
63-10 
65-20 
23-00 
42-00 
82-00 
30-00 
30-00 
84-00 
80-00 
60-00 
16  00 
15-00 
16-00 
25-00 
12-00 
7'00 
7'± 
7'± 
7-± 
71-5 
42- 

Not  magnetic,  made  in  cupolas. 

MauVin  graphite  crucible.    \Silico- 
Jchrome. 

Made  in  magnesia  crucible. 
Made  in  brap-qucd  crucible. 
Made  in  a  crucible. 

Fractures  like  spiegeletsen.a 

Very  magnetic. 
Made  in  crucibles. 

Holtzer  

! 

11-00 

8-60 

9-00 

2-25 
2'70 

8-80 

2-00 

4-85 

0-30 

1-W 

I 

6  00 
4-50 
8-46 

0-40 
0-25 

0-38 
0-36 

Assailly  (St.  Chamond).  .  . 

a  The  fracture  of  No.  22  is  astonishingly  like  that  of  spiege 
is  Paid  to  be  present.     We  have  in  the  central  vug  the  same 
yellowish  brown  iridescent  surface.      Yet  No.  24,   with  < 
spiegeleisun  fracture. 

eisen   though  only  0'30  of  manganese 
broad-bladed  crystals,  with  the  same 
osely  similar  composition,  lacks  the 

Chrome-steel  is  shown  by  no  less  than  ten  exhibitors," 
and  has  evidently  become  of  considerable  commercial  im- 
portance. Thus,  Holtzer  has  made  about  fl,0(>0  projectiles, 
10,000  thin  plates  for  cuirasses,  and  several  hundred  tons 


T.UII.K  211.— PHYSICAL  PROPERTIES  OF  SILICON-STEEL— HOLTZER.    (Cf.  Table  19,  p.  49.) 


Number. 

Tensile  strength,  pounds  per  square  Inch. 

Elastic  limit,  pounds  per  square  inch. 

Elongation,  -f  in  7-9  inches. 

Contraction  of  area,  •£. 

Natural 

state. 

Oil-hardened  and 
tempered. 

Oil-hardened  and 
annealed. 

Natural 
state. 

Oil-hardened  and 
tempered. 

Oil-hardened  and 
annealed. 

Natural 
state. 

Oil-hardened  and 
tempered. 

Oil-hardened  and 
annealed. 

Natural 
state. 

Oil-hardened  and 
tempered. 

Oil-hardened  and 
annealed. 

'{ 

100,555 

66,705 

22-8 

54-5 

179,849 

168,967 

47 

114,067 

75,949 

18-5 

54-5 

j 

142,228 

77,087 

10'8 

19 

198,977 

178,354 

2-8 

10-8 

159,722 

147,063 

7-8 

31 

'{ 

97,710 

65,567 

22-2 

59 

170,674 

152,184 

10-5 

88-5 

189,580 

181,184 

14-2 

50 

- 

The  "natural  state  "  pieces  are  simplv  cooled  slowly  after  forging. 

The  **  oil-hardened  and  tempered  "  pieces  are  quenched  in  oil  from  a  low  yellow,  and  slightly  reheated. 

The  "oil-hardened  and  annealed  "  piece*  are  quenched  similarly,  reheated  to  very  dull  redness,  and  cooled  slowly. 

It  is  possible  that  the  labels  cf  some  of  these  pieces  have  been  misplaced. 


Gautierb  gives  also  the  following  siliciferous  steels,  and 
reports  that  their  quality  is  excellent: 


TABLE  211  A. — GOOD  SILICIFEBOUS  STEELS. 


C. 

0  788 
0-826 
0-574 
1-07B 
1-091 


81. 
0-843 
0-840 
0-478 
0-675 
u-«80 


Mn. 
0-870 
0-480 
0-200 
0-520 
0.870 


P. 

0'019± 
0'019± 
0'019± 
0-023 
•0-019 


C. 

1-114 
0-941 
1-050 
1-188 


81. 

0-684 
0-877 
0-299 
0-575 


Mn. 
0-40 
0-860 
0-410 
0-400 


P. 

'6-023 
0-015 
0-018 


These  examples  tend  to  justify  the  doubts  expressed  on 
page  40  as  to  the  deleterious  effects  of  silicon. 

§  415.  CHROME-STEEL. — Most  of  the  ferro-chromes  of 
Table  212  are  shown  at  the  Paris  Exhibition.  Those  of 
St.  Louis  and  of  Firminy  are  made  in  the  blast-furnace, 
of  course  with  heavy  consumption  of  fuel  and  small  out- 
put. Some  at  least  of  those  of  Boucau  are  made  in  cu- 
polas, making  5  to  6  tons  per  campaign  we  are  told.  There 
are  besides  those  in  Table  2 1 2  two  other  exhibits  of  ferro- 
chrome.  This  gives  us  an  idea  of  the  attention  that  is 
being  paid  it.  Note  how  chromium  raises  the  saturation 

a  J.  Hopkinson,  Discussion  of  Hadflcld'8  paper  on  manganese-steel,  excerpt  Proc. 
Inst.  Civ.  Eng.,  XCIII.,  III.  p.  97, 1888. 

b  Leg  Alliages  Mctalliques.  Excerpt  Bulletin  Soc.  Indust.  Mini-rule,  2nd.  Ser., 
III.,  1889,  pp.  91,  92. 


1 

~ 
= 

n 

i 

2 

Maker. 

Composition. 

Use,  etc. 

0. 

roo 

fl-no 

SI. 
•30 

Mn. 

•20 

P. 

S. 

Cr. 

St.  Etienne. 
Holtzer 

•01 

•01 

1-5 
12 

(  Razors,  milling  tools,  wire  dies,  lathe-tools  for  white 
1  cast-iron,  etc.  Made  in  a  basic  open-hci'rth  furnace. 
Limit  between  chrome  steel  and  cast-iron. 

of  plates  0'16-inch  thick  for  protection  against  musketry  ; 
Firminy  has  made  over  4,000  projectiles,  etc.     The  more 

TABLE  218.—  CHROME-STEEL,  COMPOSITION.    (See  Table  82,  p.  76.) 


important  uses  beside  those  just  mentioned  are  (1 )  for 
tools  for  cutting  chilled  cast-iron  and  hardened  steel  with- 
out shock,  (2)  three-cornered  files,  and  (n)  wire-dies. 
There  are  no  less  than  six  exhibitors  of  chrome-steel  files 
or  of  chrome-steel  for  files.  The  actual  consumption  for 
these  uses  is  probably  less  than  one  might  infer,  for, 
though  the  makers  have  evidently  convinced  themselves 
that  chrome-steel  is  especially  adapted  to  them,  the  in- 
numerable consumers  naturally  proceed  cautiously.  While 
the  very  hardest  of  the  chrome-steels  are  so  brittle  that 
they  cannot  be  used  for  tools  cutting  by  impact  the 


<•  Among  them  Chatillon  et  Commentry,  Uoltzer,  St.  Etiennc,  and  St.  Chamond  of 
France,  and  Bochler  of  Vienna. 


CHROME    STEEL.      §  415. 


softer  classes  still  have  a  combination  of  great  hardness 
and  very  high  elastic  limit  with  sufficient  toughness  to 
prevent  their  cracking  under  even  violent  shock,  such  as 
projectiles  and  armor-plates  are  exposed  to. 

The  thin  chrome-steel  armor-plates,  0-16  inches  thick, 
are  hardened  and  subsequently  fully  annealed,  so  that 
they  can  be  bent  double  and  hammered  close.  At  the 
same  time  it  is  specified  that  they  must  not  be  pierced  by 
a  lead  musket-ball  with  a  velocity  of  about  1,500  feet,  at 
a  distance  of  33  feet. 

The  chrome-steel  projectiles,  I  am  informed,  are  hard- 
ened in  cold-wate  -,  and  only  tempered  by  heating  in  boil- 
ing water,  after  which  they  are  again  plunged  into  cold 
water. 

St.  Etienne,  though  a  maker  of  chrome-steel,  has  sought 
to  make  a  material  which,  in  the  form  of  plates,  would  re- 
sist light  projectiles  nearly  as  well  as  chrome-steel,  and 
would  be  considerably  cheaper.  The  special  plate,  how- 
ever, which  St.  Etienne  makes  for  this  purpose  has  to  be 
25%  thicker  than  a  chrome-steel  plate  in  order  to  offer 
equal  resistance  to  impact. 


other  of  these  shells,  16i-inches  in  diameter,  has  pierced 
a21£-inch  Creusot  steel  plate  in  direct  fire,  but  here  the 
shell  itself  was  broken. 


TAIILK  215.—  TRIAL  OK  I'IIKIIMK-STKKL  AND  OTIIKK 


Number. 

Maker. 

Penetration, 
Inches, 

('•iiiditinji  of  projectile  after  tire. 

Ui-oken  or  in- 
tact. 

Shortening, 

Bulging, 

1. 

Holtaer,  chrome. 
Krupp. 
St.  Chaui.md. 

»•« 
(-46 
(•II 

g-« 

8'T8 
8-90 

1         9-76  and 
I         !>"vl 

Intact. 

Broken. 

1   •!•-'(./  "Jl 
-    -47    . 

•08 
Fell  into 

•1)1   ,:,       Oli 

0- 

0 
the  sea. 

2. 

8  

4... 

5 

6  

7... 

8... 

9  

10  

11  

Trials  at  Spezla,  September,  1886.    79  to   82-pound   projectiles  ,V9  Inches  in  diameter  were 
flred  with  40-pouiKl  chaws  of  powder  from  a  5-ll-ineh  Armstrong  gun  with  a  velocity  <>t  l.-7n  i  . 
1,900  feet,  ngainst  a  Creusot  steel  plate  1S'9  inches  thick,  at  a  distance  of  -".'.')  feet. 

Holtzer  also  shows  chrome-steel  which  he  claims  will 
drill  through  Mushet's  tungsten-steel,  and  chrome-steel 
with  I2f0  of  chromium  and  2%  of  carbon  which  can  be 


TABLE  214.- PHYSICAL  PROPERTIES  OF  CHROME-STEEL  AND  TUNGSTO-CHROME  STEEL— HOLTZER  AND  OTHERS.    (Uf.  Table  32,  p.  76.) 


Number. 

Tensile  strength,  pounds  per  square  inch. 

Klastic  limit,  pounds  per  square  inch 

Elongation,  %  in  7'9  Inches. 

Contraction  of  area,  %. 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

Natural 
state. 

Oil  hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

Natural 
state. 

Oil-hardened 

and  tempered. 

Oil-hardened 

and  anneale-I. 

l  j 

156,877 

95 

54-5 

199,017 

152,184 

8 

43 

1 

104,538 

63,575 

19-5 

63 

T  j 

109,230 

64,571 

18-3 

59 

195,421 

6 

80-5 

1 

136,112 

118,760 

18 

58-1 

*  \ 

93,443 

55,758 

22'S 

88-5 

212,772 

0-5 

0 

1 

124,592 

109,230 

6 

17-5 

H 

94,43'J 

55,753 

26-5- 

50-5 

172,949 

159,580 

6'5 

26 

122,600 

106,886 

12-2 

80 

t 

95.292 

56,749 

20-8 

80 

204,096 

190,017 

2-5 

6 

1 

116,769 

104,588 

7 

33 

H 

103,115 

65,425 

17'5 

83 

212,772 

193,480 

1-8 

7 

137,107 

123,596 

6-2 

15 

'•••{ 

114,635 

72,251 

14-5 

24 

210,497 

189,163 

148,201 

138,409 

5 

18 

8  .. 
9  .. 
10.     . 

142,000^156,000 
114,000 
128,000(<M42,000 

113,800(8128,000 
68,800 

10@12*  in  8-9'' 
13-5a 
9@10a 

42@45 

The  "natural  state  "  pieces  are  simply  cooled  slowly  after  forging. 

1  to  S.  inclusive,  are  Holder's;  8  is  for  plates  0'59-inch  thick,  for  the  French  navy. 

9.  Railway  tiro   which  has  resisted  14  Ijfows  of  a  1-ton  ram  falling 32  feet  lOinches.    St.  diamond. 

10.  St.  Etienne :  usual  properties  of  their  armor-plates  016  to  1-18  inch  thick, 
a,  the  length  in  which  the  elongation  is  measured  is  not  given. 


St.  Etienne  shows  a  13-4-inch  chrome-steel  projectile 
which  has  pierced  a  15-7-inch  iron  plate  obliquely  without 
appreciable  deformation,  while  Iloltzer  points  with  pride 
to  the  comparative  tests  of  his  chrome-steel  projectiles 
with  projectiles  of  Krupp  and  St.  Chamond,  given  in 
Table  215. 

At  Firminy  is  shown  a  most  instructive  wooden  model 
of  a  20-inch  wrought-iron  armor-plate,  pierced  at  an  angle 
of  20°,  and  apparently  like  so  much  butter  by  a  )4j-inch 
chrome-steel  shell,  which  seems  wholly  uninjured.  An- 


forged,  but  which  lies  at  the  limit  between  chrome-steel 
and  chromiferous  cast-iron. 

Most  of  the  chrome-steel  is  made  in  crucibles,  but  that 
of  St.  Etienne  and  of  another  maker  is  made  in  the  basic 
open-hearth  furnace.  The  procedure  at  one  mill  is  as 
follows :  The  carbon  of  the  bath  in  the  basic  open-hearth 
furnace  being  brought  to  the  desired  point,  enough  ferro- 
chrome  is  added  to  give  the  desired  proportion  of  chro- 
mium, allowing  for  a  loss  of  20$  of  the  chromium  added. 
This  loss  is  fairly  constant.  Neither  ferro-silicon  nor 


868 


THE    METALLURGY     OF     STEEL. 


ferro-manganese  is  added,  the  chromium  at  once  prevent- 
ing blowholes  and  giving  forgeahleness.  As  soon  as  the 
ferro- chrome  is  melted  the  charge  is  tapped.  Chrome- 
steel  has  also  been  made  tentatively  in  the  acid  open -hearth 
furnace,  but  I  am  informed  that  80%  of  the  chromium 
charged  passed  into  the  slag. 

It  is  now  thought  that  the  proportion  of  chromium  in 
chrome-steel  should  not  exceed  2%,  and  that  for  most  pur- 
poses it  should  be  rather  less  than  2%. 

Brustleina  gives  us  the  following  information  touching 
ferro-chrome  and  chrome-steel. 

The  fracture  of  ferro-chrome  depends  more  on  the  pro- 
portion of  carbon  and  silicon  present  than  on  that  of 
chromium.  Ferro-chromes  rich  in  carbon,  or  in  carbon 
and  silicon,  are  likely  to  have  an  acicular  structure,  and 
are  always  hard  and  brittle.  As  the  carbon  diminishes, 
so  does  the  brittleness.  Thus  number  26,  though  with 
71-5$  of  chromium,  is  less  brittle  than  nu Tiber  16,  which 
has  only  60$  of  chromium. 

Chromium  interferes  with  the  magnetism  of  the  metal 


The  effects  of  quenching  penetrate  deeper  in  chrome- 
steel  than  in  carbon-steel.  But  the  extreme  hardness  of 
quenched  chrome-steel  seems  to  be  coupled  with  a  dis- 
proportionate shock-resisting  power:  hence  its  special 
fitness  for  projectiles  and  armor-plate  already  pointed 
out. 

§416.  TUNGSTEN-STEEL  (Cf.  §141,  p.  81).— The  Paris 
exhibition  indicates  that  the  use  of  tungsten-steel  has 
increased  much,  but  decidedly  less  than  that  of  chrome- 
steel.  I  found  but  three  exhibits  of  ferro-tungsten,  which 
in  one  case  contained  from  43  to  45%  of  tungsten.  P.  E. 
Martin  reports  having  made  ferro-tungsten  of  2-%  in  the 
blast-furnace.  One  specimen  of  ferro-tungsten  has  a 
smooth  conchoidal  fracture  much  like  that  of  "white 
metal,"  which  is  approximately  cuprous  sulphide,  Cu  S, 
and  like  that  of  chalcocite  and  argentite. 

At  least  six  exhibitors  display  tungsten-steel,  at  least 
one  of  whom  has  ceased  to  make  it.  It  is  recommended 
by  most  of  them  for  cutting  extremely  hard  metals,  e.  cj. 
hardened  steel  and  chilled  cast-iron,  but  by  one  exhibitor 


TABLE  216.— TUNGSTEN  STEEL    HOLTZER.    (Cf.  Table  34,  p.  81.) 


Number. 

Tensile  strength,  pounds  per  square  inch. 

Elastic  limit,  pounds  per  square  inch. 

Elongation,  f  in  7-9". 

Contraction  of  area,  %, 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil  hardened 
and  annealed. 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

Natural 
state. 

Oil-hardened 
and  tempered. 

Oil-hardened 
and  annealed. 

H 

68,553 

47,504 

23-7 

75'5 

82,492 

67,558 

17-5 

H 

7ti,l)'.»2 

52,197 

19-5 

72-3 

H 

71,114 

50,348 

28-5 

CO 

71,114 

48,499 

8-2 

i 

98,017 

15 

59 

i  J 

77,941 

41  672 

28-S 

45-1 

179,849 

185,117 

2-5 

2-5 

1 

116,769 

90,172 

10-2 

40 

1   5 

93,017 

47  504 

17 

33 

216,186 

4'5 

4 

I 

184,406 

104,588 

8-5 

24 

j 

106,886 

62  580 

9 

213,842 

2-8 

1 

' 

140,306 

109,230 

8-3 

27 

The  "  natural  state"  pieces  are  simply  cooled  slowly  after  forging. 

The  "oil-hardened  and  tempered"  pieces  are  quenched  in  oil  from  a  low  yellow  h:at  and  slightly  reheated. 

The  "  oil-hardened  and  annealed ''  pieces  are  similarly  quenched,  reheated  to  very  dull  redness,  and  cooled  slowly. 

It  is  possible  that  the  labels  of  some  of  these  pieces  have  been  misplaced. 


much  less  than  carbon  and  silicon.  Thus  number  26  is 
strongly  magnetic. 

Chromium  has  a  strong  tendency  to  oxidize.  The  oxi- 
dized compounds  which  it  forms  do  not  separate  readily 
from  the  molten  steel,  and  hence  are  very  liable  to  form 
in  the  ingots  ineradicable  internal  flaws,  especially  if  the 
metal  be  rich  in  chromium  and  poor  in  carbon.  Hence 
the  successful  manufacture  of  soft  chrome-steel,  say  with 
01  or  0-2$  of  carbon  and  1  or  2%  of  chromium,  is  hardly 
to  be  looked  for.  For  like  reason  chrome-steels  rich  in 
chromium  weld  with  difficulty  if  at  all.  So,  too,  the  em- 
ployment of  ferro-chrome  as  a  recarburizer  in  the  Besse- 
mer and  open-hearth  processes  is  likely  to  cause  internal 
flaws. 

Once  made,  however,  chrome-steel  according  to  Brust- 
lein  requires  in  the  forge  no  further  precautions  than 
carbon-steel  of  like  hardness,  though  when  hot,  as  well 
as  when  cold,  it  offers  rather  more  resistance  to  deforma- 
tion than  carbon-steel.  So  too  it  is  a  little  harder  to 
machine  than  carbon-steel,  but  if  it  be  well  annealed  the 
difference  is  not  very  great. 


a  "Le  Ferro-Ohrome,"  excerpt  Bull.  Soc.  Indust,  Morale,  2nd  Ser.  III.,  1889. 


for  cutting  soft  and  half-hard  metals  instead.  Some  of 
the  best  makers,  who  make  both  chrome-  and  tungsten- 
steel,  believe  that  the  latter  is  much  the  better  fitted  for 
tools  for  cutting  hard  metal,  explaining  its  limited  use  by 
its  high  price,  and  by  the  scarcity  of  tungsten.  St. 
diamond  recommends  tungsten-steel  especially  for 
springs,  stating  that  the  carrying-power  for  given 
size  of  spring  is  about  one-third  greater  than  that  of  the 
best  carbon  spring-steel,  and  giving  the  elastic  elongation 
after  quenching  and  annealing  as  0'75  per  cent  (0'0()7.;>). 
The  only  analysis  of  tungsten-steel  whose  results  I  saw 
gave  the  proportion  of  tungsten  as  about  2%.  But  I  under- 
stand that  some  of  Holtzer's  tungsten-sfeels  contain  as 
much  as  8%  of  tungsten. 

Table  21 6  gives  the  properties  of  tungsten-steel  shown 
by  Holtzer  at  Pails. 

§  417.  COPPKS-STKKL  (Cf.  §  142,  p.  82).— Three  lots  of 
this  surprising  substance  are  shown  at  Paris  by  Holtzer. 
Their  properties  are  given  in  Table  217. 

M.  Brustlein  informs  me  that  the  copper  in  these  steels 
rises  to  three  or  four  per  cent.  :  that  with  more  than  one 
per  cent  they  are  decidedly  redshort ;  that  they  have  been 


TITANIUM    STEEL        §  418 


369 


made  only  as  an  experiment :  that  he  believes  that  cop- 
per-steel lias  no  future:  that  the  copper  does  not  appear 
to  be  uniformly  distributed  through  the  metal :  and  that 
it  appears  to  favor  the  formation  of  blowholes. 

The  fracture  of  bars  of  Numbers  2  and  3  which  have 
been  nicked  before  breaking  is  most  extraordinary.  It 
consists  of  flat  tables  parallel  with  the  surface  of  the 
fracture  ;  in  Number  3  a  single  table  seems  to  occupy  the 
whole  surface  of  the  fracture,  which,  indeed,  looks  as  if 
it  had  been  roughly  ground  on  a  grind-stone. 

Note  the  exceedingly  high  elastic  limit  of  the  hardened 
bars,  almost  equalling  their  tensile  strength,  though  the 
elongation  is  still  considerable.  The  combination  of  elas- 
tic limit  and  elongation  of  bar  Number  5  is  quite  as  good 
as  that  of  any  nickel-steel  which  I  have  seen  described, 
and  of  course  far  better  than  that  of  manganese-steel. 
Indeed,  I  know  but  little  carbon-steel  which  excels  it  in 
this  respect. 

It  has  been  thought  that  the  redshortness  which  usually 
accompanies  the  presence  of  copper  is  due  rather  to  the 
formation  of  sulphide  of  copper,  the  copper  taking  up 
sulphur  from  the  furnace  gases,  than  to  the  copper  itself. 


ant  and  but  little  less  remarkable  substance,  nickel-steel. 
Our  information  is  so  meagre  and  contradictory  that  the 
following  statements  are  only  provisional. 

Nickel-steel  is  made  in  the  open-hearth  furnace,  with- 
out especial  difficulty,  by  the  addition  of  metallic  nickel 
to  the  bath,  practically  the  whole  of  the  nickel  as  well  as 
that  of  any  scrap  nickel-steel  added  being  recovered.  The 
open-hearth  heat  lasts  about  seven  hours,  and  a  final  ad- 
dition of  ferromanganese  is  made  as  usual.  No  especial 
care  is  required  either  in  the  open-hearth  furnace,  in 
casting,  heating  or  forging,  unless  the  proportion  of 
nickel  be  very  high,  say  25$,  when  the  temperature  of 
heating  must  be  kept  somewhat  lower  than  in  case  of 
carbon-steel  of  like  carbon-content.  When  molten  nickel- 
steel  is  thinner,  it  sets  quicker,  and  pipes  deeper  than 
carbon-steel,  with  apparently  little  tendency  to  liquation, 
yielding  ingots  whose  outside  is  clean.  It  forges  easily, 
whether  it  contain  much  or  little  nickel :  with  1$  of 
nickel  it  welds  "fairly  readily,"  but  with  increasing 
nickel -content  the  welding-power  diminishes,  while  the 
hardness  and  the  ductility,  whether  as  measured  by 
elongation  or  by  endurance  of  twisting,  increase,  the  hard- 


TABLE  217.— PHYSICAL  PROPERTIES  OF  COPPER-STEEL— HOLTZKR.    (Of.  §  142,  p.  82.) 


Number. 

*of 

copper. 

Tensile  strength,  pounds  per  square  inch. 

Elastic  limit,  pounds  per  square  inch. 

Elongation,  %  in  7  '9  Inches. 

Contraction  of  area,  %. 

Natural 
state. 

Oil-hardened 
and  teiiiin-ivil. 

Oil-hardened 
aud  annealed. 

Natural 
state. 

Oil-hardened 
and  tempered 

Oil-hardened 
and  annealed. 

Natural 

state. 

Oil  hanl- 

encil  anil 
tempered. 

Oil-hnrd- 
enril  jinil 
:tnnr:ilril. 

Natural 
state. 

Oil-hard- 
ened and 
tempered. 

Oil-hard- 
ened and 

:imu-;i]i-il. 

I., 

(        77,941 

43,004 

22-5 

51- 

118,497 

95,008 

18-0 

60- 

j  

110,227 

99,701 

17'5 

59' 

Q 

(        88,914 

65,425 

IS'6 

50" 

173  045 

142.228 

0-2 

24- 

1  

168  989 

121  605 

ir 

86.5 

3.. 

3®4 

(        77,941 

48,664 

22-5 

51- 

16«,451 

j 

2- 

8' 

)  

121,  60S 

95,008 

14-5 

80- 

The  "natural  state"  pieces  are  simply  cooled  slowly  after  forfrinjr. 

The  "oil-hardened  and  tempered"  pieces  are  quenched  in  oil  from  a  dull  yellow  heat  and  slifhly  reheated. 

The  "oil  hardened  and  annealed"  pieces  are  similarly  quenched,  reheated  to  very  dull  redness,  and  cooled  slowly. 

It  is  possible  that  the  labels  of  some  of  these  pieces  have  been  misplaced. 


The  experiments  made  with  copper-steel  at  Holtzer's  works 
do  not  seem  to  bear  out  this  view. 

§  418.  TITANIUM-STEEL  (Of.  §  145,  p.  85).— St.  Chamond 
shows  at  Paris  ferro-titanium  in  small  irregular  lumps,  up 
to  say  one-inch  cube,  containing  22$  of  titanium,  and 
titanium-steel  containing  1-30$  of  carbon  and  0-45$  of 
titanium.  The  lumps  of  ferro-titanium  look  as  if  they 
had  formed  as  a  species  of  salamander  in  the  crevices  of 
the  brickwork  in  the  hearth  of  a  blast-furnace,  much  as 
cyano-nitride  of  titanium  often  does. 

The  titanium-steel  in  its  unquenched  state  looks  much 
like  carbon-steel  of  like  percentage  of  carbon,  but  when 
quenched  its  fracture  is  unusually  satinlike.  M.  Groboi* 
informs  me  that  he  is  certain  that  the  steel  actually  con- 
tains titanium,  as  he  determined  it  himself,  and  that  he 
knows  of  no  sure  way  of  making  titanium-steel  regularly. 
Note  that,  in  spite  of  the  large  proportion  of  carbon  in 
this  titanium-steel,  the  proportion  of  titanium  is  small. 

§419  NICKEL-STEEL  (Cf.  §  US,  p.  86). b -Hardly  have 
we  begun  to  recover  from  our  surprise  at  Hadfield'  s  dis- 
coveries as  to  manganese-steel  when  J.  Riley  startles  us 
with  his  statements  concerning  a  probably  more  import- 


a  Director  of  the  AciMes  d'Assailly,  where  this  remarkable  product  was  made, 
b  Journ.  Iron  and  Steel  Inst.,  1889, 1.;  Engineering,  XLVII.,  p.  573,  1889:  Pamphlet 
of  "  Le  Ferro-Nickel"  (or  the  jurors  of  the  Paris  Exhibition  of  1889. 


ness  reaching  a  maximum  with  20$  of  nickel.  The 
fracture  is  fibrous,  sometimes  astonishingly  so.  The 
metal  takes  a  high  polish,  is  sometimes  highly  sonorous, 
and  becomes  the  whiter  the  larger  the  proportion  of 
nickel. 

With  less  than  5%  of  nickel,  nickel-steels  can  be  worked 
cold  readily,  provided  the  proportion  of  carbon  be  low. 
As  the  proportion  of  nickel  rises  higher,  cold-working 
becomes  less  easy. 

Nickel-steel  has  a  lower  combination  of  tensile  strength 
with  elongation  but  (even  with  only  one  per  cent,  of  nickel) 
a  higher  combination  of  elastic  limit  with  elongation  than 
manganese-steel.  I  have  met  descriptions  of  but  few 
carbon-steels  which  excel  the  best  of  these  nickel-steels  in 
this  latter  and  more  important  combination. 

Even  when  thus  excelling  manganese-steel  in  its  com- 
bination of  elastic  limit  and  elongation,  nickel-steel  lacks 
the  extreme  hardness  of  the  latter  material :  but  it  is  still 
so  hard  that  its  machining  will  probably  be  expensive.  I 
find  no  data  for  comparing  the  combination  of  hardness 
and  toughness  of  the  harder  manganese- and  harder  nickel- 
steels. 

If  we  confine  our  attention  to  the  best  specimens,  a  little 

nickel  (say  1  to  5  #)  seems  to  increase  the  tensile  strength 

jmuch  and  the  elongation  a  little :  much  nickel,  say 


370 


THE    METALLURGY     OF    STEEL. 


seems  to  increase  the  elongation  much  while  sometimes 
raising  sometimes  lowering  the  tensile  strength.  But 
almost  any  theory,  except  that  the  effects  of  nickel 
are  uniform,  could  be  deduced  from  the  scanty  and 
conflicting  data.  The  effects  of  nickel  in  nickel-steel 
seem  to  vary  much  more  than  those  of  manganese  in 
manganese-steel. 
In  the  single  case  given  annealing  does  not  materially 


steel.  Its  electric  resistance  is  great,  but  less  than  that 
of  manganese-steel,  becoming  6 '5  times  as  great  as  that  of 
wrought  iron  only  when  the  nickel  reaches  25$.  It  is 
much  denser,  and  even  with  only  5%  of  nickel .  corrodes 
slightly  less  than  carbon-steel,  density  and  resistance  to 
corrosion  increasing  with  the  proportion  of  nickel. 
Nickel-steel  with  25%  of  nickel  is  said  to  be  non- 
magnetic. 


TABLE  218.-TEN8ILE  TESTS  OF  NICKEL-STEEL— J.  RILE  Y.  a 


Composition. 

Tensile  strength,  pounds  per  square  inch. 

Elastic  limit,  pounds  per  square  inch. 

Elongation,  %  in  8  inches. 

Elongation,  %  in  4  inches. 

Contraction  of  area,  g. 

Nickel. 

Carbon. 

Manganese. 

1 

Cast  and  an- 
nealed. 

Rolled. 

Rolled  and 
annealed. 

i 

ao 

Cast  and  an- 
nealed. 

2 
1 

Rolled  and 
annealed. 

J 

Cast  and  an- 
nealed. 

£ 

M 

Kolled  and 
annealed. 

i 

Cast  and  an- 
nealed. 

I 
"o 
H 

Kolled  and 
annealed. 

* 

Cast  nnd  an- 
nealed. 

"o 
H 

Rolled  and 
annealed. 

1-0 

•42 

•58 

\    b 

b 

b 

b 

122,304 

61,152 

1  '5 

9-5 

1 

129,024 

71,904 

11-0 

24-0 

45-6' 

{,.". 

128,424 

67424 

18'7 

2-0 

•90 

•50 

Unmachinable. 

c 

3-0 

•35 

•57 

f  78,176 

44,852 

2-5 

5-6 

78,176 

53,760 

2-5 

9'0 

•s  

114,240 

70,886 

20-3 

87-0 

(........ 

108,640 

62,720 

20-3 

42-0 

8-0 

•60 

•26 

r    . 

\ 

115860 

65,856 

9-0 

10-1 

9-0 

(::....:. 

96,096 

67,872 

7-5 

9-0 

12-0 

4'0 

•85 

•50 

Unmachinable. 

4-7 

•22 

•23 

1  '  .  . 

J  

j 

90,720 

66,224 

17'75 

23-4 

42-0 

[.".". 

90,944 

62,720 

20'0 

25-0 

44-8 

5-0 

•30 

•80 

f 

f* 

•• 
1 

103,936 

67  200 

10-0 

12-5 

22-5 

i":::::: 

95,424 

62,720 

15  0 

17  5 

18-5 

r»'o 

•50 

•84 

/ 

\  

116,480 

69  664 

14'0 

15-6 

14-0 

i  .. 

104,832 

72  SOO 

13'5 

14-0 

17-0 

10-0 

•50 

•50 

Unmachinable. 

e 

25-0 

•27 

•85 

. 

... 

115,186 

85,568 

10'5 

11-7 

:::::::: 

102,592 

28,560 

29-0 

80-0 

2S-6 

25-0 

•82 

•52 

/ 

f  

\  

106  624 

49  280 

43'5 

47-6 

60'0 

'43:6' 

I'..'.:' 

94304 

83,824 

40-0 

45-3 

49-4 

•85 

•57 

83776 

45920 

12-0 

24-0 

82,880 

47,040 

20-0 

29-0 

214.144  f 
219,884  f 
210,246  f 

120,960 
116,602 
120,780 

7;8'g' 
8-2  g 

9-37 

49-2 
52'4 
80-0 

a  J.  Rtley,  Engineering,  May  17th,  1899,  p.  574,  a  paper  read  before  the  Iron  and  Steel  Institute. 

b  Test-piece  defective. 

c  Too  hard  to  machine  with  Mushet's  steel.     Good  tools  may  be  made  from  it  by  quenching  from  dull  redness  in  boiling  water. 

d  The  average  is  reduced  by  the  low  results  given  by  one  test-piece. 

e  Too  hard  to  machine.    Good  cutting  tools  may  be  made  from  it  by  cooling  in  a  blast  of  cold  air. 

f  We  are  not  told  how  these  pieces  have  been  treated  before  testing. 

g  The  length  in  which  the  elongation  ia  measured  is  not  given. 


improve  the  unforged  castings,  but  forging  improves  them 
very  greatly,  raising  the  tensile  strength  and  elastic  limit 
by  50^,  and  increasing  the  contraction  of  area  and  the 
elongation  six-  and  seven-fold  respectively.  Like  man- 
ganese-steel, nickel-steel  seems  to  elongate  over  its  entire 
length  under  tensile  stress,  instead  of  necking  like  carbon- 


Let  us  now  take  up  a  few  of  these  points  in  more  de- 
tail. 

The  hardness  depends  on  the  proportion  of  nickel  and 
of  carbon  jointly,  nickel  up  to  a  certain  percentage  in- 
creasing the  hardness,  beyond  this  lessening  it.  Thiis 
while  steel  with  2%  of  nickel  and  0-90$  of  carbon  cannot 


KTICKEL.STEEL.      §  410, 


371 


be  machined,  steel  with  '&%  of  nickel  and  0'60$  of  carbon 
can.  The  most  striking  instances  are  summed  up  in 
Table  220. 

TABLE  219.— TORSIONAL  TESTS  or  NICKEL-STEEL.    (J.  Biley.)a 


NUMBER. 

Number  in  Table  218. 

Composition,  per 
cent. 

Breaking  load, 
pounds. 

Load  at 

elastic  limit, 
pounds. 

Number  of 
twi»ts  in  8 
Inches. 

Nickel. 

Carbon. 

Manganese. 

Hainmered. 

Hammered  and 
imnealed. 

Iluunnert-'l. 

ILiinmt'red  and 
annealed. 

Hammered. 

1  hmiMHTr'l  and 
annealed. 

Nickel-steel. 

I  

1 

1-0 

0-42 

0-58 

1,849 

Si7 

U 

!.S<t9 

COT 

U 

11  .                                          3 

I.MI 

i'-::;,     (FBI 

Boo 

1! 

III  

C 

4-7 

0-22 

0'23 

1,418 

621 

]  j 

aa 

IV 

' 

s-o 

O'SO 

0-30 

1,.W 

C77 

2i 

1.4s:, 

KB 

2! 

v 

10 

25-0 

0-27 

0-85 

1,960 

610 

8 

2.1(10 

860 

5 

I  

Mm 

0-S5              |    I,i04 

.VB 

•1- 

Open-hearth  carbon-stee  . 

n-r.i 

|     1,1189 

0(11 

1    ifS 

VIII  

0-51 

1,697 

6(11    1 

1™ 

IX  

1  ,2:!li 

445 

1  •<•• 

a  The  pieces  tested  were  one-inch  in  diameter,  and   were  twisted  by  means  of  a  lever  one-foot 
long,  with  the  loads  above  given. 
J.  Kiley,  Kntr  m:erin(;,  Mny  17th,  1889,  p.  r>74,  :i  puiicr  rend  liefore  the  Iron  and  Steel  Institute, 

TABLE  220.—  HARDNESS  OF  NICKEL-STKKL. 

(J.  Eiley.) 

Nickel  *. 

Carbon  %. 

Machinable  or  not. 

2. 

0-90 

No. 

Yes. 
Yes. 

Yes. 
Yes. 
Yes. 

8. 

0-60 

4. 

0-85 

No. 

5. 

0-60 

10. 

0-50 

No. 

25. 

49-4 

10-82 
10'27 
0-88 

Density.  —  Riley  reports  the  following  determinations  : 

%  Nickel.               Sn.gr. 
100.                8-86 
25.                  8-08 
10.               T'866 
5.              7-846 
0.  (?)        7'84  mean  of  Biley's  results  for  hammered  (carbon  ?)  steel. 
0.               7-85@7'87,  ueual  limits  for  nnhardened  carbon  steel  in  Table  149,  p.  257. 

Corrosion. — Riley  states  that  the  rich  nickel-steels  are 
practically  incorrodible,  and  that  even  those  with  little 
nickel  corrode  less  than  carbon-steels,  giving  the  follow- 
ing results: 

TABLE  220  A. — KATES  OF  CORROSION  OF  NICKEL  AND  OTHER  STEELS  IN  ABEL'S  CORBOSITK  LIQTTTD. 


Metals  compared. 

Katio  of  corrosion  of  nickel 

Nickel  steel. 

Other 

teel. 

steel  to  other  steel. 

Sf  nickel 

Carbon  steel  0*1S#  carbon. 

1:1.2 

Of  nickel 

Steel  of  .40^  carbon  and 

1:1.5 

25*  nickel 

Carbon  steel  0*1S£  carbon 

( 
1:87 

25£  nickel      | 

Steel  of  .40Jf  carbon  and 

1:116 

I 

Immersing  steel  said  to  contain  25$  of  nickel  in  fresh 
water  in  contact  with  carbon-steel  rich  in  carbon,  I  found 
that  the  carbon-steel  began  to  rust  within  a  few  hours,  at 
the  same  time  losing  its  polish :  but  even  after  three  days 
the  nickel-steel  showed  no  certain  sign  of  rusting.  Im- 
mersed in  fresh  water  alone  for  eighteen  days  the  same 
nickel-steel  showed  not  the  least  symptom  of  rusting. 

The  Fracture  of  a  bar,  said  to  be  of  nickel-steel  and 
shown  me  by  "  Le  Ferro-Nickel,"  nicked  on  one  side  and 
bent  away  from  the  nick,  was  astonishingly  fibrous, 
''barking"  like  very  tough  fibrous  wrought-iron  (Cf. 
p.  196,  1st  column).  In  another  case  the  sheared  fracture 
of  a  bar  about  1  '25  inches  square,  said  to  contain  30$  of 


nickel  and  1'00$  of  carbon,"  was  exceedingly  silky,  and 
much  like  that  of  the  softest  basic  steel,  except  that  its 
color  was  very  much  darker,  indeed,  almost  black. 

Ductility.— In  the  case  of  nickel-  as  in  that  of  maganese- 
steel  the  elongation,  exaggerated  by  the  tendency  of  the 
test-piece  to  stretch  over  its  entire  length  instead  of  neck- 
ing, may  be  found  to  give  a  greatly  exaggerated  idea  of 
the  metal's  toughness  and  value.  Thus  the  contraction 
of  area  and  the  endurance  of  twisting  are  less  than  would 
be  anticipated  from  the  elongation,  the  percentage  of  con- 
traction of  area  being  actually  less  than  that  of  elongation 
in  four  out  of  twenty  cases.  Number  4  of  Table  218  and 
the  rolled  and  annealed  specimen  of  number  7  in  the  same 
table  are  very  fair  steels,  if  judged  by  their  combination 
of  tensile  strength  and  elongation,  but  not  if  judged  by 
that  of  tensile  strength  and  contraction  of  area.  These 
facts  suggest  great  caution  in  deciding  as  to  the  value  and 
uses  of  this  promising  alloy. 

Blowholes. — A  small  broken  ingot,  about  2 '25  inches 
square,  of  steel  with  30%  of  nickel  and  \%  of  carbon  shown 
by  St.  Chamond,  has  many  blowholes  besides  the  central 
pipe.  Its  columnar  structure  is  very  marked. 

Source  of  Nickel. — It  is  believed  that  highly  ferruginous 
nickel,  which  is  quite  as  suitable  as  pure  nickel  for  mak- 
ing nickel-steel,  can  be  made  at  a  much  lower  cost  per 
unit  of  nickel  than  the  nickel  now  in  the  market,  which 
contains  relatively  little  iron.  M.  Qarnier  proposes  to 
smelt  nickel  ores  in  a  common  blast-furnace,  obtaining 
thereby  a  highly  sulphurous  and  ferruginous  crude  nickel, 
which  he  would  desulphurize  by  repeated  fusions  in  a 
cupola  with  a  very  calcareous  slag  thinned  by  fluor-spar, 
(Relief  s  process),  finally  melting  the  desulphurized  pro- 
duct in  the  basic  open-hearth  furnace. 

Future. — I  do  not  think  that  we  can  forecast  the  future 
of  this  remarkable  alloy  with  complete  confidence  from 
the  data  at  hand.  On  the  one  hand,  apparently,  even 
with  but  short  experience,  nickel-steels  have  been  made 
which  greatly  surpass  most  of  the  best  carbon-steel  in 
their  combinations  (1)  of  tensile  strength  with  elongation, 
and  (2)  of  elastic  limit  with  elongation,  and  are  but 
slightly  excelled  in  these  combinations  by  even  the  very 
best  carbon-steels  which  I  have  met :  whence  we  might 
hope  that,  with  greater  experience,  nickel-steel  would 
excel  the  very  best  carbon-steels  decidedly.  On  the  other 
hand  we  must  bear  in  mind  that  our  data  suggest  that 
the  useful  ductility  of  nickel-steel  may  prove  to  be  much 
less  than  would  be  inferred  from  its  elongation :  that  its 
properties  appear  to  vary  capriciously :  that  those  in- 
terested in  it  preserve  an  attitude  of  reserve,  not  to  say 
concealment,  which,  while  it  is  reasonably  attributed  to 
other  causes,  may  be  due  to  the  discovery  of  some  grave 
defect :  that  many  another  remarkable  alloy  has  been 
discovered,  for  which  we  have  anticipated  a  great  future, 
only  to  see  it  play  an  unimportant  role  :  and,  finally,  that 
the  cost  of  nickel  and  the  difficulty  of  machining  are  likely 
to  be  serious  obstacles  to  the  extended  use  of  this  alloy. 

The  claim  that  the  properties  of  nickel-steel  are  due  to 
the  particular  mode  of  introducing  the  nickel,  and  not  to 
the  mere  presence  of  that  element,  will  genemlly  bo  re- 
ceived with  extreme  skepticism.  Like  claims  are  made, 
apparently  with  no  supporting  evidence,  for  most  of  the 
patented  alloys  offered  to  investors. 

a  Shown  by  St.  Chamond  at  the  Paris  Exhibition  of  1889. 


372 


THE    METALLURGY    OF    STEEL. 


APPENDIX     II. 

ANTI-RUST  COATINGS. 


§  420  (Cf.  §  168,  p.  104).— Finding  no  data  as  to  the  rela- 
tive protection  against  rusting  afforded  by  different  pro- 
tective coatings,  Mr.  R.  W.  Lodge  and  the  author  have 
carried  out  a  series  of  experiments  with  exposures  lasting 
from  ten  months  to  a  year,  with  both  thin  sheet  wrought- 
iron  and  plates  of  cast-iron,  under  four  different  condi- 
tions of  exposure  and  with  six  protective  coatings,  speci- 
mens of  the  same  irons  without  protective  coating  being 
exposed  simultaneously.  A  fifth  series  of  plates  was  im- 
mersed in  sea-water,  but,  in  spite  of  very  considerable 
precautions  to  prevent  their  being  carried  away  by  the 
water  or  by  men,  they  cannot  be  found.  To  facilitate 
comparison  with  Table  44,  p.  94,  the  results  are  reduced 
to  the  same  standard. 

TABLE  221, — Loss  OF  WEIGHT  OP  WROUGHT-  AND  CAST-IRON  WITH  DIFFERENT   PROTECTIVE 
COATINGS,  IN  POUNDS  PER  SQUARE  FOOT  OF  BURFACB  PKR  ANNUM.    (Cf.  Table  44,  p.  94). 


Exposed  to  the  weather 
inland. 

Immersed. 

Average. 

In  Canada. 

In  New 
York  State. 

In  fresh 
water. 

In  sewage. 

WROUGKT-IRON  SHEETS. 

Bower-Barffed  

0 
gain,  '002,0 
0 
gain,  '000,4 

gain,  '000,3 
•000,1 
•000,5 

•006,7 
•019,4 
•050,4 
•045,9 
•088,9 
•187,0 
•179,0 
•074,6 

•008,6 
•007,1 
•008,1 
•080,5 
•117,0 
•169.0 
•182,0 
•080,8 

•002,5 
•006,2 
•013,5 
•042,0 
•051,2 
•082,5 
•091,6 
•040 

Tinned  

Nickel-plated  

Galvanized  .  .  . 

Barfled             

•001,0 
•001,8 
•000,2 
•000,02 

•008,1 
•022,6 
•005,0 
•005,1 

Copper-plated  

Average  

CAST-IRON  PLATES. 

Bower-Barffed  

gain,  '004,0 
•000,6 
0 

gain,  -003,1 
•001,9 
0 
gain,  -008,1 
•002,5 
•005,0 
•012,0 
•002,1 

gain,  -005.5 
•000,2 
•049,1 
•065,5 
•181,7 
•150,8 
•148,8 
.077,2 

•001,4 
•008.4 
•061,0 
•061,0 
•088,8 
•119,2 
•272.4 
•086,7 

gain,  -002,8 
•002,8 
•027,5 
•041,1 
•058,5 
•067,8 
•106,6 
•041 

"        '•        and  paraffined  
Galvanized  

Tinned 

Nickel-plated  

gain,  -008,4 
gain,  '004,0 
gain,  -006,3 
gain,  '002,9 

• 

Copper-plated  

A  single  sheet  of  No.  23  gauge  refined  wrought-iron  was  cut  into  plates  6"  X  12"  and  others 
6"  X  6".  Of  the  6"  X  12"  pieces  some  were  exposed  without  treatment  of  any  kind,  the  sciile 
being  left  on:  others  were  tinned;  still  others  were  galvanized  by  the  Rhode  Island  Tool  Com- 
pany. Of  the  6"  X  6"  plates  some  were  Bower-Barffed  (Cf.  §  167  C,  p.  102)  by  the  Yale  & 
Towne  Company,  others  were  Barffed  by  the  Pratt  &  Cady  Company,  still  others  were  nickel- 
plated  and  copper-plated,  in  each  case  after  pickling.  Tho  cast  iron  pieces  were  skin-bearing 
plate*,  4"  X  3*5"  X  OMS7",  presented  by  Prof.  G.  W.  Maynard.  These  were  subsequently  given 
the  coatings  indicated,  theirorigin.il  skin  being  retained  in  all  cases. 

One  set  of  the  pieces  thus  prepared  was  exposed  on  the  roof  of  a  dwelling-house  in  the  Eastern 
Townships  of  the  Province  of  Quebec,  Canada,  by  Mr.  E.  C.  Hale,  of  Sherbrooke,  Canada:  a 
second  was  similarly  exposed  in  a  village  in  Rensselaer  County,  New  York  State  :  a  third  was 
immersed  in  the  Chestnut-Hill  (Boston)  reservoir  by  Mr.  Desmond  FitzGerald,  of  Boston:  a 
fourth  was  immersed  in  the  Boston  main  sewer,  near  the  pumping  station,  by  Mr.  H.  H.  Carter, 
of  Boston. 

Our  thanks  are  due  to  these  gentlemen  and  to  the  companies  already  named  for  their  kind 
assistance  in  preparing  or  exposing  the  specimens. 

We  intend  to  describe  these  experiments  in  more  detail  in  the  Transactions  of  the  American 
Institute  of  Mining  Engineers.  Suffice  it  here  to  say  that  in  each  of  the  conditions  of  exposure 
the  wro  tight-iron  pieces  were  in  one  open  wooden  crate,  the  cast-iron  ores  in  a  second,  the  cor- 
ners of  the  pieces  (and  in  case  of  the  6''  X  1'2"  wrought-iron  pi -ces  a  small  space  in  tho  middle 
of  the  long  sides)  alone  being  in  contact  with  the  crate;  and  that  care  was  taken  that  the  speci- 
mens should  not  touch  each  other  or  any  other  metallic  substance.  Though  exposed  nearly 
a  year,  including  autumn,  winter  an  i  spring,  at  the  end  of  the  experiments  the  gummed  labels 
atill  adhered  to  twelve  out  of  the  twenty-six  specimens  exposed  in  Canada  and  in  New  York. 

In  'brief^  the  Bower-Barffed  pieces  lost  much  less  and 
the  copper-plated  and  naked  pieces  decidedly  more  than 
the  others :  the  cast-iron  lost  about  as  much  as  the 
wrought-iron  :  the  loss  was  about  the  same  in  fresh  water 


as  in  sewage,  and  slightly  less  in  Canada  than  in  New 
York.  * 

Comparing  the  different  conditions  of  exposure.,  im- 
mersion of  course  greatly  accelerates  rusting.  Thus  in 
ten  out  of  the  fourteen  sets  of  cases  the  pieces  immersed 
in  fresh  water  lost  at  least  twenty  times  as  much  as  those 
exposed  to  the  weather  in  New  York.  The  loss  is  slightly 
but  fairly  constantly  greater  in  New  York  than  in  Canada, 
which  helps  to  explain  the  celebrated  brightness  of  the 
tinned  roofs  of  the  Canadian  churches.  The  loss  in 
sewage  is  slightly  greater  than  in  fresh  water,  but  far 
from  constantly,  for  in  seven  out  of  the  fourteen  cases  the 
loss  in  fresh  water  excels  or  about  equals  that  in  sewage,  a 
result  most  unlocked  for,  and  wholly  at  variance  with  Mal- 
let's results  with  fresh  water.  It,  however,  recalls  Mallet's 
results  with  sea-water,  in  which  sewage  on  the  whole 
retarded  the  corrosion  of  skin-bearing  cast-iron  (p.  97). 

Comparing  the  different  protective  coatings  the  Bower- 
Barffed  pieces  win  easily,  undergoing  no  loss  in  five  out 
of  the  eight  cases,  and  with  the  single  exception  of  the 
nickel-plated  wrought-iron  in  sewage,  losing  less  than 
half  as  much  as  any  of  the  other  irons  in  the  three  other 
cases.  The  copper-plated  and  the  uncoated  iron  lose 
most  heavily,  copper-plating  on  the  whole  accelerating 
the  rusting,  especially  in  case  of  the  wrought-iron  sheets. 
The  tinned  pieces  come  in  as  a  good  second  in  case  of 
wrought-iron,  the  galvanized  as  a  bad  second  in  case  of 
cast-iron.  As  between  nickel-plating  and  galvanizing  in 
case  of  wrought-iron,  and  as  between  nickel-plating  and 
tinning  in  case  of  cast-iron,  it  is  not  easy  to  decide  whether 
the  apparent  difference  is  not  due  to  individual  peculiarities 
of  the  pieces  tested. 

The  most  surprising  result  is  the  practically  identical 
loss  of  cast-  and  of  wrought-iron,  not  only  on  a  general 
average  of  the  whole,  but  in  at  least  three  out  of  four  of 
the  sets  of  cases.  It  harmonizes  with  the  belief  expressed 
in  §165,  p.  98,  that  the  slower  rusting  of  cast-  than  of 
wrought-iron  is  due  chiefly  if  not  wholly  to  the  protection 
which  the  skin  of  the  cast-iron  affords,  rather  than  to  the 
difference  in  the  nature  of  the  two  substances.  Just  as 
we  there  saw  that,  when  wrought-  and  cast-iron  were 
brought  to  terms  of  equality  by  planing  the  skin  from  the 
latter,  it  ceased  to  resist  rusting  better  than  wronght-iron, 
so  it  does  in  the  experiments  of  Table  221,  in  which  we 
may  suppose  that  the  protective  coatings  applied  put  the 
materials  nearly  on  equal  terms.  Still,  even  when  un- 
protected the  wrought-iron  here  resists  rusting  about  as 
well  as  the  cast-iron. 


LEAD-QUENCHING.      g  421. 


873 


APPENDIX     III. 

LEAD-QUENCHING. 


§421.  Quenching  in  lead  instead  of  in  oil  has  been 
adopted  by  the  (Jhatillon  et  Commentry  Company  of 
France,  especially  for  forged  projectiles  for  piercing 
armor-plates.  The  metal  is  first  heated  to  the  desired  tem- 
perature (probably  the  W  of  Brinnell  and  b  of  Chernoff), 
and  then  plunged  into  a  bath  of  molten  lead,  in  which  it 
cools  undisturbed.  Owing  to  its  density  and  high  con- 
ductivity, lead  should  at  first  cool  the  piece  more  rapidly 
than  oil  or  water,  but  later,  as  the  temperature  of  the 
piece,  sinking  below  the  V  of  Brinnell,  approaches  that 
of  the  lead  bath,  the  cooling  grows  slower  and  slower, 
ceasing  asymptotically.  Lead-quenching  then  should 
cool  the  metal  more  quickly  through  the  higher  ranges  of 
temperature  and  less  quickly  through  the  lower  ranges 
than  oil-quenching.  We  may  surmise  that  the  fine  grain 
acquired  when  the  metal  is  heated  to  W  will  therefore  be 
preserved  better  by  lead-  than  by  oil-quenching,  and  we 
would  rather  expect  that  the  former  operation  would 


in  elongation.  Thus,  taking  the  last  eight  sets  of  bars, 
with  carbon  from  0'70  to  1*30$,  we  find  that  the  average 
elongation  of  the  lead-quenched  pieces  is  14$  greater 
while  their  average  tensile  strength  and  elastic  limit  are 
1 0$  and  I  8$  less  respectively  than  those  of  the  oil-quen < •  1 1  <  •  <  I 
bars.  It  is  not  yet  clear  that  the  properties  acquired  by 
lead-quenching  cannot  be  as  readily  and  more  cheaply 
given  by  oil-quenching  followed  by  a  more  complete  an- 
nealing, nor  indeed  that  this  latter  combination  of  oper- 
ations may  not  give  higher  elastic  limit  for  given  elonga- 
tion than  lead-quenching  does. 

Comparing  now  the  lead-quencned  with  the  simply 
annealed  bars,  we  find  that  the  former  invariably 
excel  the  latter  in  tensile  strength  and  elastic  limit,  but 
are  excelled  by  the  latter  in  elongation  in  nine  out  of 
twelve  cases. 

Finally,  comparing  the  simply  annealed,  the  water- 
quenched  and  the  oil-quenched  bars,  we  find  that  the 


TABLE  222.— PROPERTIES  OF  STEEL  ANNEALED  AFTER  DIFFERENT  KINDS  OF  HEAT-TREATMENT— CHATILLON  ET  COMMENTRY. 


II 

Tensile  strength,  pounds  per  sq.  in  ,  when  annealed  after 

Elastic  limit,  pounds  per  square  inch,  when  annealed  (?)  after 

Elongation,  f  in  8  inches,  when  annealed  after 

Ss 

og 

forging. 

quenching     in 
water. 

quenching     in 
oil. 

quenching     in 
lead. 

forging. 

quenching     in 
water. 

quenching    in 
oil. 

quenching    in 
lead. 

forging. 

quenching    in 
water. 

quenching     in 
oil 

quenching    in 
lead. 

0*10 

44  090 

51  628 

26  170 

85,130 

80 

20 

0-20 

43,379 

64,429 

t8,4M 

44,375 

25,601 

48,857 

86,979 

26,738 

84 

28 

30 

81 

0'80 

65,567 

80,785 

71,256 

72,251 

86.979 

52,840 

41,815 

43,806 

24 

SI 

24 

22 

70,402 

88,089 

81.496 

74,100 

89,112 

59,024 

58.47T 

45,989 

20 

18 

22 

81 

(1-50 

77,941 

105,891 

98,706 

86,190 

43,806 

72,251 

65,567 

51,486 

21 

IB 

19-5 

20 

0-60 

85,386 

112.:ili(l 

102,404 

89,608 

46,935 

81,070 

70,402 

53,198 

18 

18 

IT 

IT 

0-70 

91,026 

126.588 

113,782 

99,559 

52,624 

88,181 

78,958 

61,158 

16 

14 

14 

16 

0-80 

93,  MO 

137,961 

119,472 

1011,1171 

54,046 

92,448 

76,803 

56,891 

IT 

11 

18 

14 

11-90 

98,137 

140.S06 

118,781 

108.093 

54046 

93,870 

79,647 

64,002 

16 

10 

18 

15 

1.00 

106,671 

153,606 

129,428 

115,  '205 

55,469 

106,671 

81,070 

69,691 

IT 

10-5 

11 

15 

1-10 

118,782 

163,562 

145,072 

129.428 

56891 

116,627 

92,448 

79,647 

14 

T 

9-5 

13 

1  20 
1-80 

122,316 
128,005 

170,674 
180,629 

163,562 
168,562 

150,761 
156,451 

64,002 
69,691 

128,005 
125,161 

115,205 
116,627 

98,187 
95,292 

12 
10 

8 
6 

p 

9 
9 

10  ' 
10 

Thirteen  sets  of  IJ-inch  square  steel  bars,  apparently  eight  inches  long  between  marks,  each  set  being  of  constant  composition,  are  tested  tensile!/  in  four  different  conditions. 
Klitions  are  as  follows  : 

1st,  fimply  annealed,  apparently  by  slow-cooling  from  dull  redness  after  previous  forging. 

2d.  quenched  in  cold  water  from  about  W.  (b  of  Chernun"),  then  reheated  to  750°  F.  (400°  C.)  and  cooled  slowly, 

3d,  the  same,  except  that  they  are  quenched  in  oil  instead  of  water. 

4th,  the  same,  except  that  they  are  quenched  in  molten  lead  instead  of  water. 

The  proportion  of  carbon  ia  approximately  that  given  in  the  second  column,  and  but  little  silicon,  manganese,  etc.,  is  present,  i.  e.  the  metal  is  true  carbon-steel. 


Thes» 


con 


induce  less  powerful  internal  tension  than  the  latter. 
Which  of  the  two  should  the  more  completely  prevent 
the  carbon  from  passing  from  the  hardening  to  the  cement 
or  non-hardening  state  it  would  be  hard  to  judge  before- 
hand. 

At  the  Paris  exhibition  of  1889  the  Chatillon  et  Com- 
mentry Company  gives  certain  results  of  lead-quenching, 
which  are  reproduced  in  a  modified  form  in  Table  222. 

Here  the  influence  of  lead-quenching  is  m.uch  milder 
than  that  of  oil-quenching,  the  lead-quenched  piece  ex- 
celling the  oil-quenched  in  elongation  in  9  out  of  the  12 
cases,  and  being  excelled  by  the  oil-quenched  piece  in 
tensile  strength  and  in  elastic  limit  in  1 1  out  of  the  12 
cases.  This  milder  quenching  should  be  desirable  for 
certain  cases :  but  it  can  hardly  be  claimed  that  the  effect 
of  lead-quenching  is  absolutely  better  than  that  oil- 
quenching,  for  the  oil-  excel  the  lead-quenched  pieces  as 
much  in  strength  as  the  lead-excel  the  oil-quenched  ones 


water-quenched  bars  invariably  excel  the  oil-quenched, 
and  these  in  turn  always  excel  the  corresponding  simply 
annealed  pieces,  in  both  tensile  strength  and  elastic  limit ; 
while  as  regards  elongation  the  order  is  as  we  would  expect 
reversed,  the  simply  annealed  excelling  the  oil-quenched 
and  the  oil-quenched  excelling  the  water-quenched,  in 
either  case  with  a  single  exception,  in  which  the  elonga- 
tions are  equal. 

These  results  agree  in  a  rough  way  with  those  discussed 
on  pages  19  and  20.  The  fact  that,  although  the  latter 
indicated  that  oil-quenching  gives  high-carbon  steel 
greater  strength  than  water-quenching  does,  all  the  water- 
quenched  pieces  of  Table  222  are  stronger  than  the  oil- 
quenched  ones,  may  be  due  to  the  fact  that  here  both 
have  been  tempered  after  quenching,  so  that  some  of 
that  intense  stress  which  water-quenching  gives,  and 
which  probably  directly  lowers  the  tensile  strength,  has 
been  removed. 

V"  fir    ---  ~    ^ 

I  UN  -ITY 


INDEX. 


Page. 
ABEL,  EXPERIMENTS  ON  CONDITION  OK  CARBON..      S,  35 

"      on  segregation 202 

Accidents  in  Bessemer  mills 331.  315.  349 

Acid,  consumption  of,  for  pickling 221 

Acker  on  segregation 203,  204 

Adamson  on  blue-shortness 235 

"  trustworthiness  of  steel 240 

welding 250.251 

After-glow  of  steel  185,187 

Agitation  to  prevent  blowholes 155 

Akerman,  histheoryof  hardening 34 

"          on  Caspersson's  converter-ladle 360 

desulphurization 61 

effect  of  phosphorus 68 

"  en  volatilization  of  phosphorus 67 

Allen's  agitator 208,  209 

Allotropic  theory  of  cold- working 217 

"  "  hardening   189 

Alloys,  copper-iron. 83 

"       tin-iron  85 

"       zinc-iron 84 

AlDha  and  beta  iron 189,  217 

Aluminum  and  iron 86 

"        in  Mitis  castings 310 

American  bloomary  process 270 

Ammonia  from  steel 113 

Analyses.    See  Composition 

Andrews  on  corrosion 97, 103 

Annable  on  Whitworth's  compression 161 

Annealing,  in  general 17 

"         ChernofTs  experiments 248 

"          effects  of,  in  general 25 

"  "       on  cold-worked  iron 217 

"  copper-steel 369 

•(  chrome-steel 366 

"  "  manganese-steel 361  to  363 

"  :•  nickel-steel 370 

"  "  silicon-steel 367 

"  "  tungsten-steel 368 

"  "  tungsto-chrome  steel. . .        368 

"          for  wire-drawing 224 

"         rationaleof 30 

"         removes  effects  of  punching 231 

"         temperature,  etc.,  for 24 

Annular  casting  pits 337 

Antimony  and  iron 86 

Armor-plate  of  chrome-steel 366,  387 

"  manganese-steel 362,  365 

Arsenic  and  iron 85 

Aufbrechschmiede  process 293 

A  vesta  Bessemer  plant ; 

"     metal,  its  toughness  ascribed  to  slag.  —         196 


BAKER  ON  EFFECT  OF  VIBRATION 

"        punching 

"        trustworthiness  of  steel  

"       proves  stress  in  cold-worked  iron. . 

Ball-stuff,  composition 

"          use  of 

Barba,  effects  of  punching 

Barffed  iron,  rusting  of 

BarfT  s  anti-rusting  process 

Barium  and  iron 

Barking  of  wrought-iron 

Barus  and  Strouhal  on  annealing    at   low  tem- 
peratures   

"  "       density 

"  "       effect    of     cold-working 

and  of  quenching 

Bauernofen  

Baushinger,  instructions  for  welding 

"  on  Wohler-treatment 

"  results  in  welding 

"  "       of  cold-working 

Bcardslee  on  crystallization  of  iron 


198 
232 
240 
220 
352 

348,350 
230 
372 

102,372 
89 
196 

31 

29 

218 
270 
254 
198 
251 
211 
199 


Page. 

Beck-Gnerhard  on  punching 230 

Bell,  action  of  carbonic  acid  on  iron 120 

'     heat-requirement  of  blast-furnace 262 

'     Krupp  dephosphorizing  process 66 

'     washed  metal 308 

'     on  Blair's  process 280 

charcoal-hearth  process '.  292 

'          dephosphorlzation 56, 62,  67 

desulphurization 51 

reducing  power  of  hydrogen 263 

Bennett  on  punching 231 

Bernardo's  electric-welding  process 255 

Bessemer  and  crucible  processes  compared 298 

"          converter.  See  Converter,  Bessemer 
"          escape  of  carbonic  oxide  from  molten 

iron 124 

"          inventorof  liquid  compression 155 

"         plant,  arrangement  of  tracks 337 

"                "      Bochum 333 

"               "     Bochumer  verein 336 

"               "     capacity  of  a  single  pit 325 

"                "     converging-axed 333 

"               "     diverging-axed 334 

"               "     early  British 328 

"     Holley 328 

"                "      Joliet 334 

"               "     levels  in  339 

"             "     Peine  336 

"                "     Phcenix    335 

"           plants,  large  vs.  small 326 

"  "     miscellaneous  dimensions  of..  329,330 

"          process,  arrangement  of  plant  for 318 

length  of 321 

"                "        machinery  for 316 

"          steel,  perhaps  affected  by  nitrogen 109 

"     production  of,  in  United  States.  356 

Bethlehem  Bessemer  plant 319 

Billings'  cold  drawing  apparatus 227 

"       liquid  compression 157 

"       on  effect  of  copper  83 

"       prevention  of  blowholes 163 

"       on  zinc  and  tin  with  iron 84 

Bismuth  and  iron 86 

Bissell  on  strain-diagrams  of  brass 213 

Blair  on  aluminum  in  iron 89 

"     direct  process 278 

"     process,  cost  of  plant 263 

Blaseofen 270 

Blast,  Bessemer,  power  for 349 

Blast-furnace,  cost  of 263 

•<          efficiency  of 262267 

"          heat-requirement  of 262 

"          in   competition   with  direct    pro- 

"             cesses 260 

Blinding  tuyeres  in  Bessemer  vessels 355 

Blister  steel  for  the  crucible  process 307 

Bloomary,  cost  of  installation  for 262 

"        iron,  composition  of 270 

"         process,  American 270 

Blooms  of  Husgaf  vel  furnace,  composition  of —  273 
Blowholes  as  affected  by    recarburizing    addi- 
tions   128 

"         formationof 126 

"         formed  by  rapid  solidification 130 

"          influence  of  process  of  manufacture 

on 129 

"          in  nickel  steel 371 

"          mechanical  theory  of 135 

"         microscopic  intrusions  in 146 

"         prevention  by  agitation. 155 

"                   "               chemical  additions...  162 

"                    "               exhaustion 161 

"                    "               slow  cooling 161 

"          rationale  of     their  prevention    by 

silicon  139 

375 


Page. 

Blowholes,  shape  and  position  of 146 

"         solution  or  hydrogen,  theory  of 134,136 

'*          theory  of,  r6sum6  of  discussion 145 

"          what  causes  them 134 

Blue-shortness- 234 

Bochum  Beseemer  plant 333 

Bochumer  Verein  Bessemer  plant 336 

Boker  on  burning 202 

"        crucible  process 314 

Bottom-joint  of  Bessemer  vessel 350 

Bottom   repair  shop 337 

"       for  Bessemer  vessels,  composition  of.  —  352 

"         inspection 355 

liteof 343,355 

"                                 "          number  needed...  354 

"          preparation 354 

"                                 "         repairs 355 

"  "  "         time  needed     for 

changing 321 

Boulton's  sinking-head  arrangement. 154 

Boussingault  on  chrome  steel 77 

Bower-Barffed  iron,  rusting  of 372 

Bowers'  anti-rusting  process 102,  372 

Brackelaberg's  experiments  on  phosphorus 56,  67 

Brand's  experiments  on  crucible  process 312 

Brinnell's  carbon  condition  studies 170 

'•         fracture  studies 172 

British  early  Bessemer  plant 328 

Brown,  Richard,  dephosphorizing  idea 71 

Brustlein  discovered  manganese  steel 365 

"        on  chrome  steel 78,368 

"         "  copper  steel 368 

*'        experiment  on  rapid  solidification 130 

Bufflngton's  anti-rusting  process 103 

Bull's  direct  process 277 

Burning 200 

"       rationaleof....           201 


CALCIUM  AND  IRON 

Calvert  on  corrosion  of  iron. 

Carbide  of  iron,  Fe3C  ...  

'*  "  titanium  in  cast  iron 

Carbon,  absorption  in  crucible  process . 

"       and  iron,  in  general 

"         "  oxygen  in  molten  iron 

"       condition,  Brinnell's  study  of.. 

"  "          in  iron 


89 

98 

....  5 

7 

314 
4 

94 
170 

5 

"              "         of,  affected  by  temperature...  10 

"              "           "  in  manganese  steel 364 

"       diffusing  power 4 

"      distribution  between  different  states —  7 

"       effect  on  dephosphorization 61 

'*       effect  on  recalescence 188,  189 

"       effect  on  welding 251 

"      evidence  of  two  states  of  combination. . .  5 

*'       impregnation  or  deposition 120 

"       influences  effects  of  phosphorus 69 

••              "              "        "  rolling,  etc 244 

"       Iron  Company's  direct  process 283 

"       its  condition  not  changed  by  cold-rolling  35 

"       "  influence  on  physical  properties  of  iron  13 

"       nitric  acid  spotting 170 

"       saturation-point  for 5 

"       segregation  of 205 

Carbonic  acid  and  iron 118 

"       oxide  and  acid,  equilibrium  between. . .  119 

"            "      "     iron,  in  general 118 

"  "    condition  in  iron 105,122 

"            "    its  absorption  by  iron 124 

"            "      "  effect  on  dephosphorization ...  62 

"            "      "   escape  from  iron 124 

"           "  influence  on  the  physical  proper- 
ties   125 

Caron,  experiments  on  absorption  of  silicon 38 

"                "             "  condition  of  carbon 3$ 


376 


HOWE'S    METALLURGY    OF    STEEL. 


Page. 

Caron,  on  density   256 

"      on  sulphur  and  manganese   44 

Caspersson's  converter-ladle 360 

Casting-pits,  annular — 337 

for  Bessemer  process,  capacity  of..  325 
"  size  needed..  324 
"  suppression 

of 334 

Casting-pits,  straight  vs.  circular 335 

Casting-scrap 360 

Castings,  steel,  composition  and  properties  of . . . 

Catalan  hearth  process 269 

Cellular  theory  of  steel 189 

Cementite 161,166 

Changing  bottoms   in  Bessemer  process,  time 

needed  for S21 

Charcoal-hearth  processes 289 

•'       applied  to  making  steel.        296 

"       classification  of 293 

"       economic  features 292 

"       material  for  289 

Chatillon  &  Commentry,  experience  with  man- 
ganese steel 362 

Chatillon  &  Coramentry,  on  lead  quenching. 373 

Cheeveron  phosphates  in  steel 55 

Chemical  combinations,  nature  of 2 

Chemistry  of  the  crucible  process 310 

Chenot's  direct  process 277 

Chernoff,  experiments  on  heat-treatment 248 

"        on  density 257 

"         "  fracture 175 

"         "  intrusions  in  blowholes 146 

"         "  slow  cooling 161 

"        heat  treatment  process 180 

, ,        prevention  of  blowholes 155 

Chickie's  rock,  composition  of 352 

Chrome-steel 75,76,366 

"    composition  and  properties 76 

"    forging,  welding,  homogeneousness          78 

"          "    status 79 

Chromium,  effect  on  recalescence 189 

"          in  general 75 

Clapp-Grifflths  converter. 71,342 

"          American    326 

"          description.. 356 

"          life  of  linings. 353 

"          number  of 356 

output  of 356,  357 

"          phenomena  of 343 

process 35£ 

Classification  of  Bessemer  converters 341 

"         "  charcoal-hearth  processes 

"         "  iron 

Clay  crucibles,  preparation  and  use 300 

Clay's  direct  process 281 

Clearance,  influence  on  effects  of  punching. 231 

Clemandot's  process 180 

Cobalt  and  iron 

Codorus  steel? 41 

Coffin's  axle-process 181 

"     bend 185,186 

"     experiments  in  tempering 192 

"     onfracture 175-6-7 

' '     rail  process 179 

"     weld 184 

Cold-drawing 227 

Cold-hammering..    , 234 

Cold,  its  effect  on  brittleness 70 

"     "   influence  on  the  effects  of  phosphorus  . .          70 

Cold-rolling  226 

"          "     does  not  change  the  carbon  condi- 
tion           35 

"          "     effect  on  tensile  strength  and  elastic 

limit S15 

Cold-work,  effect  of  manganese  steel 3S4 

"        "       in  general  — , 110 

Cold-working  compared  with  hardening 218,  220 

"        rationale  of 217 

Columnar  structure  of  ingots 183 

Composition  of  blast-furnace  charge  for  silico- 
spiegel  365 

bloomary  iron 270 

blooms    from    C.    W.   Siemens' 

direct  process 287,  288 

charcoal-hearth  iron 290 

chrome  steel 76,  368 

cupola  linings : 359 

cupreous  steels 83,368 

Dannemora  iron 308 

ferro-chrome 76,  366 

ferro-silicon 36,365 

ferro-titanium 369 

ferro-tungsten 81,368 

forgeable  and  unforgeable  steels.     45,  46 


Page 

Composition  of  gas  evolved  from  iron  132 

evolved      during      solidification 

ofiron 107 

obtained    by    heating    iron    In 

vacuo 108 

gas  obtained  on  boring  iron  106 

good  manganiferous  steels 4 

Husgafvel  blooms 27 

"                 ladle-linings 35 

manganese  steel 48,  361,  365 

"                many  kinds  of  steel 258 

"                nickel-steel 369 

"                 nozzles 35 

phosphoric  steels 69,  7 

"                pure  phosphates  and  silicates. ...  5 
"                refractory  materials    for  Besse- 
mer process 35. 

"                siliciferous  steel 38,366 

silicon  steel  41 

silico-spiegel    3S 

slag  of  crucible  process 29" 

'•   "  C.  W.  Siemen's  direct  pro- 
cess   287 

"   .                 "   "  Barnes  direct  process 485 

"                    "    "  silico-spiegel  365 

"  spiegeleisen       and       ferro-man- 

ganese 43 

steel  castings 162 

"                   "      miscellaneous 258 

stoppers 359 

"                stopper  sleeves 359 

"                sulphurous  rails 53,54 

"  titanium  steel 

"                tungsten  steel 81,368 

vessel  kidneys 353 

vessel  lining,  proximate 331 

"                welding  steels 251 

wrought-iron       from      Dupuy'B 

direct  process 2S 

Compression,  liquid.  See  Liquid  compression. 

Compresslve  strength  as  affected  by  carbon 17 

"        of  manganese-steel 8ft 

Concentric  vs.  excentrlc  vessel  noses 344 

Conley's  direct  process 277 

Construction,  cost  of,  for  Bessemer  plant 324 

"             "     "     "    blastfurnace 262 

"  direct  process  

Contraction  cavities  in  steel  ingots 149 

Converging-axed  Bessemer  plant 333 

Con  verier,  Bessemer,  in  general 

"          Avesta 341 

"                "          Bethlehem 341 

blast-pipe 345 

bottom 348.351,354 

"          inspection  of 355 

"                "          bottom-joint 350 

"                "          Cambria 341 

Clapp-Grifflths.  See  Clapp- 
Grifflth's  converter. 

"          classification  of 341 

"                "          corrosion  of 353 

Davy's 358 

"          details  of  construction 345 

"          Durfee's 342 

early 339 

"          Edgar  Thomson 341 

"          Eaton 341 

"          excentrio  vs.  concentric. . .  344 

"          false-plate 318 

"               "         fixed  vs.  rotating 341 

"                "          Hatton's 357 

"          Holley's  movable 347 

"                "          inspection  of  bottom 355 

"          internal  tuyeres  in 344 

"                "          Laureau's 358 

lining  351,353 

"          names  of  parts 341 

"          number  built  lately 356 

"          number  in  United  States..  356 

"  "          number  needed 

"          power  for  blast 349 

•'                "          racks  for  rotating 349 

"          repairs  to 348,351,355 

"                "          Robert.    See  Robert  con- 
verter  

"                "          rotating  apparatus 349 

"                "          shell 346 

"          side  vs.  bottom-blowing. . .  342 

size 324 

"                "          size  of  tuyeres 348 

"                 "           skulling  in 353 

"          South  Chicago 341,345 

"                "          straight  vs.  contracted....  344 

"  "         Swedlshflxed 340,343 


Converter,  Bessemer,  trunnion  axis. 

trunnions 

tuyere  box.... 

tuyere  plate... 

Union 

volume  of 

Converter-ladle,  Caspersson's 

Cooper,  Edward,  his  direct  process, 
on  punching . 


Page. 

348 

345 

348 

348 

341 

345 

360 

275 

230 

Copper  and  iron,  in  general 82,368 

"      behavior  in  crucible  process 316 

Copper-box  experiments 191 

"     effect  on  welding 251 

"     its  effect  on  f orgeableness 83 

plated  iron,  rusting  of 372 

"     steel 368 

Copperas  from  pickling  liquors 221 

Corrosion  of  iron,  in  general 91 

"        as  affected  by  composition 97 

difference  of  potential ...  102 

"                structure 98 

surface  exposure 95 

temperature 95 

"        best  vs.  common  wrought  iron 103 

"        Bower  and  Barff  processes  against 102,372 

"        cast  vs.  malleable  iron 98,372 

"        hastened  by  copper,  brass,  etc 103,  372 

"        in  different  media 95,372 

"        insewage 97,372 

"        protective  coatings  against 104,  372 

"        retarded  by  silicon 41 

"              zinc 103,372 

"         steel  vs.  wrought-iron 98 

"        of  nickel  steel  371 

Cost  of  crucible  process 310 

installation    direct  process  and    blast- 
furnace   262 

Cracks,  effect  of,  on  rupture 195 

in  steel  ingots 152 

Cranes,  casting,  for  Bessemer  mills 131 

number  needed    for  Bessemer 

plant 324 

Ingot,  location  of 337 

"       number    needed    for  Bessemer 

process £24 

ingot,  time  occupied  by  their  motions. . .  322 

Cremer,  J.  H.,  composition  of  vessel  kidneys 353 

Critical  temperatures  for  steel 184 

hardening 12 

Crucible  process,  in  general 296 

furnaces  compared 302 

process  compared  with  others 297 

"       composition  of  slag 297 

"       details  and  manipulation 304 

"       economic  features 296 

clay,  preparation  and  use 300 

graphite  and  clay  compared 298 

life,  use  and  preparation 298 

Crusts  on  cast-iron 208 

Crystalline  vs.  fibrous  iron 194 

Crystallization  favored  by  phosphorus 70 

hindered  by  quenching SO 

of  iron,  changes  in  181 

Crystals,  largo  in  iron 147, 148, 178 

of  hot-forged  iron  equiaxed 192,193 

Cupola-linings,  composition 352,359 

life 359 

Cupolas,  location  of,  in  Bessemer  mills 318,  345 

Cylinder,  hydraulic,  for  Bessemer  vessel 349 

DAELEN'S  COMPRESSION 156 

Dannemora  iron 293,  307,  308 

Darlington,  rapid  work  at 322 

Davenport  on  the  use  of  aluminum 87 

Dead-melting  to  prevent  blowholes 163 

Dean's  process 234 

DC'bris,  cupola,  track  for 338 

Definitions,  hardening,  tempering  and  annealing  17 

of  steel 1 

"     "    Holley 179 

3'Elhuyar,  first  alloyed  iron  and  tungsten 81 

Density  of  iron  in  general 256 

affected  by  quenching  from  100°  C 31 

lowered  by  cold-working 214,  220 

"         "punching 228 

"        "quenching 29,218 

of  chrome  steel 74 

"  molten  and  of  plastic  cast-iron 259 

"nickelsteel 371 

)coxidation.    See  Reduction. 
Dephosphorization,  as  affected  by  carbon,  etc.,  in 

the  iron 61 

carbonic  oxide  62 

manganese.. . .  66 


INDEX. 


377 


Page. 

Dephosphorization,  as  affected  by  temperature. .  62 

"                    by  alkaline   nitrates 66 

"  "  ferruginous  vs.  calcareous 

slag* 59 

"fluor-spar 61,6) 

"                     "  fused     carbonates. 66 

"                    "slags 56 

"                   in  charcoal-hearth  process. .  296 

"                    "   cupola  furna  es  65 

"                   "   direct  processes 2til 

"                    "   Barnes'  direct  process. .  285 

"                    "    Husgafvei's  furnace 273 

"                   limited  by  silica  of  slag 57 

"                   silicates  vs.  phosphates 57 

"                  strength  of,  oxidizing  on —  60 
Deshayes,  effect  of  manganese  on  physical  pro- 
perties   47 

"         on  effect  of  phosphorus 68 

Desulphurizing  in  charcoal-hearth  process 296 

Detail,  rupture  in 198 

Devitrification  phenomena 65 

Diamond  theory  of  hardening 34 

Dies,  wire  and  mint,  composition  of 223 

Dies,  wire,  of  chrome-steel 366  | 

Diffusion  of  molten  metals  203 

Dilatation  of  iron  257  . 

Direction  of  rolling,  effect  on  strength 199 

Direct-metal,  bringing  to  vessels 344  | 

"           "      track  for    338 

Direct  processes,  in  general 259 

"             "      advantages  and  disadvantages  of  260 

"       at  a  balling  heat 264 

"    steel   melting  heat 265 

"              "       classified  by  mode  heating 266 

"             "      described 269 

"       difficulties  of  263 

"       futureof 259,268 


Page. 

Emmerton  on  segregation ~ 204 

Eston  Bessemer  plant 33.'! 

"       life  of   vessel-linings 352 

"       vessel-noses  at 3lf> 

Eustis'  direct  process '.'is 

Euvertc  on  phosphoric  steel 71 

Excentric  vs.  concentric  vessel  noses 34 


Exhaustion  for  preventing  blowholes 


Ifil 


FAIKBAIRK  ON  PHOSPHORIC  STKKI. 71 

Faraday  and  Htodart  on  iron-alloys 85,  87,  89 

Farquharson  on  corrosion 99 

Felton  on  effect  of  rest  on  steel 200 

Ferric  acid 91 

Ferric  oside !K) 

Ferrite  164,  165 

Ferro-chrome,  in  general  366 

Ferromanganese,  composition  of 43 

Ferro-sil  icon 38,  365 

Ferro-titanium ; 

Ferrous  oxide      90 

Fettling  for  Siemens'  direct  process 286 


Fibre  in  iron  and  steel . 


191 


"      general  scheme  of 

Diverging-axed  Bessemer  plant 

Dowlais,  composition  of  refractory  materials 

Draw-plates  for  wire-drawing 

Dreimalschmelzerei  process 

Drown,  on  Eaton  process    

"        "  slag  in  cast-iron  

Ductility  as  affected  by  carbon 

chromium 

hardening  

manganese 

nascent  hydrogen 

phosphorus 

silicon 

"          as  related  to  thickness 

"          at  a  blue  heat    

"          of  steel  castings    

Ductility.     See  also  Elongation. 

Dudley,  effect  of  manganese  on  ductility 

"       on  phosphates  in  steel 

"        "  phosphorus  units 

"        "  the  condition  of  carbon 

Dumas,  action  of  carbonic  acid  on  iron  

Du  Motay  on  phosphoric  steel 

Du  Puy's  direct  process 

Durf ce's  Bessemer  converter 

" .       vessel-rotating  mechanism 

Dynamometer  punch 


268 
334 
352 
223 
293 
66 
123 
16 
76 
20 
46 
116 
68 
37 
243 
234 
162 

48 
55 
74 
7 

120 
71 
282 
342 
350 
233 

283 
66 
338 
338 
"    rapid  work  at —         323 

Eggertz  on  effect  of  copper 83 

Eglest  on  on  bloomary  process 270 

Ehrenwerth  on  dephosphorization 59,  64 

"    size  of  Bessemer  plants 326 

Einmalschnielzerei  process 293 

Elastic  limit  as  affected  by  chromium 76 

"         "       "  "       "   cold-working 213 

"         "       "  "       "   hardening 20 

"         "       "  **       "   phosphorus 67 

"         "       "   related  to  thickness 243 

"         "       exaltation  of,  during  rest 213 

"         "      temporary  depression  of 185-6 

Elasticity,  modulus  of,  as  affected  by  carbon 17  j 

Electric  welding 254 

Electrical  resistance  of  nickel-steel 370 

"  "  silicon-steel .     366 

Elevators  for  Bessemer  works 337  | 

Elongation  affected  by  mode  of  rupture 195 

"  "  carbon 16 

hardening 20  i 

"          its  relation  to  tensile  strength 17 

"          peculiar,  of  manganese-steel      ,         363 

"         See  also  Ductility, 


EAMES'  DIRECT  PROCESS 
Eaton  dephosphorizing  process 
Ebbw  vale,  direct  metal  track  at 
Edgar  Thomson  Bessemer  Mill 


r'.ue  partly  to  mode  of  rupture 194 

Files  of  chrome  steel ; 

Finkener  on  dephosphorization 57 

"          "  sulphur  and  iron 49 

Finishing-temperature 246 

Flexibility  of  iron   lessened  by  nascent  hydro- 
gen   114 

Floating  of  cold  iron  explained 2,7 

Fluid-compression.    See  Liquid  Compression. 

Fluidity  of  iron,  affected  by  silicon 41 

Fluor-spar  on  dephosphorization 61,  63 

Fluxes  for  the  crucible  process 308 

"       for  welding 253 

Ford  on  the  condition  of  carbon 7 

"     spiegel  reaction 43 

Forgeableness  as  affected  by  copper 83,  368.  369 

"                                   manganese 44 

oxygen 91 

phosphorus 72 

"                "                silicon 37 

sulphur 52 

tin        84 

"        of  chrome-steel 78 

"        of  tungsten-steel 82 

Forging,  effect  on  manganese-steel 3G2 

Forsyth  Bessemer  plant 331 

"        composition  of  refractory  materials  —  352 

"        on  effects  of  silicon 40 

"         "  segregation    203 

"        rapid  Bessemer  work  by .121,  331 

"        prevention  of  blowholes 155 

"        steam  on  sulphur  in  Bessemer  process..  52 

Foster,  Morrison,  on  Blair's  process 280 

Fracture  of  iron  and  steel,  in  general 170 

.  "         at  a  blue  heat    . 235 

"         Brinnell's  studies 172 

Franche-Comte  process 295 

Freson  on  cold -rolling 227 

Friction,  behavior  of  manganese-steel  towards. .  354 

Frigo-tension 234 

Fritz,  John,  on  straight  casting-pits 337 

Fuel,  quantity  needed  for  charcoal-hearth  pro- 
cesses       292 

Fuel,  quantity  needed  for  crucible  process 296 

"          "  "          "    direct  processes.    260, 

268  to  271,  273,  275.  277, 

278,  281,  283,  285,  287 

Fume,  crusts  on  cast-iron  208 

Furnace.C.  W.  Siemens' cascade 288 

"         for  Lancashire-hearth  process 293 

"           "  F.  Siemens  direct  process 288 

"           "  the  crucible  process 301 

"    "    Lancashire-hearth  process 289 

"          heating,  location  in  Bessemer  works..  S39 
"          rotary,  for  C.  W.  Siemens  direct  pro- 
cess   285 

Fusibility  as  affected  by  ch  romium 79 

"           "           "          silicon 41 

GALVANIZED  IRON,  RUSTING  OF 372 

Galy-Cazalat's  liquid-compression  157 

Canister,  composition  and  definition 352 

(iarrett  on  burning 201 

Garrison,  F.  L.,  on  Osmund  and  Husgafvel  fur- 
naces    271 

Garrison,  microscopic  study 178 

Gases,  apparatus  for  collecting  them  on  boring 

iron 142 

Gase.«,  escape  of  influenced  by  pressure 130 

"      condition  in  iron. .             105 

"      supposed  to  cause  hardening — . ,.,..  34 


Page. 
Gas-furnaces,   difficulties  of  obtaining  reducing 

flame  in 264 

Has,  its  absorption  and  escape  from  iron,  in  gen- 
eral      125 

C.iis.  quantity  obtained  on  boring,  solidification 

and  heating 10G-108 

Gas,  quantity  of  evolved  from  iron 131 

(ins  producers,  \\YIlinan  <•».  Siemens :V2 

<  Jalcwond,  his  results  analyzed 46 

iiilliK-ricc  of  carbon  (in  tensile  strength  13 

GiiuiK's,  wire •_)£( 

(!a micron  silicon-steel 366 

Genoese  catalan-hearth 269 

Gerhardt's  direct  process 283 

German  charcoal-hearth  process 293 

Gilchrist  on  dephosphnrizalion 65 

G ilmore,  effect  of  cold-working 212 

Gjers,  Bessemer  plant  shown  by 328 

Goetz,  on  ammonia  from  steel  114 

Gold  and  iron 89 

Gordon,  F.  W.,  internal   tuyere   for   Bessemer 

vessel 344 

Gordon,  Strobcl  and  Laureau's  Bessemer  plant. .  327 

Gore's  phenomenon  185 

Graphite  cannot  exist  in  molten  iron 10 

"        crucibles,  life,  use  and  preparation 298 

"        formation  affected  by  temperature 10 

proportion  of,   affected  by  other  ele- 
ments.   9 

Grobot  on  titanium-steel 309 

Gruneron  the  Ileaton  process 66,  67 

basic  Bessemer  process '. . . .  57 

Gun-iron,  sulphur  added  to  it  purposely 54 

"   steel,  siliciferous,  composition  of. 38 

Gurlts  direct  process 275 

HADFIELD  ON  MANGANESE-STEEL  48,351 

Hainworth's  casting  arrangements    3'JO 

Hammer-hardening 234 

Hardening,  in  general 17 

allotropic  theory  of 187-9 

"          cooling  effect  of  different  media 21.35 

"          diamond,  gas  and  Akerman's  theo- 
ries of 34 

does  not  occur  below  redness       12 

effect  on  the  physical  properties—. .  30 

"          heating  for 21 

"          in  molten  zinc  explained 12 

"          its  rationale ....  27 

"          Jarolimek's  methods 21,24,36 

"          media  for  quenching 21 

"          of  iron  and  carbon-steel 18,373 

"           "chrome-steel 77,367 

"          "  copper-steel 369 

"manganese-steel    361-363 

"          "  silico-manganese  steel 363 

"           "silicon-steel 366 

"           "  tungsto-cliromesteel. 367 

"tungsten-steel 82,368 

"          precautions 22 

"          temperature  needed  for 21 

Hardenite 154,  1(57 

llardisty  on  sulphur  and  iron  19 

Hardness  as  affected  by  carbon 17 

hardening 20 

hydrogen 116 

"         conferred  by  tungsten gl 

"         of  chrome  steel 77 

nickel  steel 371 

quenched  steel  due  to  changed  con- 
dition of  carbon 34 

Harrisburg  Bessemer  mill 333 

"    rapid  work  at 323 

"    tracks  at 338 

Harvey's  direct  process....   283 

Hatton's  Bessemer  converter 357 

Hawkins' direct  process 277 

Heath  introduced  use  of  manganese 42 

Heath's  modification  of  Huntsman's  process 296 

Heat  evolved  on  dissolving  iron 7 

Heat-requirement  of  blast  furnace.        262 

direct  processes       260 

Heat  treatment,  ChernofFs  experiments 218 

effect  on  carbon-steel 373 

"       "chrome-steel 367 

"       "  copper-steel 359 

"  manganese-steel 361-303 

"       "nickel-steel 370,  371 

"  silico-manganese  steel.  361 

"       "silicon-steel %o 

"  tungsten  steel 368 

"       "  tungsto-chrome  steel  .  367 

methods  of 179 

Heating  for  hardening , 21 


878 


HOWE'S    METALLURGY    OF     STEEL. 


Page, 

Heating  for  tempering 22 

Heaton  dephosphorizing  process 52,  63,  67,  70 

Henderson,   early  experiments   on    dephospho- 

rization 63 

Heterogeneousness,  prevention  of 208 

Hilgenstock  on  dephosphorization 57,61 


tetracalcic  phosphate . 

Hinsdale's   casting  arrangement 

"         liquid-compression  

Hochstatter,   experiments    on    sulphides  and 

phosphides 

Hoerde,  ladle  oar  at 

Hoists  for  Bessemer  works       

Holley  and  Pears'  bottum  joint 

''      Bessemer  plant 

"      comp  jsition  of  refractory  materials. 

definition  of  steel 

"      exposes  Sherman  process 

"      on  Codorus  uteel 

"       "  effect  of  copper 

*'       "       "      "  silicon 

'•       "  fired  Bessemer  vessels 

"       "  forging 

"       "  heat-treatment 

"       "  steel  castings 

"       "  vessel-noses 

"       "  welding 

Holley's  bottom-ioint 

"       shell-shifting  device 

"       stopper  attachment 


65 
154 

157 

66 

335 

337 

350 

328 

352 

179 

71 

41 

83 

39 

312 

246 

216 

246 

344 

252 

350 

347 

359 


Holtzer's  steels  at  Paris  exhibition 363  to  369 

Homestead  Bessemer  plant 331 

rapid  work  at. ...  321,  323,  331 


Hood  of  Bessemer  vessel,  location 

Houston  on  treachery  of  steel 

Howard,  J.  E.,  on  dilatation 

Hughes  on  effect  of  nascent  hydrogen 

Hunt,  A.  E.,  effects  of  hardening 

"  on  Eames'  direct  process 

"  effect  of  work  on  iron 

"  R.  W.,  On  Clapp-Grifflths  converter 

Huntsman's  crucible  process 

Hupfeld's  results  in  welding  

Husgaf vel's  high  bloomary 

Hydraulic  cylinder  for  Bessemer  vessels 

Hydrogen  and  iron,  in  general 

"         condition  in  iron 

"          its  absorption 

"  "  effects  on  iron 

"         reducing  power  of 

"         reduction  by 

"         saturation  point  for 

"         theorj- of  blowholes       


345 
239 
257 
114 
18 
284 
245 

71.  343 
296 
251 
271 
349 
110 
105 
110 
114 
263 
117 
113 

134, 138 


usually  present  in  commercial  iron. . .  110 

INGOT  CRANES,  LOCATION 337 

Ingots,  columnar  structure  of 183 

Installation,  cost  of,  tor  Bessemer  Plant. 324 

"       "       direct  process  and  blast- 
furnace   26.2 

Internal  tuy.  res  in  Bessemer  vessels 344 

Ireland  on  Blair's  process 280 

Ireland's  direct  process 288 

Iron,  classification 1 

JAROLIHEK,   HEATING    HARDENED   AND   COLD- 
WORKED  IRON 219 

his  methods  of  hardening 21,  24,  36 

Jog  in  strain  diagrams 219 

Johnson  on  effect  of  nascent  hydrogen 114 

Joint  in  Bessemer  vessel 350 

Jo.iet  Bessemer  plant 31(5,  334 

Jones,  W.  R.,  link-bolt  for  Bessemer  bottoms... .  ?48 

"        liquid  compression 157 

Jordan  on  v  olatilization  of  manganese 42 

Justice's  vessel  shifting  arrangement 348 


KALAKOUTSKY  ON  SEGREGATION 

Karsten  on  effect  of  phosphorus 

Kent  on  effect  of  phosphorus 

"       "  mysterious  failures  of  steel. .  . 
"       "  sulphurous  acid  corrodes  iron. . 

Kerl  on  charcoal-hearth  processes 

Kidneys,  vessel,  composition 

Killing  in  the  crucible  process 

"     prevents  blowholes 

Kirk,  A.  C.t  on  trustworthiness  of  stool 
Kirkaldy,  deductions  from  his  results 

'*         hammering  vs.  rolling 

KJeinbessemerei 

Krupp-Bell  dephosphorizing  process. ... 

"    record  of  his  guns    

Krupp's  liquid  compression  . . , . . 


74 


238 

97 

293 

353 

305 

163 

240 

...17,  26,  27,  243 

249 

326 


240 
1ST 


Page. 

LABOR  FOR  CHARCOAL-HEARTH  PROCESS 292 

Labor  for  crucible  process     306 

"  direct  process. . .  .268  to  271,  273,  278,  281,  J-  >.  _'S7 

Lacquer  for  wire-drawing '222 

Ladle  car  at  Hoerde 335 

"       "    "  Peine 336 

"     repair  shop 337 

Ladles  for  Bessemer  process 358 

Lake  Champlain  bloomary  process 270 

Lake  Superior  quartz,  composition 352 

Lancashire-hearth  process 293 

"    (or  scrap  iron  296 

Langley  on  density 31,  257 

Laurcau's  direct  process 277 

Lead  and  iron 85 

Lead-quenching 373 

Leckie's  direct  process 288 

Ledebur  on  burning 201.202 

"        "  crucible  process 314 

"         "   desulphurization 51 

"         "   effect  of  nascent  hydrogen 114 

"         "        "       "  phosphorus 68 

"         "on  segregation 207 

"         "   sulphur  and  manganese 44 

Leeds,  reported  experiments  on  burning 201 

Lengthwise  vs.  crosswise  properties  of  steel 199 

Levels  in  Bessemer  works 339 

Lifts  for  Bessemer  works 337 

Lime  hastens  deoxidation  in  Blair's  process 280 

Liquation.    See  Segregati on. 

Liquid  compression,  Billings' 157 

"          by  gaseous  pressure 157 

"          Daelen's 156 

"          effects  of 158 

*'           Galy-Cazalat's 1?7 

Hinsdale's 157 

"          invented  by  Bessemer 155 

"          Jones' 157 

Krupp's 157 

"           methods  of 155 

Whitworth's 156 

Williams' 156 

Lividiacase,  mysterious  failure  of  steel 236 

Lodge  on  anti-rust  coatings 372 

Loss  of  iron  in  charcoal-hearth  processes 292, 296 

"       concentric  Bessemer  vessels 345 

"       direct  processes 263  to  268,  270, 

273,  280,  282,  284,  287 

"          "       open-hearth  process .           281 

"          "       Robert  converter  358 

"           '        side-blown  vessels 343 

"          "       the  crucible  process 307 

Lubrication  in  wire-drawing 222 

Lucas'  direct  process 277 

237 


MAGINNIS  CAS-?,  MYSTERIOUS  FAILURE  OF  STEEL 

Magnesium  and  iron 89 

Magnetic  oxide  go 

"       as  a  protecting  coating 102,  372 

Magnetism  of  chrome-steel 79 

"          "  nickel-steel 370 

"          "  tungsten-steel    82 

Magnetization  of  manganese-steel 364 

Maillard,  admirable  unforged  casting 248 

Maitland  on  rupture  by  explosion 195 

Mallet  on  corrosion  93 

"     "  phosphoric  steel 71 

Manganese,  in  general 42 

absorption  in  crucible  process 315 

and  dephosphorization 61,  66 

effect  on  formation  of  graphite 9 

"     "  oxidation 42 

"     "  recalescence 188, 189 

"      "  saturation-point  for  carbon  5 
"     "  tensile  strength  and  duc- 
tility   46 

"     "  vessel  linings       353 

its  influence  on  the  effects  of  copper.  83 

power  of  combining  with  iron 42 

promotes  forgeableness 42,44 

removes  sulphur 43,51 

segregation  of       207 

undesirable  in  charcoal-hearth  pro- 
cess      290 

volatilization  of 42 

vs  phosphorus,  copper  and  silicon..  44 

Manganese-steel 48,361 

"     strain  diagrams 362 

Marshall,  effect  of  work  and  heat-treatment 244,  248 

Martens  on  blowholes 146 

"         "   burnt  iron 201 

"  distortion  of  grain  by  cold  work 193 

"        "  effect  of  vibration 198 

Mathesius  on  dephosphorization  , , , , ,  58,  64 


Matthiessen  on  annealing  at  low  temperatures  . 
Maynard,  composition  of  refractory  materials  . 
on  Siemens'  direct  process  ............ 

Mechanical  theory  of  blowholes  ................. 

Mercury  and  iron  .................................. 

Metci  If,  instructions  for  welding  ............... 

"        on  direct-process  iron  .................... 


Page. 
31 
352 

287 
135 
89 
254 
283 
"fracture  ........................  175,178,177 

"         "   liquid  compression  ...................          157 

"         "    nature  of  welding  ....................         250 

"         "    nitrogen  in  Bessemer  steel  ...........         109 

"         "   resistance  to  shock  .................          199 

Metcalf's  differential  h  xrJoning  experiments  ...  20 

Meteoric  iron,  structure  of  ........................         164 

Mica-schist,  for  vessel-linings  ...................  352 

Microscopic  study  of  polishei  sections  ...........          163 

Miller  on  phosphoric  steel  ........................          71 

Mill-stone  grit  for  vessel-linings  ...................         352 

Minerals  whish  compose  iron  ...................         164 

Mint-dies,  composition  of  ..........................         223 

Mitis  castings  ...................................  87 

"     process  ...............  235,  297,  238,  3,12,  315,  3D7,  308 

Modulus  of  elasticity  ai  affected  by  annealing.  ..          27 
"         "  "  "         "       "     carbon  ......  17 

"         "  "  "         "       "     cold  working  214,217 

'*        **       "     nascent  hy- 

drogen ____         116 

"        "       "    phosphorus.          73 
remarks     on      its    con- 

stancy ................         190 

Morgan  on  wire-drawing  ..........................  221,  223 

Morrell  on  density  ................................        257 

"       "   segregation  ..........   ..................         207 

"       "   results  of  wearing-test  ................          54 

Morrell's  gas-furnace  ..............................         264 

Moulds  for  crucible  process  .......................        305 

"       length  of  cy  cle  for  .......................          322 

"       number  needed  in  Bessemer  pit  ..........        324 

Mrazek  on  effect  of  silicon  .......................  .  38 

MUller  on  blowholes  ..............................  127,134 

"        "   effects  of  silicon  .......................  38 

"       "   the  condition  of  carbon  ................  6 

M  filler's  boring  apparatus  for  gases  ..............         142 

"       experiments  on  crucible  process  .........        311 

**        Spiegel-reaction  studies  ..................    92,123 

"       graphite  crucibles  ........................         298 

Mushet  on  copper  and  iron  .....................  .          82 

Mushet's  direct  process  ..........................        283 

steel  ...........................  ....81,367 


NECKING  DOES  NOT  OCCUR  IN  MANGANESE-STEEL 

"          "          "  nickel-steel 

Needles  for  sewing  machines 

Newton's  direct  process 

Nickel  and  iron 

Nickel-plated  iron,  rusting  of 

Nickel-steel 

Nitric  acid  spottteg-test  for  carbon-condition. . . . 
Nitrogen  and  iron  in  general 

"        condition  of,  in  iron 

"        in  commercial  iron 

Nitrogenized  iron 

Nobel  crucible  furnace 

North-Eastern  Steel  Works,  plan  of 

Nose-blocking  in  Bessemer  process 

Noses  for  Bessemer  vessels,  excentric  vs.  concen 
trio 

"  "  "        size 

Nozzles  for  casting-ladles  composition    

life 

Nyhammar  continuous  bloomary 


ODELSJERNA  ON  SULPHUR  AND  IRON 

Oncosimeter  diagrams 

Open-hearth,  chrome-steel  made  in 

"          "       process,  loss  in 

Osmium-iridium  and  iron 

Osmond,  cellular  theory  of  steel  

"        furnace 

"        his  theory  of  hardening 

"        on  cold-hammering    

"         "  composite  structure 

"         "  heat  of  solution 

''         **  structure 

"        theory  of  cold-working 

Ostberg  OH  Mitis  castings 

"  *•      process 

Output  of  American  Bessemer  plants. . 

"        crucible  furnaces  

Overheating 

Oxidation.    See  Corrosion. 

Oxidation  vs.  burning 

Oxides  of  iron 

Oxide-tints  for  tempering 

Oxygen  and  iron,  in  general 


363 
370 
233 
277 

86,  369 
372 
369 
170 
106 
105 
109 
108 

302,  3D3 
333 
353 

345 
345 

352,359 
359 
274 

49 
257 
367 
281 

89 
16D 
271 
187 
193 
182 
7 

163 
217 

87 
302 
323 
302 
200 

201 
90 
23 
90 


INDEX. 


370 


Page. 

Oxygen  co-exists  with  carbon  in  molten  iron 94 

'*       in  commercial  iron 91 

"       "  molten  iron 91 

"       its  effects  on  iron 91 


PALLADIUM  AND  IKON 89 

Parker,  W.,   effects  of  cold  working 212 

"                    "     vibration  on  fracture 198 

"                    "      work  on  iron 245 

"         on  corrosion 97,  101 

"          "    punching 231 

"           "   treachery  of  steel 239 

Parry,  experiments  on  gas  in  iron    Ill 

"     extraction  of  carbonic  oxide  from  iron  . .  123 

"     on  absorption  of  zinc,  etc.,  by  iron 84 

"     steam  removes  sulphur 52 

Pearlyte 101, 166 

Poarse,  J.  B.,  and  Ilolley's  bottom-joint 350 

"        hammering  vs.  rolling 250 

Peine,  ladle-crane  at 336 

Percy  on  Heath's  invention 296 

"      "    sulphur  and  iron  49 

Pernot  furnace,  claimed  to  promote  homogene- 

ousness 208 

Phillips,  D.,  on  corrosion 99 

Phoenix  Bessemer  plant 335 

Phosphates,  composition  of 56 

"           exist  in  iron 55 

"           tetracalcic,  in  slags 65 

Phosphorus,  in  general 51 

"            action  of  sulphide  of 68 

"            behavior  in  crucible  process 316 

"            combination  with  iron 56 

"            illusions  concerning  its  effects 71 

"            its  condition  in  iron 55 

"            effect  as  influenced  by  carbon 69 

cold 70 

"                 "                    "               silicon 70 

"                "on  crystallization  70 

"         ductility 68 

"                 *'         f  orgeablenese 72 

"                "         structure 70 

"  "         tensile  strength  and  clastic 

limit 67 

"                 "         the  formation  of  graphite.  10 

"                 "         welding  73 

44            proportion  of  permissible  in  steel. . .  73 
"           removal  of.  See  Dephosphorization. 

segregation  of 5j,  205 

•'            units 74 

"            volatilization  of 63,67 

Physical  properties— See  also  Tensile  strength 

and  elongation. 

"                "        as  affected  by  carbonic  oxide  125 

"                 "                  "           "  lead-quenching  373 

"                "        effect  of  carbon  on 13 

"                 "         of  charcoal-hearth  iron 290 

"                 "          "chrome-steel 76,367 

"                 "          "copper-steel 369 

"                 "          "manganese-steel ...  361-361 

••  "         "  nickel-steel  369, 370.  371 

"                 "          "  phosphoric  steels  69,  71 

"                 "         "  silico-manganese  steel 363 

"                 "         "silicon-steel 366 

"                "         "  tungsto-chrome  steel 367 

"                 "         "tungsten-steel 81,368 

Physics  for  the  crucible  process 308 

Pickling  for  cold-rolling 227 

"         "    wire-drawing 221 

Pig  washing 66,  308 

Pionchon  on  specific  heat 184,  190 

Pipe  in  ingots,  shape,  etc 146 

"         "        volume  of 151 

Piping 127 

Pit.    Sec  Casting-pit. 

Pits  on  steel  plates 147 

Plastic-compression 158 

Platinum  and  iron  

Poling  for  mixing  metal 208 

Ponsard's  direct  process  283 

Potassium  and  iron        90 

Pots,  steel-melting.    See  Crucibles SCO 

Pourcel,  experiments  on  dephosphorization —  61,  63,  65 

"        finds  silicious  network  in  steel 37,  43 

*'        on  blowholes 

I  ower  for  Bessemer  blast 349 

Practice  as  to  blue-working 236 

"         "  "punching 233 

Projectiles  of  chrome-steel 366 

Protective  coatings  against  rusting 104,  372 

"         for  wire 226 

Punching  in  general  228 

"         factors  influencing  its  effects , ,  ! 


Punrhinjr.  its  effects  local 

"          practice  as  to 

"          rationale  of  its  effects. . 

"          special  forms  of  punch 
Pyrophorism  of  iron 


Page. 
230 
233 
232 
233 
M 


QUENCHING.    See  Hardening. 


RACK  FOR  TURNING  BESSEMER  VESSELS 31!) 

Rails,  proportion  of  phosphorus  in 74 

"     silicifcrous,  composition 38 

"     sulphurous,  composition  of 53,   54 

Ramdohr's  direct  process 275 

Rapid  work  at  American  Bessemer  mill  3.     .  321,  323,  331 

Rationale  of  burning 201 

"        "cold-work  217 

"         "  effects  of  punching 232 

"        "       "       "  work  on  iron 246 

Raymond,  on  effect  of  manganese 4  ; 

"           "        "       silicon 38 

Reaction  theory  of  blowholes 131,136. 

Reaming  removes  effects  of  punching 231 

Recalescence  of  steel 185,  187 

Recarburizing  additions,  effect  on  blowholes    ..  128 

reactions  in  Bessemer  process...  128 

Redshortness 52 

does  silicon  cause  it  1 37 

"            due  to  burning !00 

"      copper 83,?68.  369 

"      oxygen 91 

"      sulphur 52 

prevented  by  manganese U 

See  also  Forgeablenoss 

Reducing  flame,  confusion  concerning 26t 

Reduction  by  carbonic  oxide  ...         118 

"         "hydrogen 117 

"          "  rolling,  etc.,  effect  of 212 

"         Quantitative  effect   on   properties  of 

iron 245 

Reed,  E.  J.,  on  trustworthiness  of  steel  210 

Refractory  materials  for  the  Bessemer  process, 

351,  352,  353.  355.  359 
"  "        Bessemer   vessels, 

Alpine 332 

"  "        Bessemer  vessels. 

Avesta 352 

"  "         Bessemer  vessels, 

c  o  m  p  o  s  i  tion, 

proximate 331 

•'  "         Bessemer  vessels, 

compos  ition, 

ultimate 352 

"         Bessemer  vessels, 

life  of 351,  353 

"  "         Bessemer  vessels, 

preparation 351,  351 

"         Bessemer  vessels, 

Swedish 352 

•'        Bessemer  vessels, 

wear 353,355 

Reiser's  exoeriments  on  the  crucible  process 311 

Renton's  direct  process 282 

Repair-shop  for  ladles,  etc 337 

Repairs  to  Bessemer  tuyeres 318 

"        "  bottom  of  Bessemer  converters 354,  353 

"        "crucible-furnaces 332 

"        "  linings  of  Bessemei  converters 351,  353 

Resilience  as  affected  by  cold-working 214 

Rest,  does  it  improve  iron  ? ] 

Rhodium  and   iron 89 

Rhymney  Bessemer  plant 333 

Richards,   Winsor,  gas  on  boring  ingots 142 

"                  "         on  heterogeneousness 209 

Riley,  hammering  vs.  rolling 249 

"       on  effect  of  work  on  Iron 245 

"        "  lengthwise  vs.  crosswise  properties  of 

steel 

"        "   nickel-steel i 

"        "   sulphur  and  manganese 11 

Rising  of  steel  castings 126 

Riveting,  its  influence  on  effects  of  punching —  231 

Robert-Bessemer  converter 343 

"                                "         description  357 

"          life  of  lining 353 

"             "                **         preparation    of     tu- 
yeres    355 

Robert  process 356, 357 

Roberts-Austen  on  diffusion  of  molten  metals —  203 

"              "              hardening  steel 34 

"              "              hydrogen  from  iron  117 

"              "        tints  on  steel  are  of  oxide 23 

Rodman  guns,  relief  of  stress  in 200 

Roger's  direct  process .  ! 

Rollet  on  dephosphorization  in  cupolas 65 


Page. 

Rollet  on  desulphurization  in  cupolas  . .  51 

Rolling,  direction  of,  effect  on  strength ....  199 

"       effect  of.    Nee  Reduction. 

"  vs.  hammering 249 

Rotating  mechanism  for  Bessemer  vessels 319 

Runners  fur  molten  iron,  inclination  of 318 

"  in  livsxrmer  mills 344 

Rupture  in  detail 198 

Rust 90 

Rusting.  See  Corrosion. 


SALT  AS  A  LUBRICANT  IN  WIRE-DRAWING. 

Sa leu n  on  effect  of  manganese 

phosphorus 

silicon 

Sandberg  on  composition  of  rails    

silicon  

sulphur  in  rail  steel  

Sand,  moulding,  composition. . 


221 


74 

41 

53 

352 

Sandviken  early  Bessemer  vessel 341 

Sarnstriin  on  Nyhammar  bloomary 274 

Scale  oxide 91 

Scattering  of  different  classes  of  iron 129 

steel  castings 126 

Schmidhainraar's  direct  process 282 

Schneider  on  condition  of  phosphorus  55 

iron-tungsten  compounds 81 

Schreibersite 164 

Scranton,  on  cupreous  rails 83 

"          works,  rapid  work  at 321,  323 

Scrap,  casting,  reduced  by  use  of  Caspersson's 

ladle 360 

Scrap-iron  in  competition  with  direct   process 

metal 259 

"         "    use  in  crucible  process 308 

Sea-water,  effect  on  rusting. 95,  96,  372 

Segregation 202 

"         in  manganese-steel 364 

"        of  copper  and  iron 82 

"         "  phosphorus 56 

"         "  sulphur  and  manganese 44 

"         prevention  of 208 

"         usual  extent  of 209 

Scraing  Bessemer  plant,  output  of 331 

"       composition  of  refractory  materials 352 

Sewage,  effect  on  rusting  96,  372 

Shaft  furnaces  for  the  crucible  process 301 

Shearing ..  230 

Sheffield,  composition  of  refractory  materials. . .  352 

Shell  of  Bessemer  converter 346 

Sherman  process 71 

Shimer  on  condition  of  phosphorus  in  iron 55 

"       "titanium-carbide 7 

Shock,  effect  on  fracture  of  iron 1!U.  1% 

"          "       "   manganese-steel 364 

resistance  of  low  vs.  high-carbon  steel  to.  199 

Siemens  kC.  W.)  cascade  furnace 288 

"            "        direct  process 285 

"       crucible  furnace 301 

"       (F.)  direct  process 288 

"       rotator,  cost  of  installation 263 

"       retort  direct  process 283 

Silica  as  dust  in  steel  37 

"      in  crusts  and  druses  37 

"      skeletons  of,  in  steel 37,43 

Silicates,  composition  of 57 

Silicon  in  general 38 

"       absorption  of,  by  iron  38 

"       absorpt  ion  of ,  in  crucible  process 310 

"       and  carbon  not  incompatible  in  good  steel  38 

"       condition  in  iron  37 

"       effect  on  Bessemer  vessel  linings 353 

"               "       cast-iron 41 

"               "       formation  of  graphite 9 

"       fusibility 41 

"       saturation  point  for  carbon 5,9 

"               "       soundness 41 

"               "       tensile  strength,  etc 37 

"              "       welding  251 

"       influence  on  the  effects  of  phosphorus 70 

rationale  of  its  action  in  preventing  blow- 
holes   139 

"       removal  from  iron  36 

"       segregation  of 207 

"       steel 40,365 

'•       sulphide  of 37 

"       undesirable  in  charcoal-hearth  process . . .  290 

Silico-spiegel 365 

Silver  and  iron 

Sinking-head,  special  forms 153 

"          "      volume  of 153 

Skulling  in  Bessemer  vessels 353 

Slade  on  phosphoric  steel 69,  70,  71,  73 

Slag,  does  it  exist  iu  cast  iron? 123 


S80 


HOWE'S    METALLURGY    OF    STEEL. 


Slag,  does  it  toughen  iron?  ........................ 

"    effect  on  vessel-linings  .........  '.  ........ 

"    in  weld-iron,  arrangement  of  .............. 

"    its  occurrence    i  iron  ...................... 

"    of  crucible  process,  composition  .....  .*.  ...... 

"    "  Husgafvel  furnace,  composition  ........ 

"     "  wrought-iron,  composition  .............. 

"     '•         '*  "      effect  on  welding  .......... 

"    proportion  of.  in  weld-iron  ................. 

"    removal  of  phosphorus  by  ................... 

Slopping  in  Bessemer  vessels  .................... 

Slurry,  use  of  ................................ 

Smith's  dynamometer  punch  ................... 

Snakes  on  steel  plates  ........................... 

Snelu?,  composition  of  refractory  matcria's  ...... 

"      on  effects  of  silicon  ........................ 

•'  "  Heaton  process  ................... 

"        "  presence  of  graphitoidal  silicon  in  iron 

44        "  punching  ............................. 

"        "segregation  ........................... 

Soaking-pits,  location  in  Bessemer  works  ......... 

"          "    should  be  gas-fired  .................. 

Sodium  and  iron  .................................... 

Solidification,  behavior  of  different  irons  during. 
Solution,  nature  .................................... 

"        of  iron,  thermal  effects  ................ 

theory  of  blowholes 


Page. 

196 

343 

199 

168 

297 

273 

168 

252 

246 

56 

315 

350 

233 

152 

352 

4D 

66 

37 

231 

203 

339 

339 

90 

129 

2 

7 

134 


Sorbite  .............................................  164,168 

Sorby  on  effect  of  vibration  ........................  198 

"       "   microscopic  structure  ..................  200 

"       "  polished  sections  .......................  181 

"       "   structure  ..............................  163 

"       "  the  condition  of  carbon  .................  6 

"       "   the  grain  of  iron  .....................  193 

Soundness  as  affected  by  silicon  ..................  41 

South  Chicago  Bessemer  Mill  ...................  332 

"           "                "          "    rapidworkat  ......  323 

"                "          "    tracks  at  ...........  338-9 

"  "        bottom-drying  arrangement.      .  354,  355 

South  Wales  process  ..............................  293,  595 

Special  steels,  their  future  ........................  80 

Specific  gravity.    See  Density. 

Spiegeleiscn,  composition  of  ......................  43 

Spiegel  reaction    ..........................    43,92,93,128 

"          "        oxygen  removed  in  .............  92,93 

Bpllsbury,  effects  of  wire-drawing    .............  216 

Sponge-making  processes,  difficulties  of  ..........  263 

Springs  from  tungsten  steel  .......................  3G8 

Stead  on  dephosphorization  .....................  58,  61,  65 

"       segregation  ..............................  207 

Steam  removes  sulphur  ..........................  52 

Steel,  cellular  theory  of  ...........................  169 

"      composition  of  many  kinds  .................  258 

"      deflnitionof  ..............    .................  1,  179 

"      treacheryof  ..........................  .  .....  236 

"      trustworthiness  of  ..........................  240 

Step-punch  ........................................  233 

Sterro-metal  ......................................  83,  84 

Stiffness  as  affected  by  cold-working  .............  214 

"        of  low  vs.  high-carbon  steel  .............  214 

Stopper  for  casting-ladles  .......................  359 

St.  Pancras,  converter  used  at  ..................  340 

Strain-diagrams  by  interrupted  strain  ...........  213 

jogin  .............................  219 

"             "        of  cold-worked  steel  .............  »12 

"             "         "  manganese-steel  ..............  362 

•'             "         "  nickel-steel  ...................  370 

Stratification  of  molten  iron  .......................  208 

Strength-carbon  ..................................  7 

Stress  affects  strength  of  hardened  steel      ......  33 

"     detected  in  hardened  steel  .....  ............  29,32 

"     relief  of  during  resc  .........................  200 

Stretching,   effect   of,  on   tensile   strength  and 

clastic  limit  .......................................  215 

Stromeyer  on  blue  shortness  ...................    234,  235 

"        results  with  manganese-steel  ........  363 

Strontium  and  iron  .................................  89 

Strouhal.    See  Barus  and  Strouhal. 

Structure,  composite,  of  copper  and  zinc  .........  169 

"        its  effect  on  rusting  ..................  88 

"        of  ingots,  columnar  ....................  183 

"         "  iron,  in  general  ....................  163 

"         "manganese-steel  .....................  361 

Stubbs  on  segregation  ............  ,  .................  20'3 

Stub's  wire  .........................................  234 

Stlickofen  ......................................  271 

Sulphur,  in  general  ................................. 

"        absorbed  from  furnace  gases  ...........  49 

"        absorption  of,  in  crucible  process  .......  316 

44                "          "   "  direct  processes  ........  263 

"        and  carbon  mutually  exclusive  ........  50 

"           "     silicon  in  iron  .......................  50 

"        causes  redshortness  ......................  52 

"        combination  with  iron    .  ,  ........  ......  *9 


Pare. 

Sulphur,  effect  on  formation  of  graphiie 10 

"       "   saturation-point  for  carbon.. .  5 

"       "    welding 53,251 

"         expulsion  of,  by  manganese 361 

"         proportion  uf,  permissible 52,  53 

purposely  added  to  gun-iron 54 

"        removal **> 

"               "       by  alkalies 51 

"                MM    manganese,  hydrogen 51 

"         removed  better  by  lime  than  by  mag- 
nesia   51 

"               "       by  ferric  oxide,  etc  52 

"  manganese 43,51 

"                "         "  nitrates 52 

"        segregation  of 205 

Sulphurous  acid  corrodes  irou 97 

"        rail -steels,  composition 53 

Sweden,  use  of  Casper.?son's  ladle 360 

Swedish  Bessemer  vessels,  slag  spout  on 356 

"            "           works,  short  blows  at 321 

"       charcoal-he .  rth  iron  composition 290 

"    (Dannemora)  "           "                          308 

"       fixed  Bessemer  converter 340,  343 

"       Walloon  process 293 

TEEMING  IN  BESSEMER  PROCESS,  LENGTH  OF    . .  321 

"         "  crucible  process  '. 305 

Temperature  at  which  annealing  begins 31 

44  "  hydrogen  begins  to  reduce 

iron 117 

"             effect  on  condition  of  carbon 10 

"                "       "  dephosphorization 62 

for  annealing 24 

needed  for  hardening 21 

"             of  casting,  effect  on  blowholes 127 

"  limiting  action  of  carbonic  oxide 

and  acid  118 

Tempering,  in  general 17 

"          Coffin's  experiments  on 192 

effectsof  22 

heating  for 

'*           rationale  of 30 

"          temperature  for 23 

Tensile  strength.    See  also  Physical  properties. 

as  affected  by  carbon 13 

"                             "           chromium 7G 

"                             ••           cracks 195 

"                             "           hardening    19 

"                             "           manganese 46 

"                                         nascent    hydro- 
gen    116 

"                               "            phosphorus 67 

44                                         silicon 37 

"                 as  related   o  thickness .  243 

"                 at  a  blue  heat 234 

"                 Its  relation  to  elongation 17 

"                 longitudinal  vs.  transverse —  199 

"                 of  steel  castings 162 

W  hit  worth  and  other  steel ....  161 

Tests  for  wire .  226 

Thermo-tcnsion 180 

Thomas  direct  process .  283 

Thompson,  C.  O.,  on  rusting 07 

"            '*       salt  in  wire-drawing 222 

Thomson's  electric  welding  process 25t 

Three  versus  two- ves  el  Bessemer  plan. s 323 

Thurston,  effect  of  cold-rolling 216 

"          on  punching 23J 

"           strain-diagrams  of  cold-rolled  iron 213 

Time  needed  for  transporting  ingot? 339 

'     of  operations  in  Bessemer  process 320,  321,  322 

Tin  and  iron 81 

Tinned  iron,  rusting  of 372 

Titanium  and  iron    85 

Titanium-carbide  in  cast-iron 

Titanium-steel 363 

Tomlinson  on  recalescence 137 

Tongs  for  crucible  process "15 

Tourangin's  direct  process  279 

Tourangin,  using  Gurll's  process 275 

Tracks,  arrangement  of,  for  Bcs  einer  works —  337 

Transportation  of  ingots,  time  needed 330 

Treachery  of  steel ••  236 

Trip-hammer  bolts,  reported  crystallization  of . ..  19 i 
Troost  and  Hautefeuille,  experiments  on  absorp- 
tion of  silicon 86 

Troost  and  Hautefeuille  on  heat  of  solution  ....  7 

Trosca's  direct  process  281 

Trustworthiness  of  steel 210 

Tucker's  method  of  determining  oxygen 93 

Tungsten  and  iron,  in  general 81,  368 

*'         effect  on  recalescence 187-8 

Tunner,  effect  of  work  and  heat-treatment  248 

"      on  charcoal-hearth  processes..,,  ••.,,,,  293 


Page. 

Turner,  Siemens  direct  process 287 

Turner  finds  silicious  dust,  in  steel 37 

41  on  effect  of  silicon 39,11 

44  on  silicon  in  cast  iron  9 

Tuyeres,  Bessemer,  composit  ion 352 

repairs  during  blow 348 

44  4I  size  of 348 

44  internal,  in  Bessemer  vessels 344 

44  use  of,  in  Bessemer  vessels 354 

Two  versus  three-vessel  Bessemer  plants 323 

UCHATIUS  PROCESS .* 297 

Uniformity  in  tbe  crucible  process 308 

Union  works,  rapid  work  at 321,  323,  331 

VALTON  DESCRIBED  BLUE-SHORTNESS  EARLY.  ..  235 

Vanadium  and  iron 86 

Venetian  red  from  pickling-liquors 221 

Vessels,  Bessemer.    Sec  Converters 

Vibration,  effect  on  fracture  of  iron 194, 196 

Volatilization  of  phosphorus 67 

44           "  silicon 37 

WALKER,  COMPOSITION  OF  REFRACTORY  MATE- 
RIALS   352 

Walloon  charcoal-hearth  process 293 

Walrand  converter.  See  Robert-Bessemer  vessel. 

"       experiment  on  blowholes    138, 112 

44        on  blowholes 146,147 

44         "  desulphurization  in  cupolas 51 

"         "  sulphur  and  manganese 44 

Ward  on  punching 232 

Washed  pig  for  crucible  process 308 

Waterford  moulding  sand,  composition  of 352 

Water-gas  made  in  Cooper's  direct  process 276 

44            use  in  blast  furnace 277 

Webb's  prevention  of  blowholes 155 

Wedding,  definition  of  wcl.ling  250 

41  on  blowholes 112,113 

44            "slaginiron 169 

44            44  structure 170 

44            "  the  grain  of  iron 199 

Weighing  arrangements  in  Bessemer  process... .  32J 

Welding 250 

44          as  affected  by  phosphorus 73 

44           44       t4         44    silicon 41 

44          fluxesfor       '. 253 

•4         of  chrome-steel 78,  368 

"          44  nickel-steel 269 

44         4I  tungsten-steel 82 

*4         opposed  by  sulphur 53 

44          steels,  composition  of 251 

strength  of  251,  255 

Wellman  gas-producer 302 

Wendel  on  phosphoric  steel. .   73 

Wendel's  formula  for  manganese 45 

Worth.    See  Osmond. 

Westanfors,  use  of  Caspersson's  ladle 360 

West  Cumberland,  vessel-noses  at 345 

Westman's  direct  process  —            276 

Weyl's  method  of  studying  structure 163 

White,  Maunsel,  on  forging  phosphoric  steel 73 

44              "          "    sulphur  and  iron  49 

Whitworth's  compression 155 

44                     -<           invented  by  Bessemer..  155 

Widmanstiitten  figuring 164 

Williams'  compres  ion 156 

Williams.  M.  W.,  on  burning 201,  202 

Willis  on  sulphur  and  iron  49 

VVilsrn's  direct  process 

Wing-piston  for  turning  converter  -• 350 

Wire  dies,  composition  nf  223 

Vv  ire-drawing,  in  general 220 

and 


effect   on   tensile    strength 

elastic  limit  — 
44          examples  of  general  procedure. . . 

44          resistance  in 

gauges  

|      44     manganese  steel,  strength  of 

44     strength  of  33,21. 

i  Witherow's  improved  Clapp-Gritflths  vessels — 
I  W<">hler,  as  discoverer  of  exaltation  of  clusucliiiiii 

41        b..ra  broken  after  his  method 

Wootz 

,  Worm  for  turning  Bessemer  vessel  

Work,  effect  of 

4'       quantitative  effect   of,  on   properties  of 

iron 

rationale  of  its  effect 

Wrightson  on  dilatation 


215 


YATES'  DIRECT  PROCESS. 


ZINC  AND  IRON 

Zweimalschmelzerei  process. 


213 
191 
87 
350 
212 

245 
246 

257 

281 
84 


ADVERTISERS'     INDEX 


Archer,  J.  B.  . 

Books,  Scientific  and  Technical  xii 

Brown  Hoisting  and  Conveying  Machine  Co    -  x 

Chester  Steel  Castings  Co.                                                               -  vii 

D.  Frisbie  Co.  x 

Engineering  and  Mining  Journal  iii 

Everette,  Dr.  Willis  E.  ix 

Ford,  David  M.  ix 

Gordon,  Strobel  &  Laureau,  Ltd.                                              -  v 

Hanna,  M.  A.  &  Co.  vii 

Ingersoll-Sergeant  Rock  Drill  Co.  ii 

Jeffrey  Manufacturing  Co.                                                                                        -  ix 

Kennedy,  Julian  -  xi 

Ledoux  &  Co.                                                                                                 -  xi 

Magnolia  Anti-Friction  Metal  Co.  i 

Norwalk  Iron  Works  Co.  x 

Queen  &  Co.  vii 

Rand  Drill  Co.  iv 

Riverside  Iron  Works       -  ix 

Roth  well,  Richard  P.                                                                                                -  xi 

Scaife  Foundry  and  Machine  Co.  Ltd.  vi 

Scaife,  Wm.  B.  &  Sons           -    .  vi 

Taylor  Gas  Producer  Co.  x 

Troemner,   Henry       -  vii 

Wedding's  Basic  Bessemer  Process  vii 

Wherewithal  Co.  vii 

Wyatt,  Dr.  Francis  xi 


ADVERTISEMENTS. 


]\Iagnolia    .Anti-friction    JVIetal. 

PROF.  H.  G.  TORREY  recently  made  an  extended  series  of  tests  to  ascertain  the  qualities  of  the  best  known  anti-friction  metals  under 

the  severest  conditions.      In   each  case  in  the  final  test  the  best  oil   was  used   as  a  lubricant,  extreme  care  was 

exercised  in  fitting  the  bearings  and  journals,  and  an  accurate  record  was  taken  as  the  test  progressed. 

Diameter  of  Shaft,   5   inches.  Velocity  o(   Rubbing  Surface   per  minute,   2,083  feet   for  all   the   metals. 

Revolutions  of  Shaft  per  minute,   1,600,  for  all  the  metals. 

The  four  results  shown  below  indicate  very  clearly  that  MAGNOLIA  A NTI- FRICTION  METAL,  under  much  more  secere  ana 
longer  tests  than  the  other  three,  sustained  its  reputation  as  the  best  in  the  world. 

WILLIAM  A.  WINDSOR,  Chief  Eng.,  U.  S.  N.,  and  F.  C.  BOWERS,  Asst.  Eng.,  U.  S.  N.,  declared  MAGNOLIA  METAL  to  be  four 
times  as  good  as  Standard  Metal  of  United  States  and  English  Navies,  and  recommended  its  use  by  the  Government. 


POST'S    ZERO    METAL. 

Ran  ten  minutes  with  1,200  pounds  per  square  inch  with  this  result. 


MAGNOLIA  METAL 


Ran  fifty   minutes  with   1,200  pounds  per  square  inch 

then  twenty-five  minutes  with   1,425  pounds  per 

square    inch,    with    this    result. 


HOYT'S    GENUINEIflBABBlTT. 

Ran  five  minutes  -with  1,000  pounds  per  square  inch  with  this  result. 


Mem.  Am.  Soc.  of  Mech.  Engrs,  and  Assayer  at  U.  S.  Mint,  N.  Y.,for  the  last  30  years. 


Assistant. 

DEOXIDIZED  GENUINE  BABBITT. 

Ran  fifteen  minutes  with  1,000  pounds  per  square  inch  with  this  result. 

MAGNOLIA    ANTI-FRICTION    METAL    CO., 

NEW    YORK    OFFICE  :     74    CORTLANDT    STREET.  CHICAGO    OFFICE  :     41     TRADER! 

LONDON    OFFICE:     75    QUEEN    VICTORIA     STREET.  BERLIN    OFFICE:     14    PTJTTKAMER    STRASSE. 


ADVERTISEMENTS. 


n 


FACTS   OF   RECORD. 

Ingersoll  Rock  Drills,  Air  Compressors  and  General  Mining  Machinery 

Have  been  USED  IN  EVERY  STATE  IN  THE  UNION  and  in  NEARLY  EVERY  COUNTRY  ON  THE  GLOBE.  The 
position  of  the  INGERSOLL  Drill  has  been  thoroughly  established  by  a  RECORD  OF  TWENTY  YEARS,  during  which  time, 
in  its  successive  stages  of  improvement,  it  has  been  ADOPTED  IN  EVERY  TUNNEL  OF  MAGNITUDE  FROM  THE  SUTRO 
TO  THE  NEW  YORK  AQUEDUCT  and  in  such  mines  as  the  COMSTOCK,  ANACONDA,  REPUBLIC  and  EL  CALLAO. 


INGERSOLL  DRILLS  AT  WORK  IN  THE  NEW  YORK  AQUEDUCT  TUNNEL. 

THE  SERGEANT   DRILL  is  eminently  a  drill  for  Hard  Rock — largely  used  in  the  Lake  Superior  Iron  Mines,  of  which  we 
name  the  Tamarack,  Lake  Angeline  and  Lumberman's  Mine.     It  is  fast  becoming  the  favorite  drill  for  mining  work. 

The  SERGEANT    Drill  is  the  result  of   the  experience  of  20  years  in  designing  and  operating  mining  machinery,  and  is  ex- 
tremely economicalin  repairs. 

One  of  its  most  important  features  is  the  combined  independent,  valve  operated  by   an  auxiliary  valve, 
containing  a  release  rotation  which  distinguishes  the  SERGEANT  from  other  Rock  Drills. 

The  experience  of  the  past  4  years   with   this  drill    has  conclusively  proved  that  it  is  not  only  remark- 
ably efficient  in   cutting  capacity,    but   that  it  does   its  work  after  years  of  use   equally 
as  well  as  when  new,  and,  like  the  INGERSOLL  Drill,  it  strikes  an  uncushioned  blow. 
It  has  a  perfect  valve  motion,  which  g'ves  the  full  value  of  the  steam  or  air  press- 
ure to  the   blow,  giving  the  greatest   economy  in  the  amount  of  steam  or  air  used. 

THE  SERGEANT  COAL  MINING  MACHINE.— Designed  with  a  special  view 

to  simplicity  of  parts  and  for 
the  use  of  compressed  air,  hav- 
ing a  novel  self-acting  feature 
in  a  duplex  balanced  valve 
movement,  with  variable 
stroke,  thoroughly  under  the 
control  of  the  operator. 

THE   SERGEANT  COAL  CUTTER. 

10,000  INGERSOLL  DRILLS  HAVE  BEEN  MADE  AND  SOLD  TO  DATE. 

COAL  MINING  MACHINERY 

AND 

Complete  Plaits  of  Minim  Tunneling  anfl  Quarrying  Machinery. 

INGERSOLL-SERGEANT  ROCK  DRILL  CO., 

NO.    1O    F-A/RK   PLACE,   NEW  YOEK. 


Ill 


ADVERTISEMENTS. 


RICHARD  P.  ROTHWELL,  C.E.,  M.E.,  Editor. 


ROSSITER  W.    RAYMOND,  Ph.D  ,  M.E.,  Special  Contributor. 


The  latest  and  best  of  every- 
thing of  interest  and  value  in 
general  engineering,  in  mining 
and  metallurgy  presented  in 
attractive  form,  from  the  best 
and  most  reliable  sources.  The 
JOURNAL  has  special  corre- 
spondents all  over  the  world. 

Illustrated  articles  on  engi- 
neering inventions,  scientific 
discoveries,  mechanical  appli- 
ances and  everything  of  interest 
and  practical  value.  The  illus- 
trations are  the  work  of  lead- 
ing artists,  reproduced  by  the 
best  processes. 

What  inventors  are  doing  all 
over  the  world. 

Accurate  coal,  iron,  metal, 
chemical  and  building  material 
market  and  stock  reports  from 
all  parts  of  the  country;  also 
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relating  to  imports  and  exports 
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The  ENGINEERING  AND  MINING  JOURNAL,  which  is  now 
completing  its  twenty-fifth  year,  holds  a  unique  position  in 
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The  course  it  has  laid  out  and  steadfastly  pursued  has 
earned  for  it  the  respect  and  support  of  the  best  elements  in 
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The  entire  absence  of  sensationalism,  the  absolute  reli- 
ance on  the  contents  of  its  pages,  the  independence  and  fear- 
lessness of  its  editorial  opinions,  its  truthfulness  and  accuracy 
in  the  treatment  of  scientific  and  technical  and  financial  sub- 
jects, and  the  admitted  fact  that  it  is  never  influenced  by  fear 
or  favor,  have  secured  for  it  during  a  quarter  of  a  century 
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ing Company  on  its  achievement. 

In  the  fulfillment  of  its  duty  to  its  thousands  of  old,  as 
well  as  to  the  constantly  increasing  number  of  new  supporters, 
the  ENGINEERING  AND  MINING  JOURNAL  will  commence  its 
second  quarter  of  a  century  with  a  strict  adherence  to  those 
principles  and  practices  which  have  made  its  past  career  so 
successful. 

The  ENGINEERING  AND  MINING  JOURNAL  is  universally 
pronounced  "  The  best  mining  paper  in  the  world."  It 
reaches  the  largest  manufacturers,  contractors  and  consumers, 
the  engineering,  mining  and  metallurgical  experts,  and  all  con- 
cerned in  scientific  and  engineering  work.  It  is  a  reliable 
authority  and  guide. 


ADVERTISING. 


In  no  other  publication  can 
advertisers  reach  the  varied  in- 
terests represented  by  the  EN- 
GINEERING AND  MINING  JOUR- 
NAL. Many  of  our  most  suc- 
cessful manufacturers  have  ad- 
vertised in  its  columns  continu- 
ously for  from  15  to  25  years. 
This  is  a  tact  more  eloquent 
than  any  words. 

Advertisers  are  well  satisfied 
with  the  returns  on  their  in- 
vestments, and  continue  to  use 
the  pages  of  the  ENGINEERING 
AND  MINING  JOURNAL. 

"  We  are  perfectly  satisfied  with 
your  Engineering  and  Mining 
Journal  as  a  good  advertising 
medium." 

THE  WALKER  MFG.  Co., 
Cleveland,  O. 

"  From,  our  experience  your 
paper  is  one  of  the  best  advertis- 
ing mediums  we  are  acquainted 
with." 

THE  T.  W.  HARVEY 
LUMBER  Co., 

Chicago,  III. 

"  I  am    advocating  extensive 
advertisement    in    the   Journal, 
from  which  we  have  already  ob 
tained  a  great  deal  of  good." 
CHAS.  CATLETT, 

Hale  Pavement  Co., 
Staunton,  Va. 


The  monthly  Export  Edition  of   the  ENGINEERING    AND    MINING  JOURNAL  is  acknowledged  to  be  the  most  profitable  medium 

in  America  for  reaching  buyers,  agents,  shippers  and  consumers  in  all  the  markets  of  the  world.      Its  columns 

offer  special  facilities  to  those  who  are  establishing  an  exporting  business. 


SUBSCRIPTION,    INCLUDING   POSTAGE; 


Weekly  Edition  (which  includes  the  Export  Edition),  for  the  United 
States,  Mexico  and  Canada,  $4  per  annum;  $2.25  for  six  months;  all  other 
countries  in  the  postal  union,  $5.00. 

Monthly  Export  Edition,  all  countries,  $2.50  gold  value  per  annum. 


Remittances  should  always  be  made  by  Bank  Drafts,  Post  Office  Orders 
or  Express  Money  Orders  on  New  York,  payable  to  the  Scientific  Publishing 
Company.  All  payments  must  be  made  m  advance. 


THE    SCIENTIFIC    PUBLISHING    COMPANY, 


PUBLISHERS    AND    BOOKSELLERS, 


R.  P.  ROTHWELL,  PRESIDENT  AND  GENERAL  MANAGER. 
SOPHIA  BRAEUNLICH,  SECRETARY  AND  TREASURER. 


27  PARK  PLACE,  NEW  YORK. 


ADVERTISEMENTS.  iv 


RAND    ROCK    DRILLS 


AIR   COMPRESSORS. 

THE   STANDARD  AMERICAN    ROCK    DRILLING 

AND    AIR    COMPRESSING  MACHINERY. 


Used  Practically  to  the  Exclusion  of  all  Others  in  the  Mining  Regions. 


OF  THE  MACHINE-MINED  MINERAL  IN  THE  UNITED  STATES  FOR  1889 

EIGHTY   PER  CENT.  OF  THE  COPPER  AND  IRON  ORES 


-WAS   MINED  WITH- 


RAND    DRILLS. 

The  Reason  for  this  is  that   these  mines  are  Permanent  Institutions  and   must   use   the 
Machines  that  consume  the  least  compressed.  Air  while  doing  the  Most  Work. 


A  NOTABLE:  KACT 

IS   THAI  IN  MOST  OF  THESE  MINES  THE  WORK  IS  DONE  BY  THE  MINERS  ON  CONTRACi 

They  have  become  equally  important  of  late  vears  in  the  silver  mines  of  Colorado, 

Utah,  Montana,  a,nd  the  West  in  general. 

OUR    COMPRESSORS    DELIVER    DRY   AIR. 


WE  HAVE  PATTERNS  FROM  6  IN.  X  9  IN.  TO  36  IN.    X   60    IN. 

Straight    Line    and    Duplex,    Slide    Valve    and 

Corliss     Patterns. 


SINGLE,  COMPOUND,   CONDENSING  AND  NON-CONDENSING. 


j    CO., 


23   PA.RK   PLACE,   NEW   YOKK,   U.   S. 


ADVERTISEMElSrTS. 


ON,  STROBEL  &  LAIEAD,  Llitti, 


Works  and  Main  Office,  -  -  Mifflin  and  Meadow  Streets,  Philadelphia,  Pa. 

BLAST  FURNACES  AND  EQUIPMENT. 

Bessemer  and  Open  Hearth  Steel  Plants, 


Cor/iss  and  Poppett  Valves, 

Blowing  Engines, 
Feed    Water    Heaters, 

Snort    Valves, 
Gas  Cut-Off  Valves. 


Hydraulic 

Cranes, 

Ingot  Pushers, 

Accumulators, 
Hydraulic    Cars, 
Ladles. 


, 
••-      -*  ••••••- •- ' •' 


Centra/  and  Outside  Combus- 
tion Chamber, 

Fire   Brick 
Hot  Blast    Stoves, 

Tuyere   Stocks, 

Bell  and    Hoppers, 

Gas  Burners. 


Converters, 

Cupolas, 
Gas  Producers, 


Reversing 


Valves. 


BRANCH j  [OFFICES : 

DREXEL    BUILDING,    PHILADELPHIA,    PA.  45    BROADWAY,    NEW    YORK. 

PENN  BUILDING,    PITTSBURGH,    PA. 


ADVEETISEMENTS. 


FOUBY  &  MACHINE  CO.,  Lift 

'  i 


Twenty-eighth    and    Smallman    Sts.,    Pittsburgh,    fa.,    U.  S.  A-» 

ENGINEERS    AND    BUILDERS    OF    MACHINERY    FOR 

Rolling  Mills,  Blast   Furnaces,   Bessemer  and  Open-Hearth  Steel  Plants  and 

Inclined    Planes. 


IMPROVED  HYDRAULIC  AND   OTHER    CRANES, 

Stock  Hoists,  Accumulators,  Roll  Lathes, 

COLD    SAWS,    HOT   SAWS,  and   Special    Labor-Saving  Machines. 


SOLE     MAKERS     OF     THE 


DIESCHER     PATENT     COAL-WASHER, 

And  Builders  of  Coal- Washing  Plants  for  Improving  Coal  and  Coke. 

WM.  B.  SCAIFE  &  SONS, 

ESTABLISHED    18O2. 
Office:     7/9     FIRST    AVPNUE,     PITTSBURGH,     PA.,     U.  S.  A. 

Design,  Manufacture  and  Erect 

Iron  Buildings  and  Roof  Frames 


For  Iron  and  Steel  Plants  and  other  Manufacturing1  Purposes. 


CORRUGATED    IRON   FOR   ROOFING   AND   SIDING. 


CALDWELL   PATENT   SPIRAL  CONVEYOR 

For  Coal,  Ashes,  Grain,  Sand,  Tanbark,  Cotton  Seed,  Concrete  Mixers,  etc. 


SCAIFE  SEAMLESS  STEEL  ELEVATOR  BUCKETS. 

SHEET    A/ND    PI^TE    IRON 

For  Rolling  Mills,  Steel  Plants,  Casting  Houses,   etc. 


Vll 


ADVERTISEMENTS. 


An    Intellectual    Tool. 


'S 


A  two-page  book,  5J4  X  8!4  inches  Cloth  and  silicate.  Seven  words.  Six 
topical  tests,  showing  how  it  makes  us  think.  Price  $1.00  to  any  address. 

Scientific  American  says  of  it:  "  There  is  a  great  deal  in  the  method."  You  may 
know  all  about  mechanical  tools,  but  this  excels  them  all. 

A  recent  purchaser  of  a  copy  on  re-ordering  says  it  is  worth  $1,000. 

WHEREWITHAL  COMPANY, 


BTJILTDI3STG-., 
BROAD  AND  CHESTNUT   STS.,   PHILADELPHIA,   PA. 


Chemicals  and  Apparatus 


FOR  THE  ANALYSIS   OF 


IRON,  STEEL,  GASES,  Etc. 

Specialties: 

Bohemian  and  German  Glassware, 

Analytical   Balances  and   Weights, 
Royal  Berlin,  Royal   Meissen  and 

Thuringian   Porcelain. 
Platinum   Goods,    Bunsen    Burners. 

Strictly  C.   P.  Acids  and  Chemicals. 

Our  Catalogue  Contains  3O**  rages. 

QJJEEN   &  CO.,  PHILADELPHIA. 


STEEL    CASTINGS. 

From  1-4  to  15,000  Pounds  Weight. 

True  to  pattern,  sound,  solid,  free  from  blow-holes,  and  of 
unequaled  strength.  Stronger  and  more  durable  than  iron  forg- 
ings  in  any  position  or  for  any  service  whatever. 

Fifty  thousand  CRANK  SHAFTS  and  forty  thousand  GEAR 
WHEELS  of  this  steel  now  .running  prove  this. 

STEEL    CASTINGS    for    Stamp    Mills   and   other   Mining 
Machinery  a  specialty. 

STEEL  CASTINGS  of  every  description. 

Send   for  Circulars  and   Prices  to 

CHESTER  STEEL  CASTINGS  COMPANY, 

WORKS  :    CHESTER,.     E»jV. 

Office :  407   Library  Street,  Philadelphia,  Pa. 


o 

0, 

HENRY 

TROEMNER, 

710  Market  St., 
PHILADELPHIA, 

MAKER  OF 

FINE  BALANCES  AND 
WEIGHTS 

For   Iron    Works,    Steel 

Works  and  Chemical 

Laboratories. 

Price-list  on  application. 

Our  balances  are  in  use  at  all 
the  mints  and  assay  offices  of 
the  U.  S.  Government. 


M.  A.  HANNA  &  CO. 

Sales     Agents, 

Lake  Superior  Iron   Ores, 
Bessemer, 

Crescent,     Millie, 

Aragon,    Hennepin,    Ingalls, 

Trezona,     Ruby, 
Non-Bessemer, 

Chapin, 

Winthrop,     Mitchell, 

Buffalo,    South     Buffalo, 
B.    B., 

Norway 

IRON  ORES, 

,    O. 


NOW     IN     PRESS. 


WEDDING'S 

Basic   Bessemer  Process, 


TRANSLATED    FROM    THE    GERMAN,    WITH 
PERMISSION    OF    THE    AUTHOR. 


BY 


1890. 


WM.  B.   PHILLIPS,   Ph.  D., 

Late  Professor  of  Mining  and  Metallurgy  in  the  University 
of  North  Carolina,  Chapel  Hill,  N.  C., 


AND 


ERNST  PROCHASKA,  Met.  E., 

Late  Engineer  at  the  Basic  Steel  Works,  Teplitz,  Bohemia,  and  at  the  works  of  the 
Pottstown  Iron  Company,  Pottstown,  Pa. 


PUBLISHED    BY 


The  {Scientific  publishing  Co., 

PUBLISHERS    AND    BOOKSELLERS, 

27    PARK    PLACE,    NEW    YORK. 


ADVERTISEMENTS. 


viii 


ARCHER  GAS-FUEL  PROCESS 


This  Process  solves  the  Problem  of  cheap  Gaseous  Fuel, 
meeting  every  requirement  of  Natural  Gas,  as  to  EFFI- 
CIENCY and  ECONOMY.  It  has  been  in  successful  opera- 
tion on  a  large  scale,  from  3  to  31  months,  in  many  of  the 
largest  Iron,  Steel,  Glass,  Pipe,  Copper  Works  ;  Agate  and 
Granite  Ware  Works;  Iron  Ship  Yards,  and  other  manufactur- 
ing establishments  in  the  United  States.  i^f"  IT  IS  THE 
ONLY  PRACTICALLY  RUNNING  AND  COMMER- 
CIALLY SUCCESSFUL  WATER  OIL-GAS  SYSTEM 
IN  THE  WORLD., 


We  invite  manufacturers  and  all  users  of  fuel  to  the  most 
rigid  examination  into  the  practical  working  of  the  ARCHER 
GAS-FUEL  SYSTEM.  This  Process  is  applicable  for  all 
uses,  from  a  RIVET  and  BOLT  HEAD  furnace  to  the  largest 
OPEN-HEARTH  Melting  and  Heating  Furnaces ;  also  for 
Steam  Boilers,  burning  Brick,  Lime,  Cement,  Pottery-tile, 
etc.  It  is  ABSOLUTELY  SAFE.  But  one  man  required 
on  turn  to  furnish  fuel  for  the  largest  Iron  and  Steel  Works. 

Lima  or  other  crude  oil  used. 


THIS    PROCESS    HAS    BEEN    RUNNING    CONSTANTLY    FOR    OVER 


31  months  on  a  large  scale  In  the 

Bethlehem  (Pa.)  Iron  Co.  Works. 

•  For  over  24  months  in  the 

Penna.  Steel  Co.  Works,  Steelton,  Pa. 

For  over  20  months  in  the 

Cleveland  Rolling  Mill,  Cleveland,  Ohio. 

For  over  22  months  in  the 

Allison  Mlg.  Co.  Pipe  Works,  Philadelphia. 

For  over  20  months  in  the 

Oliver  Iron  (Chilled  Plow)   Works,    South   Bend,   Intl.— Running 
Boilers,  Heating,  Welding,  Malleable  Iron  Annealing  Furnaces 
etc.,  etc. 
For  over  14  months  in  the 

Otis  &  Co.  Steel  Works,  Cleveland,  Ohio. 

For  over  20  months  in  the 

Detroit  (Mich.)  Steel  and  Spring  Works. 

For  over  18  months  in  the 

Burden  (Horseshoe)  Iron  Co.  Works,  Troy,  N.  Y. 

For  over  16  months  in  the 

Illingworth  Co.  Steel  Works,  Newark,  N.  J. 

For  over  10  months  in  the 

Lincoln  Iron  Co,  Works,  Boonton,  Jf.  J 


For  over  10  months  in  the 

Albertson  Glass  Works,  Norristown,  Pa. 

For  over  9  months  in  the 

Illinois  Steel  Co.  (Joliet  Works). 

For  over  6  months  in  the 

Brookfield  Glass  Works,  Brooklyn. 

For  over  7  months  in  the 

Iron  Ship  Yard,  West  Bay  City,  Michigan. 

For  over  6  months  in  the 

Lalance  &  Grosjean  Agate  Ware  Works,  Woodhaven,  L.  I. 

For  over  6  months  in  the 

Iowa  Barb  Wire  Works,  Allentown,  Pa. 

For  over  8  months  in  the 

Johnson  Co.  Steel  Works,  Johnstown,  Pa.,  superseding  Natural 

Gas,  also  for  House  Heating  and  Illumination. 
F.  W.  Wurster  &  Co.  Iron  Works,  Brooklyn,  N.  Y. 
Heberman's  Granite  Waie  Works,   Brooklyn,  If.  Y. 
Pencoyd  Iron  and  Steel  Works,  Pencoyd,  Pa. 
Pennsylvania  Salt  Mfg.  Co.,  Natrona,  Pa. 
Cooper,  Hewitt  &  Co.'s  Trenton  (ST.  J.)  Iron  Works. 


And  in  many  other  first-class  Manufacturing  establishments,  while  neu,  Plants  are  beivg  contracted  for  throughout  the  Country. 

VST  We  are  manufacturing  the  Archer  Gas-Fuel  Proiucers^^ge^le^actories,  and  are  prepared  to  fill  all  orders  at  short  notice,  and 
furnish  competent  Superintendents  to  erect  Plants  and  apply  the  gas. 

For    Domestic    Fuel    and    for    Illuminating    Cas 


-d  «„  . 


FOR     FURTHER     INFORMATION     CALL    ON     OR    ADDRESS 

J.     B.    ARCHE^R,    45    Broadway,    New    York:. 


ix 


ADVERTISEMENTS. 


Attention     Miners  ! 


EVERETTE'S  MINING  OFFICE. 

Pioneer    Mining    and    Assay    Office  of 
Pacific    North-west. 

Having  the  largest  permanent  brick  assay  furnaces,  chemical  labora- 
tory and  mining  office  on  the  Northwest  coast,  with  a  collection  of 
about  4,000  samples  of  the  ores  of  Alaska,  British  Columbia,  Oregon 
and  the  Northwest  Territories,  and  having  made  personal  examinations 
of  nearly  every  mining  camp  on  the  Pacific  Slope,  from  California  to 
Alaska,  I  am  prepared  to  do  any  class  of  legitimate  and  honest  min- 
ing work,  such  as 

Examining,  Sampling  and  Reporting  on  the  Value  of  all 

Mineral,  Coal  and  Fire  Clay  Properties,  Building 

Stones,  Earths,  Assays  and   Analysis  of 

Ores,  Check,   Samples  of  Ore, 

Pulp  "Organic  Analysis"  work,  and,  in  fact,  any  work  connected  with 
*he  office  of  a  first-clays  mining  geologist  and  chemist.  Any  information 
mining  men  may  desire  to  know  relative  to  the  MINERAL  OR  COAL 
RESOURCES  of  the  entire  Pacific  northwest  will  be  honestly  given. 


-ADDRESS- 


DR.  WILLIS  E.  EVERETTE, 


1318    E 

TACOMA,    WASH.    TER.,   U.    S.    A. 


JEFFREY 

ELECTRIC  COAL  MINING 

MACHINES,  DRILLS  AND  MOIOR  CARS 

FOR  UNDERCUTTING,  DRILLING  AND  MINE  HAULAGE. 

ALSO  AIE  POWEE  COAL  MINING  MACHINES  AND  DEILLS. 


DAVID    M.    FORD, 


ISHPEMING.    L    S.,   MICH. 


DEALER     IN 


,  tat  Copper 


THE  RICHEST  MINES  IN  THE  WORLD." 


THE  LARGEST  DIVIDEND  PAYERS.1 


CORRESPONDENCE    SOLICITED. 


Mining  properties  examined,  estimates  made,  and  machines  furnished 
subject  to  sale  after  having  worked  on  the  basis  of  the  estimate. 


Send  for 
Illustrated 
Catalogue, 


Correspondence 
Solicited. 


-ALSO  MANUFACTURE- 


Chain    Elevators,   Conveyers,    Screens,    Etc., 

FOR  HANDLING  COAL,  OKES,  GRAIN,  ETC'.,  ETC. 


-AJDDIRESS 


THE  JEFFREY  MFG.  CO., 


COLUMBUS,    OHIO. 


RIVERSIDE  IRON  WORKS, 


WHEELING,  W.  VA , 

MANUFACTURERS  OF 


Bessemer, 
Foundry 
And  Forge 


Steel  Pipe, 

FOR  WK  TER.  OIL  &  GAS. 


PIG  IRON. 


Steel  Blooms, 
Steel  Billets. 


SMALL  STEEL  T  HAILS 
AND  FLAT  RAILS. 


PLATE 

AND  BAR 

STEEL 


ADVERTISEMENTS. 


\ 


07er  4,000.000  Tons  of  Iron  Ore  and  1.000,000  Tons  of  Coal 
Were  Handled  in  1889  by 

THE   BROWN   HOISTS." 


THE    BROWN    HOISTING    AND    CONVEYING    MACHINE   :CO,,  Cleveland,  Ohio,  U.  S.  A, 

's''t.  and  Mgr.  SOLE  MANUFACTURERS  UNDER  THK  BROWN  PATENTS.     | 


H.  H.  HltoWN.  Treasurer. 
E.  T.  Scoviu,,  Secretary. 


ELEVATORS 


AND 


FRICTION    PULLEYS. 


THE    D.   FRISBIE    COMPANY, 


WORKS,    NEW    HAVEN,    CONN. 


OFFICE,    112    LIBERTY    ST.,    NEW    YORK. 


THE  TAYLOR  REVOLVING-BOTTOM  GAS  PRODUCER. 

PATENTED  MARCH  19,  1889,  and  MAY  20,  1890. 

Nos.  399,793,   399,79-4,  899,795,  399,796,  399,797,  399,798,  399,799,   428,'J37 

and  in  all  foreign  Countries, 


The  best   Producer  for  either  Bituminous  or  Anthracite  Coal  or  Lignite.    Applicable  to  all  regenerative    furnaces;    also    for    gas- 
firing  Lime,  Brick  and  Pottery  Kilns,  Sugar-home  Char  Kilns,  Boilers  etc.    Also  Producer  Gas  for  Gas  Engines. 


For  illustrated    descriptive    pamphlet  and  all  particulars  address 


TAYLOR    GAS    PRODUCER    CO., 

Brown  Building,  Fourth  and  Chestnut  Sts.,  Philadelphia.  Pa. 


THE 


Honrali  Iron  forks  Co, 

SOUTH    NORWALK,    CONN. 


XI 


ADVERTISEMENTS. 


JULIAN"  KENNEDY, 


RICHARD  P.  ROTH  WELL, 


ing  and  Contracting  Engineer.  Civil  and  Mining  Engineer, 


HAMILTON    BDILDIM,    PITTSBURGH,    PA. 

Blast   Furnaces,  Bessemer  and  Open 

Hearth     Steel     Works, 

Rolling   Mills. 

STEAM  AND  HYDRAULIC  MACHINERY,  ETC. 

LEDOUX  &  CO., 

Chemists  and  Assayers, 

r 

Office  and  Laboratories,  No.  9  Cliff  Street. 
Sampling  Works,  Bergen  Junction,   N.  J.  (Jersey  City). 


Assay  and    Analyze    Ores,    Fluxes,    Iron, 
Steel   and    other   metals. 

SPECIAL    CONTRACTS 

By    the     year    with    Mines,     Furnaces, 
Rolling    Mills,    Etc. 

SEND  FOR  LIST  OF  PRICES  AND  TERMS. 


EDITOR    OF 


THE  ENGINEERING  AND  MINING  JOORNAL, 

NEW    YORK. 

Examines  and  Reports  on  Mineral  Properties.  Advises 

on  the  Working  and   Management  of  Mines. 

Acts  as    Consulting    Engineer 

to  Companies 


ADVERTISEMENTS.  xii 


THE   SCIENTIFIC   PUBLISHING   COMPANY, 


PUBL1SHKKS    OF    THE    FOLLOWING    STANDARD    BOOKS: 


The  Metallurgy  of  Steel, 

By  HENRY  MARION  HOWE.     Illustrated Trice,  $10.00 

Weddings'  Basic  Bessemer  Process. 

Translated  from   the  German,  with    permission   of  the  author,  by  WILLIAM   B.   PHILLIPS 

and  ERNST  PROCHASKA Now  in  Press. 

Gems  and  Precious  Stones  of  North  America. 

By  GEORGE  FREDERICK  KUNZ.     Illustrated  with  Eight  Colored  Plates  and  numerous 

Engravings Price,  $10.00 

Modern  American  Methods  of  Copper  Smelting. 

By  EDWARD  D.  PETERS,  Jr.     Illustrated.     Second  Edition  in  Press Price,  $4.00 

Copper  Smelting,  its  History  and  Processes. 

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The  Lixiviation  of  Silver  Ores. 

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Mining  Accidents  and  Their  Prevention. 

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The  Mining  Code  of  the  Republic  of  Mexico 

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Chemical  and  Geological  Essays. 

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Mineral  Physiology  and  Physiography. 

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A  New  Basis  for  Chemistry. 

By  Dr.  T.  STERRY  HUNT Price,  $2.00 

Systematic  Mineralogy,  Based  on  a  Natural  Classification. 

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